Compact all-fiber optical Faraday components using 65-wt%-terbium-doped fiber with a record Verdet constant of -32 rad/(Tm).

PubMed

Sun, L; Jiang, S; Marciante, J R

2010-06-07

A compact all-fiber Faraday isolator and a Faraday mirror are demonstrated. At the core of each of these components is an all-fiber Faraday rotator made of a 4-cm-long, 65-wt%-terbium-doped silicate fiber. The effective Verdet constant of the terbium-doped fiber is measured to be -32 rad/(Tm), which is 27 x larger than that of silica fiber. This effective Verdet constant is the largest value measured to date in any fiber and is 83% of the Verdet constant of commercially available crystal used in bulk optics-based isolators. Combining the all-fiber Faraday rotator with fiber polarizers results in a fully fusion spliced all-fiber isolator whose isolation is measured to be 19 dB. Combining the all-fiber Faraday rotator with a fiber Bragg grating results in an all-fiber Faraday mirror that rotates the polarization state of the reflected light by 88 +/- 4 degrees .

Double-clad photonic crystal fiber coupler for compact nonlinear optical microscopy imaging.

PubMed

Fu, Ling; Gu, Min

2006-05-15

A 1 x 2 double-clad photonic crystal fiber coupler is fabricated by the fused tapered method, showing a low excess loss of 1.1 dB and a splitting ratio of 97/3 over the entire visible and near-infrared wavelength range. In addition to the property of splitting the laser power, the double-clad feature of the coupler facilitates the separation of a near-infrared single-mode beam from a visible multimode beam, which is ideal for nonlinear optical microscopy imaging. In conjunction with a gradient-index lens, this coupler is used to construct a miniaturized microscope based on two-photon fluorescence and second-harmonic generation. Three-dimensional nonlinear optical images demonstrate potential applications of the coupler to compact all-fiber and nonlinear optical microscopy and endoscopy.

Compact high reliability fiber coupled laser diodes for avionics and related applications

NASA Astrophysics Data System (ADS)

Daniel, David R.; Richards, Gordon S.; Janssen, Adrian P.; Turley, Stephen E. H.; Stockton, Thomas E.

1993-04-01

This paper describes a newly developed compact high reliability fiber coupled laser diode which is capable of providing enhanced performance under extreme environmental conditions including a very wide operating temperature range. Careful choice of package materials to minimize thermal and mechanical stress, used with proven manufacturing methods, has resulted in highly stable coupling of the optical fiber pigtail to a high performance MOCVD-grown Multi-Quantum Well laser chip. Electro-optical characteristics over temperature are described together with a demonstration of device stability over a range of environmental conditions. Real time device lifetime data is also presented.

Fiber-Optic/Photoelastic Flow Sensors

NASA Technical Reports Server (NTRS)

Wesson, Laurence N.; Cabato, Nellie L.; Brooks, Edward F.

1995-01-01

Simple, rugged, lightweight transducers detect periodic vortices. Fiber-optic-coupled transducers developed to measure flows over wide dynamic ranges and over wide temperature ranges in severe environments. Used to measure flows of fuel in advanced aircraft engines. Feasibility of sensors demonstrated in tests of prototype sensor in water flowing at various temperatures and speeds. Particularly attractive for aircraft applications because optical fibers compact and make possible transmission of sensor signals at high rates with immunity from electromagnetic interference at suboptical frequencies. Sensors utilize optical-to-optical conversion via photoelastic effect.

Fiber-optic-bundle-based optical coherence tomography.

PubMed

Xie, Tuqiang; Mukai, David; Guo, Shuguang; Brenner, Matthew; Chen, Zhongping

2005-07-15

A fiber-optic-bundle-based optical coherence tomography (OCT) probe method is presented. The experimental results demonstrate this multimode optical fiber-bundle-based OCT system can achieve a lateral resolution of 12 microm and an axial resolution of 10 microm with a superluminescent diode source. This novel OCT imaging approach eliminates any moving parts in the probe and has a primary advantage for use in extremely compact and safe OCT endoscopes for imaging internal organs and great potential to be combined with confocal endoscopic microscopy.

Fiber-based Coherent Lidar for Target Ranging, Velocimetry, and Atmospheric Wind Sensing

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Pierrottet, Diego

2006-01-01

By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable lidar suitable for operation in a space environment is being developed.

High-Sensitivity Fiber-Optic Ultrasound Sensors for Medical Imaging Applications

PubMed Central

Wen, H.; Wiesler, D.G.; Tveten, A.; Danver, B.; Dandridge, A.

2010-01-01

This paper presents several designs of high-sensitivity, compact fiber-optic ultrasound sensors that may be used for medical imaging applications. These sensors translate ultrasonic pulses into strains in single-mode optical fibers, which are measured with fiber-based laser interferometers at high precision. The sensors are simpler and less expensive to make than piezoelectric sensors, and are not susceptible to electromagnetic interference. It is possible to make focal sensors with these designs, and several schemes are discussed. Because of the minimum bending radius of optical fibers, the designs are suitable for single element sensors rather than for arrays. PMID:9691368

Fiber optic in vivo imaging in the mammalian nervous system

PubMed Central

Mehta, Amit D; Jung, Juergen C; Flusberg, Benjamin A; Schnitzer, Mark J

2010-01-01

The compact size, mechanical flexibility, and growing functionality of optical fiber and fiber optic devices are enabling several new modalities for imaging the mammalian nervous system in vivo. Fluorescence microendoscopy is a minimally invasive fiber modality that provides cellular resolution in deep brain areas. Diffuse optical tomography is a non-invasive modality that uses assemblies of fiber optic emitters and detectors on the cranium for volumetric imaging of brain activation. Optical coherence tomography is a sensitive interferometric imaging technique that can be implemented in a variety of fiber based formats and that might allow intrinsic optical detection of brain activity at a high resolution. Miniaturized fiber optic microscopy permits cellular level imaging in the brains of behaving animals. Together, these modalities will enable new uses of imaging in the intact nervous system for both research and clinical applications. PMID:15464896

A new fiber-optic non-contact compact laser-ultrasound scanner for fast non-destructive testing and evaluation of aircraft composites

PubMed Central

Pelivanov, Ivan; Buma, Takashi; Xia, Jinjun; Wei, Chen-Wei; O'Donnell, Matthew

2014-01-01

Laser ultrasonic (LU) inspection represents an attractive, non-contact method to evaluate composite materials. Current non-contact systems, however, have relatively low sensitivity compared to contact piezoelectric detection. They are also difficult to adjust, very expensive, and strongly influenced by environmental noise. Here, we demonstrate that most of these drawbacks can be eliminated by combining a new generation of compact, inexpensive fiber lasers with new developments in fiber telecommunication optics and an optimally designed balanced probe scheme. In particular, a new type of a balanced fiber-optic Sagnac interferometer is presented as part of an all-optical LU pump-probe system for non-destructive testing and evaluation of aircraft composites. The performance of the LU system is demonstrated on a composite sample with known defects. Wide-band ultrasound probe signals are generated directly at the sample surface with a pulsed fiber laser delivering nanosecond laser pulses at a repetition rate up to 76 kHz rate with a pulse energy of 0.6 mJ. A balanced fiber-optic Sagnac interferometer is employed to detect pressure signals at the same point on the composite surface. A- and B-scans obtained with the Sagnac interferometer are compared to those made with a contact wide-band polyvinylidene fluoride transducer. PMID:24737921

A liquid lens switching-based motionless variable fiber-optic delay line

NASA Astrophysics Data System (ADS)

Khwaja, Tariq Shamim; Reza, Syed Azer; Sheikh, Mumtaz

2018-05-01

We present a Variable Fiber-Optic Delay Line (VFODL) module capable of imparting long variable delays by switching an input optical/RF signal between Single Mode Fiber (SMF) patch cords of different lengths through a pair of Electronically Controlled Tunable Lenses (ECTLs) resulting in a polarization-independent operation. Depending on intended application, the lengths of the SMFs can be chosen accordingly to achieve the desired VFODL operation dynamic range. If so desired, the state of the input signal polarization can be preserved with the use of commercially available polarization-independent ECTLs along with polarization-maintaining SMFs (PM-SMFs), resulting in an output polarization that is identical to the input. An ECTL-based design also improves power consumption and repeatability. The delay switching mechanism is electronically-controlled, involves no bulk moving parts, and can be fully-automated. The VFODL module is compact due to the use of small optical components and SMFs that can be packaged compactly.

A Review of Multimode Interference in Tapered Optical Fibers and Related Applications.

PubMed

Wang, Pengfei; Zhao, Haiyan; Wang, Xianfan; Farrell, Gerald; Brambilla, Gilberto

2018-03-14

In recent years, tapered optical fibers (TOFs) have attracted increasing interest and developed into a range of devices used in many practical applications ranging from optical communication, sensing to optical manipulation and high-Q resonators. Compared with conventional optical fibers, TOFs possess a range of unique features, such as large evanescent field, strong optical confinement, mechanical flexibility and compactness. In this review, we critically summarize the multimode interference in TOFs and some of its applications with a focus on our research project undertaken at the Optoelectronics Research Centre of the University of Southampton in the United Kingdom.

A Review of Multimode Interference in Tapered Optical Fibers and Related Applications

PubMed Central

Wang, Pengfei; Zhao, Haiyan; Wang, Xianfan; Brambilla, Gilberto

2018-01-01

In recent years, tapered optical fibers (TOFs) have attracted increasing interest and developed into a range of devices used in many practical applications ranging from optical communication, sensing to optical manipulation and high-Q resonators. Compared with conventional optical fibers, TOFs possess a range of unique features, such as large evanescent field, strong optical confinement, mechanical flexibility and compactness. In this review, we critically summarize the multimode interference in TOFs and some of its applications with a focus on our research project undertaken at the Optoelectronics Research Centre of the University of Southampton in the United Kingdom. PMID:29538333

UV diode-pumped solid state laser for medical applications

NASA Astrophysics Data System (ADS)

Apollonov, Victor V.; Konstantinov, K. V.; Sirotkin, A. A.

1999-07-01

A compact, solid-state, high-efficiency, and safe UV laser medical system with optical fiber output was created for treatment of destructive forms of pulmonary tuberculosis. A frequency-quadruped quasi-CW Nd:YVO4 laser system pumped by laser-diode array is investigated with various resonator configurations. A longitudinal end-pumping scheme was used in a compact acousto-optical Q-switched laser for producing stable pulses of UV radiation at the repetition frequency 10-20 kHz and the duration 7-10 ns with the fiber-guide output power exceeding 10 mW.

Objective-lens-free Fiber-based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System.

PubMed

Ti, Chaoyang; Ho-Thanh, Minh-Tri; Wen, Qi; Liu, Yuxiang

2017-10-13

Position detection with high accuracy is crucial for force calibration of optical trapping systems. Most existing position detection methods require high-numerical-aperture objective lenses, which are bulky, expensive, and difficult to miniaturize. Here, we report an affordable objective-lens-free, fiber-based position detection scheme with 2 nm spatial resolution and 150 MHz bandwidth. This fiber based detection mechanism enables simultaneous trapping and force measurements in a compact fiber optical tweezers system. In addition, we achieved more reliable signal acquisition with less distortion compared with objective based position detection methods, thanks to the light guiding in optical fibers and small distance between the fiber tips and trapped particle. As a demonstration of the fiber based detection, we used the fiber optical tweezers to apply a force on a cell membrane and simultaneously measure the cellular response.

Thermo-optic characteristic of DNA thin solid film and its application as a biocompatible optical fiber temperature sensor.

PubMed

Hong, Seongjin; Jung, Woohyun; Nazari, Tavakol; Song, Sanggwon; Kim, Taeoh; Quan, Chai; Oh, Kyunghwan

2017-05-15

We report unique thermo-optical characteristics of DNA-Cetyl tri-methyl ammonium (DNA-CTMA) thin solid film with a large negative thermo-optical coefficient of -3.4×10^-4/°C in the temperature range from 20°C to 70°C without any observable thermal hysteresis. By combining this thermo-optic DNA film and fiber optic multimode interference (MMI) device, we experimentally demonstrated a highly sensitive compact temperature sensor with a large spectral shift of 0.15 nm/°C. The fiber optic MMI device was a concatenated structure with single-mode fiber (SMF)-coreless silica fiber (CSF)-single mode fiber (SMF) and the DNA-CTMA film was deposited on the CSF. The spectral shifts of the device in experiments were compared with the beam propagation method, which showed a good agreement.

Multiplex CARS imaging with spectral notch shaped laser pulses delivered by optical fibers.

PubMed

Oh, Seung Ryeol; Park, Joo Hyun; Kim, Kyung-Soo; Lee, Jae Yong; Kim, Soohyun

2017-12-11

We present an experimental demonstration of single-pulse coherent anti-Stokes Raman spectroscopy (CARS) using a spectrally shaped broadband laser that is delivered by an optical fiber to a sample at its distal end. The optical fiber consists of a fiber Bragg grating component to serve as a narrowband notch filter and a combined large-mode-area fiber to transmit such shaped ultrashort laser pulses without spectral distortion in a long distance. Experimentally, our implementation showed a capability to measure CARS spectra of various samples with molecular vibrations in the fingerprint region. Furthermore, CARS imaging of poly(methyl methacrylate) bead samples was carried out successfully under epi-CARS geometry in which backward-scattered CARS signals were collected into a multimode optical fiber. A compatibility of single-pulse CARS scheme with fiber optics, verified in this study, implies a potential for future realization of compact all-fiber CARS spectroscopic imaging systems.

Fiber Optic Microphone

NASA Technical Reports Server (NTRS)

Cho, Y. C.; George, Thomas; Norvig, Peter (Technical Monitor)

1999-01-01

Research into advanced pressure sensors using fiber-optic technology is aimed at developing compact size microphones. Fiber optic sensors are inherently immune to electromagnetic noise, and are very sensitive, light weight, and highly flexible. In FY 98, NASA researchers successfully designed and assembled a prototype fiber-optic microphone. The sensing technique employed was fiber optic Fabry-Perot interferometry. The sensing head is composed of an optical fiber terminated in a miniature ferrule with a thin, silicon-microfabricated diaphragm mounted on it. The optical fiber is a single mode fiber with a core diameter of 8 micron, with the cleaved end positioned 50 micron from the diaphragm surface. The diaphragm is made up of a 0.2 micron thick silicon nitride membrane whose inner surface is metallized with layers of 30 nm titanium, 30 nm platinum, and 0.2 micron gold for efficient reflection. The active sensing area is approximately 1.5 mm in diameter. The measured differential pressure tolerance of this diaphragm is more than 1 bar, yielding a dynamic range of more than 100 dB.

Fiber optic diffraction grating maker

DOEpatents

Deason, V.A.; Ward, M.B.

1991-05-21

A compact and portable diffraction grating maker is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent beam splitters, and collimating lenses or mirrors directing the split beam at an appropriate photosensitive material. The collimating optics, the output ends of the fiber optic coupler and the photosensitive plate holder are all mounted on an articulated framework so that the angle of intersection of the beams can be altered at will without disturbing the spatial filter, collimation or beam quality, and assuring that the beams will always intersect at the position of the plate. 4 figures.

Fiber optic diffraction grating maker

DOEpatents

Deason, Vance A.; Ward, Michael B.

1991-01-01

A compact and portable diffraction grating maker comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent beam splitters, and collimating lenses or mirrors directing the split beam at an appropriate photosensitive material. The collimating optics, the output ends of the fiber optic coupler and the photosensitive plate holder are all mounted on an articulated framework so that the angle of intersection of the beams can be altered at will without disturbing the spatial filter, collimation or beam quality, and assuring that the beams will always intersect at the position of the plate.

A novel all-fiber optic flow cytometer technology for Point-of Care and Remote Environments

NASA Astrophysics Data System (ADS)

Mermut, Ozzy

Traditional flow cytometry designs tend to be bulky systems with a complex optical-fluidic sub-system and often require trained personnel for operation. This makes them difficult to readily translate to remote site testing applications. A new compact and portable fiber-optic flow cell (FOFC) technology has been developed at INO. We designed and engineered a specialty optical fiber through which a square hole is transversally bored by laser micromachining. A capillary is fitted into that hole to flow analyte within the fiber square cross-section for detection and counting. With demonstrated performance benchmarks potentially comparable to commercial flow cytometers, our FOFC provides several advantages compared to classic free-space con-figurations, e.g., sheathless flow, low cost, reduced number of optical components, no need for alignment (occurring in the fabrication process only), ease-of-use, miniaturization, portability, and robustness. This sheathless configuration, based on a fiber optic flow module, renders this cytometer amenable to space-grade microgravity environments. We present our recent results for an all-fiber approach to achieve a miniature FOFC to translate flow cytometry from bench to a portable, point-of-care device for deployment in remote settings. Our unique fiber approach provides the capability to illuminate a large surface with a uniform intensity distri-bution, independently of the initial shape originating from the light source, and without loss of optical power. The CVs and sensitivities are measured and compared to industry benchmarks. Finally, integration of LEDs enable several advantages in cost, compactness, and wavelength availability.

Silicon wafer temperature monitoring using all-fiber laser ultrasonics

NASA Astrophysics Data System (ADS)

Alcoz, Jorge J.; Duffer, Charles E.

1998-03-01

Laser-ultrasonics is a very attractive technique for in-line process control in the semiconductor industry as it is compatible with the clean room environment and offers the capability to inspect parts at high-temperature. We describe measurements of the velocity of laser-generated Lamb waves in silicon wafers as a function of temperature using fiber- optic laser delivery and all-fiber interferometric sensing. Fundamental anti-symmetric Lamb-wave modes were generated in 5 inches < 111 > silicon wafers using a Nd:YAG laser coupled to a large-core multimode fiber. Generation was also performed using an array of sources created with a diffraction grating. For detection a compact fiber-optic sensor was used which is well suited for industrial environments as it is compact, rugged, stable, and low-cost. The wafers were heated up to 1000 degrees C and the temperature correlated with ultrasonic velocity measurements.

Maximum-performance fiber-optic irradiation with nonimaging designs.

PubMed

Fang, Y; Feuermann, D; Gordon, J M

1997-10-01

A range of practical nonimaging designs for optical fiber applications is presented. Rays emerging from a fiber over a restricted angular range (small numerical aperture) are needed to illuminate a small near-field detector at maximum radiative efficiency. These designs range from pure reflector (all-mirror), to pure dielectric (refractive and based on total internal reflection) to lens-mirror combinations. Sample designs are shown for a specific infrared fiber-optic irradiation problem of practical interest. Optical performance is checked with computer three-dimensional ray tracing. Compared with conventional imaging solutions, nonimaging units offer considerable practical advantages in compactness and ease of alignment as well as noticeably superior radiative efficiency.

Biocular vehicle display optical designs

NASA Astrophysics Data System (ADS)

Chu, H.; Carter, Tom

2012-06-01

Biocular vehicle display optics is a fast collimating lens (f / # < 0.9) that presents the image of the display at infinity to both eyes of the viewer. Each eye captures the scene independently and the brain merges the two images into one through the overlapping portions of the images. With the recent conversion from analog CRT based displays to lighter, more compact active-matrix organic light-emitting diodes (AMOLED) digital image sources, display optical designs have evolved to take advantage of the higher resolution AMOLED image sources. To maximize the field of view of the display optics and fully resolve the smaller pixels, the digital image source is pre-magnified by relay optics or a coherent taper fiber optics plate. Coherent taper fiber optics plates are used extensively to: 1. Convert plano focal planes to spherical focal planes in order to eliminate Petzval field curvature. This elimination enables faster lens speed and/or larger field of view of eye pieces, display optics. 2. Provide pre-magnification to lighten the work load of the optics to further increase the numerical aperture and/or field of view. 3. Improve light flux collection efficiency and field of view by collecting all the light emitted by the image source and guiding imaging light bundles toward the lens aperture stop. 4. Reduce complexity of the optical design and overall packaging volume by replacing pre-magnification optics with a compact taper fiber optics plate. This paper will review and compare the performance of biocular vehicle display designs without and with taper fiber optics plate.

Photon Counting System for High-Sensitivity Detection of Bioluminescence at Optical Fiber End.

PubMed

Iinuma, Masataka; Kadoya, Yutaka; Kuroda, Akio

2016-01-01

The technique of photon counting is widely used for various fields and also applicable to a high-sensitivity detection of luminescence. Thanks to recent development of single photon detectors with avalanche photodiodes (APDs), the photon counting system with an optical fiber has become powerful for a detection of bioluminescence at an optical fiber end, because it allows us to fully use the merits of compactness, simple operation, highly quantum efficiency of the APD detectors. This optical fiber-based system also has a possibility of improving the sensitivity to a local detection of Adenosine triphosphate (ATP) by high-sensitivity detection of the bioluminescence. In this chapter, we are introducing a basic concept of the optical fiber-based system and explaining how to construct and use this system.

"Photonic lantern" spectral filters in multi-core Fiber.

PubMed

Birks, T A; Mangan, B J; Díez, A; Cruz, J L; Murphy, D F

2012-06-18

Fiber Bragg gratings are written across all 120 single-mode cores of a multi-core optical Fiber. The Fiber is interfaced to multimode ports by tapering it within a depressed-index glass jacket. The result is a compact multimode "photonic lantern" filter with astrophotonic applications. The tapered structure is also an effective mode scrambler.

Research on spectrum broadening covering visible light of a fiber femtosecond optical frequency comb for absolute frequency measurement

NASA Astrophysics Data System (ADS)

Xing, Shuai; Wu, Tengfei; Li, Shuyi; Xia, Chuanqing; Han, Jibo; Zhang, Lei; Zhao, Chunbo

2018-03-01

As a bridge connecting microwave frequency and optical frequency, femtosecond laser has important significance in optical frequency measurement. Compared with the traditional Ti-sapphire femtosecond optical frequency comb, with the advantages of compact structure, strong anti-interference ability and low cost, the fiber femtosecond optical frequency comb has a wider application prospect. An experiment of spectrum broadening in a highly nonlinear photonic crystal fiber pumped by an Er-fiber mode-locked femtosecond laser is studied in this paper. Based on optical amplification and frequency doubling, the central wavelength of the output spectrum is 780nm and the average power is 232mW. With the femtosecond pulses coupled into two different photonic crystal fibers, the coverage of visible spectrum is up to 500nm-960nm. The spectral shape and width can be optimized by changing the polarization state for satisfying the requirments of different optical frequencies measurement.

Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

NASA Astrophysics Data System (ADS)

Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

2016-03-01

Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response

Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

PubMed Central

Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

2016-01-01

Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response PMID:27010752

Vertical Strain Measured in the Mississippi River Delta Using Borehole Optical Fiber Strainmeters

NASA Astrophysics Data System (ADS)

Hatfield, W.; Allison, M. A.; Bridgeman, J.; Dixon, T. H.; Elliott, D.; Steckler, M. S.; Tornqvist, T. E.; Williams, K.; Wyatt, F. K.; Zumberge, M. A.

2017-12-01

Three boreholes in the Mississippi River Delta, at a site 2 km from the river near Myrtle Grove, Louisiana, have been instrumented with optical fiber strainmeters. The boreholes extend to depths of 9 m, 24 m, and 37 m. Each contains an optical fiber strainmeter that records the displacement between a steel surface casing and a termination fixture cemented into the bottom of each borehole. The strainmeters consist of an optical fiber cable stretched to a length 0.2% longer than its unstressed condition. An optical interferometer is formed between each sensing fiber and a second optical fiber of equal length wrapped on a reference mandrel housed in a sonde in the wellhead casing. This arrangement relaxes stability requirements on the light source. A signal processing unit samples the interference fringe signals 50,000 times per second and calculates the optical phase shift, providing a displacement record precise to a few nm or strain sensitivity of better than 1 nanostrain. The sensors operate from solar power and transmit the data (decimated to 20 samples per second) to an archiving system via a cell phone modem. To mitigate against the effects of temperature variations, a second optical fiber sensor with a different temperature is operated in parallel with the first, sharing the same cable and processing sonde. Records from the two fibers allow the separation of optical length changes caused by temperature from the earth strain. The three individual systems provide an unprecedented measure of soil compaction. Over short periods we observe sub-micron signals such as teleseisms, and over the long term we have observed stability at the tenths of a mm level. The site has shown no compaction or subsidence greater than a few tenths of a mm over the last year, highlighting the value of strainmeters over other techniques that can not resolve such small signals. Two of the sensors began operating in July of 2016, the third began operation in May of 2017.

20 years of KVH fiber optic gyro technology: the evolution from large, low performance FOGs to compact, precise FOGs and FOG-based inertial systems

NASA Astrophysics Data System (ADS)

Napoli, Jay

2016-05-01

Precision fiber optic gyroscopes (FOGs) are critical components for an array of platforms and applications ranging from stabilization and pointing orientation of payloads and platforms to navigation and control for unmanned and autonomous systems. In addition, FOG-based inertial systems provide extremely accurate data for geo-referencing systems. Significant improvements in the performance of FOGs and FOG-based inertial systems at KVH are due, in large part, to advancements in the design and manufacture of optical fiber, as well as in manufacturing operations and signal processing. Open loop FOGs, such as those developed and manufactured by KVH Industries, offer tactical-grade performance in a robust, small package. The success of KVH FOGs and FOG-based inertial systems is due to innovations in key fields, including the development of proprietary D-shaped fiber with an elliptical core, and KVH's unique ThinFiber. KVH continually improves its FOG manufacturing processes and signal processing, which result in improved accuracies across its entire FOG product line. KVH acquired its FOG capabilities, including its patented E•Core fiber, when the company purchased Andrew Corporation's Fiber Optic Group in 1997. E•Core fiber is unique in that the light-guiding core - critical to the FOG's performance - is elliptically shaped. The elliptical core produces a fiber that has low loss and high polarization-maintaining ability. In 2010, KVH developed its ThinFiber, a 170-micron diameter fiber that retains the full performance characteristics of E•Core fiber. ThinFiber has enabled the development of very compact, high-performance open-loop FOGs, which are also used in a line of FOG-based inertial measurement units and inertial navigation systems.

Compact silicon photonics-based multi laser module for sensing

NASA Astrophysics Data System (ADS)

Ayotte, S.; Costin, F.; Babin, A.; Paré-Olivier, G.; Morin, M.; Filion, B.; Bédard, K.; Chrétien, P.; Bilodeau, G.; Girard-Deschênes, E.; Perron, L.-P.; Davidson, C.-A.; D'Amato, D.; Laplante, M.; Blanchet-Létourneau, J.

2018-02-01

A compact three-laser source for optical sensing is presented. It is based on a low-noise implementation of the Pound Drever-Hall method and comprises high-bandwidth optical phase-locked loops. The outputs from three semiconductor distributed feedback lasers, mounted on thermo-electric coolers (TEC), are coupled with micro-lenses into a silicon photonics (SiP) chip that performs beat note detection and several other functions. The chip comprises phase modulators, variable optical attenuators, multi-mode-interference couplers, variable ratio tap couplers, integrated photodiodes and optical fiber butt-couplers. Electrical connections between a metallized ceramic and the TECs, lasers and SiP chip are achieved by wirebonds. All these components stand within a 35 mm by 35 mm package which is interfaced with 90 electrical pins and two fiber pigtails. One pigtail carries the signals from a master and slave lasers, while another carries that from a second slave laser. The pins are soldered to a printed circuit board featuring a micro-processor that controls and monitors the system to ensure stable operation over fluctuating environmental conditions. This highly adaptable multi-laser source can address various sensing applications requiring the tracking of up to three narrow spectral features with a high bandwidth. It is used to sense a fiber-based ring resonator emulating a resonant fiber optics gyroscope. The master laser is locked to the resonator with a loop bandwidth greater than 1 MHz. The slave lasers are offset frequency locked to the master laser with loop bandwidths greater than 100 MHz. This high performance source is compact, automated, robust, and remains locked for days.

Compact instrument for fluorescence image-guided surgery

NASA Astrophysics Data System (ADS)

Wang, Xinghua; Bhaumik, Srabani; Li, Qing; Staudinger, V. Paul; Yazdanfar, Siavash

2010-03-01

Fluorescence image-guided surgery (FIGS) is an emerging technique in oncology, neurology, and cardiology. To adapt intraoperative imaging for various surgical applications, increasingly flexible and compact FIGS instruments are necessary. We present a compact, portable FIGS system and demonstrate its use in cardiovascular mapping in a preclinical model of myocardial ischemia. Our system uses fiber optic delivery of laser diode excitation, custom optics with high collection efficiency, and compact consumer-grade cameras as a low-cost and compact alternative to open surgical FIGS systems. Dramatic size and weight reduction increases flexibility and access, and allows for handheld use or unobtrusive positioning over the surgical field.

All-optical phase shifter and switch near 1550nm using tungsten disulfide (WS2) deposited tapered fiber.

PubMed

Wu, Kan; Guo, Chaoshi; Wang, Hao; Zhang, Xiaoyan; Wang, Jun; Chen, Jianping

2017-07-24

All-optical phase shifters and switches play an important role for various all-optical applications including all-optical signal processing, sensing and communication. In this paper, we demonstrate a fiber all-optical phase shifter using few-layer 2D material tungsten disulfide (WS 2 ) deposited on a tapered fiber. WS 2 absorbs injected 980 nm pump (control light) and generates heat, which changes the refractive index of both WS 2 and tapered fiber due to thermo-optic effect and achieves a maximum phase shift of 6.1π near 1550 nm. The device has a loss of 3.7 dB. By constructing a Mach-Zehnder interferometer with WS 2 based phase shifter in one arm, an all-optical switch is also obtained with an extinction ratio of 15 dB and a rise time of 7.3 ms. This all fiber low-cost and compact optical phase shifter and switch demonstrates the potential of 2D transition metal dichalcogenides for all-optical signal processing devices.

Compact high-resolution spectrographs for large and extremely large telescopes: using the diffraction limit

NASA Astrophysics Data System (ADS)

Robertson, J. Gordon; Bland-Hawthorn, Joss

2012-09-01

As telescopes get larger, the size of a seeing-limited spectrograph for a given resolving power becomes larger also, and for ELTs the size will be so great that high resolution instruments of simple design will be infeasible. Solutions include adaptive optics (but not providing full correction for short wavelengths) or image slicers (which give feasible but still large instruments). Here we develop the solution proposed by Bland-Hawthorn and Horton: the use of diffraction-limited spectrographs which are compact even for high resolving power. Their use is made possible by the photonic lantern, which splits a multi-mode optical fiber into a number of single-mode fibers. We describe preliminary designs for such spectrographs, at a resolving power of R ~ 50,000. While they are small and use relatively simple optics, the challenges are to accommodate the longest possible fiber slit (hence maximum number of single-mode fibers in one spectrograph) and to accept the beam from each fiber at a focal ratio considerably faster than for most spectrograph collimators, while maintaining diffraction-limited imaging quality. It is possible to obtain excellent performance despite these challenges. We also briefly consider the number of such spectrographs required, which can be reduced by full or partial adaptive optics correction, and/or moving towards longer wavelengths.

Silicon-etalon fiber-optic temperature sensor

NASA Technical Reports Server (NTRS)

Beheim, Glenn; Fritsch, Klaus; Flatico, Joseph M.; Azar, Massood Tabib

1989-01-01

A temperature sensor is described which consists of a silicon etalon that is sputtered directly onto the end of an optical fiber. A two-layer protective cap structure is used to improve the sensor's long-term stability. The sensor's output is wavelength encoded to provide a high degree of immunity from cable and connector effects. This sensor is extremely compact and potentially inexpensive.

Compact Optical Fiber 3D Shape Sensor Based on a Pair of Orthogonal Tilted Fiber Bragg Gratings

NASA Astrophysics Data System (ADS)

Feng, Dingyi; Zhou, Wenjun; Qiao, Xueguang; Albert, Jacques

2015-11-01

In this work, a compact fiber-optic 3D shape sensor consisting of two serially connected 2° tilted fiber Bragg gratings (TFBGs) is proposed, where the orientations of the grating planes of the two TFBGs are orthogonal. The measurement of the reflective transmission spectrum from the pair of TFBGs was implemented by Fresnel reflection of the cleaved fiber end. The two groups of cladding mode resonances in the reflection spectrum respond differentially to bending, which allows for the unique determination of the magnitude and orientation of the bend plane (i.e. with a ± 180 degree uncertainty). Bending responses ranging from -0.33 to + 0.21 dB/m-1 (depending on orientation) are experimentally demonstrated with bending from 0 to 3.03 m-1. In the third (axial) direction, the strain is obtained directly by the shift of the TFBG Bragg wavelengths with a sensitivity of 1.06 pm/μɛ.

Optical resolution photoacoustic microscopy using novel high-repetition-rate passively Q-switched microchip and fiber lasers.

PubMed

Shi, Wei; Kerr, Shaun; Utkin, Ilya; Ranasinghesagara, Janaka; Pan, Lei; Godwal, Yogesh; Zemp, Roger J; Fedosejevs, Robert

2010-01-01

Optical-resolution photoacoustic microscopy (OR-PAM) is a novel imaging technology for visualizing optically absorbing superficial structures in vivo with lateral spatial resolution determined by optical focusing rather than acoustic detection. Since scanning of the illumination spot is required, OR-PAM imaging speed is limited by both scanning speed and laser pulse repetition rate. Unfortunately, lasers with high repetition rates and suitable pulse durations and energies are not widely available and can be cost-prohibitive and bulky. We are developing compact, passively Q-switched fiber and microchip laser sources for this application. The properties of these lasers are discussed, and pulse repetition rates up to 100 kHz are demonstrated. OR-PAM imaging was conducted using a previously developed photoacoustic probe, which enabled flexible scanning of the focused output of the lasers. Phantom studies demonstrate the ability to image with lateral spatial resolution of 7±2 μm with the microchip laser system and 15±5 μm with the fiber laser system. We believe that the high pulse repetition rates and the potentially compact and fiber-coupled nature of these lasers will prove important for clinical imaging applications where real-time imaging performance is essential.

MEGARA spectrograph optics

NASA Astrophysics Data System (ADS)

Carrasco, E.; Sánchez-Blanco, E.; García-Vargas, M. L.; Gil de Paz, A.; Páez, G.; Gallego, J.; Sánchez, F. M.; Vílchez, J. M.

2012-09-01

MEGARA is the next optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) for Gran Telescopio Canarias. The instrument offers two IFUs plus a Multi-Object Spectroscopy (MOS) mode: a large compact bundle covering 12.5 arcsec x 11.3 arcsec on sky with 100 μm fiber-core; a small compact bundle, of 8.5 arcsec x 6.7 arcsec with 70 μm fiber-core and a fiber MOS positioner that allows to place up to 100 mini-bundles, 7 fibers each, with 100 μm fiber-core, within a 3.5 arcmin x 3.5 arcmin field of view, around the two IFUs. The fibers, organized in bundles, end in the pseudo-slit plate, which will be placed at the entrance focal plane of the MEGARA spectrograph. The large IFU and MOS modes will provide intermediate to high spectral resolutions, R=6800-17000. The small IFU mode will provide R=8000-20000. All these resolutions are possible thanks to a spectrograph design based in the used of volume phase holographic gratings in combination with prisms to keep fixed the collimator and camera angle. The MEGARA optics is composed by a total of 53 large optical elements per spectrograph: the field lens, the collimator and the camera lenses plus the complete set of pupil elements including holograms, windows and prisms. INAOE, a partner of the GTC and a partner of MEGARA consortium, is responsible of the optics manufacturing and tests. INAOE will carry out this project working in an alliance with CIO. This paper summarizes the status of MEGARA spectrograph optics at the Preliminary Design Review, held on March 2012.

Compact portable diffraction moire interferometer

DOEpatents

Deason, Vance A.; Ward, Michael B.

1989-01-01

A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.

Miniature fiber-optic multiphoton microscopy system using frequency-doubled femtosecond Er-doped fiber laser

PubMed Central

Huang, Lin; Mills, Arthur K.; Zhao, Yuan; Jones, David J.; Tang, Shuo

2016-01-01

We report on a miniature fiber-optic multiphoton microscopy (MPM) system based on a frequency-doubled femtosecond Er-doped fiber laser. The femtosecond pulses from the laser source are delivered to the miniature fiber-optic probe at 1.58 µm wavelength, where a standard single mode fiber is used for delivery without the need of free-space dispersion compensation components. The beam is frequency-doubled inside the probe by a periodically poled MgO:LiNbO3 crystal. Frequency-doubled pulses at 786 nm with a maximum power of 80 mW and a pulsewidth of 150 fs are obtained and applied to excite intrinsic signals from tissues. A MEMS scanner, a miniature objective, and a multimode collection fiber are further used to make the probe compact. The miniature fiber-optic MPM system is highly portable and robust. Ex vivo multiphoton imaging of mammalian skins demonstrates the capability of the system in imaging biological tissues. The results show that the miniature fiber-optic MPM system using frequency-doubled femtosecond fiber laser can potentially bring the MPM imaging for clinical applications. PMID:27231633

Mach-Zehnder atom interferometer inside an optical fiber

NASA Astrophysics Data System (ADS)

Xin, Mingjie; Leong, Wuiseng; Chen, Zilong; Lan, Shau-Yu

2017-04-01

Precision measurement with light-pulse grating atom interferometry in free space have been used in the study of fundamental physics and applications in inertial sensing. Recent development of photonic band-gap fibers allows light for traveling in hollow region while preserving its fundamental Gaussian mode. The fibers could provide a very promising platform to transfer cold atoms. Optically guided matter waves inside a hollow-core photonic band-gap fiber can mitigate diffraction limit problem and has the potential to bring research in the field of atomic sensing and precision measurement to the next level of compactness and accuracy. Here, we will show our experimental progress towards an atom interferometer in optical fibers. We designed an atom trapping scheme inside a hollow-core photonic band-gap fiber to create an optical guided matter waves system, and studied the coherence properties of Rubidium atoms in this optical guided system. We also demonstrate a Mach-Zehnder atom interferometer in the optical waveguide. This interferometer is promising for precision measurements and designs of mobile atomic sensors.

A micro S-shaped optical fiber temperature sensor based on dislocation fiber splice

NASA Astrophysics Data System (ADS)

Yan, Haitao; Li, Pengfei; Zhang, Haojie; Shen, Xiaoyue; Wang, Yongzhen

2017-12-01

We fabricated a simple, compact, and stable temperature sensor based on an S-shaped dislocated optical fiber. The dislocation optical fiber has two splice points, and we obtained the optimal parameters based on the theory and our experiment, such as the dislocation amount and length of the dislocation optical fiber. According to the relationship between the temperature and the peak wavelength shift, the temperature of the environment can be obtained. Then, we made this fiber a micro bending as S-shape between the two dislocation points, and the S-shaped micro bending part could release stress with the change in temperature and reduce the effect of stress on the temperature measurement. This structure could solve the problem of sensor distortion caused by the cross response of temperature and stress. We measured the S-shaped dislocation fiber sensor and the dislocation fiber without S-shape under the same environment and conditions, and the S-shaped dislocation fiber had the advantages of the stable reliability and good linearity.

High-Q Microsphere Cavity for Laser Stabilization and Optoelectronic Microwave

NASA Technical Reports Server (NTRS)

Ilchenko, V.; Yao, X.; Maleki, L.

1999-01-01

With submillimeter size and optical Q up to 10(sup 10), microspheres with whispering-gallery (WG) modes are attractive new component for fiber-optics/photonics applications and a potential core in ultra-compact high-spectral-purity optical and microwave oscillators.

Range-Gated Metrology with Compact Optical Head

NASA Technical Reports Server (NTRS)

Dubovitsky, Serge; Shaddock, Daniel; Ware, Brent; Lay, Oliver

2008-01-01

This work represents a radical simplification in the design of the optical head needed for high-precision laser ranging applications. The optical head is now a single fiber-optic collimator with dimensions of order of 1 1 2 cm, which can be easily integrated into the system being measured with minimal footprint.

Fiber sensors for molecular detection

NASA Astrophysics Data System (ADS)

Gu, Claire; Yang, Xuan; Zhang, Jin; Newhouse, Rebecca; Cao, Liangcai

2010-11-01

The demand on sensors for detecting chemical and biological agents is greater than ever before, including medical, environmental, food safety, military, and security applications. At present, most detection or sensing techniques tend to be either non-molecular specific, bulky, expensive, relatively inaccurate, or unable to provide real time data. Clearly, alternative sensing technologies are urgently needed. Recently, we have been working to develop a compact fiber optic surface enhanced Raman scattering (SERS) sensor system that integrates various novel ideas to achieve compactness, high sensitivity and consistency, molecular specificity, and automatic preliminary identification capabilities. The unique sensor architecture is expected to bring SERS sensors to practical applications due to a combination of 1) novel SERS substrates that provide the high sensitivity and consistency, molecular specificity, and applicability to a wide range of compounds; 2) a unique hollow core optical fiber probe with double SERS substrate structure that provides the compactness, reliability, low cost, and ease of sampling; and 3) an innovative matched spectral filter set that provides automatic preliminary molecule identification. In this paper, we will review the principle of operation and some of the important milestones of fiber SERS sensor development with emphasis on our recent work to integrate photonic crystal fiber SERS probes with a portable Raman spectrometer and to demonstrate a matched spectral filter for molecule identification.

A 980 nm pseudomorphic single quantum well laser for pumping erbium-doped optical fiber amplifiers

NASA Technical Reports Server (NTRS)

Larsson, A.; Forouhar, S.; Cody, J.; Lang, R. J.; Andrekson, P. A.

1990-01-01

The authors have fabricated ridge waveguide pseudomorphic InGaAs/GaAs/AlGaAs GRIN-SCH SQW (graded-index separate-confinement-heterostructure single-quantum-well) lasers, emitting at 980 nm, with a maximum output power of 240 mW from one facet and a 22 percent coupling efficiency into a 1.55-micron single-mode optical fiber. These lasers satisfy the requirements on efficient and compact pump sources for Er3+-doped fiber amplifiers.

Detecting ionizing radiation with optical fibers down to biomedical doses

NASA Astrophysics Data System (ADS)

Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; De Natale, P.; Gagliardi, G.

2013-10-01

We report on a passive ionizing radiation sensor based on a fiber-optic resonant cavity interrogated by a high resolution interferometric technique. After irradiation in clinical linear accelerators, we observe significant variations of the fiber thermo-optic coefficient. Exploiting this effect, we demonstrate an ultimate detection limit of 160 mGy with an interaction volume of only 6 × 10-4 mm3. Thanks to its reliability, compactness, and sensitivity at biomedical dose levels, our system lends itself to real applications in radiation therapy procedures as well as in radiation monitoring and protection in medicine, aerospace, and nuclear power plants.

Efficient third harmonic generation of a CW-fibered 1.5 µm laser diode

NASA Astrophysics Data System (ADS)

Philippe, Charles; Chea, Erick; Nishida, Yoshiki; du Burck, Frédéric; Acef, Ouali

2016-10-01

We report on frequency tripling of CW-Telecom laser diode using two cascaded PPLN ridge nonlinear crystals, both used in single-pass configuration. All optical components used for this development are fibered, leading to a very compact and easy to use optical setup. We have generated up to 290 mW optical power in the green range, from 800 mW only of infrared power around 1.54 µm. This result corresponds to an optical conversion efficiency P 3 ω / P ω > 36 %. To our knowledge, this is best value ever demonstrated up today for a CW-third harmonic generation in single-pass configuration. This frequency tripling experimental setup was tested over more than 2 years of continuous operation, without any interruption. The compactness and the reliability of our device make it very suitable as a transportable optical oscillator. In particular, it paves the way for embedded applications thanks to the high level of long-term stability of the optical alignments.

Compact portable diffraction moire interferometer

DOEpatents

Deason, V.A.; Ward, M.B.

1988-05-23

A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.

A compact, inexpensive infrared laser system for continuous-wave optical stimulation of the rat prostate cavernous nerves

NASA Astrophysics Data System (ADS)

Perkins, William C.; Lagoda, Gwen A.; Burnett, Arthur L.; Fried, Nathaniel M.

2014-03-01

Optical nerve stimulation (ONS) has been commonly performed in the laboratory using high-power, pulsed, infrared (IR) lasers including Holmium:YAG, diode, and Thulium fiber lasers. However, the relatively high cost of these lasers in comparison with conventional electrical nerve stimulation (ENS) equipment may represent a significant barrier to widespread adoption of ONS. Optical stimulation of the prostate cavernous nerves (CN's) has recently been reported using lower cost, continuous-wave (CW), all-fiber-based diode lasers. This preliminary study describes further miniaturization and cost reduction of the ONS system in the form of a compact, lightweight, cordless, and inexpensive IR laser. A 140-mW, 1560-nm diode laser was integrated with a green aiming beam and delivery optics into a compact ONS system. Surface and subsurface ONS was performed in a total of 5 rats, in vivo, with measurement of an intracavernous pressure (ICP) response during CW laser irradiation for 30 s with a spot diameter of 0.7 mm. Short-term, CW ONS of the prostate CN's is feasible using a compact, inexpensive, batterypowered IR laser diode system. This ONS system may represent an alternative to ENS for laboratory studies, and with further development, a handheld option for ONS in the clinic to identify and preserve the CN's during prostate cancer surgery.

Optical refractometer based on an asymmetrical twin-core fiber Michelson interferometer.

PubMed

Zhou, Ai; Zhang, Yanhui; Li, Guangping; Yang, Jun; Wang, Yuzhuo; Tian, Fengjun; Yuan, Libo

2011-08-15

We report and demonstrate an optical refractometer based on a compact fiber Michelson interferometer. The Michelson interferometer is composed of an asymmetrical twin-core fiber containing a central core and a side core. By chemically etching a segment of the twin-core fiber until the side core is exposed, the effective index of the side core in the etched region is sensitive to the environmental refractive index, which leads to a shift of the transmission spectrum of the Michelson interferometer. The experimental results show that such a device has a refractive index resolution of more than 800 nm/refractive index unit in the range of 1.34-1.37. © 2011 Optical Society of America

Compact passively Q-switched single-frequency Er3+/Yb3+ codoped phosphate fiber laser

NASA Astrophysics Data System (ADS)

Zhang, Yuanfei; Wang, Simin; Lin, Wei; Mo, Shupei; Zhao, Qilai; Yang, Changsheng; Feng, Zhouming; Deng, Huaqiu; Peng, Mingying; Yang, Zhongmin; Xu, Shanhui

2017-05-01

We present a compact passively Q-switched single-frequency fiber laser based on a 12-mm-long laboratory-built highly Er3+/Yb3+ codoped phosphate fiber (EYDPF) and a semiconductor saturable absorber mirror (SESAM). An effective cavity length of less than 20 mm ensures the stable single-frequency operation of the Q-switched fiber laser. By employing a SESAM for Q-switching, a single-pulse energy of more than 34.4 nJ is realized with the narrowest pulse duration of 95 ns, and the repetition rate of the Q-switched fiber laser reaches over 600 kHz. In addition, the optical signal-to-noise ratio of the output laser is as high as 68.0 dB.

High sensitivity optical fiber liquid level sensor based on a compact MMF-HCF-FBG structure

NASA Astrophysics Data System (ADS)

Zhang, Yunshan; Zhang, Weigang; Chen, Lei; Zhang, Yanxin; Wang, Song; Yan, Tieyi

2018-05-01

An ultra-high sensitivity fiber liquid level sensor based on wavelength demodulation is proposed and demonstrated. The sensor is composed of a segment of multimode fiber and a large aperture hollow-core fiber assisted by a fiber Bragg grating (FBG). Interference occurs due to core mismatching and different modes with different effective refractive indices. The experimental results show that the liquid level sensitivity of the sensor is 1.145 nm mm‑1, and the linearity is up to 0.996. The dynamic temperature compensation of the sensor can be achieved by cascading an FBG. Considering the high sensitivity and compact structure of the sensor, it can be used for real-time intelligent monitoring of tiny changes in liquid level.

Proximal design for a multimodality endoscope with multiphoton microscopy, optical coherence microscopy and visual modalities

NASA Astrophysics Data System (ADS)

Kiekens, Kelli C.; Talarico, Olivia; Barton, Jennifer K.

2018-02-01

A multimodality endoscope system has been designed for early detection of ovarian cancer. Multiple illumination and detection systems must be integrated in a compact, stable, transportable configuration to meet the requirements of a clinical setting. The proximal configuration presented here supports visible light navigation with a large field of view and low resolution, high resolution multiphoton microscopy (MPM), and high resolution optical coherence microscopy (OCM). All modalities are integrated into a single optical system in the endoscope. The system requires two light sources: a green laser for visible light navigation and a compact fiber based femtosecond laser for MPM and OCM. Using an inline wavelength division multiplexer, the two sources are combined into a single mode fiber. To accomplish OCM, a fiber coupler is used to separate the femtosecond laser into a reference arm and signal arm. The reflected reference arm and the signal from the sample are interfered and wavelength separated by a reflection grating and detected using a linear array. The MPM signal is collimated and goes through a series of filters to separate the 2nd and 3rd harmonics as well as twophoton excitation florescence (2PEF) and 3PEF. Each signal is independently detected on a photo multiplier tube and amplified. The visible light is collected by multiple high numerical aperture fibers at the endoscope tip which are bundled into one SMA adapter at the proximal end and connected to a photodetector. This integrated system design is compact, efficient and meets both optical and mechanical requirements for clinical applications.

High-Q Microsphere Cavity for Laser Stabilization and Optoelectronic Microwave Oscillator

NASA Technical Reports Server (NTRS)

Ilchenko, Vladimir S.; Yao, X. Steve; Maleki, Lute

2000-01-01

With submillimeter size and optical Q up to approximately 10 (exp 10), microspheres with whispering-gallery (WG) modes are attractive new component for fiber-optics/photonics applications and a potential core in ultra-compact high-spectral-purity optical and microwave oscillators. In addition to earlier demonstrated optical locking of diode laser to WG mode in a microsphere, we report on microsphere application in the microwave optoelectronic oscillator, OEO. In OEO, a steady-state microwave modulation of optical carrier is obtained in a closed loop including electro-optical modulator, fiber-optic delay, detector and microwave amplifier. OEO demonstrates exceptionally low phase noise (-140 dBc/Hz at l0kHz from approximately 10GHz carrier) with a fiber length approximately 2km. Current technology allows to put all parts of the OEO, except the fiber, on the same chip. Microspheres, with their demonstrated Q equivalent to a kilometer fiber storage, can replace fiber delays in a truly integrated device. We have obtained microwave oscillation in microsphere-based OEO at 5 to 18 GHz, with 1310nm and 1550nm optical carrier, in two configurations: 1) with external DFB pump laser, and 2) with a ring laser including microsphere and a fiber optic amplifier. Also reported is a simple and efficient fiber coupler for microspheres facilitating their integration with existing fiber optics devices.

Ultrahigh-resolution optical coherence tomography with a fiber laser source at 1 microm.

PubMed

Lim, Hyungsik; Jiang, Yi; Wang, Yimin; Huang, Yu-Chih; Chen, Zhongping; Wise, Frank W

2005-05-15

We report a compact, high-power, fiber-based source for ultrahigh-resolution optical coherence tomography (OCT) near 1 microm. The practical source is based on a short-pulse, ytterbium-doped fiber laser and on generation of a continuum spectrum in a photonic crystal fiber. The broadband emission has an average power of 140 mW and offers an axial resolution of 2.1 microm in air (<1.6 microm in biological tissue). The generation of a broad bandwidth is robust and efficient. We demonstrate ultrahigh-resolution, time-domain OCT imaging of in vitro and in vivo biological tissues.

Highly stable multi-wavelength erbium-doped fiber linear laser based on modal interference

NASA Astrophysics Data System (ADS)

Herrera-Piad, L. A.; Jauregui-Vazquez, D.; Lopez-Dieguez, Y.; Estudillo-Ayala, J. M.; Hernandez-Garcia, J. C.; Sierra-Hernandez, J. M.; Bianchetti, M.; Rojas-Laguna, R.

2018-03-01

We report a linear fiber laser cavity based on an all-fiber Fabry-Perot interferometer and bi-tapered optical fiber for multi-wavelength emission generation. Curvature and strain are used to operate the laser system and the number of lines as well, the emission regions are stronger related to the physical effect applied, due to the phase alteration between the multiple fiber optic modes involved. The original laser emissions present zero wavelength variations, minimal power fluctuations and small spacing mode (1 nm). Additionally, a nonlinear fiber was employed trying to improve the performance of the multiple lasing lines. This system offers a low implementation cost, compactness and good laser parameters.

Reflection based Extraordinary Optical Transmission Fiber Optic Probe for Refractive Index Sensing.

PubMed

Lan, Xinwei; Cheng, Baokai; Yang, Qingbo; Huang, Jie; Wang, Hanzheng; Ma, Yinfa; Shi, Honglan; Xiao, Hai

2014-03-31

Fiber optic probes for chemical sensing based on the extraordinary optical transmission (EOT) phenomenon are designed and fabricated by perforating subwavelength hole arrays on the gold film coated optical fiber endface. The device exhibits a red shift in response to the surrounding refractive index increases with high sensitivity, enabling a reflection-based refractive index sensor with a compact and simple configuration. By choosing the period of hole arrays, the sensor can be designed to operate in the near infrared telecommunication wavelength range, where the abundant source and detectors are available for easy instrumentation. The new sensor probe is demonstrated for refractive index measurement using refractive index matching fluids. The sensitivity reaches 573 nm/RIU in the 1.333~1.430 refractive index range.

High resolution (<1nm) interferometric fiber-optic sensor of vibrations in high-power transformers.

PubMed

Garcia-Souto, Jose A; Lamela-Rivera, Horacio

2006-10-16

A novel fiber-optic interferometric sensor is presented for vibrations measurements and analysis. In this approach, it is shown applied to the vibrations of electrical structures within power transformers. A main feature of the sensor is that an unambiguous optical phase measurement is performed using the direct detection of the interferometer output, without external modulation, for a more compact and stable implementation. High resolution of the interferometric measurement is obtained with this technique (<1 nm). The optical-fiber transducer is also specifically designed for magnifying the localized vibrations in order to modulate deeply the interferometric signal. Other advantages of the implementation for measurements within transformers are also highlighted.

Optofluidic in-fiber interferometer based on hollow optical fiber with two cores.

PubMed

Yuan, Tingting; Yang, Xinghua; Liu, Zhihai; Yang, Jun; Li, Song; Kong, Depeng; Qi, Xiuxiu; Yu, Wenting; Long, Qunlong; Yuan, Libo

2017-07-24

We demonstrate a novel integrated optical fiber interferometer for in-fiber optofluidic detection. It is composed of a specially designed hollow optical fiber with a micro-channel and two cores. One core on the inner surface of the micro-channel is served as sensing arm and the other core in the annular cladding is served as reference arm. Fusion-and-tapering method is employed to couple light from a single mode fiber to the hollow optical fiber in this device. Sampling is realized by side opening a microhole on the surface of the hollow optical fiber. Under differential pressure between the end of the hollow fiber and the microhole, the liquids can form steady microflows in the micro-channel. Simultaneously, the interference spectrum of the interferometer device shifts with the variation of the concentration of the microfluid in the channel. The optofluidic in-fiber interferometer has a sensitivity of refractive index around 2508 nm/RIU for NaCl. For medicine concentration detection, its sensitivity is 0.076 nm/mmolL -1 for ascorbic acid. Significantly, this work presents a compact microfluidic in-fiber interferometer with a micro-channel which can be integrated with chip devices without spatial optical coupling and without complex manufacturing procedure of the waveguide on the chips.

Compact All-Fiber Optical Faraday Components Using 65-wt%-Terbium-Doped Fiber with a Record Verdet Constant of -32 rad/(Tm)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, L.; Jiang, S.; Maricante, J.R.

2010-06-04

A compact all-fiber Faraday isolator and a Faraday mirror are demonstrated. At the core of each of these components is an all-fiber Faraday rotator made of a 4-cm-long, 65-wt%-terbium–doped silicate fiber. The effective Verdet constant of the terbium-doped fiber is measured to be –32 rad/(Tm), which is 27 × larger than that of silica fiber. This effective Verdet constant is the largest value measured to date in any fiber and is 83% of the Verdet constant of commercially available crystal used in bulk optics–based isolators. Combining the all-fiber Faraday rotator with fiber polarizers results in a fully fusion spliced all-fibermore » isolator whose isolation is measured to be 19 dB. Combining the all-fiber Faraday rotator with a fiber Bragg grating results in an all-fiber Faraday mirror that rotates the polarization state of the reflected light by 88 ± 4°.« less

Label-Free Detection of Cancer Biomarkers Using an In-Line Taper Fiber-Optic Interferometer and a Fiber Bragg Grating

PubMed Central

Sun, Dandan; Wang, Guanjun

2017-01-01

A compact and label-free optical fiber sensor based on a taper interferometer cascaded with a fiber Bragg grating (FBG) is proposed and experimentally demonstrated for detection of a breast cancer biomarker (HER2). The tapered fiber-optic interferometer is extremely sensitive to the ambient refractive index (RI). In addition, being insensitive to the RI variation, the FBG can be applied as a temperature thermometer due to its independent response to the temperature. Surface functionalization to the sensor is carried out to achieve specific targeting of the unlabeled biomarkers. The result shows that the proposed sensor presents a low limit-of-detection (LOD) of 2 ng/mL, enabling its potentials of application in early diagnosis on the breast cancer. PMID:29113127

Fiber Optic Sensor for Acoustic Detection of Partial Discharges in Oil-Paper Insulated Electrical Systems

PubMed Central

Posada-Roman, Julio; Garcia-Souto, Jose A.; Rubio-Serrano, Jesus

2012-01-01

A fiber optic interferometric sensor with an intrinsic transducer along a length of the fiber is presented for ultrasound measurements of the acoustic emission from partial discharges inside oil-filled power apparatus. The sensor is designed for high sensitivity measurements in a harsh electromagnetic field environment, with wide temperature changes and immersion in oil. It allows enough sensitivity for the application, for which the acoustic pressure is in the range of units of Pa at a frequency of 150 kHz. In addition, the accessibility to the sensing region is guaranteed by immune fiber-optic cables and the optical phase sensor output. The sensor design is a compact and rugged coil of fiber. In addition to a complete calibration, the in-situ results show that two types of partial discharges are measured through their acoustic emissions with the sensor immersed in oil. PMID:22666058

2 µm high-power dissipative soliton resonance in a compact σ-shaped Tm-doped double-clad fiber laser

NASA Astrophysics Data System (ADS)

Du, Tuanjie; Li, Weiwei; Ruan, Qiujun; Wang, Kaijie; Chen, Nan; Luo, Zhengqian

2018-05-01

We report direct generation of a high-power, large-energy dissipative soliton resonance (DSR) in a 2 µm Tm-doped double-clad fiber laser. A compact σ-shaped cavity is formed by a fiber Bragg grating and a 10/90 fiber loop mirror (FLM). The 10/90 FLM is not only used as an output mirror, but also acts as a nonlinear optical loop mirror for initiating mode locking. The mode-locked laser can deliver high-power, nanosecond DSR pulses at 2005.9 nm. We further perform a comparison study of the effect of the FLM’s loop length on the mode-locking threshold, peak power, pulse energy, and optical spectrum of the DSR pulses. We achieve a maximum average output power as high as 1.4 W, a maximum pulse energy of 353 nJ, and a maximum peak power of 84 W. This is, to the best of our knowledge, the highest power for 2 µm DSR pulses obtained in a mode-locked fiber laser.

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

PubMed Central

Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha

2016-01-01

We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging. PMID:27213392

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography.

PubMed

Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha

2016-05-20

We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging.

Miniaturized Fourier-plane fiber scanner for OCT endoscopy

NASA Astrophysics Data System (ADS)

Vilches, Sergio; Kretschmer, Simon; Ataman, Çağlar; Zappe, Hans

2017-10-01

A forward-looking endoscopic optical coherence tomography (OCT) probe featuring a Fourier-plane fiber scanner is designed, manufactured and characterized. In contrast to common image-plane fiber scanners, the Fourier-plane scanner is a telecentric arrangement that eliminates vignetting and spatial resolution variations across the image plane. To scan the OCT beam in a spiral pattern, a tubular piezoelectric actuator is used to resonate an optical fiber bearing a collimating GRIN lens at its tip. The free-end of the GRIN lens sits at the back focal plane of an objective lens, such that its rotation replicates the beam angles in the collimated region of a classical telecentric 4f optical system. Such an optical arrangement inherently has a low numerical aperture combined with a relatively large field-of-view, rendering it particularly useful for endoscopic OCT imaging. Furthermore, the optical train of the Fourier-plane scanner is shorter than that of a comparable image-plane scanner by one focal length of the objective lens, significantly shortening the final arrangement. As a result, enclosed within a 3D printed housing of 2.5 mm outer diameter and 15 mm total length, the developed probe is the most compact forward-looking endoscopic OCT imager to date. Due to its compact form factor and compatibility with real-time OCT imaging, the developed probe is also ideal for use in the working channel of flexible endoscopes as a potential optical biopsy tool.

Compact and Robust Refilling and Connectorization of Hollow Core Photonic Crystal Fiber Gas Reference Cells

NASA Technical Reports Server (NTRS)

Poberezhskiy, Ilya Y.; Meras, Patrick; Chang, Daniel H.; Spiers, Gary D.

2007-01-01

This slide presentation reviews a method for refilling and connectorization of hollow core photonic crystal fiber gas reference cells. Thees hollow-core photonic crystal fiber allow optical propagation in air or vacuum and are for use as gas reference cell is proposed and demonstrated. It relies on torch-sealing a quartz filling tube connected to a mechanical splice between regular and hollow-core fibers.

Multimodal nonlinear microscope based on a compact fiber-format laser source

NASA Astrophysics Data System (ADS)

Crisafi, Francesco; Kumar, Vikas; Perri, Antonio; Marangoni, Marco; Cerullo, Giulio; Polli, Dario

2018-01-01

We present a multimodal non-linear optical (NLO) laser-scanning microscope, based on a compact fiber-format excitation laser and integrating coherent anti-Stokes Raman scattering (CARS), stimulated Raman scattering (SRS) and two-photon-excitation fluorescence (TPEF) on a single platform. We demonstrate its capabilities in simultaneously acquiring CARS and SRS images of a blend of 6-μm poly(methyl methacrylate) beads and 3-μm polystyrene beads. We then apply it to visualize cell walls and chloroplast of an unprocessed fresh leaf of Elodea aquatic plant via SRS and TPEF modalities, respectively. The presented NLO microscope, developed in house using off-the-shelf components, offers full accessibility to the optical path and ensures its easy re-configurability and flexibility.

Higher-order micro-fiber modes for Escherichia coli manipulation using a tapered seven-core fiber

PubMed Central

Rong, Qiangzhou; Zhou, Yi; Yin, Xunli; Shao, Zhihua; Qiao, Xueguang

2017-01-01

Optical manipulation using optical micro- and nano-fibers has shown potential for controlling bacterial activities such as E. coli trapping, propelling, and binding. Most of these manipulations have been performed using the propagation of the fundamental mode through the fiber. However, along the maximum mode-intensity axis, the higher-order modes have longer evanescent field extensions and larger field amplitudes at the fiber waist than the fundamental mode, opening up new possibilities for manipulating E. coli bacteria. In this work, a compact seven-core fiber (SCF)-based micro-fiber/optical tweezers was demonstrated for trapping, propelling, and rotating E. coli bacteria using the excitation of higher-order modes. The diameter of the SCF taper was 4 µm at the taper waist, which was much larger than that of previous nano-fiber tweezers. The laser wavelength was tunable from 1500 nm to 1600 nm, simultaneously causing photophoretic force, gradient force, and scattering force. This work provides a new opportunity for better understanding optical manipulation using higher-order modes at the single-cell level. PMID:28966849

Higher-order micro-fiber modes for Escherichia coli manipulation using a tapered seven-core fiber.

PubMed

Rong, Qiangzhou; Zhou, Yi; Yin, Xunli; Shao, Zhihua; Qiao, Xueguang

2017-09-01

Optical manipulation using optical micro- and nano-fibers has shown potential for controlling bacterial activities such as E. coli trapping, propelling, and binding. Most of these manipulations have been performed using the propagation of the fundamental mode through the fiber. However, along the maximum mode-intensity axis, the higher-order modes have longer evanescent field extensions and larger field amplitudes at the fiber waist than the fundamental mode, opening up new possibilities for manipulating E. coli bacteria. In this work, a compact seven-core fiber (SCF)-based micro-fiber/optical tweezers was demonstrated for trapping, propelling, and rotating E. coli bacteria using the excitation of higher-order modes. The diameter of the SCF taper was 4 µm at the taper waist, which was much larger than that of previous nano-fiber tweezers. The laser wavelength was tunable from 1500 nm to 1600 nm, simultaneously causing photophoretic force, gradient force, and scattering force. This work provides a new opportunity for better understanding optical manipulation using higher-order modes at the single-cell level.

Compact fiber optic gyroscopes for platform stabilization

NASA Astrophysics Data System (ADS)

Dickson, William C.; Yee, Ting K.; Coward, James F.; McClaren, Andrew; Pechner, David A.

2013-09-01

SA Photonics has developed a family of compact Fiber Optic Gyroscopes (FOGs) for platform stabilization applications. The use of short fiber coils enables the high update rates required for stabilization applications but presents challenges to maintain high performance. We are able to match the performance of much larger FOGs by utilizing several innovative technologies. These technologies include source noise reduction to minimize Angular Random Walk (ARW), advanced digital signal processing that minimizes bias drift at high update rates, and advanced passive thermal packaging that minimizes temperature induced bias drift while not significantly affecting size, weight, or power. In addition, SA Photonics has developed unique distributed FOG packaging technologies allowing the FOG electronics and photonics to be packaged remotely from the sensor head or independent axis heads to minimize size, weight, and power at the sensing location(s). The use of these technologies has resulted in high performance, including ARW less than 0.001 deg/rt-hr and bias drift less than 0.004 deg/hr at an update rate of 10 kHz, and total packaged volume less than 30 cu. in. for a 6 degree of freedom FOG-based IMU. Specific applications include optical beam stabilization for LIDAR and LADAR, beam stabilization for long-range free-space optical communication, Optical Inertial Reference Units for HEL stabilization, and Ka band antenna pedestal pointing and stabilization. The high performance of our FOGs also enables their use in traditional navigation and positioning applications. This paper will review the technologies enabling our high-performance compact FOGs, and will provide performance test results.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Jihuan; Zhao Jiarong; Huang Xuguang

A simple fiber-optic sensor based on Fabry-Perot interference for refractive index measurement of optical glass is investigated both theoretically and experimentally. A broadband light source is coupled into an extrinsic fiber Fabry-Perot cavity formed by the surfaces of a sensing fiber end and the measured sample. The interference signals from the cavity are reflected back into the same fiber. The refractive index of the sample can be obtained by measuring the contrast of the interference fringes. The experimental data meet with the theoretical values very well. The proposed technique is a new method for glass refractive index measurement with amore » simple, solid, and compact structure.« less

Fiber optic light collection system for scanning-tunneling-microscope-induced light emission.

PubMed

Watkins, Neil J; Long, James P; Kafafi, Zakya H; Mäkinen, Antti J

2007-05-01

We report a compact light collection scheme suitable for retrofitting a scanning tunneling microscope (STM) for STM-induced light emission experiments. The approach uses a pair of optical fibers with large core diameters and high numerical apertures to maximize light collection efficiency and to moderate the mechanical precision required for alignment. Bench tests indicate that efficiency reduction is almost entirely due to reflective losses at the fiber ends, while losses due to fiber misalignment have virtually been eliminated. Photon-map imaging with nanometer features is demonstrated on a stepped Au(111) surface with signal rates exceeding 10(4) counts/s.

Optically resilient 3D micro-optics on the tips of optical fibers

NASA Astrophysics Data System (ADS)

Jonušauskas, Linas

2017-05-01

In this paper we present a study aimed at investigating an optical resiliency of polymers that could be applied in 3D femtosecond laser lithography. These include popular in lithography SU8 and OrmoClear as well as hybrid organic-inorganic zirconium containing SZ2080. We show that latter material in its pure (non-photosensitized) form has the best optical resiliency out of all tested materials. Furthermore, its 3D structurability is investigated. Despite threshold-like quality degradation outside fabrication window, we show that this material is suitable for creating complex 3D structures on the tips of optical fibers. Overall it is demonstrated, that unique capability of 3DLL to structure pure materials can lead to very compact functional fiber-based devices that could withstand high (GW/cm2) light intensities.

Optical fiber curvature sensor based on MMF-SCF-MMF structure

NASA Astrophysics Data System (ADS)

Wang, Qi; Liu, Yu

2018-07-01

A sensitive curvature sensor based on MMF-SCF-MMF (MMF: multimode fiber; SCF: seven core fiber) structure is proposed. The multimode fiber (MMF) are used to improve the light coupling efficiency between the input singlemode fiber (SMF) and the seven-core fiber (SCF), and the seven-core fiber is used as the main element for curvature measurement. Experimental results show that the best curvature sensitivity reaches 41.46453 nm/m-1 in the range of 0.094 m-1-0.567 m-1. The temperature sensitivity is up to 59.02 pm/°C in the range of 20 °C-55 °C. The optical curvature sensors are widely used for buildings structure health monitoring and mechanical engineering due to the advantages of compact structure, anti-electromagnetic interference, and low cost.

Compact, passively Q-switched, all-solid-state master oscillator-power amplifier-optical parametric oscillator (MOPA-OPO) system pumped by a fiber-coupled diode laser generating high-brightness, tunable, ultraviolet radiation.

PubMed

Peuser, Peter; Platz, Willi; Fix, Andreas; Ehret, Gerhard; Meister, Alexander; Haag, Matthias; Zolichowski, Paul

2009-07-01

We report on a compact, tunable ultraviolet laser system that consists of an optical parametric oscillator (OPO) and a longitudinally diode-pumped Nd:YAG master oscillator-power amplifier (MOPA). The pump energy for the whole laser system is supplied via a single delivery fiber. Nanosecond pulses are produced by an oscillator that is passively Q-switched by a Cr(4+):YAG crystal. The OPO is pumped by the second harmonic of the Nd:YAG MOPA. Continuously tunable radiation is generated by an intracavity sum-frequency mixing process within the OPO in the range of 245-260 nm with high beam quality. Maximum pulse energies of 1.2 mJ were achieved, which correspond to an optical efficiency of 3.75%, relating to the pulse energy of the MOPA at 1064 nm.

Optical fiber sensor based on surface plasmon resonance for rapid detection of avian influenza virus subtype H6: Initial studies.

PubMed

Zhao, Xihong; Tsao, Yu-Chia; Lee, Fu-Jung; Tsai, Woo-Hu; Wang, Ching-Ho; Chuang, Tsung-Liang; Wu, Mu-Shiang; Lin, Chii-Wann

2016-07-01

A side-polished fiber optic surface plasmon resonance (SPR) sensor was fabricated to expose the core surface and then deposited with a 40 nm thin gold film for the near surface sensing of effective refractive index changes with surface concentration or thickness of captured avian influenza virus subtype H6. The detection surface of the SPR optical fiber sensor was prepared through the plasma modification method for binding a self-assembled monolayer of isopropanol chemically on the gold surface of the optical fiber. Subsequently, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide/N-hydroxysuccinimide was activated to enable EB2-B3 monoclonal antibodies to capture A/chicken/Taiwan/2838V/00 (H6N1) through a flow injection system. The detection limit of the fabricated optical fiber sensor for A/chicken/Taiwan/2838V/00 was 5.14 × 10(5) EID50/0.1 mL, and the response time was 10 min on average. Moreover, the fiber optic sensor has the advantages of a compact size and low cost, thus rendering it suitable for online and remote sensing. The results indicated that the optical fiber sensor can be used for epidemiological surveillance and diagnosing of avian influenza subtype H6 rapidly. Copyright © 2016 Elsevier B.V. All rights reserved.

Computational imaging through a fiber-optic bundle

NASA Astrophysics Data System (ADS)

Lodhi, Muhammad A.; Dumas, John Paul; Pierce, Mark C.; Bajwa, Waheed U.

2017-05-01

Compressive sensing (CS) has proven to be a viable method for reconstructing high-resolution signals using low-resolution measurements. Integrating CS principles into an optical system allows for higher-resolution imaging using lower-resolution sensor arrays. In contrast to prior works on CS-based imaging, our focus in this paper is on imaging through fiber-optic bundles, in which manufacturing constraints limit individual fiber spacing to around 2 μm. This limitation essentially renders fiber-optic bundles as low-resolution sensors with relatively few resolvable points per unit area. These fiber bundles are often used in minimally invasive medical instruments for viewing tissue at macro and microscopic levels. While the compact nature and flexibility of fiber bundles allow for excellent tissue access in-vivo, imaging through fiber bundles does not provide the fine details of tissue features that is demanded in some medical situations. Our hypothesis is that adapting existing CS principles to fiber bundle-based optical systems will overcome the resolution limitation inherent in fiber-bundle imaging. In a previous paper we examined the practical challenges involved in implementing a highly parallel version of the single-pixel camera while focusing on synthetic objects. This paper extends the same architecture for fiber-bundle imaging under incoherent illumination and addresses some practical issues associated with imaging physical objects. Additionally, we model the optical non-idealities in the system to get lower modelling errors.

A compact fiber optics-based heterodyne combined normal and transverse displacement interferometer.

PubMed

Zuanetti, Bryan; Wang, Tianxue; Prakash, Vikas

2017-03-01

While Photonic Doppler Velocimetry (PDV) has become a common diagnostic tool for the measurement of normal component of particle motion in shock wave experiments, this technique has not yet been modified for the measurement of combined normal and transverse motion, as needed in oblique plate impact experiments. In this paper, we discuss the design and implementation of a compact fiber-optics-based heterodyne combined normal and transverse displacement interferometer. Like the standard PDV, this diagnostic tool is assembled using commercially available telecommunications hardware and uses a 1550 nm wavelength 2 W fiber-coupled laser, an optical focuser, and single mode fibers to transport light to and from the target. Two additional optical probes capture first-order beams diffracted from a reflective grating at the target free-surface and deliver the beams past circulators and a coupler where the signal is combined to form a beat frequency. The combined signal is then digitized and analyzed to determine the transverse component of the particle motion. The maximum normal velocity that can be measured by this system is limited by the equivalent transmission bandwidth (3.795 GHz) of the combined detector, amplifier, and digitizer and is estimated to be ∼2.9 km/s. Sample symmetric oblique plate-impact experiments are performed to demonstrate the capability of this diagnostic tool in the measurement of the combined normal and transverse displacement particle motion.

Comb-referenced ultra-high sensitivity spectroscopic molecular detection by compact non-linear sources

NASA Astrophysics Data System (ADS)

Cancio, P.; Gagliardi, G.; Galli, I.; Giusfredi, G.; Maddaloni, P.; Malara, P.; Mazzotti, D.; De Natale, P.

2017-11-01

We present a new generation of compact and rugged mid-infrared (MIR) difference-frequency coherent radiation sources referenced to fiber-based optical frequency comb synthesizers (OFCSs). By coupling the MIR radiation to high-finesse optical cavities, high-resolution and high-sensitivity spectroscopy is demonstrated for CH4 and CO2 around 3.3 and 4.5 μm respectively. Finally, the most effective detection schemes for space-craft trace-gas monitoring applications are singled out.

AN EFFICIENT, COMPACT, AND VERSATILE FIBER DOUBLE SCRAMBLER FOR HIGH PRECISION RADIAL VELOCITY INSTRUMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath

2015-06-10

We present the design and test results of a compact optical fiber double-scrambler for high-resolution Doppler radial velocity instruments. This device consists of a single optic: a high-index n ∼ 2 ball lens that exchanges the near and far fields between two fibers. When used in conjunction with octagonal fibers, this device yields very high scrambling gains (SGs) and greatly desensitizes the fiber output from any input illumination variations, thereby stabilizing the instrument profile of the spectrograph and improving the Doppler measurement precision. The system is also highly insensitive to input pupil variations, isolating the spectrograph from telescope illumination variationsmore » and seeing changes. By selecting the appropriate glass and lens diameter the highest efficiency is achieved when the fibers are practically in contact with the lens surface, greatly simplifying the alignment process when compared to classical double-scrambler systems. This prototype double-scrambler has demonstrated significant performance gains over previous systems, achieving SGs in excess of 10,000 with a throughput of ∼87% using uncoated Polymicro octagonal fibers. Adding a circular fiber to the fiber train further increases the SG to >20,000, limited by laboratory measurement error. While this fiber system is designed for the Habitable-zone Planet Finder spectrograph, it is more generally applicable to other instruments in the visible and near-infrared. Given the simplicity and low cost, this fiber scrambler could also easily be multiplexed for large multi-object instruments.« less

High-performance fiber optic link for ECM antenna remoting

NASA Astrophysics Data System (ADS)

Edge, Colin; Burgess, John W.; Wale, Michael J.; Try, Nicholas W.

1998-11-01

The ability to remotely radiate microwave signals has become an essential feature of modern electronic counter-measures (ECM) systems. The use of fiber optics allows remote microwave links to be constructed which have very low propagation loss and dispersion, are very flexible and light in weight, and have a high degree of immunity from external electromagnetic fields, crosstalk and environmental effects. This combination of desirable characteristics are very beneficial to avionic ECM antenna remoting as well as many other applications. GEC-Marconi have developed high performance fiber components for use in a towed radar decoy. The resulting rugged and compact optical transmitter and receiver modules have been developed and proven to maintain the required performance over the full hostile range of environmental conditions encountered on a fast jet. Packaged fiber optic links have been produced which can achieve a compression dynamic range of greater than 87 dB in 1 MHz bandwidth over a 2 to 18 GHz.

System Construction for the Measurement of Bragg Grating Characteristics in Optical Fibers

NASA Technical Reports Server (NTRS)

West, Douglas P.

1995-01-01

Bragg gratings are used to measure strain in optical fibers. To measure strain they are sometimes used as a smart structure. They must be characterized after they are written to determine their spectral response. This paper deals with the test setup to characterize Bragg grating spectral responses.Bragg gratings are a photo-induced phenomena in optical fibers. The gratings can be used to measure strain by measuring the shift in wavelength. They placed the fibers into a smart structure to measure the stress and strain produced on support columns placed in bridges. As the cable is subjected to strain the grating causes a shift to a longer wavelength if the fiber is stretched and a shift to a shorter wavelength shift if the fiber is compacted. Our applications involve using the fibers to measure stress and strain on airborne systems. There are many ways to write Bragg gratings into optical fibers. Our focus is on side writing the grating. Our capabilities are limited in the production rate of the gratings. The Bragg grating is written into a fiber and becomes a permanent fixture. We are writing the grating to be centered at 1300 nm because that is the standard phase mask wavelength.

A compact optical fiber positioner

NASA Astrophysics Data System (ADS)

Hu, Hongzhuan; Wang, Jianping; Liu, Zhigang; Zhou, Zengxiang; Zhai, Chao; Chu, Jiaru

2016-07-01

In this paper, a compact optical fiber positioner is proposed, which is especially suitable for small scale and high density optical fiber positioning. Based on the positioning principle of double rotation, positioner's center shaft depends on planetary gear drive principle, meshing with the fixed annular gear central motor gear driving device to rotate, and the eccentric shaft rotated driving by a coaxial eccentric motor, both center and the eccentric shaft are supported by a rolling bearings; center and eccentric shaft are both designed with electrical zero as a reference point, and both of them have position-limiting capability to ensure the safety of fiber positioning; both eccentric and center shaft are designed to eliminating clearance with spring structure, and can eliminate the influence of gear gap; both eccentric and center motor and their driving circuit can be installed in the positioner's body, and a favorable heat sink have designed, the heat bring by positioning operation can be effectively transmit to design a focal plane unit through the aluminum component, on sleeve cooling spiral airway have designed, when positioning, the cooling air flow is inlet into install hole on the focal plate, the cooling air flow can effectively take away the positioning's heat, to eliminate the impact of the focus seeing. By measuring position device's sample results show that: the unit accuracy reached 0.01mm, can meet the needs of fiber positioning.

Optical system components for navigation grade fiber optic gyroscopes

NASA Astrophysics Data System (ADS)

Heimann, Marcus; Liesegang, Maximilian; Arndt-Staufenbiel, Norbert; Schröder, Henning; Lang, Klaus-Dieter

2013-10-01

Interferometric fiber optic gyroscopes belong to the class of inertial sensors. Due to their high accuracy they are used for absolute position and rotation measurement in manned/unmanned vehicles, e.g. submarines, ground vehicles, aircraft or satellites. The important system components are the light source, the electro optical phase modulator, the optical fiber coil and the photodetector. This paper is focused on approaches to realize a stable light source and fiber coil. Superluminescent diode and erbium doped fiber laser were studied to realize an accurate and stable light source. Therefor the influence of the polarization grade of the source and the effects due to back reflections to the source were studied. During operation thermal working conditions severely affect accuracy and stability of the optical fiber coil, which is the sensor element. Thermal gradients that are applied to the fiber coil have large negative effects on the achievable system accuracy of the optic gyroscope. Therefore a way of calculating and compensating the rotation rate error of a fiber coil due to thermal change is introduced. A simplified 3 dimensional FEM of a quadrupole wound fiber coil is used to determine the build-up of thermal fields in the polarization maintaining fiber due to outside heating sources. The rotation rate error due to these sources is then calculated and compared to measurement data. A simple regression model is used to compensate the rotation rate error with temperature measurement at the outside of the fiber coil. To realize a compact and robust optical package for some of the relevant optical system components an approach based on ion exchanged waveguides in thin glass was developed. This waveguides are used to realize 1x2 and 1x4 splitter with fiber coupling interface or direct photodiode coupling.

Generation of 70-fs pulses at 286 μm from a mid-infrared fiber laser

NASA Astrophysics Data System (ADS)

Woodward, R. I.; Hudson, D. D.; Fuerbach, A.; Jackson, S. D.

2017-12-01

We propose and demonstrate a simple route to few-optical-cycle pulse generation from a mid-infrared fiber laser through nonlinear compression of pulses from a holmium-doped fiber oscillator using a short length of chalcogenide fiber and a grating pair. Pulses from the oscillator with 265-fs duration at 2.86 {\\mu}m are spectrally broadened through self-phase modulation in step-index As2S3 fiber to 141-nm bandwidth and then re-compressed to 70 fs (7.3 optical cycles). These are the shortest pulses from a mid-infrared fiber system to date, and we note that our system is compact, robust, and uses only commercially available components. The scalability of this approach is also discussed, supported by numerical modeling.

Real-time, ultrahigh-resolution, optical coherence tomography with an all-fiber, femtosecond fiber laser continuum at 1.5 microm.

PubMed

Nishizawa, N; Chen, Y; Hsiung, P; Ippen, E P; Fujimoto, J G

2004-12-15

Real-time, ultrahigh-resolution optical coherence tomography (OCT) is demonstrated in the 1.4-1.7-microm wavelength region with a stretched-pulse, passively mode-locked, Er-doped fiber laser and highly nonlinear fiber. The fiber laser generates 100-mW, linearly chirped pulses at a 51-MHz repetition rate. The pulses are compressed and then coupled into a normally dispersive highly nonlinear fiber to generate a low-noise supercontinuum with a 180-nm FWHM bandwidth and 38 mW of output power. This light source is stable, compact, and broadband, permitting high-speed, real-time, high-resolution OCT imaging. In vivo high-speed OCT imaging of human skin with approximately 5.5-microm resolution and 99-dB sensitivity is demonstrated.

Monolithic thulium-doped fiber laser

NASA Astrophysics Data System (ADS)

Aubrecht, J.; Peterka, P.; Honzátko, P.; Todorov, F.; Podrazký, O.; Kamrádek, M.; Proboštová, J.; Kašík, I.

2017-12-01

In this contribution we report and discuss the results of laser characterizations of experimental thulium-doped optical fibers. These active fibers were fabricated in house and were tested in two laser systems to verify their characteristics. The first one, a monolithic fiber laser, was of great interest to us due to its potentially lower overall resonator losses, improved laser lifetime and better robustness. The compact laser cavities with a Bragg gratings inscribed directly into the active optical fiber differs to the second laser system where the Bragg gratings were inscribed into a passive fiber which had to be spliced to the active fiber. The tested fibers were manufactured by the modified chemical vapor deposition method and a solution-doping of thulium ions with Al2O3 or alumina nanoparticles, respectively. We focused on comparison of laser output powers, slope efficiencies, and laser thresholds for particular thulium-doped fiber in different laser configurations.

NDT of fiber-reinforced composites with a new fiber-optic pump–probe laser-ultrasound system☆

PubMed Central

Pelivanov, Ivan; Buma, Takashi; Xia, Jinjun; Wei, Chen-Wei; O’Donnell, Matthew

2014-01-01

Laser-ultrasonics is an attractive and powerful tool for the non-destructive testing and evaluation (NDT&E) of composite materials. Current systems for non-contact detection of ultrasound have relatively low sensitivity compared to contact peizotransducers. They are also expensive, difficult to adjust, and strongly influenced by environmental noise. Moreover, laser-ultrasound (LU) systems typically launch only about 50 firings per second, much slower than the kHz level pulse repetition rate of conventional systems. As demonstrated here, most of these drawbacks can be eliminated by combining a new generation of compact, inexpensive, high repetition rate nanosecond fiber lasers with new developments in fiber telecommunication optics and an optimally designed balanced probe beam detector. In particular, a modified fiber-optic balanced Sagnac interferometer is presented as part of a LU pump–probe system for NDT&E of aircraft composites. The performance of the all-optical system is demonstrated for a number of composite samples with different types and locations of inclusions. PMID:25302156

Magnetic field sensor based on the magnetic-fluid-clad combined with singlemode-multimode-singlemode fiber and large core-offset splicing structure

NASA Astrophysics Data System (ADS)

Lv, Ri-qing; Qian, Jun-kai; Zhao, Yong

2018-03-01

A simple, compact optical fiber magnetic field sensor is proposed and experimentally demonstrated in this paper. It is based on the magnetic-fluid-clad combined with singlemode-multimode-singlemode fiber structure and large core-offset splicing structure. It was protected by a section of capillary tube and was sealed by UV glue. A sensing property study of the combined optical fiber structure and the proposed sensor were carried out. The experimental results show that the sensitivity of the refractive index of the optical fiber sensing structure is up to 156.63 nm/RIU and the magnetic field sensitivity of the proposed sensor is up to -97.24 pm/Oe in the range from 72.4 Oe to 297.8 Oe. The proposed sensor has several other advantages, such as simple structure, small size, easy fabrication and low cost.

All fiber magnetic field sensor with Ferrofluid-filled tapered microstructured optical fiber interferometer.

PubMed

Deng, Ming; Huang, Can; Liu, Danhui; Jin, Wei; Zhu, Tao

2015-08-10

An ultra-compact optical fiber magnetic field sensor based on a microstructured optical fiber (MOF) modal interference and ferrofluid (FF) has been proposed and experimentally demonstrated. The magnetic field sensor was fabricated by splicing a tapered germanium-doped index guided MOF with six big holes injected with FF to two conventional single-mode fibers. The transmission spectra of the proposed sensor under different magnetic field intensities have been measured and theoretically analyzed. Due to an efficient interaction between the magnetic nanoparticles in FF and the excited cladding mode, the magnetic field sensitivity reaches up to117.9pm/mT with a linear range from 0mT to 30mT. Moreover, the fabrication process of the proposed sensor is simple, easy and cost-effective. Therefore, it will be a promising candidate for military, aviation industry, and biomedical applications, especially, for the applications where the space is limited.

Ultralow-frequency-noise stabilization of a laser by locking to an optical fiber-delay line.

PubMed

Kéfélian, Fabien; Jiang, Haifeng; Lemonde, Pierre; Santarelli, Giorgio

2009-04-01

We report the frequency stabilization of an erbium-doped fiber distributed-feedback laser using an all-fiber-based Michelson interferometer of large arm imbalance. The interferometer uses a 1 km SMF-28 optical fiber spool and an acousto-optic modulator allowing heterodyne detection. The frequency-noise power spectral density is reduced by more than 40 dB for Fourier frequencies ranging from 1 Hz to 10 kHz, corresponding to a level well below 1 Hz2/Hz over the entire range; it reaches 10(-2) Hz2/Hz at 1 kHz. Between 40 Hz and 30 kHz, the frequency noise is shown to be comparable to the one obtained by Pound-Drever-Hall locking to a high-finesse Fabry-Perot cavity. Locking to a fiber delay line could consequently represent a reliable, simple, and compact alternative to cavity stabilization for short-term linewidth reduction.

Development of a compact, fiber-coupled, six degree-of-freedom measurement system for precision linear stage metrology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Xiangzhi, E-mail: xiangzhi.yu@rochester.edu; Gillmer, Steven R.; Woody, Shane C.

2016-06-15

A compact, fiber-coupled, six degree-of-freedom measurement system which enables fast, accurate calibration, and error mapping of precision linear stages is presented. The novel design has the advantages of simplicity, compactness, and relatively low cost. This proposed sensor can simultaneously measure displacement, two straightness errors, and changes in pitch, yaw, and roll using a single optical beam traveling between the measurement system and a small target. The optical configuration of the system and the working principle for all degrees-of-freedom are presented along with the influence and compensation of crosstalk motions in roll and straightness measurements. Several comparison experiments are conducted tomore » investigate the feasibility and performance of the proposed system in each degree-of-freedom independently. Comparison experiments to a commercial interferometer demonstrate error standard deviations of 0.33 μm in straightness, 0.14 μrad in pitch, 0.44 μradin yaw, and 45.8 μrad in roll.« less

Compact all-fiber interferometer system for shock acceleration measurement

NASA Astrophysics Data System (ADS)

Zhao, Jiang; Pi, Shaohua; Hong, Guangwei; Zhao, Dong; Jia, Bo

2013-08-01

Acceleration measurement plays an important role in a variety of fields in science and engineering. In particular, the accurate, continuous and non-contact recording of the shock acceleration profiles of the free target surfaces is considered as a critical technique in shock physics. Various kinds of optical interferometers have been developed to monitor the motion of the surfaces of shocked targets since the 1960s, for instance, the velocity interferometer system for any reflector, the fiber optic accelerometer, the photonic Doppler velocimetry system and the displacement interferometer. However, most of such systems rely on the coherent quasi-monochromatic illumination and discrete optic elements, which are costly in setting-up and maintenance. In 1996, L. Levin et al reported an interferometric fiber-optic Doppler velocimeter with high-dynamic range, in which fiber-coupled components were used to replace the discrete optic elements. However, the fringe visibility of the Levin's system is low because of the coupled components, which greatly limits the reliability and accuracy in the shock measurement. In this paper, a compact all-fiber interferometer system for measuring the shock acceleration is developed and tested. The advantage of the system is that not only removes the non-interfering light and enhances the fringe visibility, but also reduces polarization induced signal fading and the polarization induced phase shift. Moreover, it also does not require a source of long coherence length. The system bases entirely on single-mode fiber optics and mainly consists of a polarization beam splitter, a faraday rotator, a depolarizer and a 3×3 single-mode fiber coupler which work at 1310 nm wavelength. The optical systems of the interferometer are described and the experimental results compared with a shock acceleration calibration system with a pneumatic exciter (PneuShockTM Model 9525C by The Modal Shop) are reported. In the shock acceleration test, the interferometer system measured shock acceleration with peak accelerations of ~100,000 m/s2 and the durations of ~0.2 ms which are conformed to the results of the shock acceleration calibration system. The measured relative error of the acceleration is within 3%.

Multiple-Fiber-Optic Probe For Light-Scattering Measurements

NASA Technical Reports Server (NTRS)

Dhadwal, Harbans Singh; Ansari, Rafat R.

1996-01-01

Multiple-fiber-optical probe developed for use in measuring light scattered at various angles from specimens of materials. Designed for both static and dynamic light-scattering measurements of colloidal dispersions. Probe compact, rugged unit containing no moving parts and remains stationary during operation. Not restricted to operation in controlled, research-laboratory environment. Positioned inside or outside light-scattering chamber. Provides simultaneous measurements at small angular intervals over range of angles, made to include small scattering angles by orienting probe in appropriate direction.

A Fiber Optic Probe for the Detection of Cataracts

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Dhadwal, Harbans S.

1993-01-01

A compact fiber optic probe developed for on-orbit science experiments was used to detect the onset of cataracts, a capability that could eliminate physicians' guesswork and result in new drugs to 'dissolve' or slow down the cataract formation before surgery is necessary. The probe is based upon dynamic light scattering (DLS) principles. It has no moving parts, no apertures, and requires no optical alignment. It is flexible and easy to use. Results are presented for excised but intact human eye lenses. In a clinical setting, the device can be easily incorporated into a slit-lamp apparatus (ophthalmoscope) for complete eye diagnostics. In this set-up, the integrated fiber optic probe, the size of a pencil, delivers a low power cone of laser light into the eye of a patient and guides the light which is backscattered by the protein molecules of the lens through a receiving optical fiber to a photo detector. The non-invasive DLS measurements provide rapid determination of protein crystalline size and its size distribution in the eye lens.

Evaluation of an optical fiber probe for in vivo measurement of the photoacoustic response of tissues

NASA Astrophysics Data System (ADS)

Beard, Paul C.; Mills, Timothy N.

1995-05-01

A miniature (1 mm diameter) all-optical photoacoustic probe for generating and detecting ultrasonic thermoelastic waves in biological media at the tip of an optical fiber has been developed. The probe provides a compact and convenient means of performing pulsed photoacoustic spectroscopy for the characterization of biological tissue. The device is based upon a transparent Fabry Perot polymer film ultrasound sensor mounted directly over the end of a multimode optical fiber. The optical fiber is used to deliver nanosecond laser pulses to the tissue producing thermoelastic waves which are then detected by the sensor. Detection sensitivities of 53 mv/MPa and a 10 kPa acoustic noise floor have been demonstrated giving excellent signal to noise ratios in a strong liquid absorber. Lower, but clearly detectable, signals in post mortem human aorta have also been observed. The performance and small physical size of the device suggest that it has the potential to perform remote in situ photoacoustic measurements in tissue.

A compact fiber-optic SHG scanning endomicroscope and its application to visualize cervical remodeling during pregnancy

PubMed Central

Zhang, Yuying; Akins, Meredith L.; Murari, Kartikeya; Xi, Jiefeng; Li, Ming-Jun; Luby-Phelps, Katherine; Mahendroo, Mala; Li, Xingde

2012-01-01

We report the development of an all-fiber-optic scanning endomicroscope capable of high-resolution second harmonic generation (SHG) imaging of biological tissues and demonstrate its utility for monitoring the remodeling of cervical collagen during gestation in mice. The endomicroscope has an overall 2.0 mm diameter and consists of a single customized double-clad fiber, a compact rapid two-dimensional beam scanner, and a miniature compound objective lens for excitation beam delivery, scanning, focusing, and efficient SHG signal collection. Endomicroscopic SHG images of murine cervical tissue sections at different stages of normal pregnancy reveal progressive, quantifiable changes in cervical collagen morphology with resolution similar to that of bench-top SHG microscopy. SHG endomicroscopic imaging of ex vivo murine and human cervical tissues through intact epithelium has also been performed. Our findings demonstrate the feasibility of SHG endomicroscopy technology for staging normal pregnancy, and suggest its potential application as a minimally invasive tool for clinical assessment of abnormal cervical remodeling associated with preterm birth. PMID:22826263

65-fs Yb-doped all-fiber laser using tapered fiber for nonlinearity and dispersion management.

PubMed

Yang, Peilong; Teng, Hao; Fang, Shaobo; Hu, Zhongqi; Chang, Guoqing; Wang, Junli; Wei, Zhiyi

2018-04-15

We implement an ultrafast Yb-doped all-fiber laser which incorporates tapered single-mode fibers for managing nonlinearity and dispersion. The tapered fiber placed in the oscillator cavity aims to broaden the optical spectrum of the intracavity pulse. At the oscillator output, we use another tapered fiber to perform pulse compression. The resulting 66.1-MHz Yb-doped all-fiber oscillator self-starts and generates 0.4-nJ, 65-fs pulses, which can serve as a compact and robust seed source for subsequent high-power, high-energy amplifiers.

100-W 105-μm 0.15NA fiber coupled laser diode module

NASA Astrophysics Data System (ADS)

Karlsen, Scott R.; Price, R. Kirk; Reynolds, Mitch; Brown, Aaron; Mehl, Ron; Patterson, Steve; Martinsen, Robert J.

2009-02-01

We report on the development of a high brightness laser diode module capable of coupling over 100W of optical power into a 105 μm 0.15 NA fiber at 976 nm. This module, based on nLIGHT's Pearl product architecture, utilizes hard soldered single emitters packaged into a compact and passively-cooled package. In this system each diode is individually collimated in the fast and slow axes and free-space coupled into a single fiber. The high brightness module has an optical excitation under 0.13 NA, is virtually free of cladding modes, and has an electrical to optical efficiency greater than 40%. Additionally, this module is compatible with high power 7:1 fused fiber combiners, and initial experiments demonstrated 500W coupled into a 220 μm, 0.22 NA fiber. These modules address the need in the market for higher brightness diode lasers for pumping fiber lasers and direct material processing.

Controlled generation of different orbital angular momentum states in a hybrid optical fiber

NASA Astrophysics Data System (ADS)

Heng, Xiaobo; Gan, Jiulin; Zhang, Zhishen; Qian, Qi; Xu, Shanhui; Yang, Zhongmin

2017-11-01

A new kind of hybrid optical fiber for different orbital angular momentum (OAM) states generation is proposed and investigated by simulation. The hybrid fiber is composed of three main regions: the core, the cladding and the bow-tie-shaped stress-applying zones (SAZs). The SAZs are symmetrically distributed on both sides of the core and filled with piezoelectric material PZT-5H which would generate radial mechanical movement when subjected to an electric field. The strain applied by the SAZs introduces anisotropic variation of the material permittivity which affect the propagation of the guided modes along the fiber core. The OAM modes of | l | = 1 , 2 , 3 can be generated by setting the appropriate electric potential applied in the SAZs. This fiber-based structure and electric control design enable the generation and adjustment of OAM states with the merits of accuracy, compactness and practicality, which would have potential application in OAM optical fiber communication systems and other systems utilizing OAM light.

Fiber-optic refractometer based on an etched high-Q π-phase-shifted fiber-Bragg-grating.

PubMed

Zhang, Qi; Ianno, Natale J; Han, Ming

2013-07-10

We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q π-phase-shifted fiber-Bragg-grating (πFBG) that is chemically etched to the core of the fiber. Due to the p phase-shift, a strong πFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched πFBG demonstrated here has a diameter of ~9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit) at an ambient refractive index of 1.318. The reflection spectrum of the etched πFBG features an extremely narrow notch with a linewidth of only 2.1 pm in water centered at ~1,550 nm, corresponding to a Q-factor of 7.4 × 10(5), which allows for potentially significantly improved sensitivity over refractometers based on regular fiber Bragg gratings.

Shaping of Looped Miniaturized Chalcogenide Fiber Sensing Heads for Mid-Infrared Sensing

PubMed Central

Houizot, Patrick; Anne, Marie-Laure; Boussard-Plédel, Catherine; Loréal, Olivier; Tariel, Hugues; Lucas, Jacques; Bureau, Bruno

2014-01-01

Chalcogenide glass fibers are promising photonic tools to develop Fiber Evanescent Wave Spectroscopy (FEWS) optical sensors working in the mid-infrared region. Numerous pioneering works have already been carried out showing their efficiency, especially for bio-medical applications. Nevertheless, this technology remains confined to academic studies at the laboratory scale because chalcogenide glass fibers are difficult to shape to produce reliable, sensitive and compact sensors. In this paper, a new method for designing and fabricating a compact and robust sensing head with a selenide glass fiber is described. Compact looped sensing heads with diameter equal to 2 mm were thus shaped. This represents an outstanding achievement considering the brittleness of such uncoated fibers. FEWS experiments were implemented using alcoholic solutions as target samples showing that the sensitivity is higher than with the routinely used classical fiber. It is also shown that the best compromise in term of sensitivity is to fabricate a sensing head including two full loops. From a mechanical point of view, the breaking loads of the loop shaped head are also much higher than with classical fiber. Finally, this achievement paves the way for the use of mid-infrared technology during in situ and even in vivo medical operations. Indeed, is is now possible to slide a chalcogenide glass fiber in the operating channel of a standard 2.8 mm diameter catheter. PMID:25264953

Compact Efficient Lidar Receiver for Measuring Atmospheric Aerosols

NASA Technical Reports Server (NTRS)

Gili, Christopher; De Young, Russell

2006-01-01

A small, light weight, and efficient aerosol lidar receiver was constructed and tested. Weight and space savings were realized by using rigid optic tubes and mounting cubes to package the steering optics and detectors in a compact assembly. The receiver had a 1064nm channel using an APD detector. The 532nm channel was split (90/10) into an analog channel (90%) and a photon counting channel (10%). The efficiency of the 1064nm channel with optical filter was 44.0%. The efficiency of the analog 532nm channel was 61.4% with the optical filter, and the efficiency of the 532nm photon counting channel was 7.6% with the optical filter. The results of the atmospheric tests show that the detectors were able to consistently return accurate results. The lidar receiver was able to detect distinct cloud layers, and the lidar returns also agreed across the different detectors. The use of a light weight fiber-coupled telescope reduced weight and allowed great latitude in detector assembly positioning due to the flexibility enabled by the use of fiber optics. The receiver is now ready to be deployed for aircraft or ground based aerosol lidar measurements.

Microphotonic devices for compact planar lightwave circuits and sensor systems

NASA Astrophysics Data System (ADS)

Cardenas Gonzalez, Jaime

2005-07-01

Higher levels of integration in planar lightwave circuits and sensor systems can reduce fabrication costs and broaden viable applications for optical network and sensor systems. For example, increased integration and functionality can lead to sensor systems that are compact enough for easy transport, rugged enough for field applications, and sensitive enough even for laboratory applications. On the other hand, more functional and compact planar lightwave circuits can make optical networks components less expensive for the metro and access markets in urban areas and allow penetration of fiber to the home. Thus, there is an important area of opportunity for increased integration to provide low cost, compact solutions in both network components and sensor systems. In this dissertation, a novel splitting structure for microcantilever deflection detection is introduced. The splitting structure is designed so that its splitting ratio is dependent on the vertical position of the microcantilever. With this structure, microcantilevers sensitized to detect different analytes or biological agents can be integrated into an array on a single chip. Additionally, the integration of a depolarizer into the optoelectronic integrated circuit in an interferometric fiber optic gyroscope is presented as a means for cost reduction. The savings come in avoiding labor intensive fiber pigtailing steps by permitting batch fabrication of these components. In particular, this dissertation focuses on the design of the waveguides and polarization rotator, and the impact of imperfect components on the performance of the depolarizer. In the area of planar lightwave circuits, this dissertation presents the development of a fabrication process for single air interface bends (SAIBs). SAIBs can increase integration by reducing the area necessary to make a waveguide bend. Fabrication and measurement of a 45° SAIB with a bend efficiency of 93.4% for TM polarization and 92.7% for TE polarization are presented.

Highly compact fiber Fabry-Perot interferometer: A new instrument design

NASA Astrophysics Data System (ADS)

Nowakowski, B. K.; Smith, D. T.; Smith, S. T.

2016-11-01

This paper presents the design, construction, and characterization of a new optical-fiber-based, low-finesse Fabry-Perot interferometer with a simple cavity formed by two reflecting surfaces (the end of a cleaved optical fiber and a plane, reflecting counter-surface), for the continuous measurement of displacements of several nanometers to several tens of millimeters. No beam collimation or focusing optics are required, resulting in a displacement sensor that is extremely compact (optical fiber diameter 125 μm), is surprisingly tolerant of misalignment (more than 5°), and can be used over a very wide range of temperatures and environmental conditions, including ultra-high-vacuum. The displacement measurement is derived from interferometric phase measurements using an infrared laser source whose wavelength is modulated sinusoidally at a frequency f. The phase signal is in turn derived from changes in the amplitudes of demodulated signals, at both the modulation frequency, f, and its harmonic at 2f, coming from a photodetector that is monitoring light intensity reflected back from the cavity as the cavity length changes. Simple quadrature detection results in phase errors corresponding to displacement errors of up to 25 nm, but by using compensation algorithms discussed in this paper, these inherent non-linearities can be reduced to below 3 nm. In addition, wavelength sweep capability enables measurement of the absolute surface separation. This experimental design creates a unique set of displacement measuring capabilities not previously combined in a single interferometer.

Research on dual-parameter optical fiber sensor based on thin-core fiber and spherical structure

NASA Astrophysics Data System (ADS)

Tong, Zhengrong; Wang, Xue; Zhang, Weihua; Xue, Lifang

2018-04-01

A novel dual-parameter optical fiber sensor is proposed and experimentally demonstrated. The proposed sensor is based on a fiber in-line Mach-Zehnder interferometer, which is fabricated by sandwiching a section of thin-core fiber between two spherical structures made of single-mode fibers. The transmission spectrum exhibits the response of the interference between the core and the different cladding modes. Due to the different wavelength shifts of the two selected dips, the simultaneous measurement of temperature and the surrounding refractive index can be achieved. The measured temperature sensitivities are 0.067 nm/°C and 0.050 nm/°C, and the refractive index sensitivities are  -119.9 nm/RIU and  -69.71 nm/RIU, respectively. In addition, the compact size, simple fabrication and cost-effectiveness of the fiber sensor are also advantages.

Analysis on the impact of FBG reflectance spectrum with different optical fiber connection in vacuum thermal environment

NASA Astrophysics Data System (ADS)

Zhang, Jingchuan; Zhang, Wen; Lv, Jianfeng; Liang, Shuo; Wang, Lei; Li, Xiyuan

2018-01-01

To satisfy the application of fiber grating sensor technology in high vacuum thermal environment, FBG on sleeve compactly single model fiber with two typical different kind of connection such as fiber splicing and optical fiber connector are researched. Influence of the different connection to the characteristic of FBG reflectance spectrum in high vacuum thermal environment is analyzed and verified. First, experimental program of influence on FBG reflection spectrum characteristics is designed. Then, a hardware-in-the-loop detection platform is set up. Finally, the influence of temperature and vacuum on the reflection peak power of FBG with two typical different connections under high vacuum thermal environment is studied and verified. Experimental results indicate that: when vacuum varied from normal pressure to 10-4Pa level and then return to normal pressure, temperature of two different single-mode optical fiber connection dropped to -196 °C from room temperature and then returned to room temperature, after 224 hours, the peak power of the FBG reflectance spectrum did not change. It provided the experimental basis for the application of optical fiber sensing technology in high vacuum (pressure about 10-4Pa level) and thermal environment (-196 °C temperature cycle).

Effects of polarization mode dispersion on polarization-entangled photons generated via broadband pumped spontaneous parametric down-conversion

PubMed Central

Lim, Hyang-Tag; Hong, Kang-Hee; Kim, Yoon-Ho

2016-01-01

An inexpensive and compact frequency multi-mode diode laser enables a compact two-photon polarization entanglement source via the continuous wave broadband pumped spontaneous parametric down-conversion (SPDC) process. Entanglement degradation caused by polarization mode dispersion (PMD) is one of the critical issues in optical fiber-based polarization entanglement distribution. We theoretically and experimentally investigate how the initial entanglement is degraded when the two-photon polarization entangled state undergoes PMD. We report an effect of PMD unique to broadband pumped SPDC, equally applicable to pulsed pumping as well as cw broadband pumping, which is that the amount of the entanglement degradation is asymmetrical to the PMD introduced to each quantum channel. We believe that our results have important applications in long-distance distribution of polarization entanglement via optical fiber channels. PMID:27174100

Development of a novel fiber-optic sensor to measure radon in the deep ocean

NASA Astrophysics Data System (ADS)

Monteiro, Catarina; Guimarães, Diana; Jorge, Pedro; Barbosa, Susana

2017-04-01

The radon concentration in the deep ocean has gained increasing interest in the last decades. The underwater monitoring of this natural radioactive gas can give important information about submarine groundwater discharges, groundwater migration and contamination. Radon concentration has also been studied as a possible indicator of earthquake events which can have devastating consequences when the epicenter is located at the sea. In contrast with radon monitoring studies in caves, mines, and underground soil, there is an utter lack of information about radon in deep-sea. These measurements are particularly difficult to attain due to the challenges that marine-like environments post to electronic sensing devices and their maintenance over time. Gamma rays emitted by radon's progeny can be easily detected when interacting with a scintillator material. Recently, optical fiber doped with scintillating material has emerged has an alternative for gamma ray detection. The lightweight, low transmission loss, immunity to electromagnetic interference and the cost effectiveness makes optical fiber a compelling solution for radiation detection when compared to conventional sensors. In this work a compact all-fiber optical sensor is developed for continuous gamma ray detection in the deep sea. This sensor is composed by a scintillating optical fiber coupled to a polymeric optical fiber that allows the detection of low levels of radiation.

Small form factor optical fiber connector evaluation for harsh environments

NASA Astrophysics Data System (ADS)

Ott, Melanie N.; Thomes, W. Joe, Jr.; Chuska, Richard F.; Switzer, Robert; Blair, Diana E.

2011-09-01

For the past decade NASA programs have utilized the Diamond AVIM connector for optical fiber assemblies on space flight instrumentation. These connectors have been used in communications, sensing and LIDAR systems where repeatability and high performance are required. Recently Diamond has released a smaller form factor optical fiber connector called the "Mini-AVIM" which although more compact still includes the tight tolerances and the ratcheting feature of the heritage AVIM. NASA Goddard Space Flight Center Photonics Group in the Parts, Packaging and Assembly Technologies Office has been performing evaluations of this connector to determine how it compares to the performance of the AVIM connector and to assess its feasibility for harsh environmental applications. Vibration and thermal testing were performed on the Mini-AVIM with both multi-mode and single-mode optical fiber using insitu optical transmission monitoring. Random vibration testing was performed using typical launch condition profiles for most NASA missions but extended to 35 Grms, which is much higher than most requirements. Thermal testing was performed incrementally up to a range of -55°C to +125°C. The test results include both unjacketed fiber and cabled assembly evaluations. The data presented here indicate that the Mini-AVIM provides a viable option for small form factor applications that require a high performance optical fiber connector.

Multicore fiber beamforming network for broadband satellite communications

NASA Astrophysics Data System (ADS)

Zainullin, Airat; Vidal, Borja; Macho, Andres; Llorente, Roberto

2017-02-01

Multi-core fiber (MCF) has been one of the main innovations in fiber optics in the last decade. Reported work on MCF has been focused on increasing the transmission capacity of optical communication links by exploiting space-division multiplexing. Additionally, MCF presents a strong potential in optical beamforming networks. The use of MCF can increase the compactness of the broadband antenna array controller. This is of utmost importance in platforms where size and weight are critical parameters such as communications satellites and airplanes. Here, an optical beamforming architecture that exploits the space-division capacity of MCF to implement compact optical beamforming networks is proposed, being a new application field for MCF. The experimental demonstration of this system using a 4-core MCF that controls a four-element antenna array is reported. An analysis of the impact of MCF on the performance of antenna arrays is presented. The analysis indicates that the main limitation comes from the relatively high insertion loss in the MCF fan-in and fan-out devices, which leads to angle dependent losses which can be mitigated by using fixed optical attenuators or a photonic lantern to reduce MCF insertion loss. The crosstalk requirements are also experimentally evaluated for the proposed MCF-based architecture. The potential signal impairment in the beamforming network is analytically evaluated, being of special importance when MCF with a large number of cores is considered. Finally, the optimization of the proposed MCF-based beamforming network is addressed targeting the scalability to large arrays.

Towards co-packaging of photonics and microelectronics in existing manufacturing facilities

NASA Astrophysics Data System (ADS)

Janta-Polczynski, Alexander; Cyr, Elaine; Bougie, Jerome; Drouin, Alain; Langlois, Richard; Childers, Darrell; Takenobu, Shotaro; Taira, Yoichi; Lichoulas, Ted W.; Kamlapurkar, Swetha; Engelmann, Sebastian; Fortier, Paul; Boyer, Nicolas; Barwicz, Tymon

2018-02-01

The impact of integrated photonics on optical interconnects is currently muted by challenges in photonic packaging and in the dense integration of photonic modules with microelectronic components on printed circuit boards. Single mode optics requires tight alignment tolerance for optical coupling and maintaining this alignment in a cost-efficient package can be challenging during thermal excursions arising from downstream microelectronic assembly processes. In addition, the form factor of typical fiber connectors is incompatible with the dense module integration expected on printed circuit boards. We have implemented novel approaches to interfacing photonic chips to standard optical fibers. These leverage standard high throughput microelectronic assembly tooling and self-alignment techniques resulting in photonic packaging that is scalable in manufacturing volume and in the number of optical IOs per chip. In addition, using dense optical fiber connectors with space-efficient latching of fiber patch cables results in compact module size and efficient board integration, bringing the optics closer to the logic chip to alleviate bandwidth bottlenecks. This packaging direction is also well suited for embedding optics in multi-chip modules, including both photonic and microelectronic chips. We discuss the challenges and rewards in this type of configuration such as thermal management and signal integrity.

Conjugation of fiber-coupled wide-band light sources and acousto-optical spectral elements

NASA Astrophysics Data System (ADS)

Machikhin, Alexander; Batshev, Vladislav; Polschikova, Olga; Khokhlov, Demid; Pozhar, Vitold; Gorevoy, Alexey

2017-12-01

Endoscopic instrumentation is widely used for diagnostics and surgery. The imaging systems, which provide the hyperspectral information of the tissues accessible by endoscopes, are particularly interesting and promising for in vivo photoluminescence diagnostics and therapy of tumour and inflammatory diseases. To add the spectral imaging feature to standard video endoscopes, we propose to implement acousto-optical (AO) filtration of wide-band illumination of incandescent-lamp-based light sources. To collect maximum light and direct it to the fiber-optic light guide inside the endoscopic probe, we have developed and tested the optical system for coupling the light source, the acousto-optical tunable filter (AOTF) and the light guide. The system is compact and compatible with the standard endoscopic components.

Single Mode Fiber Optic Transceiver Using Short Wavelength Active Devices In Long Wavelength Fiber

NASA Astrophysics Data System (ADS)

Gillham, Frederick J.; Campbell, Daniel R.; Corke, Michael; Stowe, David W.

1990-01-01

Presently, single mode optical fiber technology is being utilized in systems to supply telephone service to the subscriber. However, in an attempt to be competitive with copper based systems, there are many development programs underway to determine the most cost effective solution while still providing a service that will either satisfy or be upgradeable to satisfy the demands of the consumer for the next 10 to 20 years. One such approach is to combine low cost laser transmitters and silicon receivers, which have been developed for the "compact disc" industry, with fiber that operates in the single mode regime at 1300 nm. In this paper, an optical transceiver will be presented, consisting of a compact disc laser, a silicon detector and a single mode coupler at 1300 nm. A possible system layout is presented which operates at 780 nm bi-directionally for POTS and upgradeable to 1300 nm for video services. There are several important design criteria that have to be considered in the development of such a system which will be addressed. These include: 1. Optimization of coupled power from laser to fiber while maintaining stable launched conditions over a wide range of environmental conditions. 2. Consideration of the multimode operation of the 1300 nm single mode fiber while operating in the 780 nm wavelength region. 3. Development of a low cost pseudo-wavelength division multiplexer for 1300 nm single mode/780 nm multimode operation and a low cost dual mode 50/50, 780 nm splitter using 1300 nm fiber. Details will be given of the design criteria and solution in terms of optimized design. Results of the performance of several prototype devices will be given with indications of the merits of this approach and where further development effort should be applied.

Demonstration of a stand-alone cylindrical fiber coil for optical amplifiers

NASA Astrophysics Data System (ADS)

Laxton, Steven R.; Bravo, Tyler; Madsen, Christi K.

2015-08-01

The design, fabrication and measurement of a cylindrical fiber coil structure is presented that has applications for compact fiber-optic amplifiers. A multimode fiber is used as a surrogate for a dual clad, rare-earth doped fiber for coil fabrication and optical testing. A ray trace algorithm, written in Python, was used to simulate the behavior of light travelling along the waveguide path. An in-house fabrication method was developed using 3D printed parts designed in SolidWorks and assembled with Arduino-controlled stepper motors for coil winding. Ultraviolet-cured epoxy was used to bind the coils into a rigid cylinder. Bend losses are introduced by the coil, and a measurement of the losses for two coil lengths was obtained experimentally. The measurements confirm that bend losses through a multimode fiber, representative of pump light propagating in a dual-clad rare-earth doped fiber, are relatively wavelength independent over a large spectral range and that higher order modes are extinguished quickly while lower order modes transmit through the windings with relatively low loss.

Object recognition through a multi-mode fiber

NASA Astrophysics Data System (ADS)

Takagi, Ryosuke; Horisaki, Ryoichi; Tanida, Jun

2017-04-01

We present a method of recognizing an object through a multi-mode fiber. A number of speckle patterns transmitted through a multi-mode fiber are provided to a classifier based on machine learning. We experimentally demonstrated binary classification of face and non-face targets based on the method. The measurement process of the experimental setup was random and nonlinear because a multi-mode fiber is a typical strongly scattering medium and any reference light was not used in our setup. Comparisons between three supervised learning methods, support vector machine, adaptive boosting, and neural network, are also provided. All of those learning methods achieved high accuracy rates at about 90% for the classification. The approach presented here can realize a compact and smart optical sensor. It is practically useful for medical applications, such as endoscopy. Also our study indicated a promising utilization of artificial intelligence, which has rapidly progressed, for reducing optical and computational costs in optical sensing systems.

Dual comb generation from a mode-locked fiber laser with orthogonally polarized interlaced pulses.

PubMed

Akosman, Ahmet E; Sander, Michelle Y

2017-08-07

Ultra-high precision dual-comb spectroscopy traditionally requires two mode-locked, fully stabilized lasers with complex feedback electronics. We present a novel mode-locked operation regime in a thulium-holmium co-doped fiber laser, a frequency-halved state with orthogonally polarized interlaced pulses, for dual comb generation from a single source. In a linear fiber laser cavity, an ultrafast pulse train composed of co-generated, equal intensity and orthogonally polarized consecutive pulses at half of the fundamental repetition rate is demonstrated based on vector solitons. Upon optical interference of the orthogonally polarized pulse trains, two stable microwave RF beat combs are formed, effectively down-converting the optical properties into the microwave regime. These co-generated, dual polarization interlaced pulse trains, from one all-fiber laser configuration with common mode suppression, thus provide an attractive compact source for dual-comb spectroscopy, optical metrology and polarization entanglement measurements.

Method and apparatus for monitoring and measuring the surface tension of a fluid using fiber optics

DOEpatents

Abraham, Bernard M.; Ketterson, John B.; Bohanon, Thomas M.; Mikrut, John M.

1994-01-01

A non-contact method and apparatus for measuring and monitoring the surface of a fluid using fiber optics and interferometric detection to permit measurement mechanical characteristics' fluid surfaces. The apparatus employs an alternating electric field gradient for generating a capillary wave on the surface of the fluid. A fiber optic coupler and optical fiber directs a portion of a laser beam onto the surface of the fluid, another portion of the laser beam onto the photo sensor, and directs light reflected from the surface of the fluid onto the photo sensor. The output of the photo sensor is processed and coupled to a phase sensitive detector to permit measurement of phase shift between the drive signal creating the capillary wave and the detected signal. This phase shift information is then used to determine mechanical properties of the fluid surface such as surface tension, surface elasticity, and surface inhomogeneity. The resulting test structure is easily made compact, portable, and easy to align and use.

All fiber optics circular-state swept source polarization-sensitive optical coherence tomography.

PubMed

Lin, Hermann; Kao, Meng-Chun; Lai, Chih-Ming; Huang, Jyun-Cin; Kuo, Wen-Chuan

2014-02-01

A swept source (SS)-based circular-state (CS) polarization-sensitive optical coherence tomography (PS-OCT) constructed entirely with polarization-maintaining fiber optics components is proposed with the experimental verification. By means of the proposed calibration scheme, bulk quarter-wave plates can be replaced by fiber optics polarization controllers to, therefore, realize an all-fiber optics CS SSPS-OCT. We also present a numerical dispersion compensation method, which can not only enhance the axial resolution, but also improve the signal-to-noise ratio of the images. We demonstrate that this compact and portable CS SSPS-OCT system with an accuracy comparable to bulk optics systems requires less stringent lens alignment and can possibly serve as a technology to realize PS-OCT instrument for clinical applications (e.g., endoscopy). The largest deviations in the phase retardation (PR) and fast-axis (FA) angle due to sample probe in the linear scanning and a rotation angle smaller than 65 deg were of the same order as those in stationary probe setups. The influence of fiber bending on the measured PR and FA is also investigated. The largest deviations of the PR were 3.5 deg and the measured FA change by ~12 to 21 deg. Finally, in vivo imaging of the human fingertip and nail was successfully demonstrated with a linear scanning probe.

Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis.

PubMed

Herrera-Piad, Luis A; Haus, Joseph W; Jauregui-Vazquez, Daniel; Sierra-Hernandez, Juan M; Estudillo-Ayala, Julian M; Lopez-Dieguez, Yanelis; Rojas-Laguna, Roberto

2017-10-20

A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material.

Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis

PubMed Central

Herrera-Piad, Luis A.; Jauregui-Vazquez, Daniel; Sierra-Hernandez, Juan M.; Lopez-Dieguez, Yanelis

2017-01-01

A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material. PMID:29053570

Fiber optic systems in the UV region

NASA Astrophysics Data System (ADS)

Huebner, Michael; Meyer, H.; Klein, Karl-Friedrich; Hillrichs, G.; Ruetting, Martin; Veidemanis, M.; Spangenberg, Bernd; Clarkin, James P.; Nelson, Gary W.

2000-05-01

Mainly due to the unexpected progress in manufacturing of solarization-reduced all-silica fibers, new fiber-optic applications in the UV-region are feasible. However, the other components like the UV-sources and the detector- systems have to be improved, too. Especially, the miniaturization is very important fitting to the small-sized fiber-optic assemblies leading to compact and mobile UV- analytical systems. Based on independent improvements in the preform and fiber processing, UV-improved fibers with different properties have been developed. The best UV-fiber for the prosed applications is selectable by its short and long-term spectral behavior, especially in the region from 190 to 350 nm. The spectrum of the UV-source and the power density in the fiber have an influence on the nonlinear transmission and the damaging level; however, hydrogen can reduce the UV-defect concentration. After determining the diffusion processes in the fiber, the UV-lifetime in commercially available all-silica fibers can be predicted. Newest results with light from deuterium-lamps, excimer- lasers and 5th harmonics of Nd:YAG laser will be shown. Many activities are in the field of UV-sources. In addition to new UV-lasers like the Nd:YAG laser at 213 nm, a new low- power deuterium-lamp with smaller dimensions has been introduced last year. Properties of this lamp will be discussed, taking into account some of the application requirements. Finally, some new applications with UV-fiber optics will be shown; especially the TLC-method can be improved significantly, combining a 2-row fiber-array with a diode-array spectrometer optimized for fiber-optics.

Reflective electroabsorption modular for compact base station radio-over-fiber systems

NASA Astrophysics Data System (ADS)

Wu, Yang; Chang, Wei-Xi; Yu, Paul K. L.

2003-07-01

A Radio-over-Fiber system with simplified Base Station (BS) is proposed in which a single chip DBR Reflective Electro-absorption Modulator (REAM) serves both as an optical transceiver and as a mixer at the BS. It enables full duplex optical transmission for base band and RF band services simultaneously due to good isolation between uplink and downlink at the same chip. Grating structure is incorporated into the EA modulator for the sake of system design. It also improves yield and efficiency of high-speed devices.

Optical Fiber Thermometer Based on Fiber Bragg Gratings

NASA Astrophysics Data System (ADS)

Rosli, Ekbal Bin; Mohd. Noor, Uzer

2018-03-01

Fiber Bragg grating has generated much interest in use as sensors to measure strain, temperature, and other physical parameters. It also the most common component used to develop this sensor with the advantages of simple, intrinsic sensing elements, electrically passive operation, EMI immunity, high sensitivity, compact size and potentially low cost [6]. This paper reports the design of an optical fiber thermometer based on fiber Bragg gratings. The system was developed for detecting temperature and strain by monitoring the shift of Bragg wavelength. The shifting of Bragg wavelength is used to indicate the temperature and strain due to the change in the surrounding temperature and strain. When the temperature and strain reach the exact wavelength level of the system, the temperature and strain value will display on the Arduino liquid crystal display (LCD). The optical fiber will provide the broadband light source and after passing the FBG the Bragg wavelength into the optical spectrum analyzer (OSA). The system is based on FBG as a physical quantity sensor. The temperatures measured is taken from the water bath and that of the strain is provided by amount of slotted mass used. The outcome of this project is to characterize the Bragg wavelength shifting from the fiber Bragg grating output. As the conclusion, this project provides an efficient optical fiber thermometer in measuring temperature and strain in order to replace the use of conventional electrical instruments.

Monolithic integrated optic fiber Bragg grating sensor interrogator

NASA Astrophysics Data System (ADS)

Mendoza, Edgar A.; Esterkin, Yan; Kempen, Cornelia; Sun, Songjian

2010-04-01

Fiber Bragg gratings (FBGs) are a mature sensing technology that has gained rapid acceptance in civil, aerospace, chemical and petrochemical, medicine, aviation and automotive industries. Fiber Bragg grating sensors can be use for a variety of measurements including strain, stress, vibration, acoustics, acceleration, pressure, temperature, moisture, and corrosion distributed at multiple locations within the structure using a single fiber element. The most prominent advantages of FBGs are: small size and light weight, multiple FBG transducers on a single fiber, and immunity to radio frequency interference. A major disadvantage of FBG technology is that conventional state-of-the-art fiber Bragg grating interrogation systems are typically bulky, heavy, and costly bench top instruments that are assembled from off-the-shelf fiber optic and optical components integrated with a signal electronics board into an instrument console. Based on the need for a compact FBG interrogation system, this paper describes recent progress towards the development of a miniature fiber Bragg grating sensor interrogator (FBG-TransceiverTM) system based on multi-channel monolithic integrated optic sensor microchip technology. The integrated optic microchip technology enables the monolithic integration of all of the functionalities, both passive and active, of conventional bench top FBG sensor interrogators systems, packaged in a miniaturized, low power operation, 2-cm x 5-cm small form factor (SFF) package suitable for the long-term structural health monitoring in applications where size, weight, and power are critical for operation.

Compact cantilever couplers for low-loss fiber coupling to silicon photonic integrated circuits.

PubMed

Wood, Michael; Sun, Peng; Reano, Ronald M

2012-01-02

We demonstrate coupling from tapered optical fibers to 450 nm by 250 nm silicon strip waveguides using compact cantilever couplers. The couplers consist of silicon inverse width tapers embedded within silicon dioxide cantilevers. Finite difference time domain simulations are used to design the length of the silicon inverse width taper to as short as 6.5 μm for a cantilever width of 2 μm. Modeling of various strip waveguide taper profiles shows reduced coupling losses for a quadratic taper profile. Infrared measurements of fabricated devices demonstrate average coupling losses of 0.62 dB per connection for the quasi-TE mode and 0.50 dB per connection for the quasi-TM mode across the optical telecommunications C band. In the wavelength range from 1477 nm to 1580 nm, coupling losses for both polarizations are less than 1 dB per connection. The compact, broadband, and low-loss coupling scheme enables direct access to photonic integrated circuits on an entire chip surface without the need for dicing or cleaving the chip.

All-Optical Fiber Hanbury Brown & Twiss Interferometer to study 1300 nm single photon emission of a metamorphic InAs Quantum Dot

PubMed Central

Muñoz-Matutano, G.; Barrera, D.; Fernández-Pousa, C.R.; Chulia-Jordan, R.; Seravalli, L.; Trevisi, G.; Frigeri, P.; Sales, S.; Martínez-Pastor, J.

2016-01-01

New optical fiber based spectroscopic tools open the possibility to develop more robust and efficient characterization experiments. Spectral filtering and light reflection have been used to produce compact and versatile fiber based optical cavities and sensors. Moreover, these technologies would be also suitable to study N-photon correlations, where high collection efficiency and frequency tunability is desirable. We demonstrated single photon emission of a single quantum dot emitting at 1300 nm, using a Fiber Bragg Grating for wavelength filtering and InGaAs Avalanche Photodiodes operated in Geiger mode for single photon detection. As we do not observe any significant fine structure splitting for the neutral exciton transition within our spectral resolution (46 μeV), metamorphic QD single photon emission studied with our all-fiber Hanbury Brown & Twiss interferometer could lead to a more efficient analysis of entangled photon sources at telecom wavelength. This all-optical fiber scheme opens the door to new first and second order interferometers to study photon indistinguishability, entangled photon and photon cross correlation in the more interesting telecom wavelengths. PMID:27257122

Efficient pump module coupling >1kW from a compact detachable fiber

NASA Astrophysics Data System (ADS)

Dogan, M.; Chin, R. H.; Fulghum, S.; Jacob, J. H.; Chin, A. K.

2018-02-01

In the most developed fiber amplifiers, optical pump power is introduced into the 400μm-diameter, 0.46NA first cladding of the double-clad, Yb-doped, gain fiber, using a (6+1):1 multi-mode fiber combiner. For this configuration, the core diameter and numerical aperture of the pump delivery fibers have maximum values of 225μm and 0.22, respectively. This paper presents the first fiber-coupled laser-diode pump module emitting more than 1kW of claddingmode- stripped power from a detachable 225μm, 0.22NA delivery fiber at 976nm. The electrical-to-optical power conversion efficiency at 1kW is 50%. The FWHM spectral width at 1kW output is 4nm and has an excellent overlap with the narrow absorption spectrum of ytterbium in glass. Six of these pump modules attached to a (6+1):1 multimode combiner enable a 5-6kW, single-mode, Yb-doped fiber amplifier.

Orientation-dependent fiber-optic accelerometer based on grating inscription over fiber cladding.

PubMed

Rong, Qiangzhou; Qiao, Xueguang; Guo, Tuan; Bao, Weijia; Su, Dan; Yang, Hangzhou

2014-12-01

An orientation-sensitive fiber-optic accelerometer based on grating inscription over fiber cladding has been demonstrated. The sensor probe comprises a compact structure in which a short section of thin-core fiber (TCF) stub containing a "cladding" fiber Bragg grating (FBG) is spliced to another single-mode fiber (SMF) without any lateral offset. A femtosecond laser side-illumination technique was utilized to ensure that the grating inscription remains close to the core-cladding interface of the TCF. The core mode and the cladding mode of the TCF are coupled at the core-mismatch junction, and two well-defined resonances in reflection appear from the downstream FBG, in which the cladding resonance exhibits a strong polarization and bending dependence due to the asymmetrical distribution of the cladding FBG along the fiber cross section. Strong orientation dependence of the vibration (acceleration) measurement has been achieved by power detection of the cladding resonance. Meanwhile, the unwanted power fluctuations and temperature perturbations can be referenced out by monitoring the fundamental core resonance.

Reconfigurable optical multiplexer based on liquid crystals for polymer optical fiber networks

NASA Astrophysics Data System (ADS)

Lallana, P. C.; Vázquez, C.; Pena, J. M. S.; Vergaz, R.

2006-12-01

In this work, different novel 3×1 multiplexer structures for being used in polymer optical fiber networks are proposed. Designs are compact, scalable, and of low consumption, capable of operating in a large wavelength range simultaneously 660, 850, and 1300 nm, due to the use of nematic liquid crystal cells. Light that comes from each input port is handled independently and eight operation modes are possible. Control electronics has been made using a programmable integrated circuit. Electronic system makes available the managing of the optical stage using a computer. An additional four optical sensors have been included for allowing the optical status checking. Finally, a polarization independent multiplexer has been implemented and tested. Insertion losses less than 4 dB and isolation better than 23 dB have been measured. In addition, 30-ms and 15-ms setup and rise times have been obtained. The proposed multiplexer can be used in any polymer optical fiber network, even in perfluorinated graded index one, and it can be specially useful in optical sensor networks, or in coarse wavelength division multiplexing networks.

A Very Compact, High Speed and Rugged Acousto-Optic Tunable Filter for Wavelength Division Demultiplexing in Fiber Optic Communication Networks. Phase 1

DTIC Science & Technology

1995-06-30

Novel concepts of near-collinear/collinear acousto - optic interactions have been investigated during this SBIR Phase I program. As a result, several...new acousto - optic tunable filters have been built and tested. The program is highlighted by: (1) Design, fabrication and experimental demonstration of...a novel TeO2 near-collinear acousto - optic tunable filter has been designed, fabricated and tested. The device exhibits a 1.29 nm spectral resolution

Towards an Imaging Mid-Infrared Heterodyne Spectrometer

NASA Technical Reports Server (NTRS)

Hewagama, T.; Aslam, S.; Jones, H.; Kostiuk, T.; Villanueva, G.; Roman, P.; Shaw, G. B.; Livengood, T.; Allen, J. E.

2012-01-01

We are developing a concept for a compact, low-mass, low-power, mid-infrared (MIR; 5- 12 microns) imaging heterodyne spectrometer that incorporates fiber optic coupling, Quantum Cascade Laser (QCL) local oscillator, photomixer array, and Radio Frequency Software Defined Readout (RFSDR) for spectral analysis. Planetary Decadal Surveys have highlighted the need for miniaturized, robust, low-mass, and minimal power remote sensing technologies for flight missions. The drive for miniaturization of remote sensing spectroscopy and radiometry techniques has been a continuing process. The advent of MIR fibers, and MEMS techniques for producing waveguides has proven to be an important recent advancement for miniaturization of infrared spectrometers. In conjunction with well-established photonics techniques, the miniaturization of spectrometers is transitioning from classic free space optical systems to waveguide/fiber-based structures for light transport and producing interference effects. By their very nature, these new devices are compact and lightweight. Mercury-Cadmium-Telluride (MCT) and Quantum Well Infrared Photodiodes (QWIP) arrays for heterodyne applications are also being developed. Bulky electronics is another barrier that precluded the extension of heterodyne systems into imaging applications, and our RFSDR will address this aspect.

Fiber-Optic Refractometer Based on an Etched High-Q π-Phase-Shifted Fiber-Bragg-Grating

PubMed Central

Zhang, Qi; Ianno, Natale J.; Han, Ming

2013-01-01

We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q π-phase-shifted fiber-Bragg-grating (πFBG) that is chemically etched to the core of the fiber. Due to the π phase-shift, a strong πFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched πFBG demonstrated here has a diameter of ∼9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit) at an ambient refractive index of 1.318. The reflection spectrum of the etched πFBG features an extremely narrow notch with a linewidth of only 2.1 pm in water centered at ∼1,550 nm, corresponding to a Q-factor of 7.4 × 105, which allows for potentially significantly improved sensitivity over refractometers based on regular fiber Bragg gratings. PMID:23845932

A differential detection scheme of spectral shifts in long-period fiber gratings

NASA Astrophysics Data System (ADS)

Zhelyazkova, Katerina; Eftimov, Tinko; Smietana, Mateusz; Bock, Wojtek

2010-10-01

In this work we present an analysis of the response of a compact, simple and inexpensive optoelectronic sensor system intended to detect spectral shifts of a long-period fiber grating (LPG). The system makes use of a diffraction grating and a couple of receiving optical fibers that pick up signals at two different wavelengths. This differential detection system provides the same useful information from an LPG-based sensor as with a conventional laboratory system using optical spectrum analyzers for monitoring the minimum offset of LPG. The design of the fiber detection pair as a function of the parameters of the dispersion grating, the pick-up fiber and the LPG parameters, is presented in detail. Simulation of the detection system responses is presented using real from spectral shifts in nano-coated LPGs caused by the evaporation of various liquids such as water, ethanol and acetone, which are examples of corrosive, flammable and hazardous substances. Fiber optic sensors with similar detection can find applications in structural health monitoring for moisture detection, monitoring the spillage of toxic and flammable substances in industry etc.

In-line optical fiber metallic mirror reflector for monolithic common path optical coherence tomography probes.

PubMed

Singh, Kanwarpal; Reddy, Rohith; Sharma, Gargi; Verma, Yogesh; Gardecki, Joseph A; Tearney, Guillermo

2018-03-01

Endoscopic optical coherence tomography probes suffer from various artifacts due to dispersion imbalance and polarization mismatch between reference and sample arm light. Such artifacts can be minimized using a common path approach. In this work, we demonstrate a miniaturized common path probe for optical coherence tomography using an inline fiber mirror. A common path optical fiber probe suitable for performing high-resolution endoscopic optical coherence tomography imaging was developed. To achieve common path functionality, an inline fiber mirror was fabricated using a thin gold layer. A commercially available swept source engine was used to test the designed probe in a cadaver human coronary artery ex vivo. We achieved a sensitivity of 104 dB for this probe using a swept source optical coherence tomography system. To test the probe, images of a cadaver human coronary artery were obtained, demonstrating the quality that is comparable to those obtained by OCT systems with separate reference arms. Additionally, we demonstrate recovery of ranging depth by use of a Michelson interferometer in the detection path. We developed a miniaturized monolithic inline fiber mirror-based common path probe for optical coherence tomography. Owing to its simplicity, our design will be helpful in endoscopic applications that require high-resolution probes in a compact form factor while reducing system complexity. Lasers Surg. Med. 50:230-235, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Miniature fiber optic loop subcomponent for compact sensors and dense routing

NASA Astrophysics Data System (ADS)

Gillham, Frederick J.; Stowe, David W.; Ouellette, Thomas R.; Pryshlak, Adrian P.

1999-05-01

Fiber optic data links and embedded sensors, such as Fabry- Perot and Mach-Zehnders, are important elements in smart structure architectures. Unfortunately, one problem with optical fiber is the inherent limit through which fibers and cables can be looped. A revolutionary, patented technology has been developed which overcomes this problem. Based on processing the fiber into low loss miniature bends, it permits routing the fiber to difficult areas, and minimizing the size of sensors and components. The minimum bend diameter for singlemode fiber is typically over two inches in diameter, to avoid light attenuation and limit stresses which could prematurely break the fiber. With the new miniature bend technology, bend diameters as small as 1 mm are readily achieved. One embodiment is a sub-component with standard singlemode fiber formed into a 180 degree bend and packaged in a glass tube only 1.5 mm OD X 8 mm long, Figure 1. Measured insertion loss is less than 0.2 dB from 1260 nm to 1680 nm. A final processing step which anneals the fiber into the eventual curvature, reduces the internal stress, thereby resulting in long life expectancy with robust immunity to external loading. This paper addresses the optical and physical performance of the sub-component. Particular attention is paid to attenuation spectra, polarization dependent loss, reflectance, thermal cycle, damp heat, and shock tests. Applications are presented which employs the bend technology. Concatenating right angle bends into a 'wire harness' demonstrates the ability to route fiber through a smart engine or satellite structure. Miniature optical coils are proposed for sensors and expansion joints.

Portable fiber-optic taper coupled optical microscopy platform

NASA Astrophysics Data System (ADS)

Wang, Weiming; Yu, Yan; Huang, Hui; Ou, Jinping

2017-04-01

The optical fiber taper coupled with CMOS has advantages of high sensitivity, compact structure and low distortion in the imaging platform. So it is widely used in low light, high speed and X-ray imaging systems. In the meanwhile, the peculiarity of the coupled structure can meet the needs of the demand in microscopy imaging. Toward this end, we developed a microscopic imaging platform based on the coupling of cellphone camera module and fiber optic taper for the measurement of the human blood samples and ascaris lumbricoides. The platform, weighing 70 grams, is based on the existing camera module of the smartphone and a fiber-optic array which providing a magnification factor of 6x.The top facet of the taper, on which samples are placed, serves as an irregular sampling grid for contact imaging. The magnified images of the sample, located on the bottom facet of the fiber, are then projected onto the CMOS sensor. This paper introduces the portable medical imaging system based on the optical fiber coupling with CMOS, and theoretically analyzes the feasibility of the system. The image data and process results either can be stored on the memory or transmitted to the remote medical institutions for the telemedicine. We validate the performance of this cell-phone based microscopy platform using human blood samples and test target, achieving comparable results to a standard bench-top microscope.

Compact Fiber-Parametric Devices for Biophotonics Applications

DTIC Science & Technology

2012-03-01

coming in the fiber from the pump overlap temporally and spatially with the pulses fed back from a Fabry -Perot cavity (Sharping, 2010). Fiber optical...Some laser systems such as the Nd:YAG system used in this study, uses a Fabry -Perot cavity in which two mirrors are arranged parallel to one another... Fabry -Perot cavity formed between one end of the PCF and a metallic mirror (M3). The output coupler is a short-pass dielectric (SPD) or a long-pass

Design of compact surface optical coupler based on vertically curved silicon waveguide for high-numerical-aperture single-mode optical fiber

NASA Astrophysics Data System (ADS)

Atsumi, Yuki; Yoshida, Tomoya; Omoda, Emiko; Sakakibara, Youichi

2017-09-01

A surface optical coupler based on a vertically curved Si waveguide was designed for coupling with high-numerical aperture single-mode optical fibers with a mode-field diameter of 5 µm. This coupler has a quite small device size, with a height of approximately 12 µm, achieved by introducing an effective spot-size converter configured with the combination of an extremely short Si exponential-inverse taper and a dome-structured SiO2 lens formed on the coupler top. The designed coupler shows high-efficiency optical coupling, with a loss of 0.8 dB for TE polarized light, as well as broad-band coupling with a 0.5-dB-loss band of 420 nm.

Compact Packaging of Photonic Millimeter-Wave Receiver

NASA Technical Reports Server (NTRS)

Nguyen, Hung; Pouch, John; Miranda, Felix; Levi, Anthony F.

2007-01-01

A carrier structure made from a single silicon substrate is the basis of a compact, lightweight, relatively inexpensive package that holds the main optical/electronic coupling components of a photonic millimeter-wave receiver based on a lithium niobate resonator disk. The design of the package is simple and provides for precise relative placement of optical components, eliminating the need for complex, bulky positioning mechanisms like those commonly used to align optical components to optimize focus and coupling. Although a prototype of the package was fabricated as a discrete unit, the design is amenable to integration of the package into a larger photonic and/or electronic receiver system. The components (see figure) include a lithium niobate optical resonator disk of 5-mm diameter and .200- m thickness, positioned adjacent to a millimeter- wave resonator electrode. Other components include input and output coupling prisms and input and output optical fibers tipped with ball lenses for focusing and collimation, respectively. Laser light is introduced via the input optical fiber and focused into the input coupling prism. The input coupling prism is positioned near (but not in contact with) the resonator disk so that by means of evanescent-wave coupling, the input laser light in the prism gives rise to laser light propagating circumferentially in guided modes in the resonator disk. Similarly, a portion of the circumferentially propagating optical power is extracted from the disk by evanescent-wave coupling from the disk to the output coupling prism, from whence the light passes through the collimating ball lens into the output optical fiber. The lens-tipped optical fibers must be positioned at a specified focal distance from the prisms. The optical fibers and the prisms must be correctly positioned relative to the resonator disk and must be oriented to obtain the angle of incidence (55 in the prototype) required for evanescent-wave coupling of light into and out of the desired guided modes in the resonator disk. To satisfy all these requirements, precise alignment features are formed in the silicon substrate by use of a conventional wet-etching process. These features include a 5-mm-diameter, 50- m-deep cavity that holds the disk; two trapezoidal-cross-section recesses for the prisms; and two grooves that hold the optical fibers at the correct positions and angles relative to the prisms and disk. The fiber grooves contain abrupt tapers, near the prisms, that serve as hard stops for positioning the lenses at the focal distance from the prisms. There are also two grooves for prismadjusting rods. The design provides a little slack in the prism recesses for adjusting the positions of the prisms by means of these rods to optimize the optical coupling.

Absolute dual-comb spectroscopy at 1.55 μm by free-running Er:fiber lasers

NASA Astrophysics Data System (ADS)

Cassinerio, Marco; Gambetta, Alessio; Coluccelli, Nicola; Laporta, Paolo; Galzerano, Gianluca

2014-06-01

We report on a compact scheme for absolute referencing and coherent averaging for dual-comb based spectrometers, exploiting a single continuous-wave (CW) laser in a transfer oscillator configuration. The same CW laser is used for both absolute calibration of the optical frequency axis and the generation of a correction signal which is used for a real-time jitter compensation in a fully electrical feed-forward scheme. The technique is applied to a near-infrared spectrometer based on a pair of free-running mode-locked Er:fiber lasers, allowing to perform real-time absolute-frequency measurements over an optical bandwidth of more than 25 nm, with coherent interferogram averaging over 1-s acquisition time, leading to a signal-to-noise ratio improvement of 29 dB over the 50 μs single shot acquisition. Using 10-cm single pass cell, a value of 1.9 × 10-4 cm-1 Hz-0.5 noise-equivalent-absorption over 1 s integration time is obtained, which can be further scaled down with a multi-pass or resonant cavity. The adoption of a single CW laser, together with the absence of optical locks, and the full-fiber design makes this spectrometer a robust and compact system to be employed in gas-sensing applications.

Metal-Organic Framework Thin Film Coated Optical Fiber Sensors: A Novel Waveguide-Based Chemical Sensing Platform.

PubMed

Kim, Ki-Joong; Lu, Ping; Culp, Jeffrey T; Ohodnicki, Paul R

2018-02-23

Integration of optical fiber with sensitive thin films offers great potential for the realization of novel chemical sensing platforms. In this study, we present a simple design strategy and high performance of nanoporous metal-organic framework (MOF) based optical gas sensors, which enables detection of a wide range of concentrations of small molecules based upon extremely small differences in refractive indices as a function of analyte adsorption within the MOF framework. Thin and compact MOF films can be uniformly formed and tightly bound on the surface of etched optical fiber through a simple solution method which is critical for manufacturability of MOF-based sensor devices. The resulting sensors show high sensitivity/selectivity to CO 2 gas relative to other small gases (H 2 , N 2 , O 2 , and CO) with rapid (

Design and fabrication of a microlens on the sidewall of an optical fiber with a metallized 45 degrees end face.

PubMed

Kim, Myun-Sik; Jo, Kyoung-Woo; Lee, Jong-Hyun

2005-07-01

We propose a method for designing a self-aligned microlens. We have improved its fabrication by employing metallization on a 45 degrees angled surface of the optical fiber. We designed the focal length of the microlens to be 14.0 microm, considering the dimensions of a scanning near-field optical microscopy (SNOM) probe, and we calculated possible dimensions of diameter and height by the ray-tracing method. The modeling of lens formation was also carried out with two assumptions: no volume change and no movement of peripheral parts of the photoresist (PR) on the substrate during reflow. To fabricate a microlens of diameter 16.0 microm and height 5.0 microm we exposed a coated PR to UV light guided into the optical fiber, followed by optimized reflow of 150 degrees C for 2 min. For this microlens the focal length and the beam waist were 14.0 and 1.4 microm, respectively. This lens can be used for compact optical data storage.

Eat-by-light fiber-optic and micro-optic devices for food quality and safety assessment

NASA Astrophysics Data System (ADS)

Mignani, A. G.; Ciaccheri, L.; Cucci, C.; Mencaglia, A. A.; Cimato, A.; Attilio, C.; Thienpont, H.; Ottevaere, H.; Paolesse, R.; Mastroianni, M.; Monti, D.; Buonocore, G.; Del Nobile, A.; Mentana, A.; Grimaldi, M. F.; Dall'Asta, C.; Faccini, A.; Galaverna, G.; Dossena, A.

2007-06-01

A selection is presented of fiber-optic and micro-optic devices that have been designed and tested for guaranteeing the quality and safety of typical foods, such as extra virgin olive oil, beer, and milk. Scattered colorimetry is used to authenticate various types of extra virgin olive oil and beer, while a fiber-optic-based device for UV-VIS-NIR absorption spectroscopy is exploited in order to obtain the hyperspectral optical signature of olive oil. This is done not only for authentication purposes, but also so as to correlate the spectral data with the content of fatty acids, which are important nutritional factors. A micro-optic sensor for the detection of olive oil aroma that is capable of distinguishing different ageing levels of extra virgin olive oil is also presented. It shows effective potential for acting as a smart cap of bottled olive oil in order to achieve a non-destructive olfactory perception of oil ageing. Lastly, a compact portable fluorometer for the rapid monitoring of the carcinogenic M1 aflatoxin in milk, is experimented.

Eat-by-light: fiber-optic and micro-optic devices for food safety and quality assessment

NASA Astrophysics Data System (ADS)

Mignani, A. G.; Ciaccheri, L.; Cucci, C.; Mencaglia, A. A.; Cimato, A.; Attilio, C.; Thienpont, H.; Ottevaere, H.; Paolesse, R.; Mastroianni, M.; Monti, D.; Buonocore, G.; Del Nobile, A.; Mentana, A.; Dall'Asta, C.; Faccini, A.; Galaverna, G.; Dossena, A.

2007-07-01

A selection of fiber-optic and micro-optic devices is presented designed and tested for monitoring the quality and safety of typical foods, namely the extra virgin olive oil, the beer, and the milk. Scattered colorimetry is used for the authentication of various types of extra virgin olive oil and beer, while a fiber-optic-based device for UV-VIS-NIR absorption spectroscopy is exploited in order to obtain the hyperspectral optical signature of olive oil. This is done not only for authentication purposes, but also so as to correlate the spectral data with the content of fatty acids that are important nutritional factors. A micro-optic sensor for the detection of olive oil aroma is presented. It is capable of distinguishing different ageing levels of extra virgin olive oil. It shows effective potential for acting as a smart cap of bottled olive oil in order to achieve a non-destructive olfactory perception of oil ageing. Lastly, a compact portable fluorometer is experimented for the rapid monitoring of the carcinogenic M1 aflatoxin in milk.

Highly Tm3+ doped germanate glass and its single mode fiber for 2.0 μm laser

PubMed Central

Wen, Xin; Tang, Guowu; Yang, Qi; Chen, Xiaodong; Qian, Qi; Zhang, Qinyuan; Yang, Zhongmin

2016-01-01

Highly Tm3+ doped optical fibers are urgently desirable for 2.0 μm compact single-frequency fiber laser and high-repetition-rate mode-locked fiber laser. Here, we systematically investigated the optical parameters, energy transfer processes and thermal properties of Tm3+ doped barium gallo-germanate (BGG) glasses. Highly Tm3+ doped BGG glass single mode (SM) fibers were fabricated by the rod-in-tube technique. The Tm3+ doping concentration reaches 7.6 × 1020 ions/cm3, being the reported highest level in Tm3+ doped BGG SM fibers. Using ultra short (1.6 cm) as-drawn highly Tm3+ doped BGG SM fiber, a single-frequency fiber laser at 1.95 μm has been demonstrated with a maximum output power of 35 mW when in-band pumped by a home-made 1568 nm fiber laser. Additionally, a multilongitudinal-mode fiber laser at 1.95 μm has also been achieved in a 10 cm long as-drawn active fiber, yielding a maximum laser output power of 165 mW and a slope efficiency of 17%. The results confirm that the as-drawn highly Tm3+ doped BGG SM fibers are promising in applications that require high gain and high power from a short piece of active optical fiber. PMID:26828920

Micromachined mirrors for raster-scanning displays and optical fiber switches

NASA Astrophysics Data System (ADS)

Hagelin, Paul Merritt

Micromachines and micro-optics have the potential to shrink the size and cost of free-space optical systems, enabling a new generation of high-performance, compact projection displays and telecommunications equipment. In raster-scanning displays and optical fiber switches, a free-space optical beam can interact with multiple tilt- up micromirrors fabricated on a single substrate. The size, rotation angle, and flatness of the mirror surfaces determine the number of pixels in a raster-display or ports in an optical switch. Single-chip and two-chip optical raster display systems demonstrate static mirror curvature correction, an integrated electronic driver board, and dynamic micromirror performance. Correction for curvature caused by a stress gradient in the micromirror leads to resolution of 102 by 119 pixels in the single-chip display. The optical design of the two-chip display features in-situ mirror curvature measurement and adjustable image magnification with a single output lens. An electronic driver board synchronizes modulation of the optical source with micromirror actuation for the display of images. Dynamic off-axis mirror motion is shown to have minimal influence on resolution. The confocal switch, a free-space optical fiber cross- connect, incorporates micromirrors having a design similar to the image-refresh scanner. Two micromirror arrays redirect optical beams from an input fiber array to the output fibers. The switch architecture supports simultaneous switching of multiple wavelength channels. A 2x2 switch configuration, using single-mode optical fiber at 1550 mn, is demonstrated with insertion loss of -4.2 dB and cross-talk of -50.5 dB. The micromirrors have sufficient size and angular range for scaling to a 32x32 cross-connect switch that has low insertion-loss and low cross-talk.

Research on materials for advanced electronic and aerospace application. [including optical and magnetic data processing, stress corrosion and H2 interaction, and polymeric systems

NASA Technical Reports Server (NTRS)

1975-01-01

Development and understanding of materials most suitable for use in compact magnetic and optical memory systems are discussed. Suppression of metal deterioration by hydrogen is studied. Improvement of mechanical properties of polymers is considered, emphasizing low temperature ductility and compatibility with high modulus fiber materials.

Adaptive Optics System with Deformable Composite Mirror and High Speed, Ultra-Compact Electronics

NASA Astrophysics Data System (ADS)

Chen, Peter C.; Knowles, G. J.; Shea, B. G.

2006-06-01

We report development of a novel adaptive optics system for optical astronomy. Key components are very thin Deformable Mirrors (DM) made of fiber reinforced polymer resins, subminiature PMN-PT actuators, and low power, high bandwidth electronics drive system with compact packaging and minimal wiring. By using specific formulations of fibers, resins, and laminate construction, we are able to fabricate mirror face sheets that are thin (< 2mm), have smooth surfaces and excellent optical shape. The mirrors are not astigmatic and do not develop surface irregularities when cooled. The actuators are small footprint multilayer PMN-PT ceramic devices with large stroke (2- 20 microns), high linearity, low hysteresis, low power, and flat frequency response to >2 KHz. By utilizing QorTek’s proprietary synthetic impendence power supply technology, all the power, control, and signal extraction for many hundreds to 1000s of actuators and sensors can be implemented on a single matrix controller printed circuit board co-mounted with the DM. The matrix controller, in turn requires only a single serial bus interface, thereby obviating the need for massive wiring harnesses. The technology can be scaled up to multi-meter aperture DMs with >100K actuators.

Fiber-Optic Based Compact Gas Leak Detection System

NASA Technical Reports Server (NTRS)

deGroot, Wim A.

1995-01-01

A propellant leak detection system based on Raman scattering principles is introduced. The proposed system is flexible and versatile as the result of the use of optical fibers. It is shown that multiple species can be monitored simultaneously. In this paper oxygen, nitrogen, carbon monoxide, and hydrogen are detected and monitored. The current detection sensitivity for both hydrogen and carbon monoxide is 1% partial pressure at ambient conditions. The sensitivity for oxygen and nitrogen is 0.5% partial pressure. The response time to changes in species concentration is three minutes. This system can be used to monitor multiple species at several locations.

Deep-tissue two-photon imaging in brain and peripheral nerve with a compact high-pulse energy ytterbium fiber laser

NASA Astrophysics Data System (ADS)

Fontaine, Arjun K.; Kirchner, Matthew S.; Caldwell, John H.; Weir, Richard F.; Gibson, Emily A.

2018-02-01

Two-photon microscopy is a powerful tool of current scientific research, allowing optical visualization of structures below the surface of tissues. This is of particular value in neuroscience, where optically accessing regions within the brain is critical for the continued advancement in understanding of neural circuits. However, two-photon imaging at significant depths have typically used Ti:Sapphire based amplifiers that are prohibitively expensive and bulky. In this study, we demonstrate deep tissue two-photon imaging using a compact, inexpensive, turnkey operated Ytterbium fiber laser (Y-Fi, KM Labs). The laser is based on all-normal dispersion (ANDi) that provides short pulse durations and high pulse energies. Depth measurements obtained in ex vivo mouse cortex exceed those obtainable with standard two-photon microscopes using Ti:Sapphire lasers. In addition to demonstrating the capability of deep-tissue imaging in the brain, we investigated imaging depth in highly-scattering white matter with measurements in sciatic nerve showing limited optical penetration of heavily myelinated nerve tissue relative to grey matter.

Method and apparatus for monitoring and measuring the surface tension of a fluid using fiber optics

DOEpatents

Abraham, B.M.; Ketterson, J.B.; Bohanon, T.M.; Mikrut, J.M.

1994-04-12

A non-contact method and apparatus are described for measuring and monitoring the surface of a fluid using fiber optics and interferometric detection to permit measurement of mechanical characteristics of fluid surfaces. The apparatus employs an alternating electric field gradient for generating a capillary wave on the surface of the fluid. A fiber optic coupler and optical fiber directs a portion of a laser beam onto the surface of the fluid, another portion of the laser beam onto the photo sensor, and directs light reflected from the surface of the fluid onto the photo sensor. The output of the photo sensor is processed and coupled to a phase sensitive detector to permit measurement of phase shift between the drive signal creating the capillary wave and the detected signal. This phase shift information is then used to determine mechanical properties of the fluid surface such as surface tension, surface elasticity, and surface inhomogeneity. The resulting test structure is easily made compact, portable, and easy to align and use. 4 figures.

Infrared Hollow Optical Fiber Probe for Localized Carbon Dioxide Measurement in Respiratory Tracts.

PubMed

Katagiri, Takashi; Shibayama, Kyosuke; Iida, Takeru; Matsuura, Yuji

2018-03-27

A real-time gas monitoring system based on optical absorption spectroscopy is proposed for localized carbon dioxide (CO₂) measurement in respiratory tracts. In this system, a small gas cell is attached to the end of a hollow optical fiber that delivers mid-infrared light with small transmission loss. The diameters of the fiber and the gas cell are smaller than 1.2 mm so that the probe can be inserted into a working channel of common bronchoscopes. The dimensions of the gas cell are designed based on absorption spectra of CO₂ standard gases in the 4.2 μm wavelength region, which are measured using a Fourier-transform infrared spectrometer. A miniature gas cell that is comprised of a stainless-steel tube with slots for gas inlet and a micro-mirror is fabricated. A compact probing system with a quantum cascade laser (QCL) light source is built using a gas cell with a hollow optical fiber for monitoring CO₂ concentration. Experimental results using human breaths show the feasibility of the system for in-situ measurement of localized CO₂ concentration in human airways.

Efficient terahertz wave generation from GaP crystals pumped by chirp-controlled pulses from femtosecond photonic crystal fiber amplifier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jiang; Shi, Junkai; Xu, Baozhong

2014-01-20

A chirp-tunable femtosecond 10 W, 42 MHz photonic-crystal-fiber oscillator-amplifier system that is capable of delivering sub-60 fs light pulses at 1040 nm is used to demonstrate high-efficiency terahertz radiation generation via optical rectification in GaP crystals only a few millimeters in length. The optimization of the chirp of the fiber-laser pulses is shown to radically enhance the terahertz output, indicating one possible way to more efficiently use these extended nonlinear crystals in compact fiber-pumped terahertz radiation sources.

Photonic crystal fiber Fabry-Perot interferometers with high-reflectance internal mirrors

NASA Astrophysics Data System (ADS)

Fan, Rong; Hou, Yuanbin; Sun, Wei

2015-06-01

We demonstrated an in-line micro fiber-optic Fabry-Perot interferometer with an air cavity which was created by multi-step fusion splicing a muti-mode photonic crystal fiber (MPCF) to a standard single mode fiber (SMF). The fringe visibility of the interference pattern was up to 20 dB by reshaping the air cavity. Experimental results showed that such a device could be used as a highly sensitive strain sensor with the sensitivity of 4.5 pm/μɛ. Moreover, it offered some other outstanding advantages, such as the extremely compact structure, easy fabrication, low cost, and high accuracy.

Variable path length spectrophotometric probe

DOEpatents

O'Rourke, Patrick E.; McCarty, Jerry E.; Haggard, Ricky A.

1992-01-01

A compact, variable pathlength, fiber optic probe for spectrophotometric measurements of fluids in situ. The probe comprises a probe body with a shaft having a polished end penetrating one side of the probe, a pair of optic fibers, parallel and coterminous, entering the probe opposite the reflecting shaft, and a collimating lens to direct light from one of the fibers to the reflecting surface of the shaft and to direct the reflected light to the second optic fiber. The probe body has an inlet and an outlet port to allow the liquid to enter the probe body and pass between the lens and the reflecting surface of the shaft. A linear stepper motor is connected to the shaft to cause the shaft to advance toward or away from the lens in increments so that absorption measurements can be made at each of the incremental steps. The shaft is sealed to the probe body by a bellows seal to allow freedom of movement of the shaft and yet avoid leakage from the interior of the probe.

Internal Mirror Optical Fiber Couplers

NASA Astrophysics Data System (ADS)

Shin, Jong-Dug

A fusion splicing technique has been used to produce angled dielectric mirrors in multimode and single-mode silica fibers. These mirrored fiber couplers serve as compact directional couplers with low excess optical loss (~0.2 dB for multimode and 0.5 dB for single mode at 1.3 μm) and excellent mechanical properties. The reflectance is found to be wavelength dependent and strongly polarization dependent, as expected. Far-field scans of the reflected output power measured with a white-light source show a pattern which is almost circularly symmetric. The splitting ratio in a multimode coupler measured with a laser source is much less dependent on input coupling conditions than in conventional fused biconical-taper couplers. Spectral properties of multilayer fiber mirrors have been investigated experimentally, and a matrix analysis has been used to explain the results.

Temperature sensor based on an isopropanol-sealed photonic crystal fiber in-line interferometer with enhanced refractive index sensitivity.

PubMed

Qiu, Sun-jie; Chen, Ye; Xu, Fei; Lu, Yan-qing

2012-03-01

We fabricate a simple, compact, and stable temperature sensor based on a liquid-sealed photonic crystal fiber (PCF) in-line nonpolarimetric modal interferometer. Different from other reported PCF devices, it does not need expensive polarimetric devices, and the liquid is sealed in one fiber. The device consists of a stub of isopropanol-filled PCF spliced between standard single-mode fibers. The temperature sensitivity (-166 pm/°C) increases over an order of magnitude compared with those of the previous sensors based on air-sealed PCF interferometers built via fusion splicing with the same mechanism. In addition, the refractive index sensitivity also increases. Higher temperature sensitivity can be realized by infiltrating some liquid having a higher thermo-optic coefficient into the microholes of the PCF. © 2012 Optical Society of America

An actively Q-switched fiber laser with cylindrical vector beam generation

NASA Astrophysics Data System (ADS)

Zhang, Jiaojiao; Zhang, Zuxing; Cai, Yu; Wan, Hongdan; Wang, Zhiqiang; Zhang, Lin

2018-03-01

We demonstrate an actively Q-switched fiber laser with cylindrical vector beam (CVB) emission using a few-mode fiber Bragg grating as the mode selection component and an acousto-optic modulator to achieve Q-switching. To the best of our knowledge, this is the first such demonstration. Using a linear cavity configuration, an actively Q-switched CVB with a pulse width of about 64 ns, a pulse energy of 4.25 µJ and a repetition rate of 20 kHz has been obtained. Moreover, by tuning the polarization controllers radially and azimuthally, polarized Q-switched beams can be excited separately with a polarization purity of  >94.5%. This compact Q-switched fiber laser with ns CVB pulse output could find potential applications in the field of material processing, nonlinear optics and so on.

A Highly Sensitive Fiber Optic Sensor Based on Two-Core Fiber for Refractive Index Measurement

PubMed Central

Guzmán-Sepúlveda, José Rafael; Guzmán-Cabrera, Rafael; Torres-Cisneros, Miguel; Sánchez-Mondragón, José Javier; May-Arrioja, Daniel Alberto

2013-01-01

A simple and compact fiber optic sensor based on a two-core fiber is demonstrated for high-performance measurements of refractive indices (RI) of liquids. In order to demonstrate the suitability of the proposed sensor to perform high-sensitivity sensing in a variety of applications, the sensor has been used to measure the RI of binary liquid mixtures. Such measurements can accurately determine the salinity of salt water solutions, and detect the water content of adulterated alcoholic beverages. The largest sensitivity of the RI sensor that has been experimentally demonstrated is 3,119 nm per Refractive Index Units (RIU) for the RI range from 1.3160 to 1.3943. On the other hand, our results suggest that the sensitivity can be enhanced up to 3485.67 nm/RIU approximately for the same RI range. PMID:24152878

Small core fiber coupled 60-W laser diode

NASA Astrophysics Data System (ADS)

Fernie, Douglas P.; Mannonen, Ilkka; Raven, Anthony L.

1995-05-01

Semiconductor laser diodes are compact, efficient and reliable sources of laser light and 25 W fiber coupled systems developed by Diomed have been in clinical use for over three years. For certain applications, particularly in the treatment of benign prostatic hyperplasia and flexible endoscopy, higher powers are desirable. In these applications the use of flexible optical fibers of no more than 600 micrometers core diameter is essential for compatibility with most commercial delivery fibers and instrumentation. A high power 60 W diode laser system for driving these small core fibers has been developed. The design requirements for medical applications are analyzed and system performance and results of use in gastroenterology and urology with small core fibers will be presented.

Photonic crystal fiber technology for compact fiber-delivered high-power ultrafast fiber lasers

NASA Astrophysics Data System (ADS)

Triches, Marco; Michieletto, Mattia; Johansen, Mette M.; Jakobsen, Christian; Olesen, Anders S.; Papior, Sidsel R.; Kristensen, Torben; Bondue, Magalie; Weirich, Johannes; Alkeskjold, Thomas T.

2018-02-01

Photonic crystal fiber (PCF) technology has radically impacted the scientific and industrial ultrafast laser market. Reducing platform dimensions are important to decrease cost and footprint while maintaining high optical efficiency. We present our recent work on short 85 μm core ROD-type fiber amplifiers that maintain single-mode performance and excellent beam quality. Robust long-term performance at 100 W average power and 250 kW peak power in 20 ps pulses at 1030 nm wavelength is presented, exceeding 500 h with stable performance in terms of both polarization and power. In addition, we present our recent results on hollow-core ultrafast fiber delivery maintaining high beam quality and polarization purity.

Single-Frequency Narrow Linewidth 2 Micron Fiber Laser

NASA Technical Reports Server (NTRS)

Jiang, Shibin (Inventor); Spiegelberg, Christine (Inventor); Luo, Tao (Inventor)

2006-01-01

A compact single frequency, single-mode 2 .mu.m fiber laser with narrow linewidth, <100 kHz and preferably <100 kHz, is formed with a low phonon energy glass doped with triply ionized rare-earth thulium and/or holmium oxide and fiber gratings formed in sections of passive silica fiber and fused thereto. Formation of the gratings in passive silica fiber both facilitates splicing to other optical components and reduces noise thus improving linewidth. An increased doping concentration of 0.5 to 15 wt. % for thulium, holmium or mixtures thereof produces adequate gain, hence output power levels for fiber lengths less than 5 cm and preferably less than 3 cm to enable single-frequency operation.

Fiber-Optic Temperature Sensor Using a Thin-Film Fabry-Perot Interferometer

NASA Technical Reports Server (NTRS)

Beheim, Glenn

1997-01-01

A fiber-optic temperature sensor was developed that is rugged, compact, stable, and can be inexpensively fabricated. This thin-film interferometric temperature sensor was shown to be capable of providing a +/- 2 C accuracy over the range of -55 to 275 C, throughout a 5000 hr operating life. A temperature-sensitive thin-film Fabry-Perot interferometer can be deposited directly onto the end of a multimode optical fiber. This batch-fabricatable sensor can be manufactured at a much lower cost than can a presently available sensor, which requires the mechanical attachment of a Fabry-Perot interferometer to a fiber. The principal disadvantage of the thin-film sensor is its inherent instability, due to the low processing temperatures that must be used to prevent degradation of the optical fiber's buffer coating. The design of the stable thin-film temperature sensor considered the potential sources of both short and long term drifts. The temperature- sensitive Fabry-Perot interferometer was a silicon film with a thickness of approx. 2 microns. A laser-annealing process was developed which crystallized the silicon film without damaging the optical fiber. The silicon film was encapsulated with a thin layer of Si3N4 over coated with aluminum. Crystallization of the silicon and its encapsulation with a highly stable, impermeable thin-film structure were essential steps in producing a sensor with the required long-term stability.

Compact light-emitting diode optical fiber immobilized TiO2 reactor for photocatalytic water treatment.

PubMed

O'Neal Tugaoen, Heather; Garcia-Segura, Sergi; Hristovski, Kiril; Westerhoff, Paul

2018-02-01

A key barrier to implementing photocatalysis is delivering light to photocatalysts that are in contact with aqueous pollutants. Slurry photocatalyst systems suffer from poor light penetration and require post-treatment to separate the catalyst. The alternative is to deposit photocatalysts on fixed films and deliver light onto the surface or the backside of the attached catalysts. In this study, TiO 2 -coated quartz optical fibers were coupled to light emitting diodes (OF/LED) to improve in situ light delivery. Design factors and mechanisms studied for OF/LEDs in a flow-through reactor included: (i) the influence of number of LED sources coupled to fibers and (ii) the use of multiple optical fibers bundled to a single LED. The light delivery mechanism from the optical fibers into the TiO 2 coatings is thoroughly discussed. To demonstrate influence of design variables, experiments were conducted in the reactor using the chlorinated pollutant para-chlorobenzoic acid (pCBA). From the degradation kinetics of pCBA, the quantum efficiencies (Φ) of oxidation and electrical energies per order (E EO ) were determined. The use of TiO 2 coated optical fiber bundles reduced the energy requirements to deliver photons and increased available surface area, which improved Φ and enhanced oxidative pollutant removal performance (E EO ). Copyright © 2017 Elsevier B.V. All rights reserved.

Intravital multiphoton fluorescence imaging and optical manipulation of spinal cord in mice, using a compact fiber laser system.

PubMed

Oshima, Yusuke; Horiuch, Hideki; Honkura, Naoki; Hikita, Atsuhiko; Ogata, Tadanori; Miura, Hiromasa; Imamura, Takeshi

2014-09-01

Near-infrared ultrafast lasers are widely used for multiphoton excited fluorescence microscopy in living animals. Ti:Sapphire lasers are typically used for multiphoton excitation, but their emission wavelength is restricted below 1,000 nm. The aim of this study is to evaluate the performance of a compact Ytterbium-(Yb-) fiber laser at 1,045 nm for multiphoton excited fluorescence microscopy in spinal cord injury. In this study, we employed a custom-designed microscopy system with a compact Yb-fiber laser and evaluated the performance of this system in in vivo imaging of brain cortex and spinal cord in YFP-H transgenic mice. For in vivo imaging of brain cortex, sharp images of basal dendrites, and pyramidal cells expressing EYFP were successfully captured using the Yb-fiber laser in our microscopy system. We also performed in vivo imaging of axon fibers of spinal cord in the transgenic mice. The obtained images were almost as sharp as those obtained using a conventional ultrafast laser system. In addition, laser ablation and multi-color imaging could be performed simultaneously using the Yb-fiber laser. The high-peak pulse Yb-fiber laser is potentially useful for multimodal bioimaging methods based on a multiphoton excited fluorescence microscopy system that incorporates laser ablation techniques. Our results suggest that microscopy systems of this type could be utilized in studies of neuroscience and clinical use in diagnostics and therapeutic tool for spinal cord injury in the future. © 2014 Wiley Periodicals, Inc.

Design of a frequency domain instrument for simultaneous optical tomography and magnetic resonance imaging of small animals

NASA Astrophysics Data System (ADS)

Masciotti, James M.; Rahim, Shaheed; Grover, Jarrett; Hielscher, Andreas H.

2007-02-01

We present a design for frequency domain instrument that allows for simultaneous gathering of magnetic resonance and diffuse optical tomographic imaging data. This small animal imaging system combines the high anatomical resolution of magnetic resonance imaging (MRI) with the high temporal resolution and physiological information provided by diffuse optical tomography (DOT). The DOT hardware comprises laser diodes and an intensified CCD camera, which are modulated up to 1 GHz by radio frequency (RF) signal generators. An optical imaging head is designed to fit inside the 4 cm inner diameter of a 9.4 T MRI system. Graded index fibers are used to transfer light between the optical hardware and the imaging head within the RF coil. Fiducial markers are integrated into the imaging head to allow the determination of the positions of the source and detector fibers on the MR images and to permit co-registration of MR and optical tomographic images. Detector fibers are arranged compactly and focused through a camera lens onto the photocathode of the intensified CCD camera.

Multi-wavelength photoacoustic system based on high-power diode laser bars

NASA Astrophysics Data System (ADS)

Leggio, Luca; Wiśniowski, Bartosz; Gawali, Sandeep Babu; Rodríguez, Sergio; Sánchez, Miguel; Gallego, Daniel; Carpintero, Guillermo; Lamela, Horacio

2017-03-01

Multi-wavelength laser sources are necessary for a functional photoacoustic (PA) spectroscopy. The use of high-power diode lasers (HPDLs) has aroused great interest for their relatively low costs and small sizes if compared to solid state lasers. However, HPDLs are only available at few wavelengths and can deliver low optical energy (normally in the order of μJ), while diode laser bars (DLBs) offer more wavelengths in the market and can deliver more optical energy. We show the simulations of optical systems for beam coupling of single high-power DLBs operating at different wavelengths (i.e. 808 nm, 880 nm, 910 nm, 940 nm, and 980 nm) into 400-μm optical fibers. Then, in a separate design, the beams of the DLBs are combined in a compact system making use of dichroic mirrors and focusing lenses for beam coupling into a 400-μm optical fiber. The use of optical fibers with small core diameter (< 1 mm) is particularly suggestive for future photoacoustic endoscopy (PAE) applications that require interior examination of the body.

Frequency stabilization of a 2.05 μm laser using hollow-core fiber CO2 frequency reference cell

NASA Astrophysics Data System (ADS)

Meras, Patrick; Poberezhskiy, Ilya Y.; Chang, Daniel H.; Spiers, Gary D.

2010-04-01

We have designed and built a hollow-core fiber frequency reference cell, filled it with CO2, and used it to demonstrate frequency stabilization of a 2.05 μm Tm:Ho:YLF laser using frequency modulation (FM) spectroscopy technique. The frequency reference cell is housed in a compact and robust hermetic package that contains a several meter long hollow-core photonic crystal fiber optically coupled to index-guiding fibers with a fusion splice on one end and a mechanical splice on the other end. The package has connectorized fiber pigtails and a valve used to evacuate, refill it, or adjust the gas pressure. We have demonstrated laser frequency standard deviation decreasing from >450MHz (free-running) to <2.4MHz (stabilized). The 2.05 μm laser wavelength is of particular interest for spectroscopic instruments due to the presence of many CO2 and H20 absorption lines in its vicinity. To our knowledge, this is the first reported demonstration of laser frequency stabilization at this wavelength using a hollow-core fiber reference cell. This approach enables all-fiber implementation of the optical portion of laser frequency stabilization system, thus making it dramatically more lightweight, compact, and robust than the traditional free-space version that utilizes glass or metal gas cells. It can also provide much longer interaction length of light with gas and does not require any alignment. The demonstrated frequency reference cell is particularly attractive for use in aircraft and space coherent lidar instruments for measuring atmospheric CO2 profile.

Semiconductor Lasers and Their Application in Optical Fiber Communication.

ERIC Educational Resources Information Center

Agrawal, Govind P.

1985-01-01

Working principles and operating characteristics of the extremely compact and highly efficient semiconductor lasers are explained. Topics include: the p-n junction; Fabry-Perot cavity; heterostructure semiconductor lasers; materials; emission characteristics; and single-frequency semiconductor lasers. Applications for semiconductor lasers include…

Narrowband spectral filter based on biconical tapered fiber

NASA Astrophysics Data System (ADS)

Celaschi, Sergio; Malheiros-Silveira, Gilliard N.

2018-02-01

The ease of fabrication and compactness of devices based on tapered optical fibers contribute to its potential using in several applications ranging from telecommunication components to sensing devices. In this work, we proposed, fabricated, and characterized a spectral filter made of biconical taper from a coaxial optical fiber. This filter is defined by adiabatically tapering a depressed-cladding fiber. The adiabatic taper profile obtained during fabrication prevents the interference of other modes than HE11 and HE12 ones, which play the main role for the beating phenomenon and the filter response. The evolution of the fiber shapes during the pulling was modeled by two coupled partial differential equations, which relate the normalized cross-section area, and the axial velocity of the fiber elongation. These equations govern the mass and axial momentum conservation. The numerical results of the filter characteristics are in good accordance with the experimental ones. The filter was packaged in order to let it ready for using in optical communication bands. The characteristics are: free spectral range (FSR) of 6.19 nm, insertion loss bellow 0.5 dB, and isolation > 20 dB at C-band. Its transmission spectrum extends from 1200 to 1600 nm where the optical fiber core supports monomode transmission. Such characteristics may also be interesting to be applied in sensing applications. We show preliminary numerical results assuming a biconic taper embedded into a dielectric media, showing promising results for electro-optic sensing applications.

Direct transfer of metallic photonic structures onto end facets of optical fibers

NASA Astrophysics Data System (ADS)

Zhang, Xinping; Liu, Feifei; Lin, Yuanhai

2016-07-01

We present a flexible approach to transfer metallic photonic crystals (MPCs) onto end facets of optical fibers. The MPCs were initially fabricated on a glass substrate with a spacer layer of indium tin oxide (ITO), which was used as a buffer layer in the transferring process. The fiber ends were firstly welded on the top surface of the MPCs by a drop of polymer solution after the solvent evaporated. The ITO layer was then etched by hydrochloric acid (HCl), so that the MPCs got off the substrate and were transferred to the fiber ends. Alternatively, the MPCs may be also etched off the substrate first by immersing the sample in HCl. The ultra-thin MPC sheet consisting of gold nanolines interlaced with photoresist gratings was then transferred to cap the fiber ends. In the later approach, we can choose which side of the MPCs to be used as the contact with the fiber facet. Such methods enabled convenient nanostructuring on optical fiber tips and achieving miniaturized MPC devices with compact integration, extending significantly applications of MPCs. In particular, the fabrications presented in this manuscript enrich the lab-on-fiber engineering techniques and the resultant devices have potential applications in remote sensing and detection systems.

All-fiber 3D vector displacement (bending) sensor based on an eccentric FBG.

PubMed

Bao, Weijia; Rong, Qiangzhou; Chen, Fengyi; Qiao, Xueguang

2018-04-02

We demonstrate a fiber-optic 3D vector displacement sensor based on the monitoring of Bragg reflection from an eccentric grating inscribed in a depressed-cladding fiber using the femtosecond laser side-illumination and phase-mask technique. The compact sensing probe consists of a short section of depressed cladding fiber (DCF) containing eccentrically positioned fiber Bragg gratings. The eccentric grating breaks the cylindrical symmetry of the fiber cross-section and further has bending orientation-dependence. The generated fundamental resonance is strongly sensitive to bending of the fiber, and the direction of the bending plane can be determined from its responses. When integrated with axis strain monitoring, the sensor achieves a 3D vector displacement measurement via simple geometric analysis.

Multi-parameter fiber optic sensors based on fiber random grating

NASA Astrophysics Data System (ADS)

Xu, Yanping; Zhang, Mingjiang; Lu, Ping; Mihailov, Stephen; Bao, Xiaoyi

2017-04-01

Two novel configurations of multi-parameter fiber-optic sensing systems based on the fiber random grating are reported. The fiber random grating is fabricated through femtosecond laser induced refractive index modification over a 10cm standard telecom single mode fiber. In one configuration, the reflective spectrum of the fiber random grating is directly detected and a wavelength-division spectral cross-correlation algorithm is adopted to extract the spectral shifts for simultaneous measurement of temperature, axial strain, and surrounding refractive index. In the other configuration, a random fiber ring laser is constructed by incorporating the random feedback from the random grating. Numerous polarization-dependent spectral filters are formed along the random grating and superimposed to provide multiple lasing lines with high signal-to-noise ratio up to 40dB, which enables a high-fidelity multi-parameter sensing scheme by monitoring the spectral shifts of the lasing lines. Without the need of phase mask for fabrication and with the high physical strength, the random grating based sensors are much simpler and more compact, which could be potentially an excellent alternative for liquid medical sample sensing in biomedical and biochemical applications.

Analysis of a novel sensor interrogation technique based on fiber cavity ring-down (CRD) loop and OTDR

NASA Astrophysics Data System (ADS)

Yüksel, Kivilcim; Yilmaz, Anil

2018-07-01

We present the analysis of a remote sensor based on fiber Cavity Ring-Down (CRD) loop interrogated by an Optical Time Domain Reflectometer (OTDR) taking into account both practical limitations and the related signal processing. A commercial OTDR is used for both pulse generation and sensor output detection. This allows obtaining a compact and simple design for intensity-based sensor applications. This novel sensor interrogation approach is experimentally demonstrated by placing a variable attenuator inside the fiber loop that mimics a sensor head.

Refractive index sensor based on lateral-offset of coreless silica interferometer

NASA Astrophysics Data System (ADS)

Baharin, Nur Faizzah; Azmi, Asrul Izam; Abdullah, Ahmad Sharmi; Mohd Noor, Muhammad Yusof

2018-02-01

A compact, cost-effective and high sensitivity fiber interferometer refractive index (RI) sensor based on symmetrical offset coreless silica fiber (CSF) configuration is proposed, optimized and demonstrated. The sensor is formed by splicing a section of CSF between two CSF sections in an offset manner. Thus, two distinct optical paths are created with large index difference, the first path through the connecting CSF sections and the second path is outside the CSF through the surrounding media. RI sensing is established from direct interaction of light with surrounding media, hence high sensitivity can be achieved with a relatively compact sensor length. In the experimental work, a 1.5 mm sensor demonstrates RI sensitivity of 750 nm/RIU for RI range between 1.33 and 1.345. With the main attributes of high sensitivity and compact size, the proposed sensor can be further developed for related applications including blood diagnosis, water quality control and food industries.

Measurement of chlorine concentration on steel surfaces via fiber-optic laser-induced breakdown spectroscopy in double-pulse configuration

NASA Astrophysics Data System (ADS)

Xiao, X.; Le Berre, S.; Fobar, D. G.; Burger, M.; Skrodzki, P. J.; Hartig, K. C.; Motta, A. T.; Jovanovic, I.

2018-03-01

The corrosive environment provided by chlorine ions on the welds of stainless steel dry cask storage canisters for used nuclear fuel may contribute to the occurrence of stress corrosion cracking. We demonstrate the use of fiber-optic laser-induced breakdown spectroscopy (FOLIBS) in the double-pulse (DP) configuration for high-sensitivity, remote measurement of the surface concentrations of chlorine compatible in constrained space and challenging environment characteristic for dry cask storage systems. Chlorine surface concentrations as low as 5 mg/m2 have been detected and quantified by use of a laboratory-based and a fieldable DP FOLIBS setup with the calibration curve approach. The compact final optics assembly in the fieldable setup is interfaced via two 25-m long optical fibers for high-power laser pulse delivery and plasma emission collection and can be readily integrated into a multi-sensor robotic delivery system for in-situ inspection of dry cask storage systems.

An In-situ Real-Time Optical Fiber Sensor Based on Surface Plasmon Resonance for Monitoring the Growth of TiO2 Thin Films

PubMed Central

Tsao, Yu-Chia; Tsai, Woo-Hu; Shih, Wen-Ching; Wu, Mu-Shiang

2013-01-01

An optical fiber sensor based on surface plasmon resonance (SPR) is proposed for monitoring the thickness of deposited nano-thin films. A side-polished multimode SPR optical fiber sensor with an 850 nm-LD is used as the transducing element for real-time monitoring of the deposited TiO2 thin films. The SPR optical fiber sensor was installed in the TiO2 sputtering system in order to measure the thickness of the deposited sample during TiO2 deposition. The SPR response declined in real-time in relation to the growth of the thickness of the TiO2 thin film. Our results show the same trend of the SPR response in real-time and in spectra taken before and after deposition. The SPR transmitted intensity changes by approximately 18.76% corresponding to 50 nm of deposited TiO2 thin film. We have shown that optical fiber sensors utilizing SPR have the potential for real-time monitoring of the SPR technology of nanometer film thickness. The compact size of the SPR fiber sensor enables it to be positioned inside the deposition chamber, and it could thus measure the film thickness directly in real-time. This technology also has potential application for monitoring the deposition of other materials. Moreover, in-situ real-time SPR optical fiber sensor technology is in inexpensive, disposable technique that has anti-interference properties, and the potential to enable on-line monitoring and monitoring of organic coatings. PMID:23881144

An in-situ real-time optical fiber sensor based on surface plasmon resonance for monitoring the growth of TiO2 thin films.

PubMed

Tsao, Yu-Chia; Tsai, Woo-Hu; Shih, Wen-Ching; Wu, Mu-Shiang

2013-07-23

An optical fiber sensor based on surface plasmon resonance (SPR) is proposed for monitoring the thickness of deposited nano-thin films. A side-polished multimode SPR optical fiber sensor with an 850 nm-LD is used as the transducing element for real-time monitoring of the deposited TiO2 thin films. The SPR optical fiber sensor was installed in the TiO2 sputtering system in order to measure the thickness of the deposited sample during TiO2 deposition. The SPR response declined in real-time in relation to the growth of the thickness of the TiO2 thin film. Our results show the same trend of the SPR response in real-time and in spectra taken before and after deposition. The SPR transmitted intensity changes by approximately 18.76% corresponding to 50 nm of deposited TiO2 thin film. We have shown that optical fiber sensors utilizing SPR have the potential for real-time monitoring of the SPR technology of nanometer film thickness. The compact size of the SPR fiber sensor enables it to be positioned inside the deposition chamber, and it could thus measure the film thickness directly in real-time. This technology also has potential application for monitoring the deposition of other materials. Moreover, in-situ real-time SPR optical fiber sensor technology is in inexpensive, disposable technique that has anti-interference properties, and the potential to enable on-line monitoring and monitoring of organic coatings.

Bidirectional optical subassembly-shaped 20-Gbit/s compact single-mode four-channel wavelength-division multiplexing optical modules for optical multimedia interfaces

NASA Astrophysics Data System (ADS)

Lim, Kwon-Seob; Yu, Hong-Yeon; Park, Hyoung-Jun; Kang, Hyun Seo; Jang, Jae-Hyung

2016-06-01

Low-cost single-mode four-channel optical transmitter and receiver modules using the wavelength-division multiplexing (WDM) method have been developed for long-reach fiber optic applications. The single-mode four-channel WDM optical transmitter and receiver modules consist of two dual-wavelength optical transmitter and receiver submodules, respectively. The integration of two channels in a glass-sealed transistor outline-can package is an effective way to reduce cost and size and to extend the number of channels. The clear eye diagrams with more than about 6 dB of the extinction ratio and the minimum receiver sensitivity of lower than -16 dBm at a bit error rate of 10-12 have been obtained for the transmitter and receiver modules, respectively, at 5 Gbps/channel. The 4K ultrahigh definition contents have been transmitted over a 1-km-long single-mode fiber using a pair of proposed four-channel transmitter optical subassembly and receiver optical subassembly.

Head-mounted LED for optogenetic experiments of freely-behaving animal

NASA Astrophysics Data System (ADS)

Kwon, Ki Yong; Gnade, Andrew G.; Rush, Alexander D.; Patten, Craig D.

2016-03-01

Recent developments in optogenetics have demonstrated the ability to target specific types of neurons with sub-millisecond temporal precision via direct optical stimulation of genetically modified neurons in the brain. In most applications, the beam of a laser is coupled to an optical fiber, which guides and delivers the optical power to the region of interest. Light emitting diodes (LEDs) are an alternative light source for optogenetics and they provide many advantages over a laser based system including cost, size, illumination stability, and fast modulation. Their compact size and low power consumption make LEDs suitable light sources for a wireless optogenetic stimulation system. However, the coupling efficiency of an LED's output light into an optical fiber is lower than a laser due to its noncollimated output light. In typical chronic optogenetic experiment, the output of the light source is transmitted to the brain through a patch cable and a fiber stub implant, and this configuration requires two fiber-to-fiber couplings. Attenuation within the patch cable is potential source of optical power loss. In this study, we report and characterize a recently developed light delivery method for freely-behaving animal experiments. We have developed a head-mounted light source that maximizes the coupling efficiency of an LED light source by eliminating the need for a fiber optic cable. This miniaturized LED is designed to couple directly to the fiber stub implant. Depending on the desired optical power output, the head-mounted LED can be controlled by either a tethered (high power) or battery-powered wireless (moderate power) controller. In the tethered system, the LED is controlled through 40 gauge micro coaxial cable which is thinner, more flexible, and more durable than a fiber optic cable. The battery-powered wireless system uses either infrared or radio frequency transmission to achieve real-time control. Optical, electrical, mechanical, and thermal characteristics of the head-mounted LED were evaluated.

Metal–Organic Framework Thin Film Coated Optical Fiber Sensors: A Novel Waveguide-Based Chemical Sensing Platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Ki-Joong; Lu, Ping; Culp, Jeffrey T.

Integration of optical fiber with sensitive thin films offers great potential for the realization of novel chemical sensing platforms. In this study, we present a simple design strategy and high performance of nanoporous metal–organic framework (MOF) based optical gas sensors, which enables detection of a wide range of concentrations of small molecules based upon extremely small differences in refractive indices as a function of analyte adsorption within the MOF framework. Thin and compact MOF films can be uniformly formed and tightly bound on the surface of etched optical fiber through a simple solution method which is critical for manufacturability ofmore » MOF-based sensor devices. The resulting sensors show high sensitivity/selectivity to CO 2 gas relative to other small gases (H 2, N 2, O 2, and CO) with rapid (< tens of seconds) response time and excellent reversibility, which can be well correlated to the physisorption of gases into a nanoporous MOF. We propose a refractive index based sensing mechanism for the MOF-integrated optical fiber platform which results in an amplification of inherent optical absorption present within the MOF-based sensing layer with increasing values of effective refractive index associated with adsorption of gases.« less

Metal–Organic Framework Thin Film Coated Optical Fiber Sensors: A Novel Waveguide-Based Chemical Sensing Platform

DOE PAGES

Kim, Ki-Joong; Lu, Ping; Culp, Jeffrey T.; ...

2018-01-18

Integration of optical fiber with sensitive thin films offers great potential for the realization of novel chemical sensing platforms. In this study, we present a simple design strategy and high performance of nanoporous metal–organic framework (MOF) based optical gas sensors, which enables detection of a wide range of concentrations of small molecules based upon extremely small differences in refractive indices as a function of analyte adsorption within the MOF framework. Thin and compact MOF films can be uniformly formed and tightly bound on the surface of etched optical fiber through a simple solution method which is critical for manufacturability ofmore » MOF-based sensor devices. The resulting sensors show high sensitivity/selectivity to CO 2 gas relative to other small gases (H 2, N 2, O 2, and CO) with rapid (< tens of seconds) response time and excellent reversibility, which can be well correlated to the physisorption of gases into a nanoporous MOF. We propose a refractive index based sensing mechanism for the MOF-integrated optical fiber platform which results in an amplification of inherent optical absorption present within the MOF-based sensing layer with increasing values of effective refractive index associated with adsorption of gases.« less

Chemical-assisted femtosecond laser writing of lab-in-fibers.

PubMed

Haque, Moez; Lee, Kenneth K C; Ho, Stephen; Fernandes, Luís A; Herman, Peter R

2014-10-07

The lab-on-chip (LOC) platform has presented a powerful opportunity to improve functionalization, parallelization, and miniaturization on planar or multilevel geometries that has not been possible with fiber optic technology. A migration of such LOC devices into the optical fiber platform would therefore open the revolutionary prospect of creating novel lab-in-fiber (LIF) systems on the basis of an efficient optical transport highway for multifunctional sensing. For the LIF, the core optical waveguide inherently offers a facile means to interconnect numerous types of sensing elements along the optical fiber, presenting a radical opportunity for optimizing the packaging and densification of diverse components in convenient geometries beyond that available with conventional LOCs. In this paper, three-dimensional patterning inside the optical fiber by femtosecond laser writing, together with selective chemical etching, is presented as a powerful tool to form refractive index structures such as optical waveguides and gratings as well as to open buried microfluidic channels and optical resonators inside the flexible and robust glass fiber. In this approach, optically smooth surfaces (~12 nm rms) are introduced for the first time inside the fiber cladding that precisely conform to planar nanograting structures when formed by aberration-free focusing with an oil-immersion lens across the cylindrical fiber wall. This process has enabled optofluidic components to be precisely embedded within the fiber to be probed by either the single-mode fiber core waveguide or the laser-formed optical circuits. We establish cladding waveguides, X-couplers, fiber Bragg gratings, microholes, mirrors, optofluidic resonators, and microfluidic reservoirs that define the building blocks for facile interconnection of inline core-waveguide devices with cladding optofluidics. With these components, more advanced, integrated, and multiplexed fiber microsystems are presented demonstrating fluorescence detection, Fabry-Perot interferometric refractometry, and simultaneous sensing of refractive index, temperature, and bending strain. The flexible writing technique and multiplexed sensors described here open powerful prospects to migrate the benefits of LOCs into a more flexible and miniature LIF platform for highly functional and distributed sensing capabilities. The waveguide backbone of the LIF inherently provides an efficient exchange of information, combining sensing data that are attractive in telecom networks, smart catheters for medical procedures, compact sensors for security and defense, shape sensors, and low-cost health care products.

A stable dual-wavelength Q-switch using a compact passive device containing photonics crystal fiber embedded with carbon platinum

NASA Astrophysics Data System (ADS)

Safaei, R.; Amiri, I. S.; Rezayi, M.; Ahmad, H.

2018-01-01

A compact fiber laser utilizing platinum nanoparticles doped on carbon (Pt/C) embedded in photonic crystal fiber capable of generating a stable Q-switch dual-wavelength is designed and verified. Stable Q-switch pulses, with a repetition rate of 73.6 kHz, pulse width of 1.45 µs and power of 3.8 nJ in two separated wavelengths of 1557.39 nm and 1558.86 nm at a pump power of 350 mW, have been obtained. This is a novel method for generating Q-switch dual-wavelength pulses using a well-protected component that introduces both a saturable absorber and Mach-Zehnder interferometer effects simultaneously in the laser cavity. Furthermore, to best of our knowledge, this is the first time that Pt/C nanoparticles have been used in a saturable absorber for optical pulse generation.

Fiber-optic beam control systems using microelectromechanical systems

NASA Astrophysics Data System (ADS)

Sumriddetchkajorn, Sarun

This dissertation, for the first time, proposes, studies, and experimentally demonstrated novel fiber-optic beam control systems based on the use of microelectromechanical system (MEMS) technology in which the miniaturized versions of mechanical systems can be obtained. Beam control modules include optical add/drop filters, optical switches, variable photonic delay lines (VPDLs), and variable optical attenuators (VOAs). The optical add/drop filter functions as a multiwavelength optical switch that offers the ability to drop and add a certain number of desired wavelengths at an intermediate location where access to all the propagating optical channels is not required between transmission terminals. The VOA can also be used in networks where stocking and tracking of fixed attenuators is difficult. Other specific applications of the VOA are optical gain equalization and polarization dependent loss and gain compensation required in high data-rate wavelength division multiplexed (WDM) lightwave systems. A VPDL can be used to adjust timing amongst multiwavelength optical signals in order to reduce timing jitter and burst traffic in photonic packet switching and parallel signal processing systems. In this dissertation, a small tilt micromirror device is proposed for the implementation of all fiber-optic beam control modules. In particular, the macro-pixel approach where several micromirrors are used to manipulate the desired optical beam is introduced to realize high speed and fault tolerant beam control modules. To eliminate the need of careful optical alignment, an all fiber-connectorized multiwavelength optical switch structure is presented and experimentally demonstrated by using a fiber-loop mirror concept with polarization control. In addition, liquid crystal (LC) devices are studied and are used to implement a compact retro- reflective 2 x 2 fiber-optic switch. Compared to MEMS- based mirror technology, the LC technology is more sensitive to temperature, thereby inappropriate to deploy in a harsh environment. With the benefit provided by WDM systems, wavelength sensitive fiber-optic beam controllers are proposed, offering wavelength sensitive time delay and amplitude controls that can be applied in several applications ranging from optical communications to high speed parallel signal processing. (Abstract shortened by UMI.)

Biwavelength transceiver module for parallel simultaneous bidirectional optical interconnections

NASA Astrophysics Data System (ADS)

Nguyen, Nga T. H.; Ukaegbu, Ikechi A.; Sangirov, Jamshid; Cho, Mu-Hee; Lee, Tae-Woo; Park, Hyo-Hoon

2013-12-01

The design of a biwavelength transceiver (TRx) module for parallel simultaneous bidirectional optical interconnects is described. The TRx module has been implemented using two different wavelengths, 850 and 1060 nm, to send and receive signals simultaneously through a common optical interface while optimizing cost and performance. Filtering mirrors are formed in the optical fibers which are embedded on a V-grooved silicon substrate for reflecting and filtering optical signals from/to vertical-cavity surface-emitting laser (VCSEL)/photodiode (PD). The VCSEL and PD are flip-chip bonded on individual silicon optical benches, which are attached on the silicon substrate for optical signal coupling from the VCSEL to fiber and from fiber to the PD. A high-speed and low-loss ceramic printed circuit board, which has a compact size of 0.033 cc, has been designed to carry transmitter and receiver chips for easy packaging of the TRx module. Applied for quad small form-factor pluggable applications at 40-Gbps operation, the four-channel biwavelength TRx module showed clear eye diagrams with a bit error rate (BER) of 10-12 at input powers of -5 and -5.8 dBm for 1060 and 850 nm operation modes, respectively.

Plasmonic fiber-optic vector magnetometer

NASA Astrophysics Data System (ADS)

Zhang, Zhaochuan; Guo, Tuan; Zhang, Xuejun; Xu, Jian; Xie, Wenping; Nie, Ming; Wu, Qiang; Guan, Bai-Ou; Albert, Jacques

2016-03-01

A compact fiber-optic vector magnetometer based on directional scattering between polarized plasmon waves and ferro-magnetic nanoparticles is demonstrated. The sensor configuration reported in this work uses a short section of tilted fiber Bragg grating (TFBG) coated with a nanometer scale gold film and packaged with a magnetic fluid (Fe3O4) inside a capillary. The transmission spectrum of the sensor provides a fine comb of narrowband resonances that overlap with a broader absorption of the surface plasmon resonance (SPR). The wavelength of the SPR attenuation in transmission shows high sensitivity to slight perturbations by magnetic fields, due to the strong directional scattering between the SPR attenuated cladding modes and the magnetic fluid near the fiber surface. Both the orientation (2 nm/deg) and the intensity (1.8 nm/mT) of magnetic fields can be determined unambiguously from the TFBG spectrum. Temperature cross sensitivity can be referenced out by monitoring the wavelength of the core mode resonance simultaneously.

Fiber Delivery of mid-IR lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kriesel, J.M.; Gat, N.; Bernacki, Bruce E.

2011-08-24

Fiber optics for the visible to near infrared (NIR) wavelength regimes (i.e. = 0.42 {mu}m) have proven to be extremely useful for a myriad of applications such as telecommunications, illumination, and sensors because they enable convenient, compact, and remote delivery of laser beams. Similarly, there is a need for fiber optics operating at longer wavelengths. For example, systems operating in the mid-IR regime (i.e., = 314 {mu}m) are being developed to detect trace molecular species with far-reaching applications, such as detecting explosives on surfaces, pollutants in the environment, and biomarkers in the breath of a patient. Furthermore, with the increasingmore » availability of quantum cascade lasers (QCLs) which are semiconductor lasers that operate in the mid-IR regime additional uses are rapidly being developed. Here, we describe the development of hollow-core fibers for delivery of high-quality mid-IR laser beams across a broad spectral range.« less

UW Imaging of Seismic-Physical-Models in Air Using Fiber-Optic Fabry-Perot Interferometer.

PubMed

Rong, Qiangzhou; Hao, Yongxin; Zhou, Ruixiang; Yin, Xunli; Shao, Zhihua; Liang, Lei; Qiao, Xueguang

2017-02-17

A fiber-optic Fabry-Perot interferometer (FPI) has been proposed and demonstrated for the ultrasound wave (UW) imaging of seismic-physical models. The sensor probe comprises a single mode fiber (SMF) that is inserted into a ceramic tube terminated by an ultra-thin gold film. The probe performs with an excellent UW sensitivity thanks to the nanolayer gold film, and thus is capable of detecting a weak UW in air medium. Furthermore, the compact sensor is a symmetrical structure so that it presents a good directionality in the UW detection. The spectral band-side filter technique is used for UW interrogation. After scanning the models using the sensing probe in air, the two-dimensional (2D) images of four physical models are reconstructed.

NASA Tech Briefs, July 2008

NASA Technical Reports Server (NTRS)

2008-01-01

Topics covered include: Torque Sensor Based on Tunnel-Diode Oscillator; Shaft-Angle Sensor Based on Tunnel-Diode Oscillator; Ground Facility for Vicarious Calibration of Skyborne Sensors; Optical Pressure-Temperature Sensor for a Combustion Chamber; Impact-Locator Sensor Panels; Low-Loss Waveguides for Terahertz Frequencies; MEMS/ECD Method for Making Bi(2-x)Sb(x)Te3 Thermoelectric Devices; Low-Temperature Supercapacitors; Making a Back-Illuminated Imager with Back-Side Contact and Alignment Markers; Compact, Single-Stage MMIC InP HEMT Amplifier; Nb(x)Ti(1-x)N Superconducting-Nanowire Single-Photon Detectors; Improved Sand-Compaction Method for Lost-Foam Metal Casting; Improved Probe for Evaluating Compaction of Mold Sand; Polymer-Based Composite Catholytes for Li Thin-Film Cells; Using ALD To Bond CNTs to Substrates and Matrices; Alternating-Composition Layered Ceramic Barrier Coatings; Variable-Structure Control of a Model Glider Airplane; Axial Halbach Magnetic Bearings; Compact, Non-Pneumatic Rock-Powder Samplers; Biochips Containing Arrays of Carbon-Nanotube Electrodes; Nb(x)Ti(1-x)N Superconducting-Nanowire Single-Photon Detectors; Neon as a Buffer Gas for a Mercury-Ion Clock; Miniature Incandescent Lamps as Fiber-Optic Light Sources; Bidirectional Pressure-Regulator System; and Prism Window for Optical Alignment. Single-Grid-Pair Fourier Telescope for Imaging in Hard-X Rays and gamma Rays Range-Gated Metrology with Compact Optical Head Lossless, Multi-Spectral Data Compressor for Improved Compression for Pushbroom-Typetruments.

Simplified Generation of High-Angular-Momentum Light Beams

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Maleki, Lute; Matsko, Andrey; Strekalov, Dmitry; Grudinin, Ivan

2007-01-01

A simplified method of generating a beam of light having a relatively high value of angular momentum (see figure) involves the use of a compact apparatus consisting mainly of a laser, a whispering- gallery-mode (WGM) resonator, and optical fibers. The method also can be used to generate a Bessel beam. ( Bessel beam denotes a member of a class of non-diffracting beams, so named because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have high values of angular momentum.) High-angular-momentum light beams are used in some applications in biology and nanotechnology, wherein they are known for their ability to apply torque to make microscopic objects rotate. High-angular-momentum light beams could also be used to increase bandwidths of fiber-optic communication systems. The present simplified method of generating a high-angular-momentum light beam was conceived as an alternative to prior such methods, which are complicated and require optical setups that include, variously, holograms, modulating Fabry-Perot cavities, or special microstructures. The present simplified method exploits a combination of the complex structure of the electromagnetic field inside a WGM resonator, total internal reflection in the WGM resonator, and the electromagnetic modes supported by an optical fiber. The optical fiber used to extract light from the WGM resonator is made of fused quartz. The output end of this fiber is polished flat and perpendicular to the fiber axis. The input end of this fiber is cut on a slant and placed very close to the WGM resonator at an appropriate position and orientation. To excite the resonant whispering- gallery modes, light is introduced into the WGM resonator via another optical fiber that is part of a pigtailed fiber-optic coupler. Light extracted from the WGM resonator is transformed into a high-angular- momentum beam inside the extraction optical fiber and this beam is emitted from the polished flat output end. By adjusting the geometry of this apparatus, it is possible to generate a variety of optical beams characterized by a wide range of parameters. These beams generally have high angular momenta and can be of either Bessel or Bessel-related types.

Nano-Fabrication Methods for Micro-Miniature Optical Thermometers Suited to High Temperatures and Harsh Environments

NASA Astrophysics Data System (ADS)

DePew, K. A.; Ma, C.; Schiffbauer, J. D.; Wang, J.; Dong, B.; Lally, E.; Wang, A.

2012-12-01

The Center for Photonics Technology (CPT) at Virginia Tech is engaged in cutting edge research of fiber optic sensing technologies. One current research area is the design of fiber optic temperature sensors for harsh environments. Fiber optic temperature sensing offers significant advantages over electronic sensing in terms of size and insensitivity to harsh environmental conditions and electromagnetic interference. In the field, fiber optic thermometers have been used in recent snow cover studies as well as fluvial temperature profiling projects. The extended capabilities of CPT optical sensors open further possibilities for application in additional geologic realms requiring high temperature sensing in corrosive environments. Significant strides have been made in developing single-crystal sapphire based fiber optic sensing elements for high temperature environments which are otherwise difficult to instrument. Utilization of strain insensitive designs and optical sapphire materials allow for thermometers capable of operation above 1500°C with reduced sensitivity to chemical corrosion and mechanical interference. Current efforts in fabrication techniques are reducing the footprint of temperature sensors below the millimeter scale while maintaining high resolution and operating range. The FEI Helios 600 NanoLab workstation at the Virginia Tech Institute for Critical Technologies and Applied Science has been employed, providing the capabilities necessary to reduce the footprint of sensing elements to the dimensions of standard optical communication fiber using a Ga+ focused ion beam (FIB). The capability of semi-distributed multi-point sensing can also be accomplished at this scale using similar FIB milling techniques. The fiber optic thermometer designs resulting from these methods are compact, lightweight, and able to provide remote sensing without need for electrical power at the measurement point. These traits make them an ideal sensing platform for laboratory applications with minimal instrumentation egress as well as field deployment in areas where traditional electronic technologies cannot survive.

Study of nonlinear liquid effects into ytterbium-doped fiber laser for multi-wavelength generation

NASA Astrophysics Data System (ADS)

Lozano-Hernandez, T.; Jauregui-Vazquez, D.; Estudillo-Ayala, J.; Herrera-Piad, L. A.; Rojas-Laguna, R.; Hernandez-Garcia, J. M.; Sierra-Hernandez, J. M.

2018-02-01

We present an experimental study of liquid refractive index effects into Ytterbium ring fiber laser cavity configuration. The laser is operated using a bi-tapered optical fiber immersed in water-alcohol concentrations. When the tapered fiber is dipped into a distilled water, a single lasing line with a peak power centered at 1025 nm is achieved. Afterward, by changing the polarization state into the cavity the lasing line can be switched. Moreover, by modifying the refractive index liquid surrounding media the lasing lines can be controlled and special liquid provide nonlinear response. The laser offers compactness, low effective cost and good stability.

Smart-phone based computational microscopy using multi-frame contact imaging on a fiber-optic array.

PubMed

Navruz, Isa; Coskun, Ahmet F; Wong, Justin; Mohammad, Saqib; Tseng, Derek; Nagi, Richie; Phillips, Stephen; Ozcan, Aydogan

2013-10-21

We demonstrate a cellphone based contact microscopy platform, termed Contact Scope, which can image highly dense or connected samples in transmission mode. Weighing approximately 76 grams, this portable and compact microscope is installed on the existing camera unit of a cellphone using an opto-mechanical add-on, where planar samples of interest are placed in contact with the top facet of a tapered fiber-optic array. This glass-based tapered fiber array has ~9 fold higher density of fiber optic cables on its top facet compared to the bottom one and is illuminated by an incoherent light source, e.g., a simple light-emitting-diode (LED). The transmitted light pattern through the object is then sampled by this array of fiber optic cables, delivering a transmission image of the sample onto the other side of the taper, with ~3× magnification in each direction. This magnified image of the object, located at the bottom facet of the fiber array, is then projected onto the CMOS image sensor of the cellphone using two lenses. While keeping the sample and the cellphone camera at a fixed position, the fiber-optic array is then manually rotated with discrete angular increments of e.g., 1-2 degrees. At each angular position of the fiber-optic array, contact images are captured using the cellphone camera, creating a sequence of transmission images for the same sample. These multi-frame images are digitally fused together based on a shift-and-add algorithm through a custom-developed Android application running on the smart-phone, providing the final microscopic image of the sample, visualized through the screen of the phone. This final computation step improves the resolution and also removes spatial artefacts that arise due to non-uniform sampling of the transmission intensity at the fiber optic array surface. We validated the performance of this cellphone based Contact Scope by imaging resolution test charts and blood smears.

Smart-phone based computational microscopy using multi-frame contact imaging on a fiber-optic array

PubMed Central

Navruz, Isa; Coskun, Ahmet F.; Wong, Justin; Mohammad, Saqib; Tseng, Derek; Nagi, Richie; Phillips, Stephen; Ozcan, Aydogan

2013-01-01

We demonstrate a cellphone based contact microscopy platform, termed Contact Scope, which can image highly dense or connected samples in transmission mode. Weighing approximately 76 grams, this portable and compact microscope is installed on the existing camera unit of a cellphone using an opto-mechanical add-on, where planar samples of interest are placed in contact with the top facet of a tapered fiber-optic array. This glass-based tapered fiber array has ∼9 fold higher density of fiber optic cables on its top facet compared to the bottom one and is illuminated by an incoherent light source, e.g., a simple light-emitting-diode (LED). The transmitted light pattern through the object is then sampled by this array of fiber optic cables, delivering a transmission image of the sample onto the other side of the taper, with ∼3× magnification in each direction. This magnified image of the object, located at the bottom facet of the fiber array, is then projected onto the CMOS image sensor of the cellphone using two lenses. While keeping the sample and the cellphone camera at a fixed position, the fiber-optic array is then manually rotated with discrete angular increments of e.g., 1-2 degrees. At each angular position of the fiber-optic array, contact images are captured using the cellphone camera, creating a sequence of transmission images for the same sample. These multi-frame images are digitally fused together based on a shift-and-add algorithm through a custom-developed Android application running on the smart-phone, providing the final microscopic image of the sample, visualized through the screen of the phone. This final computation step improves the resolution and also gets rid of spatial artefacts that arise due to non-uniform sampling of the transmission intensity at the fiber optic array surface. We validated the performance of this cellphone based Contact Scope by imaging resolution test charts and blood smears. PMID:23939637

Compact laser transmitter delivering a long-range infrared beam aligned with a monitoring visible beam.

PubMed

Lee, Hong-Shik; Kim, Haeng-In; Lee, Sang-Shin

2012-06-10

A compact laser transmitter, which takes advantage of an optical subassembly module, was proposed and demonstrated, providing precisely aligned collinear IR and visible beams. The collimated IR beam acts as a long-range projectile for simulated combat, carrying an optical pulsed signal, whereas the visible beam plays the role of tracking the IR beam. The proposed laser transmitter utilizes IR (λ(1)=905 nm) and visible (λ(2)=660 nm) light sources, a fiber-optic collimator, and a beam combiner, which includes a wavelength division multiplexing (WDM) filter in conjunction with optical fiber. The device was built via the laser welding technique and then evaluated by investigating the characteristics of the generated light beams. The IR collimated beam produced had a Gaussian profile and a divergence angle of ~1.3 mrad, and the visible monitoring beam was appropriately collimated to be readily discernible in the vicinity of the transmitter. The two beams were highly aligned within an angle of 0.004 deg as anticipated. Finally, we performed a practical outdoor field test to assess the IR beam with the help of a receiver. An effective trajectory was observed ranging up to 660 m with an overall detectable beam width of ~60 cm.

Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities at surface monitoring sites

NASA Astrophysics Data System (ADS)

Kobayashi, N.; Inoue, G.; Kawasaki, M.; Yoshioka, H.; Minomura, M.; Murata, I.; Nagahama, T.; Matsumi, Y.; Tanaka, T.; Morino, I.; Ibuki, T.

2010-08-01

Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA) with a resolution enough to resolve rotational lines of CO2 and CH4 in the regions of 1565-1585 and 1674-1682 nm, respectively; the other is an application of an optical fiber Fabry-Perot interferometer (FFPI) to obtain the CO2 column density. Direct sunlight was collimated via a small telescope installed on a portable sun tracker and then transmitted through an optical fiber into the OSA or the FFPI for optical analysis. The near infrared spectra of the OSA were retrieved by a least squares spectral fitting algorithm. The CO2 and CH4 column densities deduced were in excellent agreement with those measured by a Fourier transform spectrometer with high resolution. The rovibronic lines in the wavelength region of 1570-1575 nm were analyzed by the FFPI. The I0 and I values in the Beer-Lambert law equation to obtain CO2 column density were deduced by modulating temperature of the FFPI, which offered column CO2 with the statistical error less than 0.2% for six hours measurement.

Ultra-low noise combs in the palm of your hand

NASA Astrophysics Data System (ADS)

Schibli, Thomas R.

Mode-locked lasers are attractive tools for precision measurements and for photonic microwave generation. The technology around these lasers has rapidly evolved, and with the invention of optical frequency combs, fs-technology has become a ubiquitous tool science and engineering. At first, most of these combs were generated by bulky and delicate Kerr-Lens mode-locked Ti:sapphire systems, but have now been mostly replaced by the much more robust and compact fiber lasers. However, the move from table-top solid-state lasers to the fully self-contained fiber systems came with a price: the optical phase noise performance degraded due to design constraints. While this is of no concern for most spectroscopic applications, it poses a challenge for applications that require excellent short-term phase noise performance, such as, for example, required for photonic microwave generation. While much of this has been improved by ingenious laser designs, it remains a challenge to obtain ultra-low phase-noise combs from high-repetition-rate fiber lasers. Here we present a new approach consisting of a monolithic cavity design, in which the laser light is fully confined inside an optical material. Thanks to this monolithic design, these solid-state lasers are inherently robust against environmental perturbations, such as acoustics, vibrations, air pressure and humidity. Opposed to the omnipresent mode-locked fiber lasers, these monolithic lasers exhibit very low round-trip loss, dispersion and nonlinearities. As a result, they produce highly stable pulse trains, with free-running relative line-widths of the order of a few Hz in the optical domain, despite their moderately high fundamental repetition rates of 1 GHz. The compact design further simplifies integration into complex systems, and eliminates the need for an optics bench or a vibration isolated platform. These lasers produce less than 0.2 W of heat, and are fully turn-key. This work was supported by the DARPA PULSE program with a Grant from AMRDEC and by the NSF Early Career Award.

Green and ultraviolet pulse generation with a compact, fiber laser, chirped-pulse amplification system for aerosol fluorescence measurements.

PubMed

Lou, Janet W; Currie, Marc; Sivaprakasam, Vasanthi; Eversole, Jay D

2010-10-01

We use a compact chirped-pulse amplified system to harmonically generate ultrashort pulses for aerosol fluorescence measurements. The seed laser is a compact, all-normal dispersion, mode-locked Yb-doped fiber laser with a 1050 nm center wavelength operating at 41 MHz. Average powers of more than 1.2 W at 525 nm and 350 mW at 262 nm are generated with <500 fs pulse durations. The pulses are time-stretched with high-dispersion fiber, amplified by a high-power, large-mode-area fiber amplifier, and recompressed using a chirped volume holographic Bragg grating. The resulting high-peak-power pulses allow for highly efficient harmonic generation. We also demonstrate for the first time to our knowledge, the use of a mode-locked ultraviolet source to excite individual biological particles and other calibration particles in an inlet air flow as they pass through an optical chamber. The repetition rate is ideal for biofluorescence measurements as it allows faster sampling rates as well as the higher peak powers as compared to previously demonstrated Q-switched systems while maintaining a pulse period that is longer than the typical fluorescence lifetimes. Thus, the fluorescence excitation can be considered to be quasicontinuous and requires no external synchronization and triggering.

Ultra-compact Watt-level flat supercontinuum source pumped by noise-like pulse from an all-fiber oscillator.

PubMed

Chen, He; Zhou, Xuanfeng; Chen, Sheng-Ping; Jiang, Zong-Fu; Hou, Jing

2015-12-28

We demonstrate Watt-level flat visible supercontinuum (SC) generation in photonic crystal fibers, which is directly pumped by broadband noise-like pulses from an Yb-doped all-fiber oscillator. The novel SC generator is featured with elegant all-fiber-integrated architecture, high spectral flatness and high efficiency. Wide optical spectrum spanning from 500 nm to 2300 nm with 1.02 W optical power is obtained under the pump of 1.4 W noise-like pulse. The flatness of the spectrum in the range of 700 nm~1600 nm is less than 5 dB (including the pump residue). The exceptional simplicity, economical efficiency and the comparable performances make the noise-like pulse oscillator a competitive candidate to the widely used cascade amplified coherent pulse as the pump source of broadband SC. To the best of our knowledge, this is the first demonstration of SC generation which is directly pumped by an all-fiber noise-like pulse oscillator.

Recent progress in InP/polymer-based devices for telecom and data center applications

NASA Astrophysics Data System (ADS)

Kleinert, Moritz; Zhang, Ziyang; de Felipe, David; Zawadzki, Crispin; Maese Novo, Alejandro; Brinker, Walter; Möhrle, Martin; Keil, Norbert

2015-02-01

Recent progress on polymer-based photonic devices and hybrid photonic integration technology using InP-based active components is presented. High performance thermo-optic components, including compact polymer variable optical attenuators and switches are powerful tools to regulate and control the light flow in the optical backbone. Polymer arrayed waveguide gratings integrated with InP laser and detector arrays function as low-cost optical line terminals (OLTs) in the WDM-PON network. External cavity tunable lasers combined with C/L band thinfilm filter, on-chip U-groove and 45° mirrors construct a compact, bi-directional and color-less optical network unit (ONU). A tunable laser integrated with VOAs, TFEs and two 90° hybrids builds the optical front-end of a colorless, dual-polarization coherent receiver. Multicore polymer waveguides and multi-step 45°mirrors are demonstrated as bridging devices between the spatialdivision- multiplexing transmission technology using multi-core fibers and the conventional PLCbased photonic platforms, appealing to the fast development of dense 3D photonic integration.

Compact system with handheld microfabricated optoelectronic probe for needle-based tissue sensing applications

NASA Astrophysics Data System (ADS)

Lee, Seung Yup; Na, Kyounghwan; Pakela, Julia M.; Scheiman, James M.; Yoon, Euisik; Mycek, Mary-Ann

2017-02-01

We present the design, development, and bench-top verification of an innovative compact clinical system including a miniaturized handheld optoelectronic sensor. The integrated sensor was microfabricated with die-level light-emitting diodes and photodiodes and fits into a 19G hollow needle (internal diameter: 0.75 mm) for optical sensing applications in solid tissues. Bench-top studies on tissue-simulating phantoms have verified system performance relative to a fiberoptic based tissue spectroscopy system. With dramatically reduced system size and cost, the technology affords spatially configurable designs for optoelectronic light sources and detectors, thereby enabling customized sensing configurations that would be impossible to achieve with needle-based fiber-optic probes.

Infrared Hollow Optical Fiber Probe for Localized Carbon Dioxide Measurement in Respiratory Tracts

PubMed Central

Katagiri, Takashi; Shibayama, Kyosuke; Iida, Takeru

2018-01-01

A real-time gas monitoring system based on optical absorption spectroscopy is proposed for localized carbon dioxide (CO2) measurement in respiratory tracts. In this system, a small gas cell is attached to the end of a hollow optical fiber that delivers mid-infrared light with small transmission loss. The diameters of the fiber and the gas cell are smaller than 1.2 mm so that the probe can be inserted into a working channel of common bronchoscopes. The dimensions of the gas cell are designed based on absorption spectra of CO2 standard gases in the 4.2 μm wavelength region, which are measured using a Fourier-transform infrared spectrometer. A miniature gas cell that is comprised of a stainless-steel tube with slots for gas inlet and a micro-mirror is fabricated. A compact probing system with a quantum cascade laser (QCL) light source is built using a gas cell with a hollow optical fiber for monitoring CO2 concentration. Experimental results using human breaths show the feasibility of the system for in-situ measurement of localized CO2 concentration in human airways. PMID:29584666

Design of a stabilized, compact gimbal for space-based free space optical communications (FSOC)

NASA Astrophysics Data System (ADS)

Cline, A.; Shubert, P.; McNally, J.; Jacka, N.; Pierson, R.

2017-02-01

Data transmits via optical communications through fibers at 10's of Terabits per second. Given the recent rapid explosion for bandwidth and competing demand for radio frequency (RF) spectrum allocations among differing interests, the need for space-based free space optical communications (FSOC) systems is ever increasing. FSOC systems offer advantages of higher data rates, smaller size and weight, narrower beam divergence, and lower power than RF systems. Lightweight, small form factor, and high performance two-axis gimbals are of strong interest for satellite FSOC applications. Small gimbal and optical terminal designs are important for widespread implementation of optical communications systems; in particular, for satellite-to-satellite crosslinks where the advantages of more secure communications links (Lower Probability of Intercept (LPI)/Lower Probability of Detect (LPD)) are very important. We developed design concepts for a small gimbal focusing on the use of commercial off-the-shelf (COTS) subsystems to establish their feasible implementation against the pointing stabilization, size, weight and power (SWaP), and performance challenges. The design drivers for the gimbal were weight, the elevation and azimuth field of regards, the form factor envelope (1U CubeSats), 100 μrad pointing accuracy, and 10 degrees per second slew capability. Innovations required in this development included a continuous fiber passed through an Azimuth Fiber Wrap and Elevation Fiber Wrap, overcoming typical mechanical and stress related limitations encountered with fiber optic cable wraps. In this presentation, we describe the configuration trades and design of such a gimbal.

Ultrastable, Zerodur-based optical benches for quantum gas experiments.

PubMed

Duncker, Hannes; Hellmig, Ortwin; Wenzlawski, André; Grote, Alexander; Rafipoor, Amir Jones; Rafipoor, Mona; Sengstock, Klaus; Windpassinger, Patrick

2014-07-10

Operating ultracold quantum gas experiments outside of a laboratory environment has so far been a challenging goal, largely due to the lack of sufficiently stable optical systems. In order to increase the thermal stability of free-space laser systems, the application of nonstandard materials such as glass ceramics is required. Here, we report on Zerodur-based optical systems which include single-mode fiber couplers consisting of multiple components jointed by light-curing adhesives. The thermal stability is thoroughly investigated, revealing excellent fiber-coupling efficiencies between 0.85 and 0.92 in the temperature range from 17°C to 36°C. In conjunction with successfully performed vibration tests, these findings qualify our highly compact systems for atom interferometry experiments aboard a sounding rocket as well as various other quantum information and sensing applications.

Microgroove fabrication with excimer laser ablation techniques for optical fiber array alignment purposes

NASA Astrophysics Data System (ADS)

Naessens, Kris; Van Hove, An; Coosemans, Thierry; Verstuyft, Steven; Vanwassenhove, Luc; Van Daele, Peter; Baets, Roel G.

2000-11-01

Currently, an ever increasing need for bandwidth, compactness and efficiency characterizes the world of interconnect and data communication. This tendency has already led to serial links being gradually replaced by parallel optical interconnect solutions. However, as the maximum capacity for the latter will be reached in the near future, new approaches are required to meet demand. One possible option is to switch to 2D parallel implementations of fiber arrays. In this paper we present the fabrication of a 2D connector for coupling a 4x8 array of plastic optical fibers to RCLED or VCSEL arrays. The connector consists primarily of dedicated PMMA plates in which arrays of 8 precisely dimensioned grooves at a pitch of 250 micrometers are introduced. The trenches are each 127 micrometers deep and their width is optimized to allow fixation of plastic optical fibers. We used excimer laser ablation for prototype fabrication of these alignment microstructures. In a later stage, the plates can be replicated using standard molding techniques. The laser ablation technique is extremely well suited for rapid prototyping and proves to be a versatile process yielding high accuracy dimensioning and repeatability of features in a wide diversity of materials. The dependency of the performance in terms of quality of the trenches (bottom roughness) and wall angle on various parameters (wavelength, energy density, pulse frequency and substrate material) is discussed. The fabricated polymer sheets with grooves are used to hold optical fibers by means of a UV-curable adhesive. In a final phase, the plates are stacked and glued in order to realize the 2D-connector of plastic optical fibers for short distance optical interconnects.

A trifurcated fiber-optic-probe-based optical system designed for AGEs measurement

NASA Astrophysics Data System (ADS)

Wang, Yikun; Zhang, Long; Zhu, Ling; Liu, Yong; Zhang, Gong; Wang, An

2012-03-01

Advanced Glycation End-products (AGEs) are biochemical end-products of non-enzymatic glycation and are formed irreversibly in human serum and skin tissue. AGEs are thought to play an important role in the pathogenesis of diabetes and corresponding complications. All conventional methods for measuring AGEs must take sampling and measure in vitro. These methods are invasive and have the problem of relatively time-consuming. AGEs have fluorescent characteristics. Skin AGEs can be assessed noninvasively by collecting the fluorescence emitted from skin tissue when excited with proper light. However, skin tissue has absorption and scattering effects on fluorescence of AGEs, it is not reliable to evaluate the accumulation of AGEs according the emitted fluorescence but not considering optical properties of skin tissue. In this study, a portable system for detecting AGEs fluorescence and skin reflectance spectrum simultaneously has been developed. The system mainly consists of an ultraviolet light source, a broadband light source, a trifurcated fiber-optic probe, and a compact charge coupled device (CCD) spectrometer. The fiber-optic probe consists of 36 optical fibers which are connected to the ultraviolet light source, 6 optical fibers connected to the broadband light source, and a core fiber connected to the CCD spectrometer. Demonstrative test measurements with the system on skin tissue of 40 healthy subjects have been performed. Using parameters that are calculated from skin reflectance spectrum, the distortion effects caused by skin absorption and scattering can be eliminated, and the integral intensity of corrected fluorescence has a strong correlation with the accumulation of AGEs. The system looks very promising for both laboratory and clinical applications to monitor AGEs related diseases, especially for chronic diabetes and complications.

One-Dimensional Scanning Approach to Shock Sensing

NASA Technical Reports Server (NTRS)

Tokars, Roger; Adamovsky, Girgory; Floyd, Bertram

2009-01-01

Measurement tools for high speed air flow are sought both in industry and academia. Particular interest is shown in air flows that exhibit aerodynamic shocks. Shocks are accompanied by sudden changes in density, pressure, and temperature. Optical detection and characterization of such shocks can be difficult because the medium is normally transparent air. A variety of techniques to analyze these flows are available, but they often require large windows and optical components as in the case of Schlieren measurements and/or large operating powers which precludes their use for in-flight monitoring and applications. The one-dimensional scanning approach in this work is a compact low power technique that can be used to non-intrusively detect shocks. The shock is detected by analyzing the optical pattern generated by a small diameter laser beam as it passes through the shock. The optical properties of a shock result in diffraction and spreading of the beam as well as interference fringes. To investigate the feasibility of this technique a shock is simulated by a 426 m diameter optical fiber. Analysis of results revealed a direct correlation between the optical fiber or shock location and the beam s diffraction pattern. A plot of the width of the diffraction pattern vs. optical fiber location reveals that the width of the diffraction pattern was maximized when the laser beam is directed at the center of the optical fiber. This work indicates that the one-dimensional scanning approach may be able to determine the location of an actual shock. Near and far field effects associated with a small diameter laser beam striking an optical fiber used as a simulated shock are investigated allowing a proper one-dimensional scanning beam technique.

Compact, High-Power, Fiber-Laser-Based Coherent Sources Tunable in the Mid-Infrared and THz Spectrum

DTIC Science & Technology

2015-02-20

conversion sources and optical parametric oscillators (OPOs) for the deep mid-infrared (mid-IR) spectral regions >5 μm. We have successfully developed... oscillators (OPOs) for the deep mid-infrared (mid-IR) spectral regions >5 µm. We have successfully developed tunable deep mid-IR systems in both...the advancement of nonlinear frequency conversion sources and optical parametric oscillators (OPOs) for the deep mid-infrared (mid- IR) spectral

Robust and Complex on-Chip Nanophotonics

DTIC Science & Technology

2015-04-17

organization, e.g. BRL-1234; AFWL-TR-85-4017-Vol-21- PT -2. 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES). Enter the name and address of the...metallic on-chip nanophotonic structures, leading to novel devices in ultra-compact wavelength splitters, and nano- lasers and modulators with very low...between optical fiber and on-chip waveguide based on a novel transformation-optics approach. Finally, in Thrust 3, the team has made substantial

Fiber-coupled THz spectroscopy for monitoring polymeric compounding processes

NASA Astrophysics Data System (ADS)

Vieweg, N.; Krumbholz, N.; Hasek, T.; Wilk, R.; Bartels, V.; Keseberg, C.; Pethukhov, V.; Mikulics, M.; Wetenkamp, L.; Koch, M.

2007-06-01

We present a compact, robust, and transportable fiber-coupled THz system for inline monitoring of polymeric compounding processes in an industrial environment. The system is built on a 90cm x 90cm large shock absorbing optical bench. A sealed metal box protects the system against dust and mechanical disturbances. A closed loop controller unit is used to ensure optimum coupling of the laser beam into the fiber. In order to build efficient and stable fiber-coupled antennas we glue the fibers directly onto photoconductive switches. Thus, the antenna performance is very stable and it is secured from dust or misalignment by vibrations. We discuss fabrication details and antenna performance. First spectroscopic data obtained with this system is presented.

High-Q optical resonators: characterization and application to stabilization of lasers and high spectral purity microwave oscillators

NASA Astrophysics Data System (ADS)

Llopis, O.; Merrer, P. H.; Bouchier, A.; Saleh, K.; Cibiel, G.

2010-02-01

Microwave optical systems for frequency generation are described in this paper. The goal is to reach high spectral purity in the microwave frequency range using ultra high Q optical resonators. The resonators investigated are of two types : resonant (passive) fiber rings and WGM tridimensional resonators. They all feature ultra high optical Q factors, in excess of 108 or 109 near 1550 nm. These resonators also sustain a large number of optical resonances, and the microwave signal is stabilized on two (or more) resonances of this optical comb. Different problems have to be overcome in order to reach a functional system, such as : resonator design and coupling, laser stabilization on a resonance, overall system design, noise optimization... This paper gives an overlook on these problems, and on some solutions we found to work towards a compact and efficient microwave opto-electronic oscillator (OEO). A first result is presented on a 10 GHz OEO based on a resonant fiber ring.

Integrated four-channel all-fiber up-conversion single-photon-detector with adjustable efficiency and dark count.

PubMed

Zheng, Ming-Yang; Shentu, Guo-Liang; Ma, Fei; Zhou, Fei; Zhang, Hai-Ting; Dai, Yun-Qi; Xie, Xiuping; Zhang, Qiang; Pan, Jian-Wei

2016-09-01

Up-conversion single photon detector (UCSPD) has been widely used in many research fields including quantum key distribution, lidar, optical time domain reflectrometry, and deep space communication. For the first time in laboratory, we have developed an integrated four-channel all-fiber UCSPD which can work in both free-running and gate modes. This compact module can satisfy different experimental demands with adjustable detection efficiency and dark count. We have characterized the key parameters of the UCSPD system.

A Core-Offset Mach Zehnder Interferometer Based on A Non-Zero Dispersion-Shifted Fiber and Its Torsion Sensing Application.

PubMed

Huerta-Mascotte, Eduardo; Sierra-Hernandez, Juan M; Mata-Chavez, Ruth I; Jauregui-Vazquez, Daniel; Castillo-Guzman, Arturo; Estudillo-Ayala, Julian M; Guzman-Chavez, Ana D; Rojas-Laguna, Roberto

2016-06-10

In this paper, an all-fiber Mach-Zehnder interferometer (MZI) based on a non-zero dispersion-shifted fiber (NZ-DSF) is presented. The MZI was implemented by core-offset fusion splicing one section of a NZ-DSF fiber between two pieces of single mode fibers (SMFs). Here, the NZ-DSF core and cladding were used as the arms of the MZI, while the core-offset sections acted as optical fiber couplers. Thus, a MZI interference spectrum with a fringe contrast (FC) of about 20 dB was observed. Moreover, its response spectrum was experimentally characterized to the torsion parameter and a sensitivity of 0.070 nm/° was achieved. Finally, these MZIs can be implemented in a compact size and low cost.

A Core-Offset Mach Zehnder Interferometer Based on A Non-Zero Dispersion-Shifted Fiber and Its Torsion Sensing Application

PubMed Central

Huerta-Mascotte, Eduardo; Sierra-Hernandez, Juan M.; Mata-Chavez, Ruth I.; Jauregui-Vazquez, Daniel; Castillo-Guzman, Arturo; Estudillo-Ayala, Julian M.; Guzman-Chavez, Ana D.; Rojas-Laguna, Roberto

2016-01-01

In this paper, an all-fiber Mach-Zehnder interferometer (MZI) based on a non-zero dispersion-shifted fiber (NZ-DSF) is presented. The MZI was implemented by core-offset fusion splicing one section of a NZ-DSF fiber between two pieces of single mode fibers (SMFs). Here, the NZ-DSF core and cladding were used as the arms of the MZI, while the core-offset sections acted as optical fiber couplers. Thus, a MZI interference spectrum with a fringe contrast (FC) of about 20 dB was observed. Moreover, its response spectrum was experimentally characterized to the torsion parameter and a sensitivity of 0.070 nm/° was achieved. Finally, these MZIs can be implemented in a compact size and low cost. PMID:27294930

Compact diode laser module at 1116 nm with an integrated optical isolation and a PM-SMF output

NASA Astrophysics Data System (ADS)

Jedrzejczyk, Daniel; Hofmann, Julian; Werner, Nils; Sahm, Alexander; Paschke, Katrin

2017-02-01

In this work, a fiber-coupled diode laser module emitting around 1116 nm with an output power P < 60 mW is realized. As a laser light source a distributed Bragg reflector (DBR) ridge waveguide diode laser is applied. The module comprises temperature stabilizing components, a micro-lens system as well as an optical micro-isolator. At the output, a polarization-maintaining single-mode fiber (PM-SMF) with a core diameter of 5.5 μm and a standard FC/APC connector are utilized. The generated diffraction limited beam is characterized by a narrow linewidth ( δν < 10 MHz) and a high polarization extinction ratio (PER > 25 dB).

Fiber optic refractive index and magnetic field sensors based on microhole-induced inline Mach-Zehnder interferometers

NASA Astrophysics Data System (ADS)

Chen, Feifei; Jiang, Yi; Zhang, Liuchao; Jiang, Lan; Wang, Sumei

2018-04-01

A compact microhole-induced fiber optic inline Mach-Zehnder interferometer (MZI) is demonstrated for measurements of refractive index (RI) and magnetic field. Inline MZIs with different etched diameters, different interaction lengths and different sizes of microholes are fabricated and assessed. The optical transmission spectra of the inline MZIs immersed into a series of liquids are characterized and analysed. Experimental results show that liquid RI sensitivity as high as 539.8436 nm RIU-1 in the RI range of 1.3352-1.4113 RIU is achieved and also exhibits good linearity with a correlation coefficient  >93%. An inline MZI is also fabricated to be a magnetic field sensor by using magnetic fluid material. The experimental results show that this magnetic field sensor has a high sensitivity of  -275.6 pm Oe-1. The inline MZI-based fiber optic sensors possess many advantages, such as small size, simple fabrication, high sensitivity and good linearity, which has a wide application potential in chemical, biological and environmental sensing fields.

Continuous-wave optical stimulation of the rat prostate nerves using an all-single-mode 1455 nm diode laser and fiber system

NASA Astrophysics Data System (ADS)

Tozburun, Serhat; Lagoda, Gwen A.; Burnett, Arthur L.; Fried, Nathaniel M.

2011-03-01

Optical nerve stimulation (ONS) has recently been reported as a potential alternative to electrical nerve stimulation. Continuous-wave (CW) laser stimulation of the prostate cavernous nerves (CN) in a rat model, in vivo, has also been demonstrated in our previous studies. The objective of this study is to present a new all-single-mode-fiber configuration for ONS with the laser operating in CW mode for potential diagnostic applications. An infrared pigtailed single-mode diode laser (λ = 1455 nm) was used in this study for noncontact ONS. This new all-fiber approach introduces several advantages including: (1) a less expensive and more compact ONS system, (2) elimination of alignment of optical components, and (3) an improved spatial beam profile. Successful optical stimulation of the rat CN using this new design was observed after the CN reached a threshold temperature of ~ 41 °C with response times as short as 3 s. Upon further study, this configuration may be useful for identification and preservation of the cavernous nerves during prostate cancer surgery.

A novel fiber optic Fabry-Perot structure with a micrometric diameter tip

NASA Astrophysics Data System (ADS)

Wang, Xingwei; Xu, Juncheng; Wang, Zhuang; Cooper, Kristie L.; Wang, Anbo

2006-08-01

This paper presents a novel fiber optic Fabry-Perot (FP) structure with a micrometric diameter tip. The fabrication of micro scale probes has become essential in intracellular surgery, in cell sensing, manipulation, and injection. It is of great importance in many fields, such as genetics, pathology, criminology, pharmacogenetics, and food safety. With such a tiny protrusion, the sensor can be inserted into micron size cells, say, for DNA analysis. With the FP cavity inside the fiber, the change of optical path difference (OPD) caused by the environment can be demodulated. In addition, the structure is intrinsically capable of temperature compensation. What's more, it is simple, cost-efficient, and compact. Last but not the least, the structure shows promise for nanometric protrusion. Once this goal is achieved, the sensor can be inserted into most cells. The sensor could pave the way for faster, more accurate medical diagnostic tests for countless conditions and may ultimately save lives by allowing earlier disease detection and intervention.

Time-domain multiplexed high resolution fiber optics strain sensor system based on temporal response of fiber Fabry-Perot interferometers.

PubMed

Chen, Jiageng; Liu, Qingwen; He, Zuyuan

2017-09-04

We developed a multiplexed strain sensor system with high resolution using fiber Fabry-Perot interferometers (FFPI) as sensing elements. The temporal responses of the FFPIs excited by rectangular laser pulses are used to obtain the strain applied on each FFPI. The FFPIs are connected by cascaded couplers and delay fiber rolls for the time-domain multiplexing. A compact optoelectronic system performing closed-loop cyclic interrogation is employed to improve the sensing resolution and the frequency response. In the demonstration experiment, 3-channel strain sensing with resolutions better than 0.1 nε and frequency response higher than 100 Hz is realized.

CO₂ laser-fabricated cladding light strippers for high-power fiber lasers and amplifiers.

PubMed

Boyd, Keiron; Simakov, Nikita; Hemming, Alexander; Daniel, Jae; Swain, Robert; Mies, Eric; Rees, Simon; Andrew Clarkson, W; Haub, John

2016-04-10

We present and characterize a simple CO₂ laser processing technique for the fabrication of compact all-glass optical fiber cladding light strippers. We investigate the cladding light loss as a function of radiation angle of incidence and demonstrate devices in a 400 μm diameter fiber with cladding losses of greater than 20 dB for a 7 cm device length. The core losses are also measured giving a loss of <0.008±0.006  dB/cm. Finally we demonstrate the successful cladding light stripping of a 300 W laser diode with minimal heating of the fiber coating and packaging adhesives.

Mid-infrared (MIR) photonics: MIR passive and active fiberoptics chemical and biomedical, sensing and imaging

NASA Astrophysics Data System (ADS)

Seddon, Angela B.

2016-10-01

The case for new, portable, real-time mid-infrared (MIR) molecular sensing and imaging is discussed. We set a record in demonstrating extreme broad-band supercontinuum (SC) generated light 1.4-13.3 μm in a specially engineered, step-index MIR optical fiber of high numerical aperture. This was the first experimental demonstration truly to reveal the potential of MIR fibers to emit across the MIR molecular "fingerprint spectral region" and a key first step towards bright, portable, broadband MIR sources for chemical and biomedical, molecular sensing and imaging in real-time. Potential applications are in the healthcare, security, energy, environmental monitoring, chemical-processing, manufacturing and the agriculture sectors. MIR narrow-line fiber lasers are now required to pump the fiber MIR-SC for a compact all-fiber solution. Rare-earth-ion (RE-) doped MIR fiber lasers are not yet demonstrated >=4 μm wavelength. We have fabricated small-core RE-fiber with photoluminescence across 3.5-6 μm, and long excited-state lifetimes. MIR-RE-fiber lasers are also applicable as discrete MIR fiber sensors in their own right, for applications including: ship-to-ship free-space communications, aircraft counter-measures, coherent MIR imaging, MIR-optical coherent tomography, laser-cutting/ patterning of soft materials and new wavelengths for fiber laser medical surgery.

Improving spatial and spectral resolution of TCV Thomson scattering

NASA Astrophysics Data System (ADS)

Hawke, J.; Andrebe, Y.; Bertizzolo, R.; Blanchard, P.; Chavan, R.; Decker, J.; Duval, B.; Lavanchy, P.; Llobet, X.; Marlétaz, B.; Marmillod, P.; Pochon, G.; Toussaint, M.

2017-12-01

The recently completed MST2 upgrade to the Thomson scattering (TS) system on TCV (Tokamak à Configuration Variable) at the Swiss Plasma Center aims to provide an enhanced spatial and spectral resolution while maintaining the high level of diagnostic flexibility for the study of TCV plasmas. The MST2 (Medium Sized Tokamak) is a work program within the Eurofusion ITER physics department, aimed at exploiting Europe's medium sized tokamak programs for a better understanding of ITER physics. This upgrade to the TCV Thomson scattering system involved the installation of 40 new compact 5-channel spectrometers and modifications to the diagnostics fiber optic design. The complete redesign of the fiber optic backplane incorporates fewer larger diameter fibers, allowing for a higher resolution in both the core and edge of TCV plasmas along the laser line, with a slight decrease in the signal to noise ratio of Thomson measurements. The 40 new spectrometers added to the system are designed to cover the full range of temperatures expected in TCV, able to measure electron temperatures (Te) with high precision between (6 eV and 20 keV) . The design of these compact spectrometers stems originally from the design utilized in the MAST (Mega Amp Spherical Tokamak) TS system located in Oxfordshire, United Kingdom. This design was implemented on TCV with an overall layout of optical fibers and spectrometers to achieve an overall increase in the spatial resolution, specifically a resolution of approximately 1% of the minor radius within the plasma pedestal region. These spectrometers also enhance the diagnostic spectral resolution, especially within the plasma edge, due to the low Te measurement capabilities. These additional spectrometers allow for a much greater diagnostic flexibility, allowing for quality full Thomson profiles in 75% of TCV plasma configurations.

High-speed, bi-directional dual-core fiber transmission system for high-density, short-reach optical interconnects

NASA Astrophysics Data System (ADS)

Geng, Ying; Li, Shenping; Li, Ming-Jun; Sutton, Clifford G.; McCollum, Robert L.; McClure, Randy L.; Koklyushkin, Alexander V.; Matthews, Karen I.; Luther, James P.; Butler, Douglas L.

2015-03-01

A complete single mode dual-core fiber system for short-reach optical interconnects is fabricated and tested for high-speed data transmission. It includes dual-core fibers capable of bi-directional data transmission, dual-core simplex LC connectors, and fan-outs. The transmission system offers simplified bi-directional traffic engineering with integrated bidirectional transceivers and compact system design, utilizing simplex dual-core LC connectors that use half the space while increasing the bandwidth density by a factor of two. The fiber has two cores that are compatible with single mode fiber and conforms to the industry standard outer diameter of 125 μm. This reduces operational complexity by reducing the size and number of fibers, cables and connectors. Measured OTDR loss for both cores was 0.34 dB/km at 1310 nm and 0.19 dB/km at 1550 nm. Crosstalk for a piece of 5.8 km long dual-core fiber was measured to be below -75 dB at 1310 nm, and below -40 dB at 1550 nm. Both free-space optics fan-outs and tapered-fiber-coupler based MCF fan-outs were evaluated for the transmission system. Error-free and penalty-free 25 Gb/s bi-directional transmission performance was demonstrated for three different fiber lengths, 200 m, 2 km and 10 km, using the complete all-fiber-based system including connectors and fan-outs. This single mode, dual-core fiber transmission system adds complementary value to systems where additional increases in bandwidth density can come from wavelength division multiplexing and multiple bits per symbol.

Use of a compact fiber optic spectrometer for spectral feedback during the laser ablation of dental hard tissues and restorative materials

NASA Astrophysics Data System (ADS)

Cheng, Joyce Y.; Fan, Kenneth; Fried, Daniel

2006-02-01

One perceived disadvantage of caries removal using lasers is the loss of the tactile feedback associated with the handpiece. However, alternative methods of acoustic and optical feedback become available with the laser that can be exploited to provide information about the chemical composition of the material ablated, the ablation efficiency and rate, the depth of the incision, and the surface and plume temperature during ablation. Such information can be used to increase the selectivity of ablation, avoid peripheral thermal damage and excessive heat deposition in the tooth, and provide a mechanism of robotic automation. The objective of this study was to test the hypothesis that a compact fiberoptic spectrometer could be used to differentiate between the ablation of sound and carious enamel and dentin and between dental hard tissues and composite. Sound and carious tooth surfaces along with composite restorative materials were scanned with λ=0.355, 2.79 and 9.3 μm laser pulses at irradiation intensities ranging from 0.5-100 J/cm2 and spectra were acquired from λ=250-900-nm using a compact fiber-optic spectrometer. Emission spectra varied markedly with the laser wavelength and pulse duration. Optical feedback was not successful in differentiating between sound and carious enamel and dentin even with the addition of various chromophores to carious lesion areas. However, the spectral feedback was successfully used to differentiate between composites and sound enamel and dentin enabling the selective removal of composite from tooth surfaces using a computer controlled λ=9.3-μm pulsed CO II laser and scanning system.

A compact frequency stabilized telecom laser diode for space applications

NASA Astrophysics Data System (ADS)

Philippe, C.; Holleville, D.; Le Targat, R.; Wolf, P.; Leveque, T.; Le Goff, R.; Martaud, E.; Acef, O.

2017-09-01

We report on a Telecom laser diode (LD) frequency stabilization to a narrow iodine hyperfine line in the green range, after frequency tripling process using fibered nonlinear waveguide PPLN crystals. We have generated up to 300 mW optical power in the green range ( 514 nm) from 800 mW of infrared power ( 1542 nm), corresponding to a nonlinear conversion efficiency h = P3?/P? 36%. Less than 10 mW of the generated green power are used for Doppler-free spectroscopy of 127I2 molecular iodine, and -therefore- for the frequency stabilization purpose. The frequency tripling optical setup is very compact (< 5 l), fully fibered, and could operate over the full C-band of the Telecom range (1530 nm - 1565 nm). Several thousands of hyperfine iodine lines may thus be interrogated in the 510 nm - 521 nm range. We build up an optical bench used at first in free space configuration, using the well-known modulation transfer spectroscopy technique (MTS), in order to test the potential of this new frequency standard based on the couple "1.5 ?m laser / iodine molecule". We have already demonstrated a preliminary frequency stability of 4.8 x 10-14 ? -1/2 with a minimum value of 6 x 10-15 reached after 50 s of integration time, conferred to a laser diode operating at 1542.1 nm. We focus now our efforts to expand the frequency stability to a longer integration time in order to meet requirements of many space experiments, such earth gravity missions, inters satellites links or space to ground communications. Furthermore, we investigate the potential of a new approach based on frequency modulation technique (FM), associated to a 3rd harmonic detection of iodine lines to increase the compactness of the optical setup.

Monolithic, High-Speed Fiber-Optic Switching Array for Lidar

NASA Technical Reports Server (NTRS)

Suckow, Will; Roberts, Tony; Switzer, Gregg; Terwilliger, Chelle

2011-01-01

Current fiber switch technologies use mechanical means to redirect light beams, resulting in slow switch time, as well as poor reliability due to moving parts wearing out quickly at high speeds. A non-mechanical ability to switch laser output into one of multiple fibers within a fiber array can provide significant power, weight, and costs savings to an all-fiber system. This invention uses an array of crystals that act as miniature prisms to redirect light as an electric voltage changes the prism s properties. At the heart of the electro-optic fiber-optic switch is an electro- optic crystal patterned with tiny prisms that can deflect the beam from the input fiber into any one of the receiving fibers arranged in a linear array when a voltage is applied across the crystal. Prism boundaries are defined by a net dipole moment in the crystal lattice that has been poled opposite to the surrounding lattice fabricated using patterned, removable microelectrodes. When a voltage is applied across the crystal, the resulting electric field changes the index of refraction within the prism boundaries relative to the surrounding substrate, causing light to deflect slightly according to Snell s Law. There are several materials that can host the necessary monolithic poled pattern (including, but not limited to, SLT, KTP, LiNbO3, and Mg:LiNbO3). Be cause this is a solid-state system without moving parts, it is very fast, and does not wear down easily. This invention is applicable to all fiber networks, as well as industries that use such networks. The unit comes in a compact package, can handle both low and high voltages, and has a high reliability (100,000 hours without maintenance).

Generation of multiphoton entangled quantum states by means of integrated frequency combs.

PubMed

Reimer, Christian; Kues, Michael; Roztocki, Piotr; Wetzel, Benjamin; Grazioso, Fabio; Little, Brent E; Chu, Sai T; Johnston, Tudor; Bromberg, Yaron; Caspani, Lucia; Moss, David J; Morandotti, Roberto

2016-03-11

Complex optical photon states with entanglement shared among several modes are critical to improving our fundamental understanding of quantum mechanics and have applications for quantum information processing, imaging, and microscopy. We demonstrate that optical integrated Kerr frequency combs can be used to generate several bi- and multiphoton entangled qubits, with direct applications for quantum communication and computation. Our method is compatible with contemporary fiber and quantum memory infrastructures and with chip-scale semiconductor technology, enabling compact, low-cost, and scalable implementations. The exploitation of integrated Kerr frequency combs, with their ability to generate multiple, customizable, and complex quantum states, can provide a scalable, practical, and compact platform for quantum technologies. Copyright © 2016, American Association for the Advancement of Science.

Ultra-compact switchable SLO/OCT handheld probe design

NASA Astrophysics Data System (ADS)

LaRocca, Francesco; Nankivil, Derek; DuBose, Theodore; Farsiu, Sina; Izatt, Joseph A.

2015-03-01

Handheld scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) systems facilitate imaging of young children and subjects that have difficulty fixating. More compact and lightweight probes allow for better portability and increased comfort for the operator of the handheld probe. We describe a very compact, novel SLO and OCT handheld probe design. A single 2D microelectromechanical systems (MEMS) scanner and a custom optical design using a converging beam prior to the scanner permitted significant reduction in the system size. Our design utilized a combination of commercial and custom optics that were optimized in Zemax to achieve near diffraction-limited resolution of 8 μm over a 7° field of view. The handheld probe has a form factor of 7 x 6 x 2.5 cm and a weight of only 94 g, which is over an order of magnitude lighter than prior SLO-OCT handheld probes. Images were acquired from a normal subject with an incident power on the eye under the ANSI limit. With this device, which is the world's lightest and smallest SLO-OCT system, we were able to visualize parafoveal cone photoreceptors and nerve fiber bundles without the use of adaptive optics.

Holographic pixel super-resolution in portable lensless on-chip microscopy using a fiber-optic array.

PubMed

Bishara, Waheb; Sikora, Uzair; Mudanyali, Onur; Su, Ting-Wei; Yaglidere, Oguzhan; Luckhart, Shirley; Ozcan, Aydogan

2011-04-07

We report a portable lensless on-chip microscope that can achieve <1 µm resolution over a wide field-of-view of ∼ 24 mm(2) without the use of any mechanical scanning. This compact on-chip microscope weighs ∼ 95 g and is based on partially coherent digital in-line holography. Multiple fiber-optic waveguides are butt-coupled to light emitting diodes, which are controlled by a low-cost micro-controller to sequentially illuminate the sample. The resulting lensfree holograms are then captured by a digital sensor-array and are rapidly processed using a pixel super-resolution algorithm to generate much higher resolution holographic images (both phase and amplitude) of the objects. This wide-field and high-resolution on-chip microscope, being compact and light-weight, would be important for global health problems such as diagnosis of infectious diseases in remote locations. Toward this end, we validate the performance of this field-portable microscope by imaging human malaria parasites (Plasmodium falciparum) in thin blood smears. Our results constitute the first-time that a lensfree on-chip microscope has successfully imaged malaria parasites.

Biosensing with optical fiber gratings

NASA Astrophysics Data System (ADS)

Chiavaioli, Francesco; Baldini, Francesco; Tombelli, Sara; Trono, Cosimo; Giannetti, Ambra

2017-06-01

Optical fiber gratings (OFGs), especially long-period gratings (LPGs) and etched or tilted fiber Bragg gratings (FBGs), are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI) change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength) as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors), and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

Flexural strength of self compacting fiber reinforced concrete beams using polypropylene fiber: An experimental study

NASA Astrophysics Data System (ADS)

Lisantono, Ade; Praja, Baskoro Abdi; Hermawan, Billy Nouwen

2017-11-01

One of the methods to increase the tensile strength of concrete is adding a fiber material into the concrete. While to reduce a noise in a construction project, a self compacting concrete was a good choices in the project. This paper presents an experimental study of flexural behavior and strength of self compacting fiber reinforced concrete (RC) beams using polypropylene fiber. The micro monofilament polypropylene fibers with the proportion 0.9 kg/m3 of concrete weight were used in this study. Four beam specimens were cast and tested in this study. Two beams were cast of self compacting reinforced concrete without fiber, and two beams were cast of self compacting fiber reinforced concrete using polypropylene. The beams specimen had the section of (180×260) mm and the length was 2000 mm. The beams had simple supported with the span of 1800 mm. The longitudinal reinforcements were using diameter of 10 mm. Two reinforcements of Ø10 mm were put for compressive reinforcement and three reinforcements of Ø10 mm were put for tensile reinforcement. The shear reinforcement was using diameter of 8 mm. The shear reinforcements with spacing of 100 mm were put in the one fourth near to the support and the spacing of 150 mm were put in the middle span. Two points loading were used in the testing. The result shows that the load-carrying capacity of the self compacting reinforced concrete beam using polypropylene was a little bit higher than the self compacting reinforced concrete beam without polypropylene. The increment of load-carrying capacity of self compacting polypropylene fiber reinforced concrete was not so significant because the increment was only 2.80 % compare to self compacting non fiber reinforced concrete. And from the load-carrying capacity-deflection relationship curves show that both the self compacting polypropylene fiber reinforced concrete beam and the self compacting non fiber reinforced concrete beam were ductile beams.

Device for aqueous detection of nitro-aromatic compounds

DOEpatents

Reagen, W.K.; Schulz, A.L.; Ingram, J.C.; Lancaster, G.D.; Grey, A.E.

1994-04-26

This invention relates to a compact and portable detection apparatus for nitro-aromatic based chemical compounds, such as nitrotoluenes, dinitrotoluenes, and trinitrotoluene (TNT). The apparatus is based upon the use of fiber optics using filtered light. The preferred process of the invention relies upon a reflective chemical sensor and optical and electronic components to monitor a decrease in fluorescence when the nitro-aromatic molecules in aqueous solution combine and react with a fluorescent polycyclic aromatic compound. 4 figures.

Device for aqueous detection of nitro-aromatic compounds

DOEpatents

Reagen, William K.; Schulz, Amber L.; Ingram, Jani C.; Lancaster, Gregory D.; Grey, Alan E.

1994-01-01

This invention relates to a compact and portable detection apparatus for ro-aromatic based chemical compounds, such as nitrotoluenes, dinitrotoluenes, and trinitrotoluene (TNT). The apparatus is based upon the use of fiber optics using filtered light. The preferred process of the invention relies upon a reflective chemical sensor and optical and electronic components to monitor a decrease in fluorescence when the nitro-aromatic molecules in aqueous solution combine and react with a fluorescent polycyclic aromatic compound.

Interconnection requirements in avionic systems

NASA Astrophysics Data System (ADS)

Vergnolle, Claude; Houssay, Bruno

1991-04-01

The future aircraft generation will have thousand smart electromagnetic sensors distributed allover. Each sensor is connected with fibers links to the main-frame computer in charge of the real time signal''s correlation. Such a computer must be compactly built and massively parallel: it needs the use of 3 D optical free-space interconnect between neighbouring boards and reconfigurable interconnects via holographic backplane. The optical interconnect facilities will be also used to build fault-tolerant computer through large redundancy.

Compact variable-temperature scanning force microscope.

PubMed

Chuang, Tien-Ming; de Lozanne, Alex

2007-05-01

A compact design for a cryogenic variable-temperature scanning force microscope using a fiber-optic interferometer to measure cantilever deflection is presented. The tip-sample coarse approach and the lateral tip positioning are performed by piezoelectric positioners in situ. The microscope has been operated at temperatures between 6 and 300 K. It is designed to fit into an 8 T superconducting magnet with the field applied in the out-of-plane direction. The results of scanning in various modes are demonstrated, showing contrast based on magnetic field gradients or surface potentials.

Thermo-optic characteristics of hybrid polymer/silica microstructured optical fiber: An analytical approach

NASA Astrophysics Data System (ADS)

Sharma, Dinesh Kumar; Sharma, Anurag; Tripathi, Saurabh Mani

2018-04-01

Microstructured optical fibers (MOFs) allow a variety of advanced materials to be infiltrated in their air-voids for obtaining the increased fiber functionality, and offering a new versatile platform for developing the compact sensors devices. We aim to investigate the thermal characteristics of high-index core triangular hybrid polymer/silica MOFs with circular air-voids infused with polymer by using the analytical field model [1]. We demonstrate that infiltration of air-voids with polymer, e.g., polydimethylsiloxane (PDMS) can facilitate to tune the fundamental modal properties of MOF such as effective index of the mode, near and the far-field profiles, effective mode area and the numerical aperture over the temperature ranging from 0 °C to 100 °C, for different values of relative air-void ratios. The evolution of the mode shape for a given temperature has been investigated in transition from near-field to far-field regime. We have studied the thermal dependence of splice losses between hybrid MOF and the standard step-index single-mode optical fiber in combination with Fresnel losses. For enhancing the evanescent field interactions, we have evaluated fraction of power associated with fundamental mode of hybrid MOF. We have compared the accuracy of our results with those based on full-vector finite-difference (FD) method, as available in the literature.

Optical fiber-based setup for in vivo measurement of the delayed fluorescence lifetime of oxygen sensors

NASA Astrophysics Data System (ADS)

Piffaretti, Filippo M.; Santhakumar, Kanappan; Forte, Eddy; van den Bergh, Hubert E.; Wagnières, Georges A.

2011-03-01

A new optical-fiber-based spectrofluorometer for in vivo or in vitro detection of delayed fluorescence is presented and characterized. This compact setup is designed so that it can be readily adapted for future clinical use. Optical excitation is done with a nitrogen laser-pumped, tunable dye laser, emitting in the UV-vis part of the spectrum. Excitation and luminescence signals are carried to and from the biological tissues under investigation, located out of the setup enclosure, by a single optical fiber. These measurements, as well as measurements performed without a fiber on in vitro samples in a thermostable quartz cell, in a controlled-atmosphere enclosure, are possible due to the efficient collection of the laser-induced luminescence light which is collected and focused on the detector with a high aperture parabolic mirror. The detection is based on a gated photomultiplier which allows for time-resolved measurements of the delayed fluorescence intensity. Thus, relevant luminescence lifetimes, typically in the sub-microsecond-to-millisecond range, can be measured with near total rejection of the sample's prompt fluorescence. The instrument spectral and temporal resolution, as well as its sensitivity, is characterized and measurement examples are presented. The primary application foreseen for this setup is the monitoring and adjustment of the light dose delivered during photodynamic therapy.

Improved Phase-Mask Fabrication of Fiber Bragg Gratings

NASA Technical Reports Server (NTRS)

Grant, Joseph; Wang, Ying; Sharma, Anup

2004-01-01

An improved method of fabrication of Bragg gratings in optical fibers combines the best features of two prior methods: one that involves the use of a phase mask and one that involves interference between the two coherent laser beams. The improved method affords flexibility for tailoring Bragg wavelengths and bandwidths over wide ranges. A Bragg grating in an optical fiber is a periodic longitudinal variation in the index of refraction of the fiber core. The spatial period (Bragg wavelength) is chosen to obtain enhanced reflection of light of a given wavelength that would otherwise propagate relatively unimpeded along the core. Optionally, the spatial period of the index modulation can be made to vary gradually along the grating (such a grating is said to be chirped ) in order to obtain enhanced reflection across a wavelength band, the width of which is determined by the difference between the maximum and minimum Bragg wavelengths. In the present method as in both prior methods, a Bragg grating is formed by exposing an optical fiber to an ultraviolet-light interference field. The Bragg grating coincides with the pattern of exposure of the fiber core to ultraviolet light; in other words, the Bragg grating coincides with the interference fringes. Hence, the problem of tailoring the Bragg wavelength and bandwidth is largely one of tailoring the interference pattern and the placement of the fiber in the interference pattern. In the prior two-beam interferometric method, a single laser beam is split into two beams, which are subsequently recombined to produce an interference pattern at the location of an optical fiber. In the prior phase-mask method, a phase mask is used to diffract a laser beam mainly into two first orders, the interference between which creates the pattern to which an optical fiber is exposed. The prior two-beam interferometric method offers the advantage that the period of the interference pattern can be adjusted to produce gratings over a wide range of Bragg wavelengths, but offers the disadvantage that success depends on precise alignment and high mechanical stability. The prior phase-mask method affords the advantages of compactness of equipment and relative insensitivity to both misalignment and vibration, but does not afford adjustability of the Bragg wavelength. The present method affords both the flexibility of the prior two-beam interferometric method and the compactness and stability of the prior phase-mask method. In this method (see figure), a laser beam propagating along the x axis is normally incident on a phase mask that lies in the (y,z) plane. The phase of light propagating through the mask is modulated with a spatial periodicity, p, along the y axis chosen to diffract the laser light primarily to first order at the angle . (The zero-order laser light propagating along the x axis can be used for alignment and thereafter suppressed during exposure of the fiber.) The diffracted light passes through a concave cylindrical lens, which converts the flat diffracted wave fronts to cylindrical ones, as though the light emanated from a line source. Then two parallel flat mirrors recombine the diffracted beams to form an interference field equivalent to that of two coherent line sources at positions A and B (virtual sources). The interference pattern is a known function of the parameters of the apparatus and of position (x,y) in the interference field. Hence, the tilt, wavelength, and chirp of the Bragg grating can be chosen through suitable adjustments of the apparatus and/or of the position and orientation of the optical fiber. In particular, the Bragg wavelength can be adjusted by moving the fiber along the x axis, and the bandwidth can be modified over a wide range by changing the fiber tilt angle or by moving the phase mask and/or the fiber. Alignment is easy because the zero-order beam defines the x axis. The interference is relatively stable and insensitive to the mechanical vibration because of the gh symmetry and compactness of the apparatus, the fixed positions of the mirrors and lens, and the consequent fixed positions of the two virtual line sources, which are independent of the translations of the phase mask and the laser relative to the lens.

Frequency noise suppression of a single mode laser with an unbalanced fiber interferometer for subnanometer interferometry.

PubMed

Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Číp, Ondřej

2015-01-12

We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency.

Hybrid MEFPI/FBG sensor for simultaneous measurement of strain and magnetic field

NASA Astrophysics Data System (ADS)

Chen, Mao-qing; Zhao, Yong; Lv, Ri-qing; Xia, Feng

2017-12-01

A hybrid fiber-optic sensor consisting of a micro extrinsic Fabry-Perot Interferometer (MEFPI) and an etched fiber Bragg grating (FBG) is proposed, which can measure strain and magnetic field simultaneously. The etched FBG is sealed in a capillary with ferrofluids to detect the surrounding magnetic field. FBG with small diameter will be more sensitive to magnetic field is confirmed by simulation results. The MEFPI sensor that is prepared through welding a short section of hollow-core fiber (HCF) with single-mode fiber (SMF) is effective for strain detection. The experiment shows that strain and magnetic field can be successfully simultaneously detected based on hybrid MEFPI/FBG sensor. The sensitivities of the strain and magnetic field intensity are measured to be up to 1.41 pm/με and 5.11 pm/mT respectively. There is a negligible effect on each other, hence simultaneously measuring strain and magnetic field is feasible. It is anticipated that such easy preparation, compact and low-cost fiber-optic sensors for simultaneous measurement of strain and magnetic field could find important applications in practice.

Optical fiber micro-displacement sensor using a refractive index modulation window-assisted reflection fiber taper

NASA Astrophysics Data System (ADS)

Bao, Weijia; Qiao, Xueguang; Yin, Xunli; Rong, Qiangzhou; Wang, Ruohui; Yang, Hangzhou

2017-12-01

We demonstrate a compact fiber-optic quasi-Michelson interferometer (QMI) for micro-displacement measurement. The sensor comprises a micro-structure of a reflection taper tip containing a refractive index modification (RIM) as a coupling window over the interface between core and cladding of the fiber. Femtosecond laser-based direct inscription technique is used to achieve this window inscription and to induce large refractive index change. The RIM acts as a window for the strong coupling and recoupling of core-to-cladding modes. As the core and cladding modes are reflected at the taper tip and coupled back to lead-in fiber, a well-defined interference spectrum is achieved. The spectral intensity exhibits a high micro-bending sensitivity of 4 . 94 dB / μm because of the sensitivity to bending of recoupled intensity of cladding modes. In contrast, the spectral wavelength is insensitive to bending but linearly responds to temperature. The simultaneous measurements, including power-referenced for displacement and wavelength-referenced for temperature, were achieved by selective interference dip monitoring.

Two-Color Laser Speckle Shift Strain Measurement System

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.; Krasowski, Michael J.; Oberle, Lawrence G.; Greer, Lawrence C., III; Spina, Daniel; Barranger, John

1996-01-01

A two color laser speckle shift strain measurement system based on the technique of Yamaguchi was designed. The dual wavelength light output from an Argon Ion laser was coupled into two separate single-mode optical fibers (patchcords). The output of the patchcords is incident on the test specimen (here a structural fiber). Strain on the fiber, in one direction, is produced using an Instron 4502. Shifting interference patterns or speckle patterns will be detected at real-time rates using 2 CCD cameras with image processing performed by a hardware correlator. Strain detected in fibers with diameters from 21 microns to 143 microns is expected to be resolved to 15 mu epsilon. This system was designed to be compact and robust and does not require surface preparation of the structural fibers.

Phase-locked, erbium-fiber-laser-based frequency comb in the near infrared.

PubMed

Washburn, Brian R; Diddams, Scott A; Newbury, Nathan R; Nicholson, Jeffrey W; Yan, Man F; Jørgensen, Carsten G

2004-02-01

A phase-locked frequency comb in the near infrared is demonstrated with a mode-locked, erbium-doped, fiber laser whose output is amplified and spectrally broadened in dispersion-flattened, highly nonlinear optical fiber to span from 1100 to >2200 nm. The supercontinuum output comprises a frequency comb with a spacing set by the laser repetition rate and an offset by the carrier-envelope offset frequency, which is detected with the standard f-to-2f heterodyne technique. The comb spacing and offset frequency are phase locked to a stable rf signal with a fiber stretcher in the laser cavity and by control of the pump laser power, respectively. This infrared comb permits frequency metrology experiments in the near infrared in a compact, fiber-laser-based system.

Ultra-compact fiber-optic two-photon microscope for functional fluorescence imaging in vivo.

PubMed

Engelbrecht, Christoph J; Johnston, Richard S; Seibel, Eric J; Helmchen, Fritjof

2008-04-14

We present a small, lightweight two-photon fiberscope and demonstrate its suitability for functional imaging in the intact brain. Our device consists of a hollow-core photonic crystal fiber for efficient delivery of near-IR femtosecond laser pulses, a spiral fiber-scanner for resonant beam steering, and a gradient-index lens system for fluorescence excitation, dichroic beam splitting, and signal collection. Fluorescence light is remotely detected using a standard photomultiplier tube. All optical components have 1 mm dimensions and the microscope's headpiece weighs only 0.6 grams. The instrument achieves micrometer resolution at frame rates of typically 25 Hz with a field-of-view of up to 200 microns. We demonstrate functional imaging of calcium signals in Purkinje cell dendrites in the cerebellum of anesthetized rats. The microscope will be easily portable by a rat or mouse and thus should enable functional imaging in freely behaving animals.

Optoacoustic diagnostic modality: from idea to clinical studies with highly compact laser diode-based systems

PubMed Central

Esenaliev, Rinat O.

2017-01-01

Abstract. Optoacoustic (photoacoustic) diagnostic modality is a technique that combines high optical contrast and ultrasound spatial resolution. We proposed using the optoacoustic technique for a number of applications, including cancer detection, monitoring of thermotherapy (hyperthermia, coagulation, and freezing), monitoring of cerebral blood oxygenation in patients with traumatic brain injury, neonatal patients, fetuses during late-stage labor, central venous oxygenation monitoring, and total hemoglobin concentration monitoring as well as hematoma detection and characterization. We developed and built optical parametric oscillator-based systems and multiwavelength, fiber-coupled highly compact, laser diode-based systems for optoacoustic imaging, monitoring, and sensing. To provide sufficient output pulse energy, a specially designed fiber-optic system was built and incorporated in ultrasensitive, wideband optoacoustic probes. We performed preclinical and clinical tests of the systems and the optoacoustic probes in backward mode for most of the applications and in forward mode for the breast cancer and cerebral applications. The high pulse energy and repetition rate allowed for rapid data acquisition with high signal-to-noise ratio from cerebral blood vessels, such as the superior sagittal sinus, central veins, and peripheral veins and arteries, as well as from intracranial hematomas. The optoacoustic systems were capable of automatic, real-time, continuous measurements of blood oxygenation in these blood vessels. PMID:28444150

Optoacoustic diagnostic modality: from idea to clinical studies with highly compact laser diode-based systems

NASA Astrophysics Data System (ADS)

Esenaliev, Rinat O.

2017-09-01

Optoacoustic (photoacoustic) diagnostic modality is a technique that combines high optical contrast and ultrasound spatial resolution. We proposed using the optoacoustic technique for a number of applications, including cancer detection, monitoring of thermotherapy (hyperthermia, coagulation, and freezing), monitoring of cerebral blood oxygenation in patients with traumatic brain injury, neonatal patients, fetuses during late-stage labor, central venous oxygenation monitoring, and total hemoglobin concentration monitoring as well as hematoma detection and characterization. We developed and built optical parametric oscillator-based systems and multiwavelength, fiber-coupled highly compact, laser diode-based systems for optoacoustic imaging, monitoring, and sensing. To provide sufficient output pulse energy, a specially designed fiber-optic system was built and incorporated in ultrasensitive, wideband optoacoustic probes. We performed preclinical and clinical tests of the systems and the optoacoustic probes in backward mode for most of the applications and in forward mode for the breast cancer and cerebral applications. The high pulse energy and repetition rate allowed for rapid data acquisition with high signal-to-noise ratio from cerebral blood vessels, such as the superior sagittal sinus, central veins, and peripheral veins and arteries, as well as from intracranial hematomas. The optoacoustic systems were capable of automatic, real-time, continuous measurements of blood oxygenation in these blood vessels.

Integrated fiber optical and thermal sensor for noninvasive monitoring of blood and human tissue

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schiffner, Gerhard

2007-05-01

A novel concept of noninvasive monitoring of human tissue and blood based on optical diffuse reflective spectroscopy combined with metabolic heat measurements has been under development. A compact integrated fiber optical and thermal sensor has been developed. The idea of the method was to evaluate by optical spectroscopy haemoglobin and derivative concentrations and supplement with data associated with the oxidative metabolism of glucose. Body heat generated by glucose oxidation is based on the balance of capillary glucose and oxygen supply to the cells. The variation in glucose concentration is followed also by a difference from a distance (or depth) of scattered through the body radiation. So, blood glucose can be estimated by measuring the body heat and the oxygen supply. The sensor pickup contains of halogen lamp and LEDs combined with fiber optical bundle to deliver optical radiation inside and through the patient body, optical and thermal detectors. Fiber optical probe allows diffuse scattering measurement down to a depth of 2.5 mm in the skin including vascular system, which contributes to the control of the body temperature. The sensor pickup measures thermal generation, heat balance, blood flow rate, haemoglobin and derivative concentrations, environmental conditions. Multivariate statistical analysis was applied to convert various signals from the sensor pickup into physicochemical variables. By comparing the values from the noninvasive measurement with the venous plasma result, analytical functions for patient were obtained. Cluster analysis of patient groups was used to simplify a calibration procedure. Clinical testing of developed sensor is being performed.

Scaling of Yb-Fiber Frequency Combs

NASA Astrophysics Data System (ADS)

Ruehl, Axel; Marcinkevicius, Andrius; Fermann, Martin E.; Hartl, Ingmar

2010-06-01

Immediately after their introduction in 1999, femtosecond laser frequency combs revolutionized the field of precision optical frequency metrology and are key elements in many experiments. Frequency combs based on femtosecond Er-fiber lasers based were demonstrated in 2005, allowing additionally rugged, compact set-ups and reliable unattended long-term operation. The introduction of Yb-fiber technology led to an dramatic improvement in fiber-comb performance in various aspects. Low-noise Yb-fiber femtosecond oscillators enabled a reduction of relative comb tooth linewidth to the sub-Hz level as well as scaling of the fundamental comb spacings up to 1 GHz. This is beneficial for any frequency-domain comb application due to the higher power per comb-mode. Many spectroscopic applications require, however, frequency combs way beyond the wavelength range accessible with broad band laser materials, so nonlinear conversion and hence higher peak intensity is required. We demonstrated power scaling of Yb-fiber frequency combs up to 80 W average power in a strictly linear chirped-pulse amplification schemes compatible with low-noise phase control. These high-power Yb-fiber-frequency combs facilitated not only the extension to the mid-IR spectral region. When coupled to a passive enhancement cavity, the average power can be further scaled to the kW-level opening new capabilities for XUV frequency combs via high-harmonic generation. All these advances of fiber-based frequency combs will trigger many novel applications both in fundamental and applied sciences. Schibli et al., Nature Photonics 2 355 (2008). Hartl et al., MF9 in Advanced Solid-State Photonics. 2009, Optical Society of America. Ruehl et al., AWC7 in Advanced Solid-State Photonics. 2010, Optical Society of America. Adler et al., Optics Letters 34 1330 (2009). Yost et al., Nature Physics 5 815 (2009).

All-fiber orbital angular momentum mode generation and transmission system

NASA Astrophysics Data System (ADS)

Heng, Xiaobo; Gan, Jiulin; Zhang, Zhishen; Qian, Qi; Xu, Shanhui; Yang, Zhongmin

2017-11-01

We proposed and demonstrated an all-fiber system for generating and transmitting orbital angular momentum (OAM) mode light. A specially designed multi-core fiber (MCF) was used to endow with guide modes different phase change and two tapered transition regions were used for providing low-loss interfaces between different fiber structures. By arranging the refractive index distribution among the multi-cores and controlling the length of MCF, which essentially change the phase difference between the neighboring cores, OAM modes with different topological charge l can be generated selectively. Through two tapered transition regions, the non-OAM mode light can be effectively injected into the MCF and the generated OAM mode light can be easily launched into OAM mode supporting fiber for long distance and high purity transmission. Such an all-fiber OAM mode generation and transmission system owns the merits of flexibility, compactness, portability, and would have practical application value in OAM optical fiber communication systems.

Improving the accuracy of a dual-comb interferometer by suppressing the relative linewidth

NASA Astrophysics Data System (ADS)

Zhu, Zebin; Xu, Guangyao; Ni, Kai; Zhou, Qian; Wu, Guanhao

2018-04-01

We present a compact system of synchronization for two fiber-based optical frequency comb lasers. We use a free-running continuous wave laser as an intermediary to obtain the relative noise of two combs and employ an intra-cavity electro-optic modulator (EOM) to achieve active phase feedback for fast synchronization. The EOM bandwidth is 150 kHz and the relative linewidth is suppressed markedly from 300 kHz to sub-hertz values. The relative effective timing jitter of the two pulse trains is also decreased from 680 fs to 25 fs. The proposed method shows promise for developing a high-performance, low-cost, fiber-based dual-comb interferometer for ranging or spectroscopy.

Simplified design of diaphragm-based fiber optic extrinsic Fabry-Perot accelerometer

NASA Astrophysics Data System (ADS)

Wang, Zhaogang; Zhang, Wentao; Han, Jing; Huang, Wenzhu; Li, Fang

2014-11-01

A fiber optic Fabry-Perot accelerometer (FOFPA) with diaphragm-mass-collimator (DMC) gathered structure is presented. This design makes the structure more compacts and the manufacturing process more controllable. The operation principle based on Fabry-Perot interference is described. Several tests using intensity demodulation scheme which can control the working point of FOFPA were carried out. Experimental results show that: axis sensitivity of the proposed FOFPA is 36.07 dB (re: 0 dB=1 V/g) with a fluctuation less than 0.9 dB in a frequency bandwidth of 10-125 Hz, the resonant frequency is about 350 Hz, measurement range is about 70 dB@100 Hz. which are much close to theoretical values

Multifunction Imaging and Spectroscopic Instrument

NASA Technical Reports Server (NTRS)

Mouroulis, Pantazis

2004-01-01

A proposed optoelectronic instrument would perform several different spectroscopic and imaging functions that, heretofore, have been performed by separate instruments. The functions would be reflectance, fluorescence, and Raman spectroscopies; variable-color confocal imaging at two different resolutions; and wide-field color imaging. The instrument was conceived for use in examination of minerals on remote planets. It could also be used on Earth to characterize material specimens. The conceptual design of the instrument emphasizes compactness and economy, to be achieved largely through sharing of components among subsystems that perform different imaging and spectrometric functions. The input optics for the various functions would be mounted in a single optical head. With the exception of a targeting lens, the input optics would all be aimed at the same spot on a specimen, thereby both (1) eliminating the need to reposition the specimen to perform different imaging and/or spectroscopic observations and (2) ensuring that data from such observations can be correlated with respect to known positions on the specimen. The figure schematically depicts the principal components and subsystems of the instrument. The targeting lens would collect light into a multimode optical fiber, which would guide the light through a fiber-selection switch to a reflection/ fluorescence spectrometer. The switch would have four positions, enabling selection of spectrometer input from the targeting lens, from either of one or two multimode optical fibers coming from a reflectance/fluorescence- microspectrometer optical head, or from a dark calibration position (no fiber). The switch would be the only moving part within the instrument.

Tapered optical fiber sensor based on localized surface plasmon resonance.

PubMed

Lin, Hsing-Ying; Huang, Chen-Han; Cheng, Gia-Ling; Chen, Nan-Kuang; Chui, Hsiang-Chen

2012-09-10

A tapered fiber localized surface plasmon resonance (LSPR) sensor is demonstrated for refractive index sensing and label-free biochemical detection. The sensing strategy relies on the interrogation of the transmission intensity change due to the evanescent field absorption of immobilized gold nanoparticles on the tapered fiber surface. The refractive index resolution based on the interrogation of transmission intensity change is calculated to be 3.2×10⁻⁵ RIU. The feasibility of DNP-functionalized tapered fiber LSPR sensor in monitoring anti-DNP antibody with different concentrations spiked in buffer is examined. Results suggest that the compact sensor can perform qualitative and quantitative biochemical detection in real-time and thus has potential to be used in biomolecular sensing applications.

1540-nm single frequency single-mode pulsed all fiber laser for coherent Doppler lidar

NASA Astrophysics Data System (ADS)

Zhang, Xin; Diao, Weifeng; Liu, Yuan; Liu, Jiqiao; Hou, Xia; Chen, Weibiao

2015-02-01

A single-mode single frequency eye-safe pulsed all fiber laser based on master oscillator power amplification structure is presented. This laser is composed of a narrow linewidth distributed laser diode seed laser and two-stage cascade amplifiers. 0.8 m longitudinally gradient strained erbium/ytterbium co-doped polarization-maintaining fiber with a core diameter of 10 μm is used as the gain fiber and two acoustic-optics modulators are adopted to enhance pulse extinction ratio. A peak power of 160 W and a pulse width of 200 ns at 10 kHz repetition rate are achieved with transform-limited linewidth and diffraction-limited beam quality. This laser will be employed in a compact short range coherent Doppler wind lidar.

Crescent shaped Fabry-Perot fiber cavity for ultra-sensitive strain measurement.

PubMed

Liu, Ye; Wang, D N; Chen, W P

2016-12-02

Optical Fabry-Perot interferometer sensors based on inner air-cavity is featured with compact size, good robustness and high strain sensitivity, especially when an ultra-thin air-cavity is adopted. The typical shape of Fabry-Perot inner air-cavity with reflection mode of operation is elliptic, with minor axis along with and major axis perpendicular to the fiber length. The first reflection surface is diverging whereas the second one is converging. To increase the visibility of the output interference pattern, the length of major axis should be large for a given cavity length. However, the largest value of the major axis is limited by the optical fiber diameter. If the major axis length reaches the fiber diameter, the robustness of the Fabry-Perot cavity device would be decreased. Here we demonstrate an ultra-thin crescent shaped Fabry-Perot cavity for strain sensing with ultra-high sensitivity and low temperature cross-sensitivity. The crescent-shape cavity consists of two converging reflection surfaces, which provide the advantages of enhanced strain sensitivity when compared with elliptic or D-shaped FP cavity. The device is fabricated by fusion splicing an etched multimode fiber with a single mode fiber, and hence is simple in structure and economic in cost.

Crescent shaped Fabry-Perot fiber cavity for ultra-sensitive strain measurement

NASA Astrophysics Data System (ADS)

Liu, Ye; Wang, D. N.; Chen, W. P.

2016-12-01

Optical Fabry-Perot interferometer sensors based on inner air-cavity is featured with compact size, good robustness and high strain sensitivity, especially when an ultra-thin air-cavity is adopted. The typical shape of Fabry-Perot inner air-cavity with reflection mode of operation is elliptic, with minor axis along with and major axis perpendicular to the fiber length. The first reflection surface is diverging whereas the second one is converging. To increase the visibility of the output interference pattern, the length of major axis should be large for a given cavity length. However, the largest value of the major axis is limited by the optical fiber diameter. If the major axis length reaches the fiber diameter, the robustness of the Fabry-Perot cavity device would be decreased. Here we demonstrate an ultra-thin crescent shaped Fabry-Perot cavity for strain sensing with ultra-high sensitivity and low temperature cross-sensitivity. The crescent-shape cavity consists of two converging reflection surfaces, which provide the advantages of enhanced strain sensitivity when compared with elliptic or D-shaped FP cavity. The device is fabricated by fusion splicing an etched multimode fiber with a single mode fiber, and hence is simple in structure and economic in cost.

Adaptable Optical Fiber Displacement-Curvature Sensor Based on a Modal Michelson Interferometer with a Tapered Single Mode Fiber

PubMed Central

Salceda-Delgado, G.; Martinez-Rios, A.; Selvas-Aguilar, R.; Álvarez-Tamayo, R. I.; Castillo-Guzman, A.; Ibarra-Escamilla, B.; Durán-Ramírez, V. M.; Enriquez-Gomez, L. F.

2017-01-01

A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal coupling device between core and cladding modes for the SMF segment. When the bi-conical taper is bent by an axial displacement, the symmetrical bi-conical shape of the tapered structure is stressed, causing a change in the refractive index profile which becomes asymmetric. As a result, the taper adiabaticity is lost, and interference between modes appears. As the bending increases, a small change in the fringe visibility and a wavelength shift on the periodical reflection spectrum of the in-fiber interferometer is produced. The displacement sensitivity and the spectral periodicity of the device can be adjusted by the proper selection of the SMF length. Sensitivities from around 1.93 to 3.4 nm/mm were obtained for SMF length between 7.5 and 12.5 cm. Both sensor interrogations, wavelength shift and visibility contrast, can be used to measure displacement and curvature radius magnitudes. PMID:28574421

Adaptable Optical Fiber Displacement-Curvature Sensor Based on a Modal Michelson Interferometer with a Tapered Single Mode Fiber.

PubMed

Salceda-Delgado, G; Martinez-Rios, A; Selvas-Aguilar, R; Álvarez-Tamayo, R I; Castillo-Guzman, A; Ibarra-Escamilla, B; Durán-Ramírez, V M; Enriquez-Gomez, L F

2017-06-02

A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal coupling device between core and cladding modes for the SMF segment. When the bi-conical taper is bent by an axial displacement, the symmetrical bi-conical shape of the tapered structure is stressed, causing a change in the refractive index profile which becomes asymmetric. As a result, the taper adiabaticity is lost, and interference between modes appears. As the bending increases, a small change in the fringe visibility and a wavelength shift on the periodical reflection spectrum of the in-fiber interferometer is produced. The displacement sensitivity and the spectral periodicity of the device can be adjusted by the proper selection of the SMF length. Sensitivities from around 1.93 to 3.4 nm/mm were obtained for SMF length between 7.5 and 12.5 cm. Both sensor interrogations, wavelength shift and visibility contrast, can be used to measure displacement and curvature radius magnitudes.

Low-NA fiber laser pumps powered by high-brightness single emitters

NASA Astrophysics Data System (ADS)

Yanson, Dan; Levy, Moshe; Peleg, Ophir; Rappaport, Noam; Shamay, Moshe; Dahan, Nir; Klumel, Genady; Berk, Yuri; Baskin, Ilya

2015-03-01

Fiber laser manufacturers demand high-brightness laser diode pumps delivering optical pump energy in both a compact fiber core and narrow angular content. A pump delivery fiber of a 105 μm core and 0.22 numerical aperture (NA) is typically used, where the fiber NA is under-filled to ease the launch of laser diode emission into the fiber and make the fiber tolerant to bending. At SCD, we have developed high-brightness NEON multi-emitter fiber-coupled pump modules that deliver 50 W output from a 105 μm, 0.15 NA fiber enabling low-NA power delivery to a customer's fiber laser network. Brightness-enhanced single emitters are engineered with ultra-low divergence for compatibility with the low-NA delivery fiber, with the latest emitters delivering 14 W with 95% of the slow-axis energy contained within an NA of 0.09. The reduced slow-axis divergence is achieved with an optimized epitaxial design, where the peak optical intensity is reduced to both lessen filamentation within the laser cavity and reduce the power density on the output facet thus increasing the emitter reliability. The low mode filling of the fiber allows it to be coiled with diameters down to 70 mm at full operating power despite the small NA and further eliminates the need for mode-stripping at fiber combiners and splices downstream from our pump modules. 50W fiber pump products at 915, 950 and 975 nm wavelengths are presented, including a wavelengthstabilized version at 976 nm.

Design of a miniature solid state NIR spectrometer

NASA Astrophysics Data System (ADS)

Zhang, Hanyi; Wang, Xiaolu L.; Soos, Jolanta I.; Crisp, Joy A.

1995-06-01

For aerospace applications a miniature, solid-state near infrared (NIR) spectrometer based on an acousto-optic tunable filter (AOTF) has been developed and built at Brimrose Corp. of America. In this spectrometer a light emitting diode (LED) array as light source, a set of optical fibers as the lightwave transmission route, and a miniature AOTF as a tunable filter were adopted. This approach makes the spectrometer very compact, light-weight, rugged and reliable, with low operating power and long lifetime.

Wavelength-multiplexed fiber optic position encoder for aircraft control systems

NASA Astrophysics Data System (ADS)

Beheim, Glenn; Krasowski, Michael J.; Sotomayor, Jorge L.; Fritsch, Klaus; Flatico, Joseph M.; Bathurst, Richard L.; Eustace, John G.; Anthan, Donald J.

1991-02-01

NASA Lewis together with John Carroll University has worked for the last several years to develop wavelength-multiplexed digital position transducers for use in aircraft control systems. A prototype rotary encoder is being built for a demonstration program involving the control of a commercial transport''s turbofan engine. This encoder has eight bits of resolution a 90 degree range and is powered by a single LED. A compact electro-optics module is being developed to withstand the extremely hostile gas turbine environment.

Non-hermetic fiber optic transceivers for space applications

NASA Astrophysics Data System (ADS)

Tabbert, Chuck

2017-11-01

There is a commercial trend in high data-rate systems to place optical components in close proximity to the data source/sink. This trend forgoes the traditional module packaging approach to create compact components that are embedded near or within the package of high-performance ASICs. This approach reduces the power consumption and electro-magnetic interference (EMI) effects by reducing the length of copper interconnect signal paths. We present an overview of commercial trends and methods for fielding this technology within spacecraft.

Stimulated Raman scattering microscopy by Nyquist modulation of a two-branch ultrafast fiber source.

PubMed

Riek, Claudius; Kocher, Claudius; Zirak, Peyman; Kölbl, Christoph; Fimpel, Peter; Leitenstorfer, Alfred; Zumbusch, Andreas; Brida, Daniele

2016-08-15

A highly stable setup for stimulated Raman scattering (SRS) microscopy is presented. It is based on a two-branch femtosecond Er:fiber laser operating at a 40 MHz repetition rate. One of the outputs is directly modulated at the Nyquist frequency with an integrated electro-optic modulator (EOM). This compact source combines a jitter-free pulse synchronization with a broad tunability and allows for shot-noise limited SRS detection. The performance of the SRS microscope is illustrated with measurements on samples from material science and cell biology.

Inexpensive Raman Spectrometer for Undergraduate and Graduate Experiments and Research

ERIC Educational Resources Information Center

Mohr, Christian; Spencer, Claire L.; Hippler, Michael

2010-01-01

We describe the construction and performance of an inexpensive modular Raman spectrometer that has been assembled in the framework of a fourth-year undergraduate project (costs below $5000). The spectrometer is based on a 4 mW 532 nm green laser pointer and a compact monochromator equipped with glass fiber optical connections, linear detector…

On the feasibility of a fiber-based inertial fusion laser driver

NASA Astrophysics Data System (ADS)

Labaune, C.; Hulin, D.; Galvanauskas, A.; Mourou, G. A.

2008-08-01

One critical issue for the realization of Inertial Fusion Energy (IFE) power plants is the driver efficiency. High driver efficiency will greatly relax the driver energy requested to produce a fusion gain, resulting in more compact and less costly facilities. Among lasers, systems based on guided wave such as diode pumped Yb:glass fiber-amplifiers with a demonstrated overall efficiency close to 70% as opposed to few percents for systems based on free propagation, offer some intriguing opportunities. Guided optics provides the enormous advantage to directly benefit from the telecommunication industry where components are made cheap, rugged, well tested, environmentally stable, with lifetimes measured in tens of years and compatible with massive manufacturing. In this paper, we are studying the possibility to design a laser driver solely based on guided wave optics. We call this concept FAN for Fiber Amplification Network. It represents a profound departure from already proposed laser drivers all based on free propagation optics. The system will use a large number of identical fibers to combines long (ns) and short (ps) pulses that are needed for the fast ignition scheme. Technical details are discussed relative to fiber type, pump, phasing, pulse shaping and timing as well as fiber distribution around the chamber. The proposed fiber driver provides maximum and independent control on the wavefront, pulse duration, pulse shape, timing, making possible reaching the highest gain. The massive manufacturing will be amenable to a cheaper facility with an easy upkeep.

Optical coupling elements for coherent optical multiport receivers

NASA Astrophysics Data System (ADS)

Langenhorst, Ralf

1992-05-01

Three by three (3 by 3) and four by four (4 by 4) port coupling elements and receivers for heterodyne multiport systems are realized. Commercial (3 by 3) fiber coupling elements were used to achieve a usual (3 by 3) port receiver and a (3 by 3) port receiver in pushpull switching, whose concept was theoretically and experimentally analyzed. It is established that intensity oscillations of laser sources are suppressed by pushpull switching. The influence of thermal noise of opto-electronic input levels is shown to be weaker than in usual (3 by 3) port and (4 by 4) port receivers. Thermal noise effect in pushpull switching is similar to this one in heterodyne receivers. An integrated optical coupling element in LiNbO3 was made with bridge circuit from four waveguide coupling elements and two phase converters, which are electro-optically tunable so that a continuous regulation of intermediate frequency phase can be compensated by temperature variations of the element. To obtain fiber-to-fiber losses lower than a dB, a compact crystal optical coupling element was developed with reference to polarization properties of optical waves. This element supplied the eight necessary intermediate frequency output signals. A direct experimental comparison of bandwidth efficiency of multiport and heterodyne receivers shows a factor two in optical area and a factor three in electrical frequency area.

Monolithic integration of elliptic-symmetry diffractive optical element on silicon-based 45 degrees micro-reflector.

PubMed

Lan, Hsiao-Chin; Hsiao, Hsu-Liang; Chang, Chia-Chi; Hsu, Chih-Hung; Wang, Chih-Ming; Wu, Mount-Learn

2009-11-09

A monolithically integrated micro-optical element consisting of a diffractive optical element (DOE) and a silicon-based 45 degrees micro-reflector is experimentally demonstrated to facilitate the optical alignment of non-coplanar fiber-to-fiber coupling. The slanted 45 degrees reflector with a depth of 216 microm is fabricated on a (100) silicon wafer by anisotropic wet etching. The DOE with a diameter of 174.2 microm and a focal length of 150 microm is formed by means of dry etching. Such a compact device is suitable for the optical micro-system to deflect the incident light by 90 degrees and to focus it on the image plane simultaneously. The measured light pattern with a spot size of 15 microm has a good agreement with the simulated result of the elliptic-symmetry DOE with an off-axis design for eliminating the strongly astigmatic aberration. The coupling efficiency is enhanced over 10-folds of the case without a DOE on the 45 degrees micro-reflector. This device would facilitate the optical alignment of non-coplanar light coupling and further miniaturize the volume of microsystem.

Development of plasma bolometers using fiber-optic temperature sensors

NASA Astrophysics Data System (ADS)

Reinke, M. L.; Han, M.; Liu, G.; van Eden, G. G.; Evenblij, R.; Haverdings, M.; Stratton, B. C.

2016-11-01

Measurements of radiated power in magnetically confined plasmas are important for exhaust studies in present experiments and expected to be a critical diagnostic for future fusion reactors. Resistive bolometer sensors have long been utilized in tokamaks and helical devices but suffer from electromagnetic interference (EMI). Results are shown from initial testing of a new bolometer concept based on fiber-optic temperature sensor technology. A small, 80 μm diameter, 200 μm long silicon pillar attached to the end of a single mode fiber-optic cable acts as a Fabry-Pérot cavity when broadband light, λo ˜ 1550 nm, is transmitted along the fiber. Changes in temperature alter the optical path length of the cavity primarily through the thermo-optic effect, resulting in a shift of fringes reflected from the pillar detected using an I-MON 512 OEM spectrometer. While initially designed for use in liquids, this sensor has ideal properties for use as a plasma bolometer: a time constant, in air, of ˜150 ms, strong absorption in the spectral range of plasma emission, immunity to local EMI, and the ability to measure changes in temperature remotely. Its compact design offers unique opportunities for integration into the vacuum environment in places unsuitable for a resistive bolometer. Using a variable focus 5 mW, 405 nm, modulating laser, the signal to noise ratio versus power density of various bolometer technologies are directly compared, estimating the noise equivalent power density (NEPD). Present tests show the fiber-optic bolometer to have NEPD of 5-10 W/m2 when compared to those of the resistive bolometer which can achieve <0.5 W/m2 in the laboratory, but this can degrade to 1-2 W/m2 or worse when installed on a tokamak. Concepts are discussed to improve the signal to noise ratio of this new fiber-optic bolometer by reducing the pillar height and adding thin metallic coatings, along with improving the spectral resolution of the interrogator.

Integration of Fiber-Optic Sensor Arrays into a Multi-Modal Tactile Sensor Processing System for Robotic End-Effectors

PubMed Central

Kampmann, Peter; Kirchner, Frank

2014-01-01

With the increasing complexity of robotic missions and the development towards long-term autonomous systems, the need for multi-modal sensing of the environment increases. Until now, the use of tactile sensor systems has been mostly based on sensing one modality of forces in the robotic end-effector. The use of a multi-modal tactile sensory system is motivated, which combines static and dynamic force sensor arrays together with an absolute force measurement system. This publication is focused on the development of a compact sensor interface for a fiber-optic sensor array, as optic measurement principles tend to have a bulky interface. Mechanical, electrical and software approaches are combined to realize an integrated structure that provides decentralized data pre-processing of the tactile measurements. Local behaviors are implemented using this setup to show the effectiveness of this approach. PMID:24743158

Non-perturbing voltage measurement in a coaxial cable with slab-coupled optical sensors.

PubMed

Stan, Nikola; Seng, Frederick; Shumway, LeGrand; King, Rex; Schultz, Stephen

2017-08-20

Voltage in a coaxial cable is measured by an electric-field optical fiber sensor exploiting the proportionality of voltage and electric field in a fixed structure. The sensor is inserted in a hole drilled through the dielectric of the RG-218 coaxial cable and sealed with epoxy to displace all air and prevent the adverse effects of charge buildup during high-voltage measurements. It is shown that the presence of the sensor in the coaxial cable does not significantly increase electrical reflections in the cable. A slab-coupled optical fiber sensor (SCOS) is used for its compact size and dielectric make. The dynamic range of 50 dB is shown experimentally with detection of signals as low as 1 V and up to 157 kV. A low corner of 0.3 Hz is demonstrated and the SCOS is shown to be able to measure 90 ns rise time.

Low-cost rapid miniature optical pressure sensors for blast wave measurements.

PubMed

Wu, Nan; Wang, Wenhui; Tian, Ye; Zou, Xiaotian; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

2011-05-23

This paper presents an optical pressure sensor based on a Fabry-Perot (FP) interferometer formed by a 45° angle polished single mode fiber and an external silicon nitride diaphragm. The sensor is comprised of two V-shape grooves with different widths on a silicon chip, a silicon nitride diaphragm released on the surface of the wider V-groove, and a 45° angle polished single mode fiber. The sensor is especially suitable for blast wave measurements: its compact structure ensures a high spatial resolution; its thin diaphragm based design and the optical demodulation scheme allow a fast response to the rapid changing signals experienced during blast events. The sensor shows linearity with the correlation coefficient of 0.9999 as well as a hysteresis of less than 0.3%. The shock tube test demonstrated that the sensor has a rise time of less than 2 µs from 0 kPa to 140 kPa.

Writing Bragg Gratings in Multicore Fibers.

PubMed

Lindley, Emma Y; Min, Seong-Sik; Leon-Saval, Sergio G; Cvetojevic, Nick; Lawrence, Jon; Ellis, Simon C; Bland-Hawthorn, Joss

2016-04-20

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.

Writing Bragg Gratings in Multicore Fibers

PubMed Central

Lindley, Emma Y.; Min, Seong-sik; Leon-Saval, Sergio G.; Cvetojevic, Nick; Lawrence, Jon; Ellis, Simon C.; Bland-Hawthorn, Joss

2016-01-01

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers. PMID:27167576

Light funneling from a photonic crystal laser cavity to a nano-antenna: overcoming the diffraction limit in optical energy transfer down to the nanoscale.

PubMed

Mivelle, Mathieu; Viktorovitch, Pierre; Baida, Fadi I; El Eter, Ali; Xie, Zhihua; Vo, Than-Phong; Atie, Elie; Burr, Geoffrey W; Nedeljkovic, Dusan; Rauch, Jean-Yves; Callard, Ségolène; Grosjean, Thierry

2014-06-16

We show that the near-field coupling between a photonic crystal microlaser and a nano-antenna can enable hybrid photonic systems that are both physically compact (free from bulky optics) and efficient at transferring optical energy into the nano-antenna. Up to 19% of the laser power from a micron-scale photonic crystal laser cavity is experimentally transferred to a bowtie aperture nano-antenna (BNA) whose area is 400-fold smaller than the overall emission area of the microlaser. Instead of a direct deposition of the nano-antenna onto the photonic crystal, it is fabricated at the apex of a fiber tip to be accurately placed in the microlaser near-field. Such light funneling within a hybrid structure provides a path for overcoming the diffraction limit in optical energy transfer to the nanoscale and should thus open promising avenues in the nanoscale enhancement and confinement of light in compact architectures, impacting applications such as biosensing, optical trapping, local heating, spectroscopy, and nanoimaging.

Detection system of capillary array electrophoresis microchip based on optical fiber

NASA Astrophysics Data System (ADS)

Yang, Xiaobo; Bai, Haiming; Yan, Weiping

2009-11-01

To meet the demands of the post-genomic era study and the large parallel detections of epidemic diseases and drug screening, the high throughput micro-fluidic detection system is needed urgently. A scanning laser induced fluorescence detection system based on optical fiber has been established by using a green laser diode double-pumped solid-state laser as excitation source. It includes laser induced fluorescence detection subsystem, capillary array electrophoresis micro-chip, channel identification unit and fluorescent signal processing subsystem. V-shaped detecting probe composed with two optical fibers for transmitting the excitation light and detecting induced fluorescence were constructed. Parallel four-channel signal analysis of capillary electrophoresis was performed on this system by using Rhodamine B as the sample. The distinction of different samples and separation of samples were achieved with the constructed detection system. The lowest detected concentration is 1×10-5 mol/L for Rhodamine B. The results show that the detection system possesses some advantages, such as compact structure, better stability and higher sensitivity, which are beneficial to the development of microminiaturization and integration of capillary array electrophoresis chip.

Ultrafast Fabry-Perot fiber-optic pressure sensors for multimedia blast event measurements.

PubMed

Zou, Xiaotian; Wu, Nan; Tian, Ye; Zhang, Yang; Fitek, John; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

2013-02-20

A shock wave (SW) is characterized as a large pressure fluctuation that typically lasts only a few milliseconds. On the battlefield, SWs pose a serious threat to soldiers who are exposed to explosions, which may lead to blast-induced traumatic brain injuries. SWs can also be used beneficially and have been applied to a variety of medical treatments due to their unique interaction with tissues and cells. Consequently, it is important to have sensors that can quantify SW dynamics in order to better understand the physical interaction between body tissue and the incident acoustic wave. In this paper, the ultrafast fiber-optic sensor based on the Fabry-Perot interferometric principle was designed and four such sensors were fabricated to quantify a blast event within different media, simultaneously. The compact design of the fiber-optic sensor allows for a high degree of spatial resolution when capturing the wavefront of the traveling SW. Several blast event experiments were conducted within different media (e.g., air, rubber membrane, and water) to evaluate the sensor's performance. This research revealed valuable knowledge for further study of SW behavior and SW-related applications.

Studies of lipid vesicle mechanics using an optical fiber dual-beam trap

NASA Astrophysics Data System (ADS)

Pinon, Tessa M.; Hirst, Linda S.; Sharping, Jay E.

2011-03-01

Fiber-based optical traps can be used for manipulating micron-sized dielectric particles such as microspheres and biological cells. Here we study the mechanics of giant unilamellar vesicles (GUVs) which are held and stretched by light forces in a fiber-based dual-beam optical trap. Our GUVs are suspended in a buffer solution and encapsulate various concentrations and molecular weights of poly(ethylene glycol) (PEG) polymer yielding a range of refractive index contrasts and trapping conditions. We find that we can trap GUVs in solution with index contrasts of less than 0.01. We explore the mechanical response of the GUV membrane to a range of forces which are proportional to laser power and refractive index contrast. Our trapping system is a compact and inexpensive platform and trapping is viewed in real time under a microscope. We hypothesize that forces within the high-tension regime will induce a linear response in vesicle surface area. This project sets the stage for membrane mechanics and lipid phase change studies. Grant: NSF award #DMR 0852791, ``CAREER: Self-Assembly of Polyunsaturated Lipids and Cholesterol in the Cell Membrane.''

MEMS micromirrors for optical switching in multichannel spectrophotometers

NASA Astrophysics Data System (ADS)

Tuantranont, Adisorn; Lomas, Tanom; Bright, Victor M.

2004-04-01

This paper reports for the first time that a novel MEMS-based micromirror switch has successfully demonstrated for optical switching in a multi-channel fiber optics spectrophotometer system. The conventional optomechanical fiber optic switches for multi-channel spectrophotometers available in market are bulky, slow, low numbers of channels and expensive. Our foundry MEMS-based micromirror switch designed for integrating with commercially available spectrophotometers offers more compact devices, increased number of probing channels, higher performance and cheaper. Our MEMS-based micromirror switch is a surface micromachined mirror fabricated through MUMPs foundry. The 280 μm x 280 μm gold coated mirror is suspended by the double-gimbal structure for X and Y axis scanning. Self-assembly by solders is used to elevate the torsion mirror 30 μm over the substrate to achieve large scan angle. The solder self-assembly approach dramatically reduces the time to assembly the switch. The scan mirror is electrostatically controlled by applying voltages. The individual probing signal from each probing head is guided by fibers with collimated lenses and incidents on the center of the mirror. The operating scan angle is in the range of 3.5 degrees with driving voltage of 0-100 V. The fastest switching time of 4 millisecond (1 ms rise time and 3 ms fall time) is measured corresponding to the maximum speed of the mirror of 0.25 kHz when the mirror is scanning at +/- 1.5 degrees. The micromirror switch is packaged with a multi-mode fiber bundle using active alignment technique. A centered fiber is the output fiber that is connected to spectrophotometer. Maximum insertion loss of 5 dB has been obtained. The accuracy of measured spectral data is equivalent to the single channel spectrophotometer with a small degradation on probing signal due to fiber coupling.

Completely monolithic linearly polarized high-power fiber laser oscillator

NASA Astrophysics Data System (ADS)

Belke, Steffen; Becker, Frank; Neumann, Benjamin; Ruppik, Stefan; Hefter, Ulrich

2014-03-01

We have demonstrated a linearly polarized cw all-in-fiber oscillator providing 1 kW of output power and a polarization extinction ratio (PER) of up to 21.7 dB. The design of the laser oscillator is simple and consists of an Ytterbium-doped polarization maintaining large mode area (PLMA) fiber and suitable fiber Bragg gratings (FBG) in matching PLMA fibers. The oscillator has nearly diffraction-limited beam quality (M² < 1.2). Pump power is delivered via a high power 6+1:1 pump coupler. The slope efficiency of the laser is 75 %. The electro/optical efficiency of the complete laser system is ~30 % and hence in the range of Rofin's cw non-polarized fiber lasers. Choosing an adequate bending diameter for the Yb-doped PLMA fiber, one polarization mode as well as higher order modes are sufficiently supressed1. Resulting in a compact and robust linearly polarized high power single mode laser without external polarizing components. Linearly polarized lasers are well established for one dimensional cutting or welding applications. Using beam shaping optics radially polarized laser light can be generated to be independent from the angle of incident to the processing surface. Furthermore, high power linearly polarized laser light is fundamental for nonlinear frequency conversion of nonlinear materials.

All-Optical Photoacoustic Sensors for Steel Rebar Corrosion Monitoring.

PubMed

Du, Cong; Owusu Twumasi, Jones; Tang, Qixiang; Guo, Xu; Zhou, Jingcheng; Yu, Tzuyang; Wang, Xingwei

2018-04-27

This article presents an application of an active all-optical photoacoustic sensing system with four elements for steel rebar corrosion monitoring. The sensor utilized a photoacoustic mechanism of gold nanocomposites to generate 8 MHz broadband ultrasound pulses in 0.4 mm compact space. A nanosecond 532 nm pulsed laser and 400 μm multimode fiber were employed to incite an ultrasound reaction. The fiber Bragg gratings were used as distributed ultrasound detectors. Accelerated corrosion testing was applied to four sections of a single steel rebar with four different corrosion degrees. Our results demonstrated that the mass loss of steel rebar displayed an exponential growth with ultrasound frequency shifts. The sensitivity of the sensing system was such that 0.175 MHz central frequency reduction corresponded to 0.02 g mass loss of steel rebar corrosion. It was proved that the all-optical photoacoustic sensing system can actively evaluate the corrosion of steel rebar via ultrasound spectrum. This multipoint all-optical photoacoustic method is promising for embedment into a concrete structure for distributed corrosion monitoring.

Frequency Noise Suppression of a Single Mode Laser with an Unbalanced Fiber Interferometer for Subnanometer Interferometry

PubMed Central

Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Číp, Ondřej

2015-01-01

We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency. PMID:25587980

A Fiber Optic Probe for Monitoring Protein Aggregation, Nucleation, and Crystallization

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Suh, Kwang I.; Arabshahi, Alireza; Wilson, William W.; Bray, Terry L.; DeLucas, Lawrence J.

1996-01-01

Protein crystals are experimentally grown in hanging drops in microgravity experiments on-board the Space Shuttle orbiter. The technique of dynamic light scattering (DLS) can be used to monitor crystal growth process in hanging droplets (approx. 30 (L)) in microgravity experiments, but elaborate instrumentation and optical alignment problems have made in-situ applications difficult. In this paper we demonstrate that such experiments are now feasible. We apply a newly developed fiber optic probe to various earth and space (micro- gravity) bound protein crystallization system configurations to test its capability. These include conventional batch (cuvette or capillary) systems, hanging drop method in a six-pack hanging drop vapor diffusion apparatus (HDVDA), a modified HDVDA for temperature- induced nucleation and aggregation studies, and a newly envisioned dynamically controlled vapor diffusion system (DCVDS) configuration. Our compact system exploits the principles of DLS and offers a fast (within a few seconds) means of quantitatively and non-invasively monitoring the various growth stages of protein crystallization. In addition to DLS capability, the probe can also be used for performing single-angle static light scattering measurements. It utilizes extremely low levels of laser power (approx. few (W)) without a need of having any optical alignment and vibration isolation. The compact probe is also equipped with a miniaturized microscope for visualization of macroscopic protein crystals. This new optical diagnostic system opens up enormous opportunity for exploring new ways to grow good quality crystals suitable for x-ray crystallographic analysis and may help develop a concrete scientific basis for understanding the process of crystallization.

Compact probing system using remote imaging for industrial plant maintenance

NASA Astrophysics Data System (ADS)

Ito, F.; Nishimura, A.

2014-03-01

Laser induced breakdown spectroscopy (LIBS) and endoscope observation were combined to design a remote probing device. We use this probing device to inspect a crack of the inner wall of the heat exchanger. Crack inspection requires speed at first, and then it requires accuracy. Once Eddy Current Testing (ECT) finds a crack with a certain signal level, another method should confirm it visually. We are proposing Magnetic particle Testing (MT) using specially fabricated the Magnetic Particle Micro Capsule (MPMC). For LIBS, a multichannel spectrometer and a Q-switch YAG laser were used. Irradiation area is 270 μm, and the pulse energy was 2 mJ. This pulse energy corresponds to 5-2.2 MW/cm2. A composite-type optical fiber was used to deliver both laser energy and optical image. Samples were prepared to heat a zirconium alloy plate by underwater arc welding in order to demonstrate severe accidents of nuclear power plants. A black oxide layer covered the weld surface and white particles floated on water surface. Laser induced breakdown plasma emission was taken into the spectroscope using this optical fiber combined with telescopic optics. As a result, we were able to simultaneously perform spectroscopic measurement and observation. For MT, the MPMC which gathered in the defective area is observed with this fiber. The MPMC emits light by the illumination of UV light from this optical fiber. The size of a defect is estimated with this amount of emission. Such technology will be useful for inspection repair of reactor pipe.

Sensitivity-enhanced Tm3+/Yb3+ co-doped YAG single crystal optical fiber thermometry based on upconversion emissions

NASA Astrophysics Data System (ADS)

Yu, Lu; Ye, Linhua; Bao, Renjie; Zhang, Xianwei; Wang, Li-Gang

2018-03-01

Optical thermometry based on Y3Al5O12 (YAG) single crystal optical fiber with end Tm3+/Yb3+ co-doped is presented. The YAG crystal fiber with end Tm3+/Yb3+ co-doped was grown by laser heated pedestal growth (LHPG) method. Under a 976 nm laser diode excitation, the upconversion (UC) emissions, originating from 3F2,3 →3H6 and 3H4 →3H6 transitions of Tm3+ ions, were investigated in the temperature range from 333 K to 733 K. Interestingly, the UC emission intensity of 3F2,3 →3H6 transition was significantly enhanced with increase of temperature, as compared with the other Tm3+/Yb3+ co-doped materials. The temperature dependence of fluorescence intensity ratio (FIR) of these two emission bands (3F2,3/3H4 →3H6) suggests that this doped YAG crystal fiber can be used as a highly sensitive optical thermal probe, which demonstrates a high absolute sensitivity with the maximum value of 0.021 K-1 at 733 K. In addition, due to the compact structure, strong mechanical strength and high thermal stability, such thermal probe may be a more promising candidate for temperature sensor with a high spatial resolution.

Effect of length of chopped pristine and intercalated graphite fibers on the resistivity of fiber networks

NASA Technical Reports Server (NTRS)

Gaier, James R.; Stahl, Mark

1988-01-01

Samples of Amoco P-100 fibers were chopped to lengths of 3.14, 2.53, 1.90, 1.27, 0.66 mm, or milled for 2 hours. The two-point resistivity of compacts of these fibers were measured as a function of pressure from 34 kPa to 143 MPa. Samples of each fiber length were intercalated with bromine at room temperature and similarly measured. The low pressure resistivity of the compacts decreased with increasing fiber length. Intercalation lowered the resistivity of each of the chopped length compacts, but raised the resistivity of the milled fiber compacts. Bulk resistivity of all samples decreased with increasing pressure at similar rates. Even though fiber volumes were as low as 5 percent, all measurements exhibited measurable resistivity. A greater change with pressure in the resistance was observed for shorter fibers than for longer, probably an indication of tighter fiber packing. Intercalation appeared to have no effect on the fiber to fiber contact resistance.

Optimization of few-mode-fiber based mode converter for mode division multiplexing transmission

NASA Astrophysics Data System (ADS)

Xie, Yiwei; Fu, Songnian; Zhang, Minming; Tang, M.; Shum, P.; Liu, Deming

2013-10-01

Few-mode-fiber (FMF) based mode division multiplexing (MDM) is a promising technique to further increase the transmission capacity of single mode fibers. We propose and numerically investigate a fiber-optical mode converter (MC) using long period gratings (LPGs) fabricated on the FMF by point-by-point CO2 laser inscription technique. In order to precisely excite three modes (LP01, LP11, and LP02), both untilted LPG and tilted LPG are comprehensively optimized through the length, index modulation depth, and tilt angle of the LPG in order to achieve a mode contrast ratio (MCR) of more than 20 dB with less wavelength dependence. It is found that the proposed MCs have obvious advantages of high MCR, low mode crosstalk, easy fabrication and maintenance, and compact size.

Fiber-optic laser Doppler turbine tip clearance probe

NASA Astrophysics Data System (ADS)

Büttner, Lars; Pfister, Thorsten; Czarske, Jürgen

2006-05-01

A laser Doppler based method for in situ single blade tip clearance measurements of turbomachines with high precision is presented for what we believe is the first time. The sensor is based on two superposed fanlike interference fringe systems generated by two laser wavelengths from a fiber-coupled, passive, and therefore compact measurement head employing diffractive optics. Tip clearance measurements at a transonic centrifugal compressor performed during operation at 50,000 rpm (833 Hz, 586 m/s tip speed) are reported. At these speeds the measured uncertainty of the tip position was less than 20 μm, a factor of 2 more accurate than that of capacitive probes. The sensor offers great potential for in situ and online high-precision tip clearance measurements of metallic and nonmetallic turbine blades.

Fiber-optic laser Doppler turbine tip clearance probe.

PubMed

Büttner, Lars; Pfister, Thorsten; Czarske, Jürgen

2006-05-01

A laser Doppler based method for in situ single blade tip clearance measurements of turbomachines with high precision is presented for what we believe is the first time. The sensor is based on two superposed fanlike interference fringe systems generated by two laser wavelengths from a fiber-coupled, passive, and therefore compact measurement head employing diffractive optics. Tip clearance measurements at a transonic centrifugal compressor performed during operation at 50,000 rpm (833 Hz, 586 m/s tip speed) are reported. At these speeds the measured uncertainty of the tip position was less than 20 microm, a factor of 2 more accurate than that of capacitive probes. The sensor offers great potential for in situ and online high-precision tip clearance measurements of metallic and nonmetallic turbine blades.

A compact multi-channel fluorescence sensor with ambient light suppression

NASA Astrophysics Data System (ADS)

Egly, Dominik; Geörg, Daniel; Rädle, Matthias; Beuermann, Thomas

2012-03-01

A multi-channel fluorescence sensor has been developed for process monitoring and fluorescence diagnostics. It comprises a fiber-optic set-up with an immersion probe and an intensity-modulated high power ultraviolet light-emitting diode as a light source for fluorescence excitation. By applying an electronic lock-in procedure, fluorescence signals are selectively detectable at ambient light levels of 1000 000 times higher intensity. The sensor was designed to be compact, low cost and easily adaptable to a wide field of application. The set-up was used to simultaneously monitor three important metabolic fluorophores: NAD(P)H, flavins and porphyrins during the cultivation of a baker's yeast. Moreover, the accumulation and degradation kinetics of protoporphyrin IX induced by 5-aminolevulinic acid on the skin could be recorded by the sensor. The detection limit for protoporphyrin IX was determined to be 4 × 10-11 mol L-1. The linear signal amplification of the sensor and time courses of fluorescence signals monitored during yeast fermentations were validated using a commercial CCD spectrometer. The robust and flexible set-up of the fiber-optic measurement system promises easy implementation of this non-invasive analytical tool to fluorescence monitoring and diagnostics in R&D and production.

High-brightness power delivery for fiber laser pumping: simulation and measurement of low-NA fiber guiding

NASA Astrophysics Data System (ADS)

Yanson, Dan; Levy, Moshe; Peleg, Ophir; Rappaport, Noam; Shamay, Moshe; Dahan, Nir; Klumel, Genady; Berk, Yuri; Baskin, Ilya

2015-02-01

Fiber laser manufacturers demand high-brightness laser diode pumps delivering optical pump energy in both a compact fiber core and narrow angular content. A pump delivery fiber of a 105 μm core and 0.22 numerical aperture (NA) is typically used, where the fiber NA is under-filled to ease the launch of laser diode emission into the fiber and make the fiber tolerant to bending. At SCD, we have developed multi-emitter fiber-coupled pump modules that deliver 50 W output from a 105 μm, 0.15 NA fiber at 915, 950 and 976 nm wavelengths enabling low-NA power delivery to a customer's fiber laser network. In this work, we address the challenges of coupling and propagating high optical powers from laser diode sources in weakly guiding step-index multimode fibers. We present simulations of light propagation inside the low-NA multimode fiber for different launch conditions and fiber bend diameters using a ray-racing tool and demonstrate how these affect the injection of light into cladding-bounded modes. The mode filling at launch and source NA directly limit the bend radius at which the fiber can be coiled. Experimentally, we measure the fiber bend loss using our 50 W fiber-coupled module and establish a critical bend diameter in agreement with our simulation results. We also employ thermal imaging to investigate fiber heating caused by macro-bends and angled cleaving. The low mode filling of the 0.15 NA fiber by our brightness-enhanced laser diodes allows it to be coiled with diameters down to 70 mm at full operating power despite the low NA and further eliminates the need for mode-stripping at fiber combiners and splices downstream from our pump modules.

Femtosecond OPO based on MgO:PPLN synchronously pumped by a 532 nm fiber laser

NASA Astrophysics Data System (ADS)

Cao, Jianjun; Shen, Dongyi; Zheng, Yuanlin; Feng, Yaming; Kong, Yan; Wan, Wenjie

2017-05-01

With the rapid progress in fiber technologies, femtosecond fiber lasers, which are compact, cost-effective and stable, have been developed and are commercially available. Studies of optical parametric oscillators (OPOs) pumped by this type of laser are demanding. Here we report a femtosecond optical parametric oscillator (OPO) at 79.6 MHz repetition rate based on MgO-doped periodically poled LiNbO3 (MgO:PPLN), synchronously pumped by the integrated second harmonic radiation of a femtosecond fiber laser at 532 nm. The signal delivered by the single resonant OPO is continuously tunable from 757 to 797 nm by tuning the crystal temperature in a poling period of 7.7 μ \\text{m} . The output signal shows good beam quality in TEM00 mode profile with pulse duration of 206 fs at 771 nm. Maximum output signal power of 71 mW is obtained for a pump power of 763 mW and a low pumping threshold of 210 mW is measured. Moreover, grating tuning and cavity length tuning of the signal wavelength are also investigated.

Simultaneous measurement of temperature and strain based on composite long-period fiber grating

NASA Astrophysics Data System (ADS)

Tong, Chengguo; Hu, Qihao; He, Jiang; Chen, XuDong; Geng, Tao; Bao, Zhanjing; Li, Zixuan; Yang, Wenlei; Sun, Weimin

2016-11-01

Long period fiber grating is a kind of transmission type optical fiber grating. Due to the advantages such as low insertion loss, wide bandwidth, low-level reflection, high sensitivity, low cost and ease of compactness, LPFGs have been widely applied in optical fiber sensing and optical fiber communication. The Mode coupling of LPFG is the coupling between the fiber core mode and the cladding mode in the same transmission direction. If the ordinary LPFG is combined with bitaper or taper, we can effectively change the original LPFG's transmission spectrum to obtain the composite LPFG, which can stimulate new resonant peaks in the original wavelength-dependent transmission loss of the grating basis, thus applying to the dual-parameter simultaneously measuring field. We report a novel all-fiber narrow-bandwidth intermodal Mach- Zehnder interferometer (MZI) based on a long-period fiber grating (LPFG) combined with a fiber bitaper. The LPFG is written by high-frequency CO2 laser pulses, and the bitaper is connected in series with the LPFG, forming the Mach- Zehnder interferometer (MZI). Experimental results indicate that the MZI has good temperature sensitivity, The temperature sensitivity of the two loss peaks are 55.35pm/°C and 48.18pm/°C respectively. The strain sensitivity of the two loss peaks are 3.35pm/μɛ and -4.925pm/μɛ respectively. By using the different temperature and strain response characteristics of the loss peaks, the temperature and strain measurement can be realized simultaneously. the proposed device has good repeatability and stability, which would be a promising candidate for precise dual-parameter sensing application.

High sensitive space electric field sensing based on micro fiber interferometer with field force driven gold nanofilm.

PubMed

Zhu, Tao; Zhou, Liming; Liu, Min; Zhang, Jingdong; Shi, Leilei

2015-10-28

The traditional electrical field sensing can be realized by utilizing electro-optic materials or liquid crystals, and has limitations of easy breakdown, free assembly and difficult measurement of low-frequency. Here, we propose a new method to realize safe measurement of spatial dynamic electric field by using a micro fiber interferometer integrated with gold nanofilm. The energy of the electric charge received through antenna forms the intrinsic electric field with two micro electrodes, one of which is the 120 nm gold film vibration beam micromachined by femtosecond lasers and integrated with the micro fiber. The change of the intrinsic electric field force due to the spatial electric field will cause the vibration of the film beam. By demodulating the output signal of the micro fiber interferometer, the electric field can be measured. We demonstrate the detectable frequency ranges from tens of Hz to tens of KHz, and the minimum electric field intensity is ~200 V/m at 1 KHz. Our electric field measurement technology combining optical fiber interference with gold nanostructures shows the advantages of security, high sensitivity, compact size, and multiplexed multi-point and remote detection.

High sensitive space electric field sensing based on micro fiber interferometer with field force driven gold nanofilm

PubMed Central

Zhu, Tao; Zhou, Liming; Liu, Min; Zhang, Jingdong; Shi, Leilei

2015-01-01

The traditional electrical field sensing can be realized by utilizing electro-optic materials or liquid crystals, and has limitations of easy breakdown, free assembly and difficult measurement of low-frequency. Here, we propose a new method to realize safe measurement of spatial dynamic electric field by using a micro fiber interferometer integrated with gold nanofilm. The energy of the electric charge received through antenna forms the intrinsic electric field with two micro electrodes, one of which is the 120 nm gold film vibration beam micromachined by femtosecond lasers and integrated with the micro fiber. The change of the intrinsic electric field force due to the spatial electric field will cause the vibration of the film beam. By demodulating the output signal of the micro fiber interferometer, the electric field can be measured. We demonstrate the detectable frequency ranges from tens of Hz to tens of KHz, and the minimum electric field intensity is ~200 V/m at 1 KHz. Our electric field measurement technology combining optical fiber interference with gold nanostructures shows the advantages of security, high sensitivity, compact size, and multiplexed multi-point and remote detection. PMID:26507680

A Wireless Optogenetic Headstage with Multichannel Electrophysiological Recording Capability

PubMed Central

Gagnon-Turcotte, Gabriel; Avakh Kisomi, Alireza; Ameli, Reza; Dufresne Camaro, Charles-Olivier; LeChasseur, Yoan; Néron, Jean-Luc; Brule Bareil, Paul; Fortier, Paul; Bories, Cyril; de Koninck, Yves; Gosselin, Benoit

2015-01-01

We present a small and lightweight fully wireless optogenetic headstage capable of optical neural stimulation and electrophysiological recording. The headstage is suitable for conducting experiments with small transgenic rodents, and features two implantable fiber-coupled light-emitting diode (LED) and two electrophysiological recording channels. This system is powered by a small lithium-ion battery and is entirely built using low-cost commercial off-the-shelf components for better flexibility, reduced development time and lower cost. Light stimulation uses customizable stimulation patterns of varying frequency and duty cycle. The optical power that is sourced from the LED is delivered to target light-sensitive neurons using implantable optical fibers, which provide a measured optical power density of 70 mW/mm2 at the tip. The headstage is using a novel foldable rigid-flex printed circuit board design, which results into a lightweight and compact device. Recording experiments performed in the cerebral cortex of transgenic ChR2 mice under anesthetized conditions show that the proposed headstage can trigger neuronal activity using optical stimulation, while recording microvolt amplitude electrophysiological signals. PMID:26371006

Scrambling and modal noise mitigation in the Habitable Zone Planet Finder fiber feed

NASA Astrophysics Data System (ADS)

Roy, Arpita; Halverson, Samuel; Mahadevan, Suvrath; Ramsey, Lawrence W.

2014-07-01

We present the baseline fiber feed design for the Habitable-zone Planet Finder (HPF), a precision radial velocity (RV) spectrograph designed to detect Earth analogs around M-dwarfs. HPF is a stabilized, fiber-fed, R˜50,000 spectrograph operating in the near-infrared (NIR) from 0.82 to 1.3 µm, and will be deployed on the Hobby- Eberly Telescope (HET) in Texas. While the essential function of the optical fibers is to deliver high throughput, this mode of light transport also provides the opportunity to introduce radial and azimuthal scrambling, which boosts instrument stability and thereby RV precision. Based on the unique requirements of HPF on the HET, we present initial tests showing very high scrambling gains via a compact scrambler in conjunction with octagonal fibers. Conversely, the propagation of light through the fibers injects modal noise, which can limit achievable RV precision. Laboratory tests of a custom-built mechanical agitator show significant gains over a static fiber feed. Overall, the fiber feed is designed to provide high relative throughput, excellent scrambling, and reliable modal noise suppression. We will also attempt to minimize focal ratio degradation (FRD) to the extent possible with the chosen configuration. HPF inculcates several other new technologies developed by the Penn State Optical-Infrared instrumentation group, including a rigorous calibration system, which are discussed separately in these proceedings.

Fiber Volume Fraction Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

NASA Astrophysics Data System (ADS)

Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

2016-06-01

Liquid resin is injected into the tapered injection chamber through the injection slots to completely wetout the fiber reinforcements in a resin injection pultrusion process. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the centerline causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to effectively penetrate through the fibers and achieve complete wetout. Fiber volume fraction in the final pultruded composite is a key to decide the mechanical and/or chemical properties of the composite. If the fiber volume fraction is too high, more fibers are squeezed together creating a fiber lean region near the wall and fiber rich region away from the wall. Also, the design of the injection chamber significantly affects the minimum injection pressure required to completely wet the fibers. A tapered injection chamber is considered such that wetout occurs at lower injection pressures due to the taper angle of the injection chamber. In this study, the effect of fiber volume fraction on the fiber reinforcement compaction and complete fiber wetout for a tapered injection chamber is investigated.

Label-free optical-resolution photoacoustic microscopy of superficial microvasculature using a compact visible laser diode excitation

PubMed Central

Zeng, Lvming; Piao, Zhonglie; Huang, Shenghai; Jia, Wangcun; Chen, Zhongping

2015-01-01

We have developed laser-diode-based optical-resolution photoacoustic microscopy (LD-OR-PAM) of superficial microvasculature which has the desirable properties of being compact, low-cost, and label-free. A 300-mW visible pulsed laser diode was operated at a 405 ± 5 nm wavelength with a pulse energy as low as 52 nJ. By using a 3.6 MHz ultrasound transducer, the system was tested on carbon fibers with a lateral resolution of 0.95 µm and an SNR of 38 dB. The subcutaneous microvasculature on a mouse back was imaged without an exogenous contrast agent which demonstrates the potential of the proposed prototype for skin chromophores. Our eventual goal is to offer a practical and affordable multi-wavelength functional LD-OR-PAM instrument suitable for clinical applications. PMID:26698732

Statistical and Detailed Analysis on Fiber Reinforced Self-Compacting Concrete Containing Admixtures- A State of Art of Review

NASA Astrophysics Data System (ADS)

Athiyamaan, V.; Mohan Ganesh, G.

2017-11-01

Self-Compacting Concrete is one of the special concretes that have ability to flow and consolidate on its own weight, completely fill the formwork even in the presence of dense reinforcement; whilst maintaining its homogeneity throughout the formwork without any requirement for vibration. Researchers all over the world are developing high performance concrete by adding various Fibers, admixtures in different proportions. Various different kinds Fibers like glass, steel, carbon, Poly propylene and aramid Fibers provide improvement in concrete properties like tensile strength, fatigue characteristic, durability, shrinkage, impact, erosion resistance and serviceability of concrete[6]. It includes fundamental study on fiber reinforced self-compacting concrete with admixtures; its rheological properties, mechanical properties and overview study on design methodology statistical approaches regarding optimizing the concrete performances. The study has been classified into seven basic chapters: introduction, phenomenal study on material properties review on self-compacting concrete, overview on fiber reinforced self-compacting concrete containing admixtures, review on design and analysis of experiment; a statistical approach, summary of existing works on FRSCC and statistical modeling, literature review and, conclusion. It is so eminent to know the resent studies that had been done on polymer based binder materials (fly ash, metakaolin, GGBS, etc.), fiber reinforced concrete and SCC; to do an effective research on fiber reinforced self-compacting concrete containing admixtures. The key aim of the study is to sort-out the research gap and to gain a complete knowledge on polymer based Self compacting fiber reinforced concrete.

Prototype of a coherent tracking and detection receiver with wideband vibration compensation for free-space laser communications

NASA Astrophysics Data System (ADS)

Giggenbach, Dirk; Schex, Anton; Wandernoth, Bernhard

1996-04-01

The Optical Communications Group of the German Aerospace Research Establishment (DLR) has investigated the feasibility of a fiberless receiver telescope for high sensitive coherent optical space communication, resulting in an elegant pointing, acquisition and tracking (PAT) concept. To demonstrate the feasibility of this new concept, an optical receiver terminal that coherently obtains both the spatial error signal for tracking and the data signal with only one set of detectors has been built. The result is a very simple and compact setup with few optical surfaces. It does not require fibers for superpositioning and is capable to compensate for microaccelerations up to about one kilohertz.

Radiation dosimetry with fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; Gagliardi, G.; De Natale, P.

2014-05-01

The measurement and monitoring of radiation dose delivered in patient tissues is a critical aspect in radiation therapy. Various dosimeters have proven effective in measuring radiations at low doses. However, there is a growing demand for new dosimeters based on small, non-invasive and high resolution devices. Here we report on a miniature dosimeter based on an optical fiber cavity. We demonstrate an ultimate detection limit of 160 mGy with an effective interaction region of 6 x 10-4 mm3. Due to its reliability, compactness and biomedical dose level sensitivity, our system shows itself suitable for applications in radiation therapy dosimetry.

High-power ultrashort fiber laser for solar cells micromachining

NASA Astrophysics Data System (ADS)

Lecourt, J.-B.; Duterte, C.; Liegeois, F.; Lekime, D.; Hernandez, Y.; Giannone, D.

2012-02-01

We report on a high-power ultra-short fiber laser for thin film solar cells micromachining. The laser is based on Chirped Pulse Amplification (CPA) scheme. The pulses are stretched to hundreds of picoseconds prior to amplification and can be compressed down to picosecond at high energy. The repetition rate is adjustable from 100 kHz to 1 MHz and the optical average output power is close to 13 W (before compression). The whole setup is fully fibred, except the compressor achieved with bulk gratings, resulting on a compact and reliable solution for cold ablation.

Gravitational Influences on the Growth of Polydiacetylene Films by Ultraviolet Solution Polymerization

NASA Technical Reports Server (NTRS)

Frazier, Donald O.

2000-01-01

Technically, the field of integrated optics using organic/polymer materials as a new means of information processing, has emerged as of vital importance to optical computers, optical switching, optical communications, the defense industry, etc. The goal is to replace conventional electronic integrated circuits and wires by equivalent miniaturized optical integrated circuits and fibers, offering larger bandwidths, more compactness and reliability, immunity to electromagnetic interference and less cost. From the Code E perspective, this research area represents an opportunity to marry "front-line" education in science and technology with national scientific and technological interests while maximizing human resources utilization. This can be achieved by the development of untapped resources for scientific research - such as minorities, women, and universities traditionally uninvolved in scientific research.

Polarization mode beating techniques for high-sensitivity intracavity sensing

NASA Astrophysics Data System (ADS)

Rosales-Garcia, Andrea

Several industries, including semiconductor, space, defense, medical, chemical and homeland security, demand precise and accurate measurements in the nanometer and sub-nanometer scale. Optical interferometers have been widely investigated due to its dynamic-range, non-contact and high-precision features. Although commercially available interferometers can have sub-nanometer resolution, the practical accuracy exceeds the nanometer range. The fast development of nanotechnology requires more sensitive, reliable, compact and lower cost alternatives than those in existence. This work demonstrates a compact, versatile, accurate and cost-effective fiber laser sensor based on intracavity polarization mode beating (PMB) techniques for monitoring intracavity phase changes with very high sensitivity. Fiber resonators support two orthogonal polarization modes that can behave as two independent lasing channels within the cavity. The fiber laser incorporates an intracavity polarizing beamsplitter that allows for adjusting independently the polarization modes. The heterodyne detection of the laser output produces a beating (PMB) signal, whose frequency is a function of the phase difference between the polarization modes. The optical phase difference is transferred from the optical frequency to a much lower frequency and thus electronic methods can be used to obtain very precise measurements. Upon changing the pathlength of one mode, changes iu the PMB frequency can be effectively measured. Furthermore, since the polarization nodes share the same cavity, the PMB technique provides a simple means to achieve suppression of common mode noise and laser source instabilities. Frequency changes of the PMB signal are evaluated as a function of displacement, intracavity pressure and air density. Refractive index changes of 10 -9 and sub-nanometer displacement measurements are readily attained. Increased refractive index sensitivity and sub-picometer displacement can be reached owing to the high finesse and resolution of the system. Experimental changes in the refractive index of air as a function of pressure are in good agreement with theoretical predictions. An alternative fiber laser configuration, which incorporates non-reciprocal elements, allows measuring the optical activity of enantiomeric mixtures using PMB techniques. The sensitivity attained through PMB techniques demonstrates a potential method for ultra-sensitive biochemical sensing and explosive detection.

Switchable dual-wavelength SOA-based fiber laser with continuous tunability over the C-band at room-temperature.

PubMed

Ummy, M A; Madamopoulos, N; Razani, M; Hossain, A; Dorsinville, R

2012-10-08

We propose and demonstrate a simple compact, inexpensive, SOA-based, dual-wavelength tunable fiber laser, that can potentially be used for photoconductive mixing and generation of waves in the microwave and THz regions. A C-band semiconductor optical amplifier (SOA) is placed inside a linear cavity with two Sagnac loop mirrors at its either ends, which act as both reflectors and output ports. The selectivity of dual wavelengths and the tunability of the wavelength difference (Δλ) between them is accomplished by placing a narrow bandwidth (e.g., 0.3 nm) tunable thin film-based filter and a fiber Bragg grating (with bandwidth 0.28 nm) inside the loop mirror that operates as the output port. A total output power of + 6.9 dBm for the two wavelengths is measured and the potential for higher output powers is discussed. Optical power and wavelength stability are measured at 0.33 dB and 0.014 nm, respectively.

100W high-brightness multi-emitter laser pump

NASA Astrophysics Data System (ADS)

Duesterberg, Richard; Xu, Lei; Skidmore, Jay A.; Guo, James; Cheng, Jane; Du, Jihua; Johnson, Brad; Vecht, David L.; Guerin, Nicolas; Huang, Benlih; Yin, Dongliang; Cheng, Peter; Raju, Reddy; Lee, Kong Weng; Cai, Jason; Rossin, Victor; Zucker, Erik P.

2011-03-01

We report results of a spatially-multiplexed broad area laser diode platform designed for efficient pumping of fiber lasers or direct-diode systems. Optical output power in excess of 100W from a 105μm core, 0.15NA fiber is demonstrated with high coupling efficiency. The compact form factor and low thermal resistance enable tight packing densities needed for kW-class fiber laser systems. Broad area laser diodes have been optimized to reduce near- and far-field performance and prevent blooming without sacrificing other electro-optic parameters. With proper lens optimization this produces ~5% increase in coupling / wall plug efficiency for our design. In addition to performance characteristics, an update on long term reliability testing of 9XX nm broad area laser diode is provided that continues to show no wear out under high acceleration. Under nominal operating conditions of 12W ex-facet power at 25C, the diode mean time to failure (MTTF) is forecast to be ~ 480 kh.

Refractive index and strain sensor based on twin-core fiber with a novel T-shaped taper

NASA Astrophysics Data System (ADS)

Zhang, Chuanbiao; Ning, Tigang; Li, Jing; Zheng, JingJing; Gao, Xuekai; Pei, Li

2018-06-01

A compact in-fiber Mach-Zehnder interferometer (MZI) based on twin-core fiber (TCF) with a novel T-shaped taper is proposed and demonstrated. The taper was firstly fabricated by a short section of TCF, and then spliced with a section of cleaved single mode fiber (SMF). When the light transmit into the TCF, multiple modes will be excited and will propagate within the TCF. In experiment, the proposed device had a maximum interferometric extinction ratio about 17 dB. And the refractive index (RI), strain, and temperature response properties of the sensor have been investigated, which show a relatively high RI, strain sensitivity and low temperature cross sensitivity. Hence, the sensor can be a suitable candidate in the biochemical and physical sensing applications. And due to its easy and controllable fabrication, the novel drawing technology can be applied to more multicore optical fibers.

A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop

PubMed Central

Reyes, Mauricio; Monzón-Hernández, David; Martínez-Ríos, Alejandro; Silvestre, Enrique; Díez, Antonio; Cruz, José Luis; Andrés, Miguel V.

2013-01-01

We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40–1.442, respectively, are demonstrated. We estimate a long range resolution of 3 × 10−4 and a short range resolution of 2 × 10−5 for water solutions. PMID:23979478

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Xuenan; Zhang Yundong; Tian He

We propose to employ the storage of light in a dynamically tuned add-drop resonator to realize an optical gyroscope of ultrahigh sensitivity and compact size. Taking the impact of the linewidth of incident light on the sensitivity into account, we investigate the effect of rotation on the propagation of a partially coherent light field in this dynamically tuned slow-light structure. It is demonstrated that the fundamental trade-off between the rotation-detection sensitivity and the linewidth will be overcome and the sensitivity-linewidth product will be enhanced by two orders of magnitude in comparison to that of the corresponding static slow-light structure. Furthermore,more » the optical gyroscope employing the storage of light in the dynamically tuned add-drop resonator can acquire ultrahigh sensitivity by extremely short fiber length without a high-performance laser source of narrow linewidth and a complex laser frequency stabilization system. Thus the proposal in this paper provides a promising and feasible scheme to realize highly sensitive and compact integrated optical gyroscopes by slow-light structures.« less

Holography and optical information processing; Proceedings of the Soviet-Chinese Joint Seminar, Bishkek, Kyrgyzstan, Sept. 21-26, 1991

NASA Astrophysics Data System (ADS)

Mikaelian, Andrei L.

Attention is given to data storage, devices, architectures, and implementations of optical memory and neural networks; holographic optical elements and computer-generated holograms; holographic display and materials; systems, pattern recognition, interferometry, and applications in optical information processing; and special measurements and devices. Topics discussed include optical immersion as a new way to increase information recording density, systems for data reading from optical disks on the basis of diffractive lenses, a new real-time optical associative memory system, an optical pattern recognition system based on a WTA model of neural networks, phase diffraction grating for the integral transforms of coherent light fields, holographic recording with operated sensitivity and stability in chalcogenide glass layers, a compact optical logic processor, a hybrid optical system for computing invariant moments of images, optical fiber holographic inteferometry, and image transmission through random media in single pass via optical phase conjugation.

Compact and low-cost fiber optic thermometer

NASA Astrophysics Data System (ADS)

Sun, Mei H.

1997-06-01

Commercial fiberoptic thermometers have been available for a number of years. The early products were unreliable and high in price. However, the continuing effort in the development of new sensing techniques along with the breakthroughs made in many areas of optoelectronics in recent years have made the production of cost competitive and reliable systems feasible. A fluorescence decay time based system has been demonstrated to successfully meet both cost and performance requirements for various medical applications. A very critical element to the success of this low cost and compact fiberoptic thermometer is the fluorescent sensor material. The very high quantum efficiency, the operating wavelengths, and the temperature sensitivity helped significantly in simplifying the design requirements for the optics and the electronics. The one to eight channel unit contains one to eight modules of a simple optical assembly: an LED light source, a small lens, and a filter are housed in an injection molded plastic container. Both the electronics and the optics reside on a small printed circuit board of approximately 6 inches by 3 inches. This system can be packaged as a stand alone unit or embedded in original manufacturer equipment.

A dual modality optical fiber sensor

NASA Astrophysics Data System (ADS)

Herrera-Piad, Luis A.; Haus, Joseph W.; Jauregui-Vazquez, Daniel; Lopez-Dieguez, Yanelis; Estudillo-Ayala, Julian M.; Sierra-Hernandez, Juan M.; Hernandez-Garcia, Juan C.; Rojas-Laguna, Roberto

2018-02-01

We propose and demonstrate a fibre optic system based on bi-tapered silica fibre that can simultaneously measure strain and fibre curvature. Both modalities on the signal can be extracted with no measurable crosstalk between them. The experimental signal has a pure phase modulation when strain is applied to the tapered fibre optic section of the sensor and the signal shows only intensity modulation when an un-tapered fibre section is bent. High sensitivity is achieved from the experimental results for strain and bending losses and the estimation of measurement errors is 0.2 and 0.1%, respectively. This system offers low-cost, compactness and it can be adapted for structural health monitoring.

A stable frequency comb directly referenced to rubidium electromagnetically induced transparency and two-photon transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Dong; Wu, Jiutao; Zhang, Shuangyou

2014-03-17

We demonstrate an approach to create a stable erbium-fiber-based frequency comb at communication band by directly locking the combs to two rubidium atomic transitions resonances (electromagnetically induced transparency absorption and two-photon absorption), respectively. This approach directly transfers the precision and stability of the atomic transitions to the comb. With its distinguishing feature of compactness by removing the conventional octave-spanning spectrum and f-to-2f beating facilities and the ability to directly control the comb's frequency at the atomic transition frequency, this stable optical comb can be widely used in optical communication, frequency standard, and optical spectroscopy and microscopy.

Resin Viscosity Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

NASA Astrophysics Data System (ADS)

Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

2018-06-01

Viscosity of the liquid resin effects the chemical and mechanical properties of the pultruded composite. In resin injection pultrusion manufacturing the liquid resin is injected into a specially designed tapered injection chamber through the injection slots present on top and bottom of the chamber. The resin is injected at a pressure so as to completely wetout the fiber reinforcements inside the tapered injection chamber. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the center of chamber causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to efficaciously penetrate through the compacted fibers and achieve complete wetout. The impact of resin viscosity on resin flow, fiber compaction, wetout and on the final product is further discussed. Injection chamber design predominantly effects the resin flow inside the chamber and the minimum injection pressure required to completely wet the fibers. Therefore, a desirable injection chamber design is such that wetout occurs at lower injection pressures and at low internal pressures inside the injection chamber.

Resin Viscosity Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

NASA Astrophysics Data System (ADS)

Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

2017-08-01

Viscosity of the liquid resin effects the chemical and mechanical properties of the pultruded composite. In resin injection pultrusion manufacturing the liquid resin is injected into a specially designed tapered injection chamber through the injection slots present on top and bottom of the chamber. The resin is injected at a pressure so as to completely wetout the fiber reinforcements inside the tapered injection chamber. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the center of chamber causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to efficaciously penetrate through the compacted fibers and achieve complete wetout. The impact of resin viscosity on resin flow, fiber compaction, wetout and on the final product is further discussed. Injection chamber design predominantly effects the resin flow inside the chamber and the minimum injection pressure required to completely wet the fibers. Therefore, a desirable injection chamber design is such that wetout occurs at lower injection pressures and at low internal pressures inside the injection chamber.

Localized surface plasmon resonance-based fiber-optic sensor for the detection of triacylglycerides using silver nanoparticles.

PubMed

Baliyan, Anjli; Usha, Sruthi Prasood; Gupta, Banshi D; Gupta, Rani; Sharma, Enakshi Khular

2017-10-01

A label-free technique for the detection of triacylglycerides by a localized surface plasmon resonance (LSPR)-based biosensor is demonstrated. An LSPR-based fiber-optic sensor probe is fabricated by immobilizing lipase enzyme on silver nanoparticles (Ag-NPs) coated on an unclad segment of a plastic clad optical fiber. The size and shape of nanoparticles were characterized by high-resolution transmission electron microscopy and UV-visible spectroscopy. The peak absorbance wavelength changes with concentration of triacylglycerides surrounding the sensor probe, and sensitivity is estimated from shift in the peak absorbance wavelength as a function of concentration. The fabricated sensor was characterized for the concentration of triacylglyceride solution in the range 0 to 7 mM. The sensor shows the best sensitivity at a temperature of 37°C and pH 7.4 of the triacylglycerides emulsion with a response time of 40 s. A sensitivity of 28.5  nm/mM of triacylglyceride solution is obtained with a limit of detection of 0.016 mM in the entire range of triacylglycerides. This compact biosensor shows good selectivity, stability, and reproducibility in the entire physiological range of triacylglycerides and is well-suited to real-time online monitoring and remote sensing. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Miniaturized video-rate epi-third-harmonic-generation fiber-microscope.

PubMed

Chia, Shih-Hsuan; Yu, Che-Hang; Lin, Chih-Han; Cheng, Nai-Chia; Liu, Tzu-Ming; Chan, Ming-Che; Chen, I-Hsiu; Sun, Chi-Kuang

2010-08-02

With a micro-electro-mechanical system (MEMS) mirror, we successfully developed a miniaturized epi-third-harmonic-generation (epi-THG) fiber-microscope with a video frame rate (31 Hz), which was designed for in vivo optical biopsy of human skin. With a large-mode-area (LMA) photonic crystal fiber (PCF) and a regular microscopic objective, the nonlinear distortion of the ultrafast pulses delivery could be much reduced while still achieving a 0.4 microm lateral resolution for epi-THG signals. In vivo real time virtual biopsy of the Asian skin with a video rate (31 Hz) and a sub-micron resolution was obtained. The result indicates that this miniaturized system was compact enough for the least invasive hand-held clinical use.

Failure monitoring of E-glass/vinylester composites using fiber grating acoustic sensor

NASA Astrophysics Data System (ADS)

Azmi, A. I.; Raju; Peng, G. D.

2013-06-01

This paper reports an application of an optical fiber sensor in a continuous and in situ failure testing of an E-glass/vinylester top hat stiffener (THS). The sensor head was constructed from a compact phase-shifted fiber Bragg grating (PS-FBG). The narrow transmission channel of the PS-FBG is highly sensitive to small perturbation, hence suitable to be used in acoustic emission (AE) assessment technique. The progressive failure of THS was tested under transverse loading to experimentally simulate the actual loading in practice. Our experimental tests have demonstrated, in good agreement with the commercial piezoelectric sensors, that the important failures information of the THS was successfully recorded by the simple intensity-type PS-FBG sensor.

Hollow fibers for compact infrared gas sensors

NASA Astrophysics Data System (ADS)

Lambrecht, A.; Hartwig, S.; Herbst, J.; Wöllenstein, J.

2008-02-01

Hollow fibers can be used for compact infrared gas sensors. The guided light is absorbed by the gas introduced into the hollow core. High sensitivity and a very small sampling volume can be achieved depending on fiber parameters i.e. attenuation, flexibility, and gas exchange rates. Different types of infrared hollow fibers including photonic bandgap fibers were characterized using quantum cascade lasers and thermal radiation sources. Obtained data are compared with available product specifications. Measurements with a compact fiber based ethanol sensor are compared with a system simulation. First results on the detection of trace amounts of the explosive material TATP using hollow fibers and QCL will be shown.

Ultra-narrow-linewidth Brillouin/erbium fiber laser

NASA Astrophysics Data System (ADS)

Chen, Mo; Wang, Chenyu; Wang, Jianfei; Luo, Hong; Meng, Zhou

2018-02-01

Ultra-narrow-linewidth lasers are of great interest in many applications, such as precise spectroscopy, optical communications, and sensors. Stimulated Brillouin scattering (SBS), as one of the main nonlinear effects in fibers, is capable of generating narrow-linewidth light emission. We establish a compact Brillouin/erbium fiber laser (BEFL) utilizing 4-m erbium-doped fiber as both the Brillouin gain and linear media. A 360-kHz-linewidth laser diode is injected into the cavity as the Brillouin pump (BP) light and generates Brillouin Stokes lasing light. Both of the phase noise of the BP and BEFL output are measured by a high-accuracy unbalanced Michelson interferometer. It is demonstrated that 53- dB phase noise reduction is achieved after the BP is transferred into Brillouin Stokes emission. The linewidth of the BEFL is indicated at Hz-range by both calculation and experiment.

Fluoride glass fibers: applications and prospects

NASA Astrophysics Data System (ADS)

Poulain, Marcel

1998-09-01

Fluoride glass fibers have been intensively developed for the last 20 years. A major effort was devoted to the fabrication of low loss fibers for repeaterless long haul telecommunications. This step which ended in the late eighties provided the basic technology for the manufacturing of multimode and single mode fibers with minimum losses below 10 dB/km. Such fibers area now used for various passive applications requiring the handling of IR signal. In this respect, fluoride fibers are complementary to silica fibers when wavelength exceeds 2 micrometers . Some practical set ups are operating for IR imaging, remote spectroscopy and thermometry. Special fibers such as polarization maintaining fibers have been developed for interferometric astronomy, which could also apply to sensors. UV transmission has still to be developed. Laser power delivery is another field of application for these fibers. YAG:Er laser at 2.9 micrometers attracts a growing interest for medical applications, ophthalmology and dentistry, while prospects for CO laser are positive. Active fibers are based on rare earth doped single mode fibers. They lead to the definition of numerous new laser lines and emphasized the potential of up conversion for the generation of visible light using IR pumping laser diodes. High power output has been achieved in the blue and the red light, which open prospects for compact and all solid state fiber lasers for a wide range of applications, from displays to medical uses. Optical amplification makes another field of R and D centered on telecommunication needs. Pr3+ doped fluoride fibers have been used for the 1.3 micrometers band, and Er based fluoride fiber amplifiers exhibit wider and flatter gain than those made from silica. Optical amplification may be implemented at other wavelengths for more general purposes.

Tunable photonic cavities for in-situ spectroscopic trace gas detection

DOEpatents

Bond, Tiziana; Cole, Garrett; Goddard, Lynford

2012-11-13

Compact tunable optical cavities are provided for in-situ NIR spectroscopy. MEMS-tunable VCSEL platforms represents a solid foundation for a new class of compact, sensitive and fiber compatible sensors for fieldable, real-time, multiplexed gas detection systems. Detection limits for gases with NIR cross-sections such as O.sub.2, CH.sub.4, CO.sub.x and NO.sub.x have been predicted to approximately span from 10.sup.ths to 10s of parts per million. Exemplary oxygen detection design and a process for 760 nm continuously tunable VCSELS is provided. This technology enables in-situ self-calibrating platforms with adaptive monitoring by exploiting Photonic FPGAs.

Simple Laser Communications Terminal for Downlink from Earth Orbit at Rates Exceeding 10 Gb/s

NASA Technical Reports Server (NTRS)

Kovalik, Joseph M.; Hemmati, Hamid; Biswas, Abhijit; Roberts, William T.

2013-01-01

A compact, low-cost laser communications transceiver was prototyped for downlinking data at 10 Gb/s from Earth-orbiting spacecraft. The design can be implemented using flight-grade parts. With emphasis on simplicity, compactness, and light weight of the flight transceiver, the reduced-complexity design and development approach involves: 1. A high-bandwidth coarse wavelength division multiplexed (CWDM) (4 2.5 or 10-Gb/s data-rate) downlink transmitter. To simplify the system, emphasis is on the downlink. Optical uplink data rate is modest (due to existing and adequate RF uplink capability). 2. Highly simplified and compact 5-cm diameter clear aperture optics assembly is configured to single transmit and receive aperture laser signals. About 2 W of 4-channel multiplexed (1,540 to 1,555 nm) optically amplified laser power is coupled to the optical assembly through a fiber optic cable. It contains a highly compact, precision-pointing capability two-axis gimbal assembly to coarse point the optics assembly. A fast steering mirror, built into the optical path of the optical assembly, is used to remove residual pointing disturbances from the gimbal. Acquisition, pointing, and tracking are assisted by a beacon laser transmitted from the ground and received by the optical assembly, which will allow transmission of a laser beam. 3. Shifting the link burden to the ground by relying on direct detection optical receivers retrofitted to 1-m-diameter ground telescopes. 4. Favored mass and volume reduction over power-consumption reduction. The two major variables that are available include laser transmit power at either end of the link, and telescope aperture diameter at each end of the link. Increased laser power is traded for smaller-aperture diameters. 5. Use of commercially available spacequalified or qualifiable components with traceability to flight qualification (i.e., a flight-qualified version is commercially available). An example is use of Telecordia-qualified fiber optic communication components including active components (lasers, amplifiers, photodetectors) that, except for vacuum and radiation, meet most of the qualifications required for space. 6. Use of CWDM technique at the flight transmitter for operation at four channels (each at 2.5 Gb/s or a total of 10 Gb/s data rate). Applying this technique allows utilization of larger active area photodetectors at the ground station. This minimizes atmospheric scintillation/turbulence induced losses on the received beam at the ground terminal. 7. Use of forward-error-correction and deep-interleaver codes to minimize atmospheric turbulence effects on the downlink beam. Target mass and power consumption for the flight data transmitter system is less than 10 kg and approximately 60 W for the 400-km orbit (900-km slant range), and 12 kg and 120 W for the 2,000-km orbit (6,000-km slant range). The higher mass and power for the latter are the result of employing a higher-power laser only.

Hole-assisted fiber based fiber fuse terminator supporting 22 W input

NASA Astrophysics Data System (ADS)

Tsujikawa, Kyozo; Kurokawa, Kenji; Hanzawa, Nobutomo; Nozoe, Saki; Matsui, Takashi; Nakajima, Kazuhide

2018-05-01

We investigated the air hole structure in hole-assisted fiber (HAF) with the aim of terminating fiber fuse propagation. We focused on two structural parameters c/MFD and S1/S2, which are related respectively to the position and area of the air holes, and mapped their appropriate values for terminating fiber fuse propagation. Here, MFD is the mode field diameter, c is the diameter of an inscribed circle linking the air holes, S1 is the total area of the air holes, and S2 is the area of a circumscribed circle linking the air holes. On the basis of these results, we successfully realized a compact fiber fuse terminator consisting of a 1.35 mm-long HAF, which can terminate fiber fuse propagation even with a 22 W input. In addition, we observed fiber fuse termination using a high-speed camera. We additionally confirmed that the HAF-based fiber fuse terminator is effective under various input power conditions. The penetration length of the optical discharge in the HAF was only less than 300 μm when the input power was from 2 to 22 W.

Fiber-optic Michelson interferometer fixed in a tilted tube for direction-dependent ultrasonic detection

NASA Astrophysics Data System (ADS)

Gang, Tingting; Hu, Manli; Qiao, Xueguang; Li, JiaCheng; Shao, Zhihua; Tong, Rongxin; Rong, Qiangzhou

2017-01-01

A fiber-optic interferometer is proposed and demonstrated experimentally for ultrasonic detection. The sensor consists of a compact Michelson interferometer (MI), which is fixed in a tilted-tube end-face (45°). Thin gold films are used for the reflective coatings of two arms and one of the interference arms is etched serving as the sensing arm. The spectral sideband filter technique is used to interrogate the continuous and pulse ultrasonic signals (with frequency of 300 KHz). Furthermore, because of the asymmetrical structure of the sensor, it presents strong direction-dependent ultrasonic sensitivity, such that the sensor can be considered a vector detector. The experimental results show that the sensor is highly sensitive to ultrasonic signals, and thus it can be a candidate for ultrasonic imaging of seismic physical models.

Polymerization shrinkage of a dental resin composite determined by a fiber optic Fizeau interferometer

NASA Astrophysics Data System (ADS)

Arenas, Gustavo; Noriega, Sergio; Vallo, Claudia; Duchowicz, Ricardo

2007-03-01

A fiber optic sensing method based on a Fizeau-type interferometric scheme was employed for monitoring linear polymerization shrinkage in dental restoratives. This technique offers several advantages over the conventional methods of measuring polymerization contraction. This simple, compact, non-invasive and self-calibrating system competes with both conventional and other high-resolution bulk interferometric techniques. In this work, an analysis of the quality of interference signal and fringes visibility was performed in order to characterize their resolution and application range. The measurements of percent linear contraction as a function of the sample thickness were carried out in this study on two dental composites: Filtek P60 (3M ESPE) Posterior Restorer and Filtek Z250 (3M ESPE) Universal Restorer. The results were discussed with respect to others obtained employing alternative techniques.

Hysteresis compensation technique applied to polymer optical fiber curvature sensor for lower limb exoskeletons

NASA Astrophysics Data System (ADS)

Gomes Leal-Junior, Arnaldo; Frizera-Neto, Anselmo; José Pontes, Maria; Rodrigues Botelho, Thomaz

2017-12-01

Polymer optical fiber (POF) curvature sensors present some advantages over conventional techniques for angle measurements, such as their light weight, compactness and immunity to electromagnetic fields. However, high hysteresis can occur in POF curvature sensors due to the polymer viscoelastic response. In order to overcome this limitation, this paper shows how the hysteresis sensor can be compensated by a calibration equation relating the measured output signal to the sensor’s angular velocity. The proposed method is validated using an exoskeleton with an active joint on the knee for flexion and extension rehabilitation exercises. The results show a decrease in sensor hysteresis and a decrease by more than two times in the error between the POF sensor and the potentiometer, which is employed for the angle measurement of the exoskeleton knee joint.

Micro-pulse upconversion Doppler lidar for wind and visibility detection in the atmospheric boundary layer.

PubMed

Xia, Haiyun; Shangguan, Mingjia; Wang, Chong; Shentu, Guoliang; Qiu, Jiawei; Zhang, Qiang; Dou, Xiankang; Pan, Jianwei

2016-11-15

For the first time, to the best of our knowledge, a compact, eye-safe, and versatile direct detection Doppler lidar is developed using an upconversion single-photon detection method at 1.5 μm. An all-fiber and polarization maintaining architecture is realized to guarantee the high optical coupling efficiency and the robust stability. Using integrated-optic components, the conservation of etendue of the optical receiver is achieved by manufacturing a fiber-coupled periodically poled lithium niobate waveguide and an all-fiber Fabry-Perot interferometer (FPI). The double-edge technique is implemented by using a convert single-channel FPI and a single upconversion detector, incorporating a time-division multiplexing method. The backscatter photons at 1548.1 nm are converted into 863 nm via mixing with a pump laser at 1950 nm. The relative error of the system is less than 0.1% over nine weeks. In experiments, atmospheric wind and visibility over 48 h are detected in the boundary layer. The lidar shows good agreement with the ultrasonic wind sensor, with a standard deviation of 1.04 m/s in speed and 12.3° in direction.

DVD pickup head based optical resolution photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Wang, Po-Hsun; Li, Meng-Lin

2012-02-01

Optical resolution photoacoustic microscopy (OR-PAM) has been shown as a promising tool for label-free microvascular and single-cell imaging in clinical and bioscientific applications. However, most OR-PAM systems are realized by using a bulky laser for photoacoustic excitation. The large volume and high price of the laser may restrain the popularity of OR-PAM. In this study, we develop a low-cost and compact OR-PAM system based on a commercially available DVD pickup head. We showed that the DVD pickup head have the required laser energy and focusing optics for OR-PAM. The firmware of a DVD burner was modified to enable its laser diode to provide a 13-ns laser pulse with 1.3-nJ energy at 650 nm. Two excitation wavelengths at 650 and 780 nm were available. The laser beam was focused onto the target after passing through a 0.6-mm thick DVD transparent polycarbonate coating, and then aligned to be confocal with a 50-MHz focused ultrasonic transducer in forward mode. To keep the target on focus, a scan involving auto-tracking procedure was performed. The lateral resolution was verified via cross-sectional imaging of a 6-μm carbon fiber. The measured -6 dB width of the carbon fiber was 6.66 μm which was in agreement with optical diffraction limit. The proposed OR-PAM has potential as an economically viable and compact blood screening tool available outside of large laboratories due to its low cost and portability. Furthermore, a better spatial resolution could be provided by using a blue ray DVD pickup head.

Development of plasma bolometers using fiber-optic temperature sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reinke, M. L., E-mail: reinkeml@ornl.gov; Han, M.; Liu, G.

Measurements of radiated power in magnetically confined plasmas are important for exhaust studies in present experiments and expected to be a critical diagnostic for future fusion reactors. Resistive bolometer sensors have long been utilized in tokamaks and helical devices but suffer from electromagnetic interference (EMI). Results are shown from initial testing of a new bolometer concept based on fiber-optic temperature sensor technology. A small, 80 μm diameter, 200 μm long silicon pillar attached to the end of a single mode fiber-optic cable acts as a Fabry–Pérot cavity when broadband light, λ{sub o} ∼ 1550 nm, is transmitted along the fiber.more » Changes in temperature alter the optical path length of the cavity primarily through the thermo-optic effect, resulting in a shift of fringes reflected from the pillar detected using an I-MON 512 OEM spectrometer. While initially designed for use in liquids, this sensor has ideal properties for use as a plasma bolometer: a time constant, in air, of ∼150 ms, strong absorption in the spectral range of plasma emission, immunity to local EMI, and the ability to measure changes in temperature remotely. Its compact design offers unique opportunities for integration into the vacuum environment in places unsuitable for a resistive bolometer. Using a variable focus 5 mW, 405 nm, modulating laser, the signal to noise ratio versus power density of various bolometer technologies are directly compared, estimating the noise equivalent power density (NEPD). Present tests show the fiber-optic bolometer to have NEPD of 5-10 W/m{sup 2} when compared to those of the resistive bolometer which can achieve <0.5 W/m{sup 2} in the laboratory, but this can degrade to 1-2 W/m{sup 2} or worse when installed on a tokamak. Concepts are discussed to improve the signal to noise ratio of this new fiber-optic bolometer by reducing the pillar height and adding thin metallic coatings, along with improving the spectral resolution of the interrogator.« less

[Research on symmetrical optical waveguide based surface plasmon resonance sensing with spectral interrogation].

PubMed

Zhang, Yi-long; Liu, Le; Guo, Jun; Zhang, Peng-fei; Guo, Ji-hua; Ma, Hui; He, Yong-hong

2015-02-01

Surface plasmon resonance (SPR) sensors with spectral interrogation can adopt fiber to transmit light signals, thus leaving the sensing part separated, which is very convenient for miniaturization, remote-sensing and on-site analysis. Symmetrical optical waveguide (SOW) SPR has the same refractive index of the-two buffer media layers adjacent to the metal film, resulting in longer propagation distance, deeper penetration depth and better performance compared to conventional SPR In the present paper, we developed a symmetrical optical, waveguide (SOW) SPR sensor with wavelength interrogation. In the system, MgF2-Au-MgF2 film was used as SOW module for glucose sensing, and a fiber based light source and detection was used in the spectral interrogation. In the experiment, a refractive index resolution of 2.8 x 10(-7) RIU in fluid protocol was acquired. This technique provides advantages of high resolution and could have potential use in compact design, on-site analysis and remote sensing.

On-line structural health and fire monitoring of a composite personal aircraft using an FBG sensing system

NASA Astrophysics Data System (ADS)

Chandler, K.; Ferguson, S.; Graver, T.; Csipkes, A.; Mendez, A.

2008-03-01

We report in this paper on the design and development of a novel on-line structural health monitoring and fire detection system based on an array of optical fiber Bragg grating (FBG) sensors and interrogation system installed on a new, precommercial compact aircraft. A combined total of 17 FBG sensors - strain, temperature and high-temperature - were installed at critical locations in an around the wings, fuselage and engine compartment of a prototype, Comp Air CA 12 all-composite, ten-passenger personal airplane powered by a 1,650 hp turbine engine. The sensors are interrogated online and in real time by a swept laser FBG interrogator (Micron Optics sm125-700) mounted on board the plane. Sensors readings are then combined with the plane's avionics system and displayed on the pilot's aviation control panel. This system represents the first of its kind in commercial, small frame, airplanes and a first for optical fiber sensors.

Low loss hollow-core waveguide on a silicon substrate

NASA Astrophysics Data System (ADS)

Yang, Weijian; Ferrara, James; Grutter, Karen; Yeh, Anthony; Chase, Chris; Yue, Yang; Willner, Alan E.; Wu, Ming C.; Chang-Hasnain, Connie J.

2012-07-01

Optical-fiber-based, hollow-core waveguides (HCWs) have opened up many new applications in laser surgery, gas sensors, and non-linear optics. Chip-scale HCWs are desirable because they are compact, light-weight and can be integrated with other devices into systems-on-a-chip. However, their progress has been hindered by the lack of a low loss waveguide architecture. Here, a completely new waveguiding concept is demonstrated using two planar, parallel, silicon-on-insulator wafers with high-contrast subwavelength gratings to reflect light in-between. We report a record low optical loss of 0.37 dB/cm for a 9-μm waveguide, mode-matched to a single mode fiber. Two-dimensional light confinement is experimentally realized without sidewalls in the HCWs, which is promising for ultrafast sensing response with nearly instantaneous flow of gases or fluids. This unique waveguide geometry establishes an entirely new scheme for low-cost chip-scale sensor arrays and lab-on-a-chip applications.

24-26  GHz radio-over-fiber and free-space optics for fifth-generation systems.

PubMed

Bohata, Jan; Komanec, Matěj; Spáčil, Jan; Ghassemlooy, Zabih; Zvánovec, Stanislav; Slavík, Radan

2018-03-01

This Letter outlines radio-over-fiber combined with radio-over-free-space optics (RoFSO) and radio frequency free-space transmission, which is of particular relevance for fifth-generation networks. Here, the frequency band of 24-26 GHz is adopted to demonstrate a low-cost, compact, and high-energy-efficient solution based on the direct intensity modulation and direct detection scheme. For our proof-of-concept demonstration, we use 64 quadrature amplitude modulation with a 100 MHz bandwidth. We assess the link performance by exposing the RoFSO section to atmospheric turbulence conditions. Further, we show that the measured minimum error vector magnitude (EVM) is 4.7% and also verify that the proposed system with the free-space-optics link span of 100 m under strong turbulence can deliver an acceptable EVM of <9% with signal-to-noise ratio levels of 22 dB and 10 dB with and without turbulence, respectively.

1.54 micron Emission from Erbium implanted GaN for Photonic Applications

NASA Technical Reports Server (NTRS)

Thaik, Myo; Hommerich, U.; Schwartz, R. N.; Wilson, R. G.; Zavada, J. M.

1998-01-01

The development of efficient and compact light sources operating at 1.54 micron is of enormous importance for the advancement of new optical communication systems. Erbium (1%) doped fiber amplifiers (EDFA's) or semiconductor lasers are currently being employed as near infrared light sources. Both devices, however, have inherent limitations due to their mode of operation. EDFA's employ an elaborate optical pumping scheme, whereas diode lasers have a strongly temperature dependent lasing wavelength. Novel light emitters based on erbium doped III-V semiconductors could overcome these limitations. Er doped semiconductors combine the convenience of electrical excitation with the excellent luminescence properties of Er(3+) ions. Electrically pumped, compact, and temperature stable optoelectronic devices are envisioned from this new class of luminescent materials. In this paper we discuss the potential of Er doped GaN for optoelectronic applications based on temperature dependent photoluminescence excitation studies.

All-Optical Photoacoustic Sensors for Steel Rebar Corrosion Monitoring

PubMed Central

Du, Cong; Owusu Twumasi, Jones; Tang, Qixiang; Guo, Xu; Zhou, Jingcheng; Yu, Tzuyang; Wang, Xingwei

2018-01-01

This article presents an application of an active all-optical photoacoustic sensing system with four elements for steel rebar corrosion monitoring. The sensor utilized a photoacoustic mechanism of gold nanocomposites to generate 8 MHz broadband ultrasound pulses in 0.4 mm compact space. A nanosecond 532 nm pulsed laser and 400 μm multimode fiber were employed to incite an ultrasound reaction. The fiber Bragg gratings were used as distributed ultrasound detectors. Accelerated corrosion testing was applied to four sections of a single steel rebar with four different corrosion degrees. Our results demonstrated that the mass loss of steel rebar displayed an exponential growth with ultrasound frequency shifts. The sensitivity of the sensing system was such that 0.175 MHz central frequency reduction corresponded to 0.02 g mass loss of steel rebar corrosion. It was proved that the all-optical photoacoustic sensing system can actively evaluate the corrosion of steel rebar via ultrasound spectrum. This multipoint all-optical photoacoustic method is promising for embedment into a concrete structure for distributed corrosion monitoring. PMID:29702554

Improved Gas Filling and Sealing of an HC-PCF

NASA Technical Reports Server (NTRS)

Poberezhskiy, Ilya; Meras, Patrick; Chang, Daniel; Spiers, Gary

2008-01-01

An improved packaging approach has been devised for filling a hollow-core photonic-crystal fiber (HC-PCF) with a gas, sealing the HC-PCF to retain the gas, and providing for optical connections and, optionally, a plumbing fitting for changing or augmenting the gas filling. Gas-filled HC-PCFs can be many meters long and have been found to be attractive as relatively compact, lightweight, rugged alternatives to conventional gas-filled glass cells for use as molecular-resonance frequency references for stabilization of lasers in some optical-metrology, lidar, optical-communication, and other advanced applications. Prior approaches to gas filling and sealing of HC-PCFs have involved, variously, omission of any attempt to connectorize the PCF, connectorization inside a vacuum chamber (an awkward and expensive process), or temporary exposure of one end of an HC-PCF to the atmosphere, potentially resulting in contamination of the gas filling. Prior approaches have also involved, variously, fusion splicing of HC-PCFs with other optical fibers or other termination techniques that give rise to Fresnel reflections of about 4 percent, which results in output intensity noise.

Toward a hyperspectral optical signature of extra virgin olive oil

NASA Astrophysics Data System (ADS)

Mignani, A. G.; Ciaccheri, L.; Thienpont, H.; Ottevaere, H.; Attilio, C.; Cimato, A.

2007-05-01

Italian extra virgin olive oils bearing labels of certified area of origin were considered. Their multispectral digital signature was measured by means of absorption spectroscopy in the 200-1700 nm spectral range. The instrumentation was a fiber optic-based, cheap, and compact device. The spectral data were processed by means of multivariate analysis and plotted on a 2D classification map. The map showed sharp clusters according to the geographical origin of the oils, thus demonstrating the potentials of UV-VIS-NIR spectroscopy for optical fingerprinting. Then, the spectral data were correlated to the content of the most important fatty acids. The good fitting achieved demonstrated that the optical fingerprinting can be used also for predicting nutritional and chemical parameters.

All-fiber optical parametric oscillator for bio-medical imaging applications

NASA Astrophysics Data System (ADS)

Gottschall, Thomas; Meyer, Tobias; Jauregui, Cesar; Just, Florian; Eidam, Tino; Schmitt, Michael; Popp, Jürgen; Limpert, Jens; Tünnermann, Andreas

2017-02-01

Among other modern imaging techniques, stimulated Raman Scattering (SRS) requires an extremely quiet, widely wavelength tunable laser, which, up to now, is unheard of in fiber laser systems. We present a compact all-fiber laser system, which features an optical parametric oscillator (OPO) based on degenerate four-wave mixing (FWM) in an endlessly single-mode photonic-crystal fiber. We employ an all-fiber frequency and repetition rate tunable laser in order to enable wideband conversion in the linear OPO cavity arrangement, the signal and idler radiation can be tuned between 764 and 960 nm and 1164 and 1552 nm at 9.5 MHz. Thus, all biochemically relevant Raman shifts between 922 and 3322 cm-1 may be addressed in combination with a secondary output, which is tunable between 1024 and 1052 nm. This ultra-low noise output emits synchronized pulses with twice the repetition rate to enable SRS imaging. We measure the relative intensity noise of this output beam at 9.5 MHz to be between -145 and -148 dBc, which is low enough to enable high-speed SRS imaging with a good signal-to-noise ratio. The laser system is computer controlled to access a certain energy differences within one second. Combining FWM based conversion, with all-fiber Yb-based fiber lasers enables the construction of the first automated, turn-key and widely tunable fiber laser. This laser concept could be the missing piece to establish CRS imaging as a reliable guiding tool for clinical diagnostics and surgical guidance.

Micro-structured optical fiber sensor for simultaneous measurement of temperature and refractive index

NASA Astrophysics Data System (ADS)

Liu, Ying-gang; Liu, Xin; Ma, Cheng-ju; Zhou, Yu-min

2018-03-01

Through using micro-machining method for optical fiber sensor, a kind of miniature, compact and composite structural all-fiber sensor is presented. Based on manufacturing two micro-holes with certain distance in ordinary single-mode fiber Bragg grating (FBG) by excimer laser processing technique, we fabricate a dual Fabry-Perot-FBG (FP-FBG) composite fiber interferometric sensor, which can be used in simultaneous measurement for liquid's refractive index (RI) and temperature change. Due to every micro-hole and the dual micro-holes in fiber acting as different Fabry-Perot (FP) cavities, this kind of sensor has not only different RI sensitivities but also different temperature sensitivities, which are corresponding to the wavelength shifts of the fine interference fringes and spectral envelope, respectively. The experimental results show that the spectral wavelength shift keep better linear response for temperature and RI change, so that we can select the higher temperature and RI sensitivities as well as the analyzed sensitivities of FBG to utilize them for constituting a sensitivity coefficients matrix. Finally, the variations of liquid's temperature and RI are detected effectively, and the resolutions can reach to 0.1 °C and 1.0 ×10-5 RIU. These characteristics are what other single-type sensors don't have, so that this kind of all-fiber dual FP-FBG composite fiber interferometric sensor can be used in extremely tiny liquid environment for measuring different physical quantities simultaneously.

Compact mode-locked diode laser system for high precision frequency comparisons in microgravity

NASA Astrophysics Data System (ADS)

Christopher, H.; Kovalchuk, E. V.; Wicht, A.; Erbert, G.; Tränkle, G.; Peters, A.

2017-11-01

Nowadays cold atom-based quantum sensors such as atom interferometers start leaving optical labs to put e.g. fundamental physics under test in space. One of such intriguing applications is the test of the Weak Equivalence Principle, the Universality of Free Fall (UFF), using different quantum objects such as rubidium (Rb) and potassium (K) ultra-cold quantum gases. The corresponding atom interferometers are implemented with light pulses from narrow linewidth lasers emitting near 767 nm (K) and 780 nm (Rb). To determine any relative acceleration of the K and Rb quantum ensembles during free fall, the frequency difference between the K and Rb lasers has to be measured very accurately by means of an optical frequency comb. Micro-gravity applications not only require good electro-optical characteristics but are also stringent in their demand for compactness, robustness and efficiency. For frequency comparison experiments the rather complex fiber laser-based frequency comb system may be replaced by one semiconductor laser chip and some passive components. Here we present an important step towards this direction, i.e. we report on the development of a compact mode-locked diode laser system designed to generate a highly stable frequency comb in the wavelength range of 780 nm.

Fiber Bragg grating interrogation using a wavelength modulated 1651-nm tunable distributed feedback laser and a fiber ring resonator for wearable biomedical sensors

NASA Astrophysics Data System (ADS)

Roy, Anirban; Chakraborty, Arup Lal; Jha, Chandan Kumar

2017-04-01

This paper demonstrates the interrogation of a fiber Bragg grating with a flat-topped reflection spectrum centred on 1649.55 nm using only a single mode tunable 1651.93 nm semiconductor laser and a fiber ring resonator. The Bragg shift is accurately measured with the fiber-optic ring resonator that has a free spectral range (FSR) of 0.1008 GHz and a broadband photo-detector. Laser wavelength modulation and harmonic detection are used to transform the gentle edges of the flat-topped FBG spectrum into prominent leading and trailing peaks, either of which can be used to accurately measure spectral shifts of the FBG reflection spectrum with a resolution of 0.9 pm. A Raspberry Pi-based low-cost embedded processor is used to measure the temperature-induced spectral shifts over the range 30˚C - 80˚C. The shift was linear with a temperature sensitivity of 12.8 pm/˚C. This technique does not use an optical spectrum analyzer at any stage of its design or operation. The laser does not need to be pre-characterized either. This technique can be readily extended to all types of tunable diode lasers and is ideally suited for compact field instruments.

Characterization of novel microsphere chain fiber optic tips for potential use in ophthalmic laser surgery.

PubMed

Hutchens, Thomas C; Darafsheh, Arash; Fardad, Amir; Antoszyk, Andrew N; Ying, Howard S; Astratov, Vasily N; Fried, Nathaniel M

2012-06-01

Ophthalmic surgery may benefit from use of more precise fiber delivery systems during laser surgery. Some current ophthalmic surgical techniques rely on tedious mechanical dissection of tissue layers. In this study, chains of sapphire microspheres integrated into a hollow waveguide distal tip are used for erbium:YAG laser ablation studies in contact mode with ophthalmic tissues, ex vivo. The laser's short optical penetration depth combined with the small spot diameters achieved with this fiber probe may provide more precise tissue removal. One-, three-, and five-microsphere chain structures were characterized, resulting in FWHM diameters of 67, 32, and 30 μm in air, respectively, with beam profiles comparable to simulations. Single Er:YAG pulses of 0.1 mJ and 75-μs duration produced ablation craters with average diameters of 44, 30, and 17 μm and depths of 26, 10, and 8 μm, for one-, three-, and five-sphere structures, respectively. Microsphere chains produced spatial filtering of the multimode Er:YAG laser beam and fiber, providing spot diameters not otherwise available with conventional fiber systems. Because of the extremely shallow treatment depth, compact focused beam, and contact mode operation, this probe may have potential for use in dissecting epiretinal membranes and other ophthalmic tissues without damaging adjacent retinal tissue.

Fiber-based confocal microscope for cryogenic spectroscopy.

PubMed

Högele, Alexander; Seidl, Stefan; Kroner, Martin; Karrai, Khaled; Schulhauser, Christian; Sqalli, Omar; Scrimgeour, Jan; Warburton, Richard J

2008-02-01

We describe the design and performance of a fiber-based confocal microscope for cryogenic operation. The microscope combines positioning at low temperatures along three space coordinates of millimeter translation and nanometer precision with high stability and optical performance at the diffraction limit. It was successfully tested under ambient conditions as well as at liquid nitrogen (77 K) and liquid helium (4 K) temperatures. The compact nonmagnetic design provides for long term position stability against helium refilling transfers, temperature sweeps, as well as magnetic field variation between -9 and 9 T. As a demonstration of the microscope performance, applications in the spectroscopy of single semiconductor quantum dots are presented.

In-line open-cavity Fabry-Pérot interferometer formed by C-shaped fiber fortemperature-insensitive refractive index sensing.

PubMed

Wu, Chuang; Liu, Zhengyong; Zhang, A Ping; Guan, Bai-Ou; Tam, Hwa-Yaw

2014-09-08

We report an open-cavity optical fiber Fabry-Pérot interferometer (FPI) capable of measuring refractive index with very low temperature cross-sensitivity. The FPI was constructed by splicing a thin piece of C-shaped fiber between two standard single-mode fibers. The refractive index (RI) response of the FPI was characterized using water-ethanol mixtures with RI in the range of 1.33 to 1.36. The RI sensitivity was measured to be 1368 nm/RIU at the wavelength of 1600 nm with good linearity. Thanks to its all-glass structure, the FPI exhibits very low temperature cross-sensitivity of 3.04 × 10⁻⁷ RIU/°C. The effects of cavity length on the performance of the sensor were also studied. A shorter cavity gives rise to broader measurement range while offering larger detection limit, and vice versa. What's more, the effect of material dispersion of analyte on the sensitivity of open-cavity FPIs was identified for the first time. The sensor is compact in size and easy to fabricate. It is potentially useful for label-free optical sensing of chemical and biological samples.

Integrated transrectal probe for translational ultrasound-photoacoustic imaging

NASA Astrophysics Data System (ADS)

Bell, Kevan L.; Harrison, Tyler; Usmani, Nawaid; Zemp, Roger J.

2016-03-01

A compact photoacoustic transrectal probe is constructed for improved imaging in brachytherapy treatment. A 192 element 5 MHz linear transducer array is mounted inside a small 3D printed casing along with an array of optical fibers. The device is fed by a pump laser and tunable NIR-optical parametric oscillator with data collected by a Verasonics ultrasound platform. This assembly demonstrates improved imaging of brachytherapy seeds in phantoms with depths up to 5 cm. The tuneable excitation in combination with standard US integration provides adjustable contrast between the brachytherapy seeds, blood filled tubes and background tissue.

Fabrication and characterization of on-chip optical nonlinear chalcogenide nanofiber devices.

PubMed

Zhang, Qiming; Li, Ming; Hao, Qiang; Deng, Dinghuan; Zhou, Hui; Zeng, Heping; Zhan, Li; Wu, Xiang; Liu, Liying; Xu, Lei

2010-11-15

Chalcogenide (As(2)S(3)) nanofibers as narrow as 200 nm in diameter are drawn by the fiber pulling method, are successfully embedded in SU8 polymer, and form on-chip waveguides and high-Q microknot resonators (Q = 3.9 × 10(4)) with smooth cleaved end faces. Resonance tuning of resonators is realized by localized laser irradiation. Strong supercontinuum generation with a bandwidth of 500 nm is achieved in a 7-cm-long on-chip chalcogenide waveguide. Our result provides a method for the development of compact, high-optical-quality, and robust photonic devices.

High power pulsed sources based on fiber amplifiers

NASA Astrophysics Data System (ADS)

Canat, Guillaume; Jaouën, Yves; Mollier, Jean-Claude; Bouzinac, Jean-Pierre; Cariou, Jean-Pierre

2017-11-01

Cladding-pumped rare-earth-doped fiber laser technologies are currently among the best sources for high power applications. Theses extremely compact and robust sources appoint them as good candidate for aeronautical and space applications. The double-clad (DC) fiber converts the poor beamquality of high-power large-area pump diodes from the 1st cladding to laser light at another wavelength guided in an active single-mode core. High-power coherent MOPA (Master Oscillator Power Amplifier) sources (several 10W CW or several 100W in pulsed regime) will soon be achieved. Unfortunately it also brings nonlinear effects which quickly impairs output signal distortions. Stimulated Brillouin scattering (SBS) and optical parametric amplification (OPA) have been shown to be strong limitations. Based on amplifier modeling and experiments we discuss the performances of these sources.

Liquid level sensor based on fiber ring laser with single-mode-offset coreless-single-mode fiber structure

NASA Astrophysics Data System (ADS)

Wang, Zixiao; Tan, Zhongwei; Xing, Rui; Liang, Linjun; Qi, Yanhui; Jian, Shuisheng

2016-10-01

A novel reflective liquid level sensor based on single-mode-offset coreless-single-mode (SOCS) fiber structure is proposed and experimentally demonstrated. Theory analyses and experimental results indicate that offset fusion can remarkably enhance the sensitivity of sensor. Ending-reflecting structure makes the sensor compact and easy to deploy. Meanwhile, we propose a laser sensing system, and the SOCS structure is used as sensing head and laser filter simultaneously. Experimental results show that laser spectra with high optical signal-to-noise ratio (-30 dB) and narrow 3-dB bandwidth (<0.15 nm) are achieved. Various liquids with different indices are used for liquid level sensing, besides, the refractive index sensitivity is also investigated. In measurement range, the sensing system presents steady laser output.

Generation of 46 W green-light by frequency doubling of 96 W picosecond unpolarized Yb-doped fiber amplifier

NASA Astrophysics Data System (ADS)

Qi, Yaoyao; Yu, Haijuan; Zhang, Jingyuan; Zhang, Ling; He, Chaojian; Lin, Xuechun

2018-05-01

We demonstrated a high efficiency and high average power picosecond green light source based on SHG (second harmonic generation) of an unpolarized ytterbium-doped fiber amplifier chain. Using single-pass frequency doubling in two temperature-tuned type-I phase-matching LBO crystals, we were able to generate 46 W, >70 ps pulses at 532 nm from a fundamental beam at 1064 nm, whose output is 96 W, 4.8 μJ, with a repetition frequency of 20 MHz and nearly diffraction limited. The optical conversion efficiency was ∼48% in a highly compact design. To the best of our knowledge, this is the first reported on ps green source through SHG of an unpolarized fiber laser with such a high output and high efficiency.

Sub-5-ps, multimegawatt peak-power pulses from a fiber-amplified and optically compressed passively Q-switched microchip laser.

PubMed

Steinmetz, A; Jansen, F; Stutzki, F; Lehneis, R; Limpert, J; Tünnermann, A

2012-07-01

We report on high-energy picosecond pulse generation from a passively Q-switched and fiber-amplified microchip laser system. Initially, the utilized microchip lasers produce pulses with durations of around 100 ps at 1064 nm central wavelength. These pulses are amplified to energies exceeding 100 μJ, simultaneously chirped and spectrally broadened by self-phase modulation using a double stage amplifier based on single-mode LMA photonic crystal fibers at repetition rates of up to 1 MHz. Subsequently, the pulse duration of chirped pulses is reduced by means of nonlinear pulse compression to durations of 2.7 ps employing a conventional grating compressor and 4.7 ps using a compact compressor based on a chirped volume Bragg grating.

Microchip laser mid-infrared supercontinuum laser source based on an As2Se3 fiber.

PubMed

Gattass, Rafael R; Brandon Shaw, L; Sanghera, Jasbinder S

2014-06-15

We report on a proof of concept for a compact supercontinuum source for the mid-infrared wavelength range based on a microchip laser and nonlinear conversion inside a selenide-based optical fiber. The spectrum extends from 3.74 to 4.64 μm at -10  dB from the peak and 3.65 to 4.9 μm at -20  dB from the peak; emitting beyond the wavelength range that periodically poled lithium niobate (PPLN) starts to display a power penalty. Wavelength conversion occurs inside the core of a single-mode fiber, resulting in a high-brightness emission source. A maximum average power of 5 mW was demonstrated, but the architecture is scalable to higher average powers.

Highly birefringent elliptical core photonic crystal fiber for terahertz application

NASA Astrophysics Data System (ADS)

Sultana, Jakeya; Islam, Md. Saiful; Faisal, Mohammad; Islam, Mohammad Rakibul; Ng, Brian W.-H.; Ebendorff-Heidepriem, Heike; Abbott, Derek

2018-01-01

We present a novel strategy for designing a highly birefringent photonic crystal fiber (PCF) with near zero flattened dispersion properties by applying elliptical air holes in the core area. The elliptical structure of the air holes in the porous-core region introduces asymmetry between x and y polarization modes, which consequently offers ultra-high birefringence. Also the compact geometry of the conventional hexagonal structure in the cladding confines most of the useful power. The optical properties including birefringence, dispersion, confinement loss, effective material loss (EML) and single modeness of the fiber are investigated using a full-vector finite element method. Simulation results show an ultra-high birefringence of 0 . 086 ultra-flattened near zero dispersion of 0 . 53 ± 0 . 07 ps/THz/cm in a broad frequency range. The practical implementation of the proposed fiber is feasible using existing fabrication technology and is applicable to the areas of terahertz sensing and polarization maintaining systems.

True time-delay photonic beamforming with fine steerability and frequency-agility for spaceborne phased-arrays: a proof-of-concept demonstration

NASA Astrophysics Data System (ADS)

Paul, Dilip K.; Razdan, Rajender; Goldman, Alfred M.

1996-10-01

Feasibility of photonics in beam forming and steering of large phased-array antennas onboard communications satellite/avionics systems is addressed in this paper. Specifically, a proof-of-concept demonstration of phased- array antenna feed network using fiber optic true time-delay (TTD) elements is reported for SATCOM phased-array antennas operating at C-band. Results of the photonic hardware design and performance analysis, including the measured radiation patterns of the antenna array fed by the photonic BFN, are presented. An excellent agreement between the analysis and measured data has been observed. In addition to being light- weight and compact, several unique characteristics such as rf carrier frequency agility and continuous steerability of the radiated beam achieved by the fiber optic TTD architecture are clear evidences of its superiority over other competing photonic architectures.

Optical cascaded Fabry-Perot interferometer hydrogen sensor based on vernier effect

NASA Astrophysics Data System (ADS)

Li, Yina; Zhao, Chunliu; Xu, Ben; Wang, Dongning; Yang, Minghong

2018-05-01

An optical cascaded Fabry-Perot interferometer hydrogen sensor based on vernier effect has been proposed and achieved. The proposed sensor, which total length is ∼594 μm, is composed of a segment of large mode area fiber (LMAF) and a segment of hollow-core fiber (HCF). The proposed sensor is coated with the Pt-loaded WO3/SiO2 powder which will result in the increase of local temperature of the sensor head when exposed to hydrogen atmosphere. Thus the hydrogen sensor can be achieved by monitoring the change of resonant envelope wavelength. The hydrogen sensitivity is -1.04 nm/% within the range of 0 % -2.4 % which is greatly improved because of the vernier effect. The response time is ∼80 s. Due to its compact configuration, the proposed sensor provides a feasible and miniature structure to achieve detection of hydrogen.

Polarization independent thermally tunable erbium-doped fiber amplifier gain equalizer using a cascaded Mach-Zehnder coupler.

PubMed

Sahu, P P

2008-02-10

A thermally tunable erbium-doped fiber amplifier (EDFA) gain equalizer filter based on compact point symmetric cascaded Mach-Zehnder (CMZ) coupler is presented with its mathematical model and is found to be polarization dependent due to stress anisotropy caused by local heating for thermo-optic phase change from its mathematical analysis. A thermo-optic delay line structure with a stress releasing groove is proposed and designed for the reduction of polarization dependent characteristics of the high index contrast point symmetric delay line structure of the device. It is found from thermal analysis by using an implicit finite difference method that temperature gradients of the proposed structure, which mainly causes the release of stress anisotropy, is approximately nine times more than that of the conventional structure. It is also seen that the EDFA gain equalized spectrum by using the point symmetric CMZ device based on the proposed structure is almost polarization independent.

Fiber-optic three axis magnetometer prototype development

NASA Technical Reports Server (NTRS)

Wang, Thomas D.; Mccomb, David G.; Kingston, Bradley R.; Dube, C. Michael; Poehls, Kenneth A.; Wanser, Keith

1989-01-01

The goal of this research program was to develop a high sensitivity, fiber optic, interferometric, three-axis magnetometer for interplanetary spacecraft applications. Dynamics Technology, Inc. (DTI) has successfully integrated a low noise, high bandwidth interferometer with high sensitivity metallic glass transducers. Also, DTI has developed sophisticated signal processing electronics and complete data acquisition, filtering, and display software. The sensor was packaged in a compact, low power and weight unit which facilitates deployment. The magnetic field sensor had subgamma sensitivity and a dynamic range of 10(exp 5) gamma in a 10 Hz bandwidth. Furthermore, the vector instrument exhibited the lowest noise level when only one axis was in operation. A system noise level of 1 gamma rms was observed in a 1 Hz bandwidth. However, with the other two channels operating, the noise level increased by about one order of magnitude. Higher system noise was attributed to cross-channel interference among the dither fields.

Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

NASA Astrophysics Data System (ADS)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

2015-04-01

A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

Issues to be addressed in the design and fabrication of ultralightweight meter-class optics

NASA Astrophysics Data System (ADS)

Krumweide, Gary C.

1998-08-01

There is a growing need for large aperture, ultralightweight, deployable optics for various science, military and commercial compact satellites. This paper will examine the engineering and manufacturing considerations that must be addressed in order to satisfy the requirements for these sought after optics. In order to limit the scope of this paper, only Graphite Fiber Reinforced/Polymer Matrix Composites (GFR/PMC) will be under consideration because of the potential to satisfy ultralightweight mirror requirements. The requirements associated with specular mirror concepts that Composite Optics, Incorporated (COI) has proposed to Air Force Research Laboratory and NASA Langley Research Center for visible range optics and LIDAR optics, respectively, will also be our interest. Moreover, it is the intent of this paper to illustrate how COI's proposed design/manufacturing concepts for visible and LIDAR optics have evolved based on overcoming, or working around, material constraints and/or undesirable characteristics associated with GFR/PMC.

Silicon-based products and solutions

NASA Astrophysics Data System (ADS)

Painchaud, Y.; Poulin, M.; Pelletier, F.; Latrasse, C.; Gagné, J.-F.; Savard, S.; Robidoux, G.; Picard, M.-.; Paquet, S.; Davidson, C.-.; Pelletier, M.; Cyr, M.; Paquet, C.; Guy, M.; Morsy-Osman, M.; Chagnon, M.; Plant, D. V.

2014-03-01

TeraXion started silicon photonics activities aiming at developing building blocks for new products and customized solutions. Passive and active devices have been developed including MMI couplers, power splitters, Bragg grating filters, high responsivity photodetectors, high speed modulators and variable optical attenuators. Packaging solutions including fiber attachment and hybrid integration using flip-chip were also developed. More specifically, a compact packaged integrated coherent receiver has been realized. Good performances were obtained as demonstrated by our system tests results showing transmission up to 4800 km with BER below hard FEC threshold. The package size is small but still limited by the electrical interface. Migrating to more compact RF interface would allow realizing the full benefit of this technology.

Compact Microwave Fourier Spectrum Analyzer

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

2009-01-01

A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

Bi-Tapered Fiber Sensor Using a Supercontinuum Light Source for a Broad Spectral Range

NASA Astrophysics Data System (ADS)

Garcia Mina, Diego Felipe

We describe the fabrication bi-tapered optical fiber sensors designed for shorter wavelength operation and we study their optical properties. The new sensing system designed and built for the project is a specialty optical fiber that is single-mode in the visible/near infrared wavelength region of interest. In fabricating the tapered fiber we control the taper parameters, such as the down-taper and up-taper rate, shape and length, and the fiber waist diameter and length. The sensing is mode is via the electromagnetic field, which is evanescent outside the optical fiber and is confined close to the fiber's surface (within a couple hundred nanometers). The fiber sensor system has multiple advantages as a compact, simple device with an ability to detected tiny changes in the refractive index. We developed a supercontinuum light source to provide a wide spectral wavelength range from visible to near IR. The source design was based on coupling light from a femtosecond laser in a photonic crystal fiber designed for high nonlinearity. The output light was efficiently coupled into the bi-tapered fiber sensor and good signal to noise was achieved across the wavelength region. The bi-tapered fiber starts and ends with a single mode fiber in the waist region there are many modes with different propagation constants that couple to the environment outside the fiber. The signals have a strong periodic component as the wavelength is scanned; we exploit the periodicity in the signal using a discrete Fourier transform analysis to correlate signal phase changes with the refractive index changes in the local environment. For small index changes we also measure a strong correlation with the dominant Fourier amplitude component. Our experiments show that our phase-based signal processing technique works well at shorter wavelengths and we extract a new feature, the Fourier amplitude, to measure the refractive index difference. We conducted experiments using aqueous medium with controlled refractive index, such as water-glycerol mixtures. We find sensitivity to changes in the refractive index close to 0.00002 in so-called Refractive Index Units (RIUs). That is smaller than reported in recent literature, but by no means a limiting value. The technique is not limited to aqueous solutions surrounding the fiber, but it can also be adapted to study volatile organic compounds. Future improvements in the fiber sensing system are discussed, including adding thin films to the surface for label-free detection and to draw the electromagnetic field to the fiber's surface.

NASA Tech Briefs, November 2004

NASA Technical Reports Server (NTRS)

2004-01-01

Topics include: Multifunction Imaging and Spectroscopic Instrument; Position-Finding Instrument Built Around a Magnetometer; Improved Measurement of Dispersion in an Optical Fiber; Probe for Sampling of Interstitial Fluid From Bone; Neuropsychological Testing of Astronauts; Method of Calibration for a Large Cathetometer System; Four-Channel PC/104 MIL-STD-1553 Circuit Board; Improved Method of Locating Defects in Wiring Insulation; Strobe Traffic Lights Warn of Approaching Emergency Vehicles; Improved Timing Scheme for Spaceborne Precipitation Radar; Concept for Multiple-Access Free-Space Laser Communications; Variable Shadow Screens for Imaging Optical Devices; Verifying Diagnostic Software; Initial Processing of Infrared Spectral Data; Activity-Centric Approach to Distributed Programming; Controlling Distributed Planning; New Material for Surface-Enhanced Raman Spectroscopy; Treated Carbon Nanofibers for Storing Energy in Aqueous KOH; Advanced Infant Car Seat Would Increase Highway Safety; Development of Biomorphic Flyers; Second-Generation Six-Limbed Experimental Robot; Miniature Linear Actuator for Small Spacecraft; Process for Making Single-Domain Magnetite Crystals; A New Process for Fabricating Random Silicon Nanotips; Resin-Transfer-Molding of a Tool Face; Improved Phase-Mask Fabrication of Fiber Bragg Gratings; Tool for Insertion of a Fiber-Optic Terminus in a Connector; Nanofluidic Size-Exclusion Chromatograph; Lightweight, Low-CTE Tubes Made From Biaxially Oriented LCPs; Using Redundancy To Reduce Errors in Magnetometer Readings; Compact Instrument for Measuring Profile of a Light Beam; Multilayer Dielectric Transmissive Optical Phase Modulator; Second-Generation Multi-Angle Imaging Spectroradiometer; Real-Time Adaptive Color Segmentation by Neural Networks; Research and Development in Optical Communications; Tests of Multibeam Scintillation Mitigation on Laser Uplinks; and Spaceborne Infrared Atmospheric Sounder.

High brightness diode laser module development at nLIGHT Photonics

NASA Astrophysics Data System (ADS)

Price, Kirk; Karlsen, Scott; Brown, Aaron; Reynolds, Mitch; Mehl, Ron; Leisher, Paul; Patterson, Steve; Bell, Jake; Martinsen, Rob

2009-05-01

We report on the development of ultra-high brightness laser diode modules at nLIGHT Photonics. This paper demonstrates a laser diode module capable of coupling over 100W at 976 nm into a 105 μm, 0.15 NA fiber with fiber coupling efficiency greater than 85%. The high brightness module has an optical excitation under 0.13 NA, is virtually free of cladding modes, and has been wavelength stabilized with the use of volume holographic gratings for narrow-band operation. Utilizing nLIGHT's Pearl product architecture, these modules are based on hard soldered single emitters packaged into a compact and passively-cooled package. These modules are designed to be compatible with high power 7:1 fused fiber combiners, enabling over 500W power coupled into a 220 μm, 0.22 NA fiber. These modules address the need in the market for high brightness and wavelength stabilized diode lasers for pumping fiber lasers and solid-state laser systems.

A Compact Frequency Agile Mid-Infrared Airborne Lidar

DTIC Science & Technology

2006-10-01

et al. demonstrated a PPLN OPO pumped by a tunable ytterbium - doped fiber laser [11]. The system delivers a tunable mid-infrared output with a peak...shared component with it. OPO Resonator Mirrors Pump Laser Signal => , =0 ..rt.«^.._S„.5lfc>..J Idler Nonlinear Optical Crystal (a) Pump...signal- to-noise ratio (Figure 31). Tuning was accomplished by rotating the crystal. The theoretical analysis of up-conversion in LiNbC>3 crystal

Remote optical sensing on the nanometer scale with a bowtie aperture nano-antenna on a fiber tip of scanning near-field optical microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atie, Elie M.; Xie, Zhihua; El Eter, Ali

2015-04-13

Plasmonic nano-antennas have proven the outstanding ability of sensing chemical and physical processes down to the nanometer scale. Sensing is usually achieved within the highly confined optical fields generated resonantly by the nano-antennas, i.e., in contact to the nanostructures. In this paper, we demonstrate the sensing capability of nano-antennas to their larger scale environment, well beyond their plasmonic confinement volume, leading to the concept of “remote” (non contact) sensing on the nanometer scale. On the basis of a bowtie-aperture nano-antenna (BNA) integrated at the apex of a SNOM (Scanning Near-field Optical Microscopy) fiber tip, we introduce an ultra-compact, moveable, andmore » background-free optical nanosensor for the remote sensing of a silicon surface (up to distance of 300 nm). Sensitivity of the BNA to its large scale environment is high enough to expect the monitoring and control of the spacing between the nano-antenna and a silicon surface with sub-nanometer accuracy. This work paves the way towards an alternative class of nanopositioning techniques, based on the monitoring of diffraction-free plasmon resonance, that are alternative to nanomechanical and diffraction-limited optical interference-based devices.« less

High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays.

PubMed

Yardimci, Nezih Tolga; Lu, Hong; Jarrahi, Mona

2016-11-07

We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. We experimentally demonstrate pulsed terahertz radiation over 0.1-5 THz frequency range with the power levels as high as 300  μ W. This is the highest-reported terahertz radiation power from a photoconductive emitter operating at telecommunication optical wavelengths.

High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays

PubMed Central

Yardimci, Nezih Tolga; Lu, Hong; Jarrahi, Mona

2016-01-01

We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. We experimentally demonstrate pulsed terahertz radiation over 0.1–5 THz frequency range with the power levels as high as 300 μW. This is the highest-reported terahertz radiation power from a photoconductive emitter operating at telecommunication optical wavelengths. PMID:27916999

Common path endoscopic probes for optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Singh, Kanwarpal; Gardecki, Joseph A.; Tearney, Guillermo J.

2017-02-01

Background: Dispersion imbalance and polarization mismatch between the reference and sample arm signals can lead to image quality degradation in optical coherence tomography (OCT). One approach to reduce these image artifacts is to employ a common-path geometry in fiber-based probes. In this work, we report an 800 um diameter all-fiber common-path monolithic probe for coronary artery imaging where the reference signal is generated using an inline fiber partial reflector. Methods: Our common-path probe was designed for swept-source based Fourier domain OCT at 1310 nm wavelength. A face of a coreless fiber was coated with gold and spliced to a standard SMF-28 single mode fiber creating an inline partial reflector, which acted as a reference surface. The other face of the coreless fiber was shaped into a ball lens for focusing. The optical elements were assembled within a 560 µm diameter drive shaft, which was attached to a rotary junction. The drive shaft was placed inside a transparent sheath having an outer diameter of 800 µm. Results: With a source input power of 30mW, the inline common-path probe achieved a sensitivity of 104 dB. Images of human finger skin showed the characteristic layers of skin as well as features such as sweat ducts. Images of coronary arteries ex vivo obtained with this probe enabled visualization of the characteristic architectural morphology of the normal artery wall and known features of atherosclerotic plaque. Conclusion: In this work, we have demonstrated a common path OCT probe for cardiovascular imaging. The probe is easy to fabricate, will reduce system complexity and overall cost. We believe that this design will be helpful in endoscopic applications that require high resolution and a compact form factor.

Numerous applications of fiber optic evanescent wave Fourier transform infrared (FEW-FTIR) spectroscopy for subsurface structural analysis

NASA Astrophysics Data System (ADS)

Afanasyeva, Natalia I.; Welser, Leslie; Bruch, Reinhard F.; Kano, Angelique; Makhine, Volodymyr

1999-10-01

A new infrared (IR) interferometric method has been developed in conjunction with low-loss, flexible optical fibers, sensors, and probes. This combination of fiber optical sensors and Fourier Transform (FT) spectrometers can be applied to many fields, including (1) noninvasive medical diagnostics of cancer and other different diseases in vivo, (2) minimally invasive bulk diagnostics of tissue, (3) remote monitoring of tissue, chemical processes, and environment, (4) surface analysis of polymers and other materials, (5) characterization of the quality of food, pharmacological products, cosmetics, paper, and other wood-related products, as well as (6) agricultural, forensic, geological, mining, and archeological field measurements. In particular, our nondestructive, fast, compact, portable, remote and highly sensitive diagnostics tools are very promising for subsurface analysis at the molecular level without sample preparation. For example, this technique is ideal for different types of soft porous foams, rough polymers, and rock surfaces. Such surfaces, as well as living tissue, are very difficult to investigate by traditional FTIR methods. We present here FEW-FTIR spectra of polymers, banana and grapefruit peels, and living tissues detected directly at surfaces. In addition, results on the vibrational spectral analysis of normal and pathological skin tissue in the region of 850 - 4000 cm-1 are discussed.

Localized surface plasmon resonance-based fiber-optic sensor for the detection of triacylglycerides using silver nanoparticles

NASA Astrophysics Data System (ADS)

Baliyan, Anjli; Usha, Sruthi Prasood; Gupta, Banshi D.; Gupta, Rani; Sharma, Enakshi Khular

2017-10-01

A label-free technique for the detection of triacylglycerides by a localized surface plasmon resonance (LSPR)-based biosensor is demonstrated. An LSPR-based fiber-optic sensor probe is fabricated by immobilizing lipase enzyme on silver nanoparticles (Ag-NPs) coated on an unclad segment of a plastic clad optical fiber. The size and shape of nanoparticles were characterized by high-resolution transmission electron microscopy and UV-visible spectroscopy. The peak absorbance wavelength changes with concentration of triacylglycerides surrounding the sensor probe, and sensitivity is estimated from shift in the peak absorbance wavelength as a function of concentration. The fabricated sensor was characterized for the concentration of triacylglyceride solution in the range 0 to 7 mM. The sensor shows the best sensitivity at a temperature of 37°C and pH 7.4 of the triacylglycerides emulsion with a response time of 40 s. A sensitivity of 28.5 nm/mM of triacylglyceride solution is obtained with a limit of detection of 0.016 mM in the entire range of triacylglycerides. This compact biosensor shows good selectivity, stability, and reproducibility in the entire physiological range of triacylglycerides and is well-suited to real-time online monitoring and remote sensing.

Wide-field lensless fluorescent microscopy using a tapered fiber-optic faceplate on a chip.

PubMed

Coskun, Ahmet F; Sencan, Ikbal; Su, Ting-Wei; Ozcan, Aydogan

2011-09-07

We demonstrate lensless fluorescent microscopy over a large field-of-view of ~60 mm(2) with a spatial resolution of <4 µm. In this on-chip fluorescent imaging modality, the samples are placed on a fiber-optic faceplate that is tapered such that the density of the fiber-optic waveguides on the top facet is >5 fold larger than the bottom one. Placed on this tapered faceplate, the fluorescent samples are pumped from the side through a glass hemisphere interface. After excitation of the samples, the pump light is rejected through total internal reflection that occurs at the bottom facet of the sample substrate. The fluorescent emission from the sample is then collected by the smaller end of the tapered faceplate and is delivered to an opto-electronic sensor-array to be digitally sampled. Using a compressive sampling algorithm, we decode these raw lensfree images to validate the resolution (<4 µm) of this on-chip fluorescent imaging platform using microparticles as well as labeled Giardia muris cysts. This wide-field lensfree fluorescent microscopy platform, being compact and high-throughput, might provide a valuable tool especially for cytometry, rare cell analysis (involving large area microfluidic systems) as well as for microarray imaging applications.

A Compact Fiber Optic Eye Diagnostic System

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Suh, Kwang I.; Dubin, Stephen; Dellavecchia, Michael A.

1995-01-01

A new fiber optic probe developed for determining transport properties of sub-micron particles in fluid experiments in a microgravity environment has been applied to study different parts of an eye. The probe positioned in front of an eye, delivers a low power (approximately few microW) light from a laser diode into the eye and guides the light which is back scattered by different components (aqueous humor, lens, and vitreous humor) of the eye through a receiving optical fiber to a photo detector. The probe provides rapid determination of macromolecular diffusivities and their respective size distributions in the eye lens and the gel-like materials in the vitreous humor. In a clinical setting, the probe can be mounted on a standard slit-lamp apparatus simply using a Hruby lens holder. The capability of detecting cataracts, both nuclear and cortical, in their early stages of formation, in a non invasive and quantitative fashion, has the potential in patient monitoring and in developing and testing new drugs or diet therapies to 'dissolve' or slow down the cataract formation before the surgery becomes necessary. The ability to detect biochemical and macromolecular changes in the vitreous structure can be very useful in identifying certain diseases of the posterior chamber and their complications, e.g., posterior vitreous detachment and diabetic retinopathy.

A Compact Fiber Optic Eye Diagnostics System

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Suh, Kwang I.; DellaVecchia, Michael A.; Dubin, Stephen; Zigler, J. Samuel, Jr.

1995-01-01

A new fiber optic probe development for determining transport properties of sub-micron particles in fluids experiments in a microgravity environment has been applied to study different parts of the eye. The probe positioned in front of an eye, delivers a low power (approximately a few mu W) light from a laser diode into the eye and guides the light which is back scattered by different components (aqueous humor, lens, and vitreous humor) of the eye through a receiving optical fiber to a photo detector. The probe provides rapid determination of macromolecular diffusivities and their respective size distributions in the eye lens and the gel-like material in the vitreous humor. For a clinical use, the probe is mounted on a standard slit-lamp apparatus simply using Hruby lens holder. The capability of detecting cataracts, both nuclear and cortical, in their early stages of formation, in a non invasive and quantitative fashion, has the potential in patient monitoring and in developing and testing new drugs or diet therapies to 'dissolve' or slow down the cataract formation before the surgery becomes necessary. The ability to detect biochemical and macromolecular changes in the vitreous structure can be very useful in identifying certain diseases of the posterior chamber and their complications, e.g., posterior vitreous detachment and diabetic retinopathy.

Development of the Concept of Recycling of Light

NASA Astrophysics Data System (ADS)

Harmer, Brian

Environmental and economic issues are the highlights of any new product or system created today. The efficient use of energy helps satisfy both of these concerns as a reduction in energy consumption contributes to a reduction both in fuel consumption and carbon emissions. Illumination efficiency has been one of the main areas of research as luminaires are one of the largest consumers of electricity in the world. The incandescent bulb is one of the oldest pieces of technology still used today, but is being phased out as compact fluorescent lamps and LED light sources have a much lower power consumption for the same amount of light emission. However, the light source design, while very important, is not the only way to improve the efficiency of an illumination system. This thesis proposes a new concept, the recycling of light (ROL). The ROL system collects, transports, and emits unused light from one area to another through the use of optical fibers. To find an optimal ROL system, many variables need to be accounted for. This thesis covers the effect of different luminaires on light collection areas. The collection area for the ROL system needs to be placed in the areas of a room that are of little or no importance, but still receive light, such as the ceiling or the upper section of the walls. The fiber-to-source distance and offset effects on fiber emission are investigated, as well as the length and type of the optical fibers. Additionally, this thesis looks at the possibility of beveling optical fiber ends to be used as a focusing mechanism for the ROL system.

All-fiber linearly polarized high power 2-μm single mode Tm-fiber laser for plastic processing and Ho-laser pumping applications

NASA Astrophysics Data System (ADS)

Scholle, K.; Schäfer, M.; Lamrini, S.; Wysmolek, M.; Steinke, M.; Neumann, J.; Fuhrberg, P.

2018-02-01

In this paper we present a high power, polarized 2 μm Thulium-doped fiber laser with high beam quality. Such laser systems are ideally suited for the processing of plastic materials which are highly transparent in the visible and 1 μm wavelength range and for the pumping of laser sources for the mid-IR wavelength region. For most applications polarized lasers are beneficial, as they can be easily protected from back reflections and combined with other laser sources or power scaled by polarization combining. The Tm-doped fiber laser is pumped in an all-fiber configuration by using a fiber coupled pump diode emitting around 790 nm. This pumping scheme allows the exploitation of the crossrelaxation process to populate the upper laser level. A compact and robust laser configuration was achieved by using an all-fiber configuration with single mode fibers and fiber Bragg gratings (FBG). Different FBG pairs with wavelength around 2 μm were tested. To achieve stable polarized output power the fibers with the FBG were 90° twisted at the splices. Stable linearly polarized output power up to 38 W with an extinction ratio of up to 50:1 was observed. With respect to the diode output power an optical-to-optical efficiency of 51 % was reached with a correspondent slope efficiency of 52 %. The emission linewidth at maximum power was measured to be < 0.3 nm which is well suitable for Ho-laser pumping. First tests of the precise processing of highly transparent plastic materials demonstrate the potentials of these laser systems.

Compact 3D Camera for Shake-the-Box Particle Tracking

NASA Astrophysics Data System (ADS)

Hesseling, Christina; Michaelis, Dirk; Schneiders, Jan

2017-11-01

Time-resolved 3D-particle tracking usually requires the time-consuming optical setup and calibration of 3 to 4 cameras. Here, a compact four-camera housing has been developed. The performance of the system using Shake-the-Box processing (Schanz et al. 2016) is characterized. It is shown that the stereo-base is large enough for sensible 3D velocity measurements. Results from successful experiments in water flows using LED illumination are presented. For large-scale wind tunnel measurements, an even more compact version of the system is mounted on a robotic arm. Once calibrated for a specific measurement volume, the necessity for recalibration is eliminated even when the system moves around. Co-axial illumination is provided through an optical fiber in the middle of the housing, illuminating the full measurement volume from one viewing direction. Helium-filled soap bubbles are used to ensure sufficient particle image intensity. This way, the measurement probe can be moved around complex 3D-objects. By automatic scanning and stitching of recorded particle tracks, the detailed time-averaged flow field of a full volume of cubic meters in size is recorded and processed. Results from an experiment at TU-Delft of the flow field around a cyclist are shown.

Compact dual-mode diffuse optical system for blood perfusion monitoring in a porcine model of microvascular tissue flaps

NASA Astrophysics Data System (ADS)

Lee, Seung Yup; Pakela, Julia M.; Helton, Michael C.; Vishwanath, Karthik; Chung, Yooree G.; Kolodziejski, Noah J.; Stapels, Christopher J.; McAdams, Daniel R.; Fernandez, Daniel E.; Christian, James F.; O'Reilly, Jameson; Farkas, Dana; Ward, Brent B.; Feinberg, Stephen E.; Mycek, Mary-Ann

2017-12-01

In reconstructive surgery, the ability to detect blood flow interruptions to grafted tissue represents a critical step in preventing postsurgical complications. We have developed and pilot tested a compact, fiber-based device that combines two complimentary modalities-diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy-to quantitatively monitor blood perfusion. We present a proof-of-concept study on an in vivo porcine model (n=8). With a controllable arterial blood flow supply, occlusion studies (n=4) were performed on surgically isolated free flaps while the device simultaneously monitored blood flow through the supplying artery as well as flap perfusion from three orientations: the distal side of the flap and two transdermal channels. Further studies featuring long-term monitoring, arterial failure simulations, and venous failure simulations were performed on flaps that had undergone an anastomosis procedure (n=4). Additionally, benchtop verification of the DCS system was performed on liquid flow phantoms. Data revealed relationships between diffuse optical measures and state of occlusion as well as the ability to detect arterial and venous compromise. The compact construction of the device, along with its noninvasive and quantitative nature, would make this technology suitable for clinical translation.

What's new in well logging and formation evaluation

USGS Publications Warehouse

Prensky, S.

2011-01-01

A number of significant new developments is emerging in well logging and formation evaluation. Some of the new developments include an ultrasonic wireline imager, an electromagnetic free-point indicator, wired and fiber-optic coiled tubing systems, and extreme-temperature logging-while-drilling (LWD) tools. The continued consolidation of logging and petrophysical service providers in 2010 means that these innovations are increasingly being provided by a few large companies. Weatherford International has launched a slimhole cross-dipole tool as part of the company's line of compact logging tools. The 26-ft-long Compact Cross-Dipole Sonic (CXD) tool can be run as part of a quad-combo compact logging string. Halliburton has introduced a version of its circumferential acoustic scanning tool (CAST) that runs on monoconductor cable (CAST-M) to provide high-resolution images in open hole and in cased hole for casing and cement evaluation.

In Situ Multi-Species (O2, N2, Fuel, Other) Fiber Optic Sensor for Fuel Tank Ullage

NASA Technical Reports Server (NTRS)

Nguyen, Quang-Viet

2007-01-01

A rugged and compact fiber optic sensor system for in situ real-time measurement of nitrogen (N2), oxygen (O2), hydrocarbon (HC) fuel vapors, and other gases has been developed over the past several years at Glenn Research Center. The intrinsically-safe, solid-state fiber optic sensor system provides a 1% precision measurement (by volume) of multiple gases in a 5-sec time window. The sensor has no consumable parts to wear out and requires less than 25 W of electrical power to operate. The sensor head is rugged and compact and is ideal for use in harsh environments such as inside an aircraft fuel tank, or as a feedback sensor in the vent-box of an on-board inert gas generation system (OBIGGS). Multiple sensor heads can be monitored with a single optical detection unit for a cost-effective multi-point sensor system. The present sensor technology is unique in its ability to measure N2 concentration directly, and in its ability to differentiate different types of HC fuels. The present sensor system provides value-added aircraft safety information by simultaneously and directly measuring the nitrogen-oxygen-fuel triplet, which provides the following advantages: (1) information regarding the extent of inerting by N2, (2) information regarding the chemical equivalence ratio, (3) information regarding the composition of the aircraft fuel, and (4) by providing a self-consistent calibration by utilizing a singular sensor for all species. Using the extra information made available by this sensor permits the ignitability of a fuel-oxidizer mixture to be more accurately characterized, which may permit a reduction in the amount of inerting required on a real-time basis, and yet still maintain a fire-safe fuel tank. This translates to an increase in fuel tank fire-safety through a better understanding of the physics of fuel ignition, and at the same time, a reduction in compressed bleed air usage and concomitant aircraft operational costs over the long-run. The present fiber optic sensor can also be used as a false-alarm-free engine/hidden/cargo space fire detector (by measuring increased CO2 and CO, and decreased O2), a multi-point in situ measurement and certification system for halogenated-compound fire protection systems, and for the testing and certification of other aircraft safety sensor systems. The technology (LEW-17826-1) developed in the present sensor system is patent pending.

Design of an optical system for interrogation of implanted luminescent sensors and verification with silicone skin phantoms.

PubMed

Long, Ruiqi; McShane, Mike

2012-09-01

Implantable luminescent sensors are being developed for on-demand monitoring of blood glucose levels. For these sensors to be deployed in vivo, a matched external hardware system is needed. In this paper, we designed a compact, low-cost optical system with highly efficient photon delivery and collection using advanced optical modeling software. Compared to interrogation with a fiber bundle, the new system was predicted to improve interrogation efficiency by a factor of 200 for native sensors; an improvement of 37 times was predicted for sensors implanted at a depth of 1 mm in a skin-simulating phantom. A physical prototype was tested using silicone-based skin phantoms developed specifically to mimic the scattering and absorbing properties of human skin. The experimental evaluations revealed that the prototype device performed in agreement with expectations from simulation results, resulting in an overall improvement of over 2000 times. This efficient system enables use of a low-cost commercial spectrometer for recording sensor emission, which was not possible using only fiber optic delivery and collection, and will be used as a tool for in vivo studies with animal models or human subjects.

Characterization of novel microsphere chain fiber optic tips for potential use in ophthalmic laser surgery

PubMed Central

Hutchens, Thomas C.; Darafsheh, Arash; Fardad, Amir; Antoszyk, Andrew N.; Ying, Howard S.; Astratov, Vasily N.

2012-01-01

Abstract. Ophthalmic surgery may benefit from use of more precise fiber delivery systems during laser surgery. Some current ophthalmic surgical techniques rely on tedious mechanical dissection of tissue layers. In this study, chains of sapphire microspheres integrated into a hollow waveguide distal tip are used for erbium:YAG laser ablation studies in contact mode with ophthalmic tissues, ex vivo. The laser’s short optical penetration depth combined with the small spot diameters achieved with this fiber probe may provide more precise tissue removal. One-, three-, and five-microsphere chain structures were characterized, resulting in FWHM diameters of 67, 32, and 30 μm in air, respectively, with beam profiles comparable to simulations. Single Er:YAG pulses of 0.1 mJ and 75-μs duration produced ablation craters with average diameters of 44, 30, and 17 μm and depths of 26, 10, and 8 μm, for one-, three-, and five-sphere structures, respectively. Microsphere chains produced spatial filtering of the multimode Er:YAG laser beam and fiber, providing spot diameters not otherwise available with conventional fiber systems. Because of the extremely shallow treatment depth, compact focused beam, and contact mode operation, this probe may have potential for use in dissecting epiretinal membranes and other ophthalmic tissues without damaging adjacent retinal tissue. PMID:22734790

Miniaturized Lab System for Future Cold Atom Experiments in Microgravity

NASA Astrophysics Data System (ADS)

Kulas, Sascha; Vogt, Christian; Resch, Andreas; Hartwig, Jonas; Ganske, Sven; Matthias, Jonas; Schlippert, Dennis; Wendrich, Thijs; Ertmer, Wolfgang; Maria Rasel, Ernst; Damjanic, Marcin; Weßels, Peter; Kohfeldt, Anja; Luvsandamdin, Erdenetsetseg; Schiemangk, Max; Grzeschik, Christoph; Krutzik, Markus; Wicht, Andreas; Peters, Achim; Herrmann, Sven; Lämmerzahl, Claus

2017-02-01

We present the technical realization of a compact system for performing experiments with cold 87Rb and 39K atoms in microgravity in the future. The whole system fits into a capsule to be used in the drop tower Bremen. One of the advantages of a microgravity environment is long time evolution of atomic clouds which yields higher sensitivities in atom interferometer measurements. We give a full description of the system containing an experimental chamber with ultra-high vacuum conditions, miniaturized laser systems, a high-power thulium-doped fiber laser, the electronics and the power management. In a two-stage magneto-optical trap atoms should be cooled to the low μK regime. The thulium-doped fiber laser will create an optical dipole trap which will allow further cooling to sub- μK temperatures. The presented system fulfills the demanding requirements on size and power management for cold atom experiments on a microgravity platform, especially with respect to the use of an optical dipole trap. A first test in microgravity, including the creation of a cold Rb ensemble, shows the functionality of the system.

Ion flow measurements during the rotating kink behavior of the central column in the HIST device

NASA Astrophysics Data System (ADS)

Yamada, S.; Yoshikawa, T.; Hashimoto, S.; Nishioka, T.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2007-11-01

Plasma flow is essentially driven in self-organization and magnetic reconnection process of compact spherical torus (ST) and spheromak in the helicity-driven systems. For example, when reversing the external toroidal field of ST, the direction not only of the plasma current but also of the toroidal ion flow is self-reversed during the formation of the flipped ST relaxed states. Mach probe measurement shows that the velocity of the ion flow reversed after the flip increases to about 20 km/s. We have been newly developing an ion Doppler spectrometer (IDS) system using a compact 16 or 64 channel photomultiplier tube (PMT) in order to measure the spatial profile of ion temperature and rotation velocity in the HIST device. The IDS system consists of a light collection system including optical fibers, 1 m-spectrometer and the PMT detector. The optical fibers covered with glass tubes are inserted into the plasma. The glass tubes can be rotated in the poloidal and the toroidal directions. The new IDS system will be applied to observations of ion temperature and plasma rotation in the flipped ST formation and in the MHD control of kinking behaviors of the central column by using the rotating magnetic field (RMF). Preliminary IDS results will be compared to those from Mach probe measurements in space.

Tunable continuous-wave terahertz generation/detection with compact 1.55 μm detuned dual-mode laser diode and InGaAs based photomixer.

PubMed

Kim, Namje; Han, Sang-Pil; Ko, Hyunsung; Leem, Young Ahn; Ryu, Han-Cheol; Lee, Chul Wook; Lee, Donghun; Jeon, Min Yong; Noh, Sam Kyu; Park, Kyung Hyun

2011-08-01

We demonstrate a tunable continuous-wave (CW) terahertz (THz) homodyne system with a novel detuned dual-mode laser diode (DML) and low-temperature-grown (LTG) InGaAs photomixers. The optical beat source with the detuned DML showed a beat frequency tuning range of 0.26 to over 1.07 THz. Log-spiral antenna integrated LTG InGaAs photomixers are used as THz wave generators and detectors. The CW THz radiation frequency was continuously tuned to over 1 THz. Our results clearly show the feasibility of a compact and fast scanning CW THz spectrometer consisting of a fiber-coupled detuned DML and photomixers operating in the 1.55-μm range.

Precast self-compacting concrete (PSCC) panel with added coir fiber: An overview

NASA Astrophysics Data System (ADS)

Afif Iman, Muhamad; Mohamad, Noridah; Samad, Abdul Aziz Abdul; Goh, W. I.; Othuman Mydin, M. A.; Afiq Tambichik, Muhamad; Bosro, Mohamad Zulhairi Mohd; Wirdawati, A.; Jamaluddin, N.

2018-04-01

Self-compacting concrete (SCC) is the alternative way to reduce construction time and improve the quality and strength of concrete. The panel system fabricated from SCC contribute to the IBS system that is sustainable and environmental friendly. The precast self-compacting concrete (PSCC) panel with added coir fiber will be overview in this paper. The properties of SCC and coir fiber are studied and reviewed from the previous researches. Finite element analysis is used to support the experimental results by conduction parametric simulation study on PSCC under flexure load. In general, it was found that coir fiber has a significant influence on the flexural load and crack propagation. Higher fiber incorporated in SCC resulted with higher ultimate load of PSCC.

Multiwavelength optical source at 12.5-GHz optical spacing based on a coupled optoelectronic oscillator with a whispering gallery mode resonator

NASA Astrophysics Data System (ADS)

Kossakovski, Dmitri; Solomatine, Iouri V.; Morozov, Nikolai; Ilchenko, Vladimir S.

2004-06-01

The evolution of optical networks calls for denser channel grids and increased number of channels. Additionally, there is a system architecture benefit to eliminate the banks of DFB lasers that act as light sources for individual channels, and use instead a single multi-wavelength source. We have demonstrated a compact multi-wavelength optical source (MWS) for 12.5 GHz DWDM. At least 16 channels are observed within 3 dB optical power bandwidth with optical spectrum contrast ratio exceeding 28 dB. The source is based on a coupled opto-electronic oscillator (COEO) with an optical whispering gallery mode (WGM) microresonator. Free spectral range of the resonator determines the spacing of the optical channels in the MWS. The spacing can be scaled up or down depending on design requirements. The resonator is robustly packaged and fiber pigtailed. In the RF domain the MWS acts as oscillator with operational frequency of 12.5 GHz.

Composite Cure Process Modeling and Simulations using COMPRO(Registered Trademark) and Validation of Residual Strains using Fiber Optics Sensors

NASA Technical Reports Server (NTRS)

Sreekantamurthy, Thammaiah; Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.

2016-01-01

Composite cure process induced residual strains and warping deformations in composite components present significant challenges in the manufacturing of advanced composite structure. As a part of the Manufacturing Process and Simulation initiative of the NASA Advanced Composite Project (ACP), research is being conducted on the composite cure process by developing an understanding of the fundamental mechanisms by which the process induced factors influence the residual responses. In this regard, analytical studies have been conducted on the cure process modeling of composite structural parts with varied physical, thermal, and resin flow process characteristics. The cure process simulation results were analyzed to interpret the cure response predictions based on the underlying physics incorporated into the modeling tool. In the cure-kinetic analysis, the model predictions on the degree of cure, resin viscosity and modulus were interpreted with reference to the temperature distribution in the composite panel part and tool setup during autoclave or hot-press curing cycles. In the fiber-bed compaction simulation, the pore pressure and resin flow velocity in the porous media models, and the compaction strain responses under applied pressure were studied to interpret the fiber volume fraction distribution predictions. In the structural simulation, the effect of temperature on the resin and ply modulus, and thermal coefficient changes during curing on predicted mechanical strains and chemical cure shrinkage strains were studied to understand the residual strains and stress response predictions. In addition to computational analysis, experimental studies were conducted to measure strains during the curing of laminated panels by means of optical fiber Bragg grating sensors (FBGs) embedded in the resin impregnated panels. The residual strain measurements from laboratory tests were then compared with the analytical model predictions. The paper describes the cure process procedures and residual strain predications, and discusses pertinent experimental results from the validation studies.

Components for IFOG based inertial measurement units using active and passive polymer materials

NASA Astrophysics Data System (ADS)

Ashley, Paul R.; Temmen, Mark G.; Diffey, William M.; Sanghadasa, Mohan; Bramson, Michael D.; Lindsay, Geoffrey A.; Guenthner, Andrew J.

2006-08-01

Highly accurate, compact, and low cost inertial measurement units (IMUs) are needed for precision guidance in navigation systems. Active and passive polymer materials have been successfully used in fabricating two of the key guided-wave components, the phase modulator and the optical transceiver, for IMUs based on the interferometric fiber optic gyroscope (IFOG) technology. Advanced hybrid waveguide fabrication processes and novel optical integration techniques have been introduced. Backscatter compensated low loss phase modulators with low half-wave drive voltage (V π) have been fabricated with CLD- and FTC- type high performance electro-optic chromophores. A silicon-bench architecture has been used in fabricating high gain low noise transceivers with high optical power while maintaining the spectral quality and long lifetime. Gyro bias stability of less than 0.02 deg/hr has been demonstrated with these components. A review of the novel concepts introduced, fabrication and integration techniques developed and performance achieved are presented.

Multisensor Instrument for Real-Time Biological Monitoring

NASA Technical Reports Server (NTRS)

Zhang, Sean (Zhanxiang); Xu, Guoda; Qiu, Wei; Lin, Freddie

2004-01-01

The figure schematically depicts an instrumentation system, called a fiber optic-based integration system (FOBIS), that is undergoing development to enable real-time monitoring of fluid cell cultures, bioprocess flows, and the like. The FOBIS design combines a micro flow cytometer (MFC), a microphotometer (MP), and a fluorescence-spectrum- or binding-force-measuring micro-sensor (MS) in a single instrument that is capable of measuring multiple biological parameters simultaneously or sequentially. The fiber-optic-based integration system is so named because the MFC, the MP, and the MS are integrated into a single optical system that is coupled to light sources and photometric equipment via optical fibers. The optical coupling components also include a wavelength-division multiplexer and diffractive optical elements. The FOBIS includes a laserdiode- and fiber-optic-based optical trapping subsystem (optical tweezers ) with microphotometric and micro-sensing capabilities for noninvasive confinement and optical measurement of relevant parameters of a single cell or other particle. Some of the measurement techniques implemented together by the FOBIS have long been used separately to obtain basic understanding of the optical properties of individual cells and other organisms, the optical properties of populations of organisms, and the interrelationships among these properties, physiology of the organisms, and physical processes that govern the media that surround the organisms. For example, flow cytometry yields information on numerical concentrations, cross-sectional areas, and types of cells or other particles. Micro-sensing can be used to measure pH and concentrations of oxygen, carbon dioxide, glucose, metabolites, calcium, and antigens in a cell-culture fluid, thereby providing feedback that can be helpful in improving control over a bioprocess. Microphotometry (including measurements of scattering and fluorescence) can yield further information about optically trapped individual particles. In addition to the multifunctionality not previously available in a single biological monitoring system, the FOBIS offers advantages of low mass, sensitivity, accuracy, portability, low cost, compactness (the overall dimensions of the fully developed FOBIS sensor head are expected to be less than 1 by 1 by 2 cm), and immunity to electromagnetic interference at suboptical frequencies. FOBIS could be useful in a variety of laboratory and field settings in such diverse endeavors as medical, veterinary, and general biological research; medical and veterinary diagnosis monitoring of industrial bioprocesses; and analysis of biological contaminants in air, water, and food.

A novel optical scanner for laser radar

NASA Astrophysics Data System (ADS)

Yao, Shunyu; Peng, Renjun; Gao, Jianshuang

2013-09-01

Laser radar are ideally suitable for recognizing objects, detection, target tracking or obstacle avoidance, because of the high angular and range resolution. In recent years, scannerless ladar has developed rapidly. In contrast with traditional scanner ladar, scannerless ladar has distinct characteristics such as small, compact, high frame rate, wide field of view and high reliability. However, the scannerless ladar is still in the stage of laboratory and the performance cannot meet the demands of practical applications. Hence, traditional scanner laser radar is still mainly applied. In scanner ladar system, optical scanner is the key component which can deflect the direction of laser beam to the target. We investigated a novel scanner based on the characteristic of fiber's light-conductive. The fiber bundles are arranged in a special structure which connected to a motor. When motor working properly, the laser passes through the fibers on incident plane and the location of laser spot on output plane will move along with a straight line in a constant speed. The direction of light will be deflected by taking advantage of transmitting optics, then the linear sweeping of the target can be achieved. A laser radar scheme with high speed and large field of view can be realized. Some researches on scanner are simply introduced on section1. The structure of the optical scanner will be described and the practical applications of the scanner in transmitting and receiving optical paths are discussed in section2. Some characteristic of scanner is calculated in section3. In section4, we report the simulation and experiment of our prototype.

Optical frequency modulation continuous wave coherent laser radar for spacecraft safe landing vector velocity measurement

NASA Astrophysics Data System (ADS)

Sui, Xiao-lin; Zhou, Shou-huan

2013-05-01

The design and performance of Optical frequency modulation continuous wave (OFMCW) coherent laser radar is presented. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed.We also give a hardware structure of the OFMCW coherent laser radar. We made a detailed analysis of the measurement error. Its accuracy in the speed range is less than 0.5%.Measurement results for the movement of the carrier has also made a detailed assessment. The results show that its acceleration vector has better adaptability. The circuit structure is also given a detailed design. At the end of the article, we give the actual authentication method and experimental results.

Cardiovascular Optical Coherence Tomography

NASA Astrophysics Data System (ADS)

Yonetsu, Taishi; Villiger, Martin; Bouma, Brett E.; Jang, Ik-Kyung

The potential of optical coherence tomography (OCT) for intravascular imaging and assessing the microstructure of atherosclerosis was suggested already by Huang et al. at the very beginning of OCT [1]. For ophthalmology, the eye provides a natural window for OCT to image the retinal microstructure, and OCT has rapidly become the standard imaging modality to diagnose retinal disease and assess disease progression and response to therapy [1, 2]. Intravascular imaging is more invasive by nature and requires imaging through a catheter probe. This has triggered the development of advanced fiber-optic OCT systems with compact, rotating fiber probes, to image the vessel by circumferentially scanning the luminal wall [3, 4]. In 1998, we established the first cardiac OCT research group at the Massachusetts General Hospital to explore the clinical applications of OCT. The first imaging of rabbit aorta was reported by Fujimoto et al. [5], followed by the first swine measurements in vivo by Tearney et al. [6], and finally the first assessment of coronary arteries in patients by Jang et al. [7]. The scope of this chapter is to highlight the steps taken to bring intravascular OCT from bench to bedside over the last 15 years. We will give a general description of atherosclerosis and its pathophysiology and the specific technical implementation of OCT for intravascular imaging through a fiber-optic probe. The motivation is to provide sufficient medical details to provide a basic introduction to the terminology, principles, and challenges of intracoronary imaging.

Low noise erbium fiber fs frequency comb based on a tapered-fiber carbon nanotube design.

PubMed

Wu, Tsung-Han; Kieu, K; Peyghambarian, N; Jones, R J

2011-03-14

We report on a low noise all-fiber erbium fs frequency comb based on a simple and robust tapered-fiber carbon nanotube (tf-CNT) design. We mitigate dominant noise sources to show that the free-running linewidth of the carrier-envelope offset frequency (fceo) can be comparable to the best reported performance to date for fiber-based frequency combs. A free-running fceo linewidth of ~20 kHz is demonstrated, corresponding to an improvement of ~30 times over previous work based on a CNT mode-locked fiber laser [Opt. Express 18, 1667 (2010)]. We also demonstrate the use of an acousto-optic modulator external to the laser cavity to stabilize fceo, enabling a 300 kHz feedback control bandwidth. The offset frequency is phase-locked with an in-loop integrated phase noise of ~0.8 rad from 10Hz to 400kHz. We show a resolution-limited linewidth of ~1 Hz, demonstrating over 90% of the carrier power within the coherent fceo signal. The results demonstrate that the relatively simple tf-CNT fiber laser design can provide a compact, robust and high-performance fs frequency comb.

Towards the mid-infrared optical biopsy

NASA Astrophysics Data System (ADS)

Seddon, Angela B.; Benson, Trevor M.; Sujecki, Slawomir; Abdel-Moneim, Nabil; Tang, Zhuoqi; Furniss, David; Sojka, Lukasz; Stone, Nick; Jayakrupakar, Nallala; Lloyd, Gavin R.; Lindsay, Ian; Ward, Jon; Farries, Mark; Moselund, Peter M.; Napier, Bruce; Lamrini, Samir; Møller, Uffe; Kubat, Irnis; Petersen, Christian R.; Bang, Ole

2016-03-01

We are establishing a new paradigm in mid-infrared molecular sensing, mapping and imaging to open up the midinfrared spectral region for in vivo (i.e. in person) medical diagnostics and surgery. Thus, we are working towards the mid-infrared optical biopsy (`opsy' look at, bio the biology) in situ in the body for real-time diagnosis. This new paradigm will be enabled through focused development of devices and systems which are robust, functionally designed, safe, compact and cost effective and are based on active and passive mid-infrared optical fibers. In particular, this will enable early diagnosis of external cancers, mid-infrared detection of cancer-margins during external surgery for precise removal of diseased tissue, in one go during the surgery, and mid-infrared endoscopy for early diagnosis of internal cancers and their precision removal. The mid-infrared spectral region has previously lacked portable, bright sources. We set a record in demonstrating extreme broad-band supercontinuum generated light 1.4 to 13.3 microns in a specially engineered, high numerical aperture mid-infrared optical fiber. The active mid-infrared fiber broadband supercontinuum for the first time offers the possibility of a bright mid-infrared wideband source in a portable package as a first step for medical fiber-based systems operating in the mid-infrared. Moreover, mid-infrared molecular mapping and imaging is potentially a disruptive technology to give improved monitoring of the environment, energy efficiency, security, agriculture and in manufacturing and chemical processing. This work is in part supported by the European Commission: Framework Seven (FP7) Large-Scale Integrated Project MINERVA: MId-to-NEaR- infrared spectroscopy for improVed medical diAgnostics (317803; www.minerva-project.eu).

A label-free fiber-optic Turbidity Affinity Sensor (TAS) for continuous glucose monitoring.

PubMed

Dutt-Ballerstadt, Ralph; Evans, Colton; Pillai, Arun P; Gowda, Ashok

2014-11-15

In this paper, we describe the concept of a novel implantable fiber-optic Turbidity Affinity Sensor (TAS) and report on the findings of its in-vitro performance for continuous glucose monitoring. The sensing mechanism of the TAS is based on glucose-specific changes in light scattering (turbidity) of a hydrogel suspension consisting of small particles made of crosslinked dextran (Sephadex G100), and a glucose- and mannose-specific binding protein - Concanavalin A (ConA). The binding of ConA to Sephadex particles results in a significant turbidity increase that is much greater than the turbidity contribution by the individual components. The turbidity of the TAS was measured by determining the intensity of light passing through the suspension enclosed within a small semi-permeable hollow fiber (OD: 220 μm, membrane thickness: 20 μm, molecular weight cut-off: 10 kDa) using fiber optics. The intensity of measured light of the TAS was proportional to the glucose concentration over the concentration range from 50mg/dL to 400mg/dL in PBS and whole blood at 37°C (R>0.96). The response time was approximately 4 min. The stability of the glucose response of the TAS decreased only slightly (by 20%) over an 8-day study period at 37°C. In conclusion, this study demonstrated proof-of-concept of the TAS for interstitial glucose monitoring. Due to the large signal amplitude of the turbidity change, and the lack of need for wavelength-specific emission and excitation filters, a very small, robust and compact TAS device with an extremely short optical pathlength could be feasibly designed and implemented for in-vivo glucose monitoring in people with diabetes. Copyright © 2014 Elsevier B.V. All rights reserved.

High-sensitivity and low-temperature magnetic field sensor based on tapered two-mode fiber interference.

PubMed

Sun, Bing; Fang, Fang; Zhang, Zuxing; Xu, Jing; Zhang, Lin

2018-03-15

A high-sensitivity and low-temperature fiber-optic magnetic field sensor based on a tapered two-mode fiber (TTMF) sandwiched between two single-mode fibers has been proposed and demonstrated. The section of TTMF has a specifically designed transition region as an efficient tool to filter higher-order modes, where the uniform modal interferometer just involved with LP 01 and LP 11 modes is achieved. The transmission spectral characteristics and the magnetic response of the proposed sensors have been investigated. The experimental results show that a maximum sensitivity of 98.2  pm/Oe within a linear magnetic field intensity ranging from 0 to 140 Oe can be achieved. Significantly, the temperature cross-sensitivity problem can be resolved owing to the lower thermal expansion coefficient of the TTMF. Finally, with its low insertion loss, compactness, and ease of fabrication, the proposed sensor would find potential applications in the measurement of a magnetic field.

Compact fiber CPA system based on a CFBG stretcher and CVBG compressor with matched dispersion profile.

PubMed

Bartulevicius, Tadas; Frankinas, Saulius; Michailovas, Andrejus; Vasilyeu, Ruslan; Smirnov, Vadim; Trepanier, Francois; Rusteika, Nerijus

2017-08-21

In this work, a compact fiber chirped pulse amplification system exploiting a tandem of a chirped fiber Bragg grating stretcher and a chirped volume Bragg grating compressor with matched chromatic dispersion is presented. Chirped pulses of 230 ps duration were amplified in a Yb-doped fiber amplifier and re-compressed to 208 fs duration with good fidelity. The compressed pulse duration was fine-tuned by temperature gradient along the fiber Bragg grating stretcher.

Portable, Fiber-Based, Diffuse Reflection Spectroscopy (DRS) Systems for Estimating Tissue Optical Properties.

PubMed

Vishwanath, Karthik; Chang, Kevin; Klein, Daniel; Deng, Yu Feng; Chang, Vivide; Phelps, Janelle E; Ramanujam, Nimmi

2011-02-01

Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.

Microlaser-based compact optical neuro-processors (Invited Paper)

NASA Astrophysics Data System (ADS)

Paek, Eung Gi; Chan, Winston K.; Zah, Chung-En; Cheung, Kwok-wai; Curtis, L.; Chang-Hasnain, Constance J.

1992-10-01

This paper reviews the recent progress in the development of holographic neural networks using surface-emitting laser diode arrays (SELDAs). Since the previous work on ultrafast holographic memory readout system and a robust incoherent correlator, progress has been made in several areas: the use of an array of monolithic `neurons' to reconstruct holographic memories; two-dimensional (2-D) wavelength-division multiplexing (WDM) for image transmission through a single-mode fiber; and finally, an associative memory using time- division multiplexing (TDM). Experimental demonstrations on these are presented.

Issues to be addressed in the design and fabrication of ultralightweight, meter class optics

NASA Astrophysics Data System (ADS)

Krumweide, Gary C.; Dyer, J.; Kasl, E. P.; Mehle, G. V.

1998-01-01

There is a growing need for large aperture, ultralightweight, deployable optics (mirrors) for various science, military and commercial compact satellites (Pleimann 1997). This paper will examine the engineering and manufacturing considerations that must be addressed in order to satisfy the requirements for these sought after optics. In order to limit the scope of this paper, only Graphite Fiber Reinforced/Polymer Matrix Composites (GFR/PMC) will be under consideration because of the potential to satisfy ultralightweight mirror requirements (5-10 Kg/m2) (Kasl 1997). The requirements associated with specular mirror concepts that Composite Optics, Incorporated (COI) has proposed to Air Force Research Laboratory (AFRL/VS) and NASA Langley Research Center for visible range optics and LIDAR (light bucket) optics, respectively, will also be our interest. Moreover, it is the intent of this paper to illustrate how COI's proposed design/manufacturing concepts for visible and LIDAR optics have evolved based on overcoming, or working around, material constraints and/or undesirable characteristics associated with GFR/PMC.

Etching twin core fiber for the temperature-independent refractive index sensing

NASA Astrophysics Data System (ADS)

Zhang, Chuanbiao; Ning, Tigang; Li, Jing; Zheng, Jingjing; Gao, Xuekai; Lin, Heng; Pei, Li

2018-04-01

We proposed an ultra-compact chemically etched twin core fiber (TCF) based optic refractive index (RI) sensor, in which the etched fiber was fabricated by immersing in an aqueous solution of hydrofluoric acid (HF) to etch the cladding. Due to the multipath evolutions of light during the TCF, the mode induced interference pattern can be used for measurement. Numerical simulations were performed, demonstrating that only the cladding mode strongly interacts with the surrounding media, and the higher cladding modes will be more sensitive to external medium. In the experiment demonstration, the RI response characteristics of the sensor were investigated, which shows a relatively high RI sensitivity and a much low temperature cross-sensitivity with about 1.06 × 10-6 RIU °C-1. Due to low cost and easy fabrication, the sensor can be a suitable candidate in the biochemical field.

The BigBOSS spectrograph

NASA Astrophysics Data System (ADS)

Jelinsky, Patrick; Bebek, Chris; Besuner, Robert; Carton, Pierre-Henri; Edelstein, Jerry; Lampton, Michael; Levi, Michael E.; Poppett, Claire; Prieto, Eric; Schlegel, David; Sholl, Michael

2012-09-01

BigBOSS is a proposed ground-based dark energy experiment to study baryon acoustic oscillations (BAO) and the growth of structure with a 14,000 square degree galaxy and quasi-stellar object redshift survey. It consists of a 5,000- fiber-positioner focal plane feeding the spectrographs. The optical fibers are separated into ten 500 fiber slit heads at the entrance of ten identical spectrographs in a thermally insulated room. Each of the ten spectrographs has a spectral resolution (λ/Δλ) between 1500 and 4000 over a wavelength range from 360 - 980 nm. Each spectrograph uses two dichroic beam splitters to separate the spectrograph into three arms. It uses volume phase holographic (VPH) gratings for high efficiency and compactness. Each arm uses a 4096x4096 15 μm pixel charge coupled device (CCD) for the detector. We describe the requirements and current design of the BigBOSS spectrograph. Design trades (e.g. refractive versus reflective) and manufacturability are also discussed.

A magnetostrictive composite-fiber Bragg Grating sensor.

PubMed

Quintero, Sully M M; Braga, Arthur M B; Weber, Hans I; Bruno, Antonio C; Araújo, Jefferson F D F

2010-01-01

This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 μm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor.

A Magnetostrictive Composite-Fiber Bragg Grating Sensor

PubMed Central

Quintero, Sully M. M.; Braga, Arthur M. B.; Weber, Hans I.; Bruno, Antonio C.; Araújo, Jefferson F. D. F.

2010-01-01

This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 μm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor. PMID:22163644

Advanced instrumentation for aircraft icing research

NASA Technical Reports Server (NTRS)

Bachalo, W.; Smith, J.; Rudoff, R.

1990-01-01

A compact and rugged probe based on the phase Doppler method was evaluated as a means for characterizing icing clouds using airborne platforms and for advancing aircraft icing research in large scale wind tunnels. The Phase Doppler Particle Analyzer (PDPA) upon which the new probe was based is now widely recognized as an accurate method for the complete characterization of sprays. The prototype fiber optic-based probe was evaluated in simulated aircraft icing clouds and found to have the qualities essential to providing information that will advance aircraft icing research. Measurement comparisons of the size and velocity distributions made with the standard PDPA and the fiber optic probe were in excellent agreement as were the measurements of number density and liquid water content. Preliminary testing in the NASA Lewis Icing Research Tunnel (IRT) produced reasonable results but revealed some problems with vibration and signal quality at high speeds. The cause of these problems were identified and design changes were proposed to eliminate the shortcomings of the probe.

Localized Surface Plasmon Resonance with Five-Branched Gold Nanostars in a Plastic Optical Fiber for Bio-Chemical Sensor Implementation

PubMed Central

Cennamo, Nunzio; D'Agostino, Girolamo; Donà, Alice; Dacarro, Giacomo; Pallavicini, Piersandro; Pesavento, Maria; Zeni, Luigi

2013-01-01

In this paper a refractive index sensor based on localized surface plasmon resonance (LSPR) in a Plastic Optical Fiber (POF), is presented and experimentally tested. LSPR is achieved exploiting five-branched gold nanostars (GNS) obtained using Triton X-100 in a seed-growth synthesis. They have the uncommon feature of three localized surface plasmon resonances. The strongest LSPRs fall in two ranges, one in the 600–900 nm range (LSPR 2) and the other one in the 1,100–1,600 nm range (LSPR 3), both sensible to refractive index changes. Anyway, due to the extremely strong attenuation (>102 dB/m) of the employed POF in the 1,100–1,600 nm range, only LSPR 2 will be exploited for refractive index change measurements, useful for bio-chemical sensing applications, as a proof of principle of the possibility of realizing a compact, low cost and easy-to-use GNS based device. PMID:24172284

Localized surface plasmon resonance with five-branched gold nanostars in a plastic optical fiber for bio-chemical sensor implementation.

PubMed

Cennamo, Nunzio; D'Agostino, Girolamo; Donà, Alice; Dacarro, Giacomo; Pallavicini, Piersandro; Pesavento, Maria; Zeni, Luigi

2013-10-29

In this paper a refractive index sensor based on localized surface plasmon resonance (LSPR) in a Plastic Optical Fiber (POF), is presented and experimentally tested. LSPR is achieved exploiting five-branched gold nanostars (GNS) obtained using Triton X-100 in a seed-growth synthesis. They have the uncommon feature of three localized surface plasmon resonances. The strongest LSPRs fall in two ranges, one in the 600-900 nm range (LSPR 2) and the other one in the 1,100-1,600 nm range (LSPR 3), both sensible to refractive index changes. Anyway, due to the extremely strong attenuation (>10(2) dB/m) of the employed POF in the 1,100-1,600 nm range, only LSPR 2 will be exploited for refractive index change measurements, useful for bio-chemical sensing applications, as a proof of principle of the possibility of realizing a compact, low cost and easy-to-use GNS based device.

Effect of hot-dry environment on fiber-reinforced self-compacting concrete

NASA Astrophysics Data System (ADS)

Tioua, Tahar; Kriker, Abdelouahed; Salhi, Aimad; Barluenga, Gonzalo

2016-07-01

Drying shrinkage can be a major reason for the deterioration of concrete structures. Variation in ambient temperature and relative humidity cause changes in the properties of hardened concrete which can affect their mechanical and drying shrinkage characteristics. The present study investigated mechanical strength and particularly drying shrinkage properties of self-compacting concretes (SCC) reinforced with date palm fiber exposed to hot and dry environment. In this study a total of nine different fibers reinforced self compacting concrete (FRSCC) mixtures and one mixture without fiber were prepared. The volume fraction and the length of fibers reinforcement were 0.1-0.2-0.3% and 10-20-30 mm. It was observed that drying shrinkage lessened with adding low volumetric fraction and short length of fibers in curing condition (T = 20 °C and RH = 50 ± 5 %), but increased in hot and dry environment.

Fiber optic and laser sensors IX; Proceedings of the Meeting, Boston, MA, Sept. 3-5, 1991

NASA Technical Reports Server (NTRS)

Depaula, Ramon P. (Editor); Udd, Eric (Editor)

1991-01-01

The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.

Multiphoton microscopy system with a compact fiber-based femtosecond-pulse laser and handheld probe

PubMed Central

Liu, Gangjun; Kieu, Khanh; Wise, Frank W.; Chen, Zhongping

2012-01-01

We report on the development of a compact multiphoton microscopy (MPM) system that integrates a compact and robust fiber laser with a miniature probe. The all normal dispersion fiber femtosecond laser has a central wavelength of 1.06 μm, pulse width of 125 fs and average power of more than 1 W. A double cladding photonic crystal fiber was used to deliver the excitation beam and to collect the two-photon signal. The hand-held probe included galvanometer-based mirror scanners, relay lenses and a focusing lens. The packaged probe had a diameter of 16 mm. Second harmonic generation (SHG) images and two-photon excited fluorescence (TPEF) images of biological tissues were demonstrated using the system. MPM images of different biological tissues acquired by the compact system which integrates an FBFP laser, an DCPCF and a miniature handheld probe. PMID:20635426

Recent development on high-power tandem-pumped fiber laser

NASA Astrophysics Data System (ADS)

Zhou, Pu; Xiao, Hu; Leng, Jinyong; Zhang, Hanwei; Xu, Jiangmin; Wu, Jian

2016-11-01

High power fiber laser is attracting more and more attention due to its advantage in excellent beam quality, high electricto- optical conversion efficiency and compact system configuration. Power scaling of fiber laser is challenged by the brightness of pump source, nonlinear effect, modal instability and so on. Pumping active fiber by using high-brightness fiber laser instead of common laser diode may be the solution for the brightness limitation. In this paper, we will present the recent development of various kinds of high power fiber laser based on tandem pumping scheme. According to the absorption property of Ytterbium-doped fiber, Thulium-doped fiber and Holmium-doped fiber, we have theoretically studied the fiber lasers that operate at 1018 nm, 1178 nm and 1150 nm, respectively in detail. Consequently, according to the numerical results we have optimized the fiber laser system design, and we have achieved (1) 500 watt level 1018nm Ytterbium-doped fiber laser (2) 100 watt level 1150 nm fiber laser and 100 watt level random fiber laser (3) 30 watt 1178 nm Ytterbium-doped fiber laser, 200 watt-level random fiber laser. All of the above-mentioned are the record power for the corresponded type of fiber laser to the best of our knowledge. By using the high-brightness fiber laser operate at 1018 nm, 1178 nm and 1150 nm that we have developed, we have achieved the following high power fiber laser (1) 3.5 kW 1090 nm Ytterbium-doped fiber amplifier (2) 100 watt level Thulium-doped fiber laser and (3) 50 watt level Holmium -doped fiber laser.

Optical NIR monitoring of skeletal muscle contraction

NASA Astrophysics Data System (ADS)

Lago, Paolo; Gelmetti, Andrea; Pavesi, Roberta; Zambarbieri, Daniela

1996-12-01

NIR spectroscopy allows monitoring of muscle oxygenation and perfusion during contraction. The knowledge of modifications of blood characteristics in body tissues has relevant clinical interest. A compact and reliable device, which makes use of two laser diodes at 750 and 810 nm coupled with the skin surface through optical fibers, was tested. NIR and surface EMG signals during isometric contractions both in normal and ischaemic conditions were analyzed. A set of parameters from the 750/810 spectroscopic curve was analyzed. Two different categories depending on the recovery rate from maximal voluntary contraction to basal oxygenation conditions were found. This behavior can give information about metabolic modifications during muscle fatigue. Interesting results in testing isokinetic rehabilitation training were also obtained.

Portable and cost-effective pixel super-resolution on-chip microscope for telemedicine applications.

PubMed

Bishara, Waheb; Sikora, Uzair; Mudanyali, Onur; Su, Ting-Wei; Yaglidere, Oguzhan; Luckhart, Shirley; Ozcan, Aydogan

2011-01-01

We report a field-portable lensless on-chip microscope with a lateral resolution of <1 μm and a large field-of-view of ~24 mm(2). This microscope is based on digital in-line holography and a pixel super-resolution algorithm to process multiple lensfree holograms and obtain a single high-resolution hologram. In its compact and cost-effective design, we utilize 23 light emitting diodes butt-coupled to 23 multi-mode optical fibers, and a simple optical filter, with no moving parts. Weighing only ~95 grams, we demonstrate the performance of this field-portable microscope by imaging various objects including human malaria parasites in thin blood smears.

Broadband SLED-based light source (BeST-SLEDTM) and spectrometer

NASA Astrophysics Data System (ADS)

Yadid-Pecht, Orly; Dattner, Yonathan

2016-03-01

A small footprint, low power, cost effective single mode fiber coupled broadband light source and spectrometer is presented. It is based on Super Luminescent Diode (SLED) devices and a compact design enables coverage of the 1250 nm-1750 nm region with a total optical power of 50 mW at the output of the fiber. This Broad Spectrum Tunable Super Luminescent (BeST-SLEDTM) light source can operate at temperatures ranging from -40°C to 60°C, and resides in a custom designed 26-pin package. The fiber is a polarization maintaining fiber with a FC/APC connector at the output. Three variations of the BeST-SLEDTM were developed, BEST-SLED™ Bands, BeST-SLEDTM Tunable and BeST-SLEDTM FTNIR. In the Bands version six SLEDs were packaged allowing for one SLED on at a time or any combination of the SLEDs on. In the Tunable version an Acoustic Optical Tunable Filter (AOTF) was integrated into the package allowing the user to select one wavelength at a time to pass into the fiber with resolution of ~1 nm @1550nm. In the FTNIR version, a Silicon Photonic based interferometer (the Nano-SpecTM) was integrated into the package for a Fourier Transform Near Infrared based Spectrometer and light source. The BeST-SLEDTM is being used in process control applications such as steam quality measurements, oil in water, gas composition and air quality monitoring.

Multi-mJ energy extraction using Yb-fiber based coherent pulse stacking amplification of fs pulses (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ruppe, John M.; Pei, Hanzhang; Chen, Siyun; Sheikhsofla, Morteza; Wilcox, Russell B.; Nees, John A.; Galvanauskas, Almantas

2017-03-01

We report multi-mJ energy (>5mJ) extraction from femtosecond-pulse Yb-doped fiber CPA using coherent pulse stacking amplification (CPSA) technique. This high energy extraction has been enabled by amplifying 10's of nanosecond long pulse sequence, and by using 85-µm core Yb-doped CCC fiber based power amplification stage. The CPSA system consists of 1-GHz repetition rate mode-locked fiber oscillator, followed by a pair of fast phase and amplitude electro-optic modulators, a diffraction-grating based pulse stretcher, a fiber amplifier chain, a GTI-cavity based pulse stacker, and a diffraction grating pulse compressor. Electro-optic modulators are used to carve out from the 1-GHz mode-locked pulse train an amplitude and phase modulated pulse burst, which after stretching and amplification, becomes equal-amplitude pulse burst consisting of 27 stretched pulses, each approximately 1-ns long. Initial pulse-burst shaping accounts for the strong amplifier saturation effects, so that it is compensated at the power amplifier output. This 27-pulse burst is then coherently stacked into a single pulse using a multiplexed sequence of 5 GTI cavities. The compact-footprint 4+1 multiplexed pulse stacker consists of 4 cavities having rountrip of 1 ns, and one Herriott-cell folded cavity - with 9ns roundtrip. After stacking, stretched pulses are compressed down to the bandwidth-limited 300 fs duration using a standard diffraction-grating pulse compressor.

Pulse position modulation for compact all-fiber vehicle laser rangefinder development

NASA Astrophysics Data System (ADS)

Mao, Xuesong; Cheng, Yongzhi; Xiong, Ying; Inoue, Daisuke; Kagami, Manabu

2017-10-01

We propose a method for developing small all-fiber vehicle laser rangefinders that is based on pulse position modulation (PPM) and data integration and present a theoretical study on its performance. Compared with spatial coupling, which is employed by most of the current commercial vehicle laser rangefinders, fiber coupling has the advantage that it can guide laser echoes into the interior of a car, so the electronic components following the photodiode can operate in a moderate-temperature environment. However, optical fibers have numerical apertures (NAs), which means that a laser beam from a receiving lens cannot be coupled into an optical fiber if its incident angle exceeds the critical value. Therefore, the effective size of the receiving lens is typically small since it is limited by its focal length and the NA of the fiber, causing the power of the laser echoes gathered by the receiving lens to be insufficient for performing target identification. Instead of increasing the peak transmitting laser power unrestrictedly, PPM and data integration effectively compensate for the low signal-to-noise ratio that results from the effective receiving lens size reduction. We validated the proposed method by conducting numerical simulations and performance analysis. Finally, we compared the proposed method with pseudorandom noise (PN) code modulation and found that, although the two methods perform equally well in single-target measurement scenarios, PPM is more effective than PN code modulation for multitarget measurement. In addition, PPM enables the transmission of laser beams with higher peak powers and requires less computation than PN code modulation does.

Solid state lasers for use in non-contact temperature measurements

NASA Technical Reports Server (NTRS)

Buoncristiani, A. M.

1989-01-01

The last decade has seen a series of dramatic developments in solid state laser technology. Prominent among these has been the emergence of high power semiconductor laser diode arrays and a deepening understanding of the dynamics of solid state lasers. Taken in tandem these two developments enable the design of laser diode pumped solid state lasers. Pumping solid state lasers with semiconductor diodes relieves the need for cumbersome and inefficient flashlamps and results in an efficient and stable laser with the compactness and reliability. It provides a laser source that can be reliably used in space. These new coherent sources are incorporated into the non-contact measurement of temperature. The primary focus is the development and characterization of new optical materials for use in active remote sensors of the atmosphere. In the course of this effort several new materials and new concepts were studied which can be used for other sensor applications. The general approach to the problem of new non-contact temperature measurements has had two components. The first component centers on passive sensors using optical fibers; an optical fiber temperature sensor for the drop tube was designed and tested at the Marshall Space Flight Center. Work on this problem has given insight into the use of optical fibers, especially new IR fibers, in thermal metrology. The second component of the effort is to utilize the experience gained in the study of passive sensors to examine new active sensor concepts. By active sensor are defined as a sensing device or mechanism which is interrogated in some way be radiation, usually from a laser. The status of solid state lasers as sources for active non-contact temperature sensors are summarized. Some specific electro-optic techniques are described which are applicable to the sensor problems at hand. Work on some of these ideas is in progress while other concepts are still being worked out.

In-situ formation compaction monitoring in deep reservoirs by use of fiber optics

NASA Astrophysics Data System (ADS)

Murai, Daisuke; Kunisue, Shoji; Higuchi, Tomoyuki; Kokubo, Tatsuo

2013-04-01

1. Background The Southern Kanto gas field, the largest field of natural gas dissolved in water in Japan, is located primarily under the Chiba Prefecture. In this field 8 companies produce 460*10^6m3/y of natural gas. In addition, the concentration of the iodine in the brine is almost 2000 times that in seawater and the iodine as well as natural gas is collected from the brine. Iodine is industrially useful and essential for the human body. About 30% of world production is produced in this area in recent years. On the other hand, the land subsidence has become the big problem since 1965 and more than 10cm/mm of land subsidence was observed by leveling in 1972. The natural gas and iodine producers in this area have made a land subsidence prevention agreement with the local government and made effort to prevent and control land subsidence. Although their pumping brine for the gas and the iodine production is inferred to be the main cause of land subsidence from that time, the ratio of the formation compaction caused by pumping brine in the total land subsidence hasn't been well known. Therefore, the measurement of the actual formation compaction has become an important technological issue for the companies and they jointly have developed a new monitoring system for the formation compaction. 2. Contents (1) By using fiber optics technology, we have developed a world's first monitoring system which measures each of the in-situ formation compactions continuously without running tools into the well. (2) In order to check a reliability of this system and the problems when construction, we carried out the preliminary test. We installed the prototype system in the shallow observation well with a depth of 80 m and measured the actual formation compaction. The water well was drilled at the 10m away from the observation well and the formation was artificially compacted by pumping groundwater from it. (3) We installed the monitoring system in the deep observation well with a depth of about 800m, and have been measuring the formation compaction of the natural gas reservoir now. 3. Conclusions (1) We succeeded in installing the monitoring system into the observation well and measure the each of 6 formation compactions in the gas reservoir. (2) As a result of the preliminary test we confirmed that the monitoring system run without big problems even in the field. The formation compacted/expanded with the groundwater level fallen/risen according to the pump rate. (3) We improved the monitoring system based on the knowledge acquired by the demonstration test and installed it into the deep observation well. We are carrying out the long term observation now. 4. Acknowledgements This research was carried out by the support for application of new technologies and technical studies program which Japan Oil, Gas and Metals National Corporation (JOGMEC) undertook.

Simple approach to three-color two-photon microscopy by a fiber-optic wavelength convertor.

PubMed

Li, Kuen-Che; Huang, Lynn L H; Liang, Jhih-Hao; Chan, Ming-Che

2016-11-01

A simple approach to multi-color two-photon microscopy of the red, green, and blue fluorescent indicators was reported based on an ultra-compact 1.03-μm femtosecond laser and a nonlinear fiber. Inside the nonlinear fiber, the 1.03-μm laser pulses were simultaneously blue-shifted to 0.6~0.8 μm and red-shifted to 1.2~1.4 μm region by the Cherenkov radiation and fiber Raman gain effects. The wavelength-shifted 0.6~0.8 μm and 1.2~1.4 μm radiations were co-propagated with the residual non-converted 1.03-μm pulses inside the same nonlinear fiber to form a fiber-output three-color femtosecond source. The application of the multi-wavelength sources on multi-color two-photon fluorescence microscopy were also demonstrated. Overall, due to simple system configuration, convenient wavelength conversion, easy wavelength tunability within the entire 0.7~1.35 μm bio-penetration window and less requirement for high power and bulky light sources, the simple approach to multi-color two-photon microscopy could be widely applicable as an easily implemented and excellent research tool for future biomedical and possibly even clinical applications.

Grout compactness monitoring of concrete-filled fiber-reinforced polymer tube using electromechanical impedance

NASA Astrophysics Data System (ADS)

Shi, Yaokun; Luo, Mingzhang; Li, Weijie; Song, Gangbing

2018-05-01

The concrete-filled fiber-reinforced polymer tube (CFFT) is a type of structural element widely used in corrosive environments. Poor grout compactness results in incomplete contact or even no contact between the fiber-reinforced polymer (FRP) tube and the concrete grout, which reduces the load bearing capacity of a CFFT. The monitoring of grout compactness for CFFTs is important. The piezoceramic-based electromechanical impedance (EMI) method has emerged as an efficient and low-cost structural health monitoring technique. This paper presents a feasibility study using the EMI method to monitor grout compactness of CFFTs. In this research, CFFT specimens with different levels of compactness (empty, 1/5, 1/3, 1/2, 2/3, and full compactness) were prepared and subjected to EMI measurement by using four piezoceramic patches that were bonded circumferentially along the outer surface of the CFFT. To analyze the correlation between grout compactness and EMI signatures, a compactness index (CI) was proposed based on the root-mean-square deviation (RMSD). The experimental results show that the changes in admittance signatures are able to determine the grout compactness qualitatively. The proposed CI is able to effectively identify the compactness of the CFFT, and provides location information of the incomplete concrete infill.

High-power lightweight external-cavity quantum cascade lasers

NASA Astrophysics Data System (ADS)

Day, Timothy; Takeuchi, Eric B.; Weida, Miles; Arnone, David; Pushkarsky, Michael; Boyden, David; Caffey, David

2009-05-01

Commercially available quantum cascade gain media has been integrated with advanced coating and die attach technologies, mid-IR micro-optics and telecom-style assembly and packaging to yield cutting edge performance. When combined into Daylight's external-cavity quantum cascade laser (ECqcL) platform, multi-Watt output power has been obtained. Daylight will describe their most recent results obtained from this platform, including high cw power from compact hermetically sealed packages and narrow spectral linewidth devices. Fiber-coupling and direct amplitude modulation from such multi-Watt lasers will also be described. In addition, Daylight will present the most recent results from their compact, portable, battery-operated "thermal laser pointers" that are being used for illumination and aiming applications. When combined with thermal imaging technology, such devices provide significant benefits in contrast and identification.

A compact OPO/SFG laser for ultraviolet biological sensing

NASA Astrophysics Data System (ADS)

Tiihonen, Mikael; Pasiskevicius, Valdas; Laurell, Fredrik; Jonsson, Per; Lindgren, Mikael

2004-07-01

A compact parametric oscillator (OPO) with intracavity sum-frequency generation (SFG) to generate 293 nm UV laser irradiation, was developed. The OPO/SFG device was pumped by a 100 Hz Nd:YAG laser (1064 nm) of own design, including subsequent second harmonic generation (SHG) in an external periodically poled KTiOPO4 (KTP) crystal. The whole system could be used to deliver more than 30 μJ laser irradiation per pulse (100 Hz) at 293 nm. The UV laser light was introduced in an optical fiber attached to a sample compartment allowing detection of fluorescence emission using a commercial spectrometer. Aqueous samples containing biomolecules (ovalbumin) or bacteria spores (Bacillus subtilis) were excited by the UV-light at 293 nm resulting in strong fluorescence emission in the range 325 - 600 nm.

Noncontact acousto-ultrasonics using laser generation and laser interferometric detection

NASA Technical Reports Server (NTRS)

Green, Robert E., Jr.; Huber, Robert D.

1991-01-01

A compact, portable fiber-optic heterodyne interferometer designed to detect out-of-plane motion on surfaces is described. The interferometer provides a linear output for displacements over a broad frequency range and can be used for ultrasonic, acoustic emission, and acousto-ultrasonic (AU) testing. The interferometer in conjunction with a compact pulsed Nd:YAG laser represents a noncontact testing system. This system was tested to determine its usefulness for the AU technique. The results obtained show that replacement of conventional piezoelectric transducers (PZT) with a laser generation/detection system make it possible to carry out noncontact AU measurements. The waveforms recorded were 5 MHZ PZT-generated ultrasound propagating through an aluminum block, detection of the acoustic emission event, and laser AU waveforms from graphite-epoxy laminates and a filament-wound composite.

The all-optical modulator in dielectric-loaded waveguide with graphene-silicon heterojunction structure

NASA Astrophysics Data System (ADS)

Sun, Feiying; Xia, Liangping; Nie, Changbin; Shen, Jun; Zou, Yixuan; Cheng, Guiyu; Wu, Hao; Zhang, Yong; Wei, Dongshan; Yin, Shaoyun; Du, Chunlei

2018-04-01

All-optical modulators based on graphene show great promise for on-chip optical interconnects. However, the modulation performance of all-optical modulators is usually based on the interaction between graphene and the fiber, limiting their potential in high integration. Based on this point, an all-optical modulator in a dielectric-loaded waveguide (DLW) with a graphene-silicon heterojunction structure (GSH) is proposed. The DLW raises the waveguide mode, which provides a strong light-graphene interaction. Sufficient tuning of the graphene Fermi energy beyond the Pauli blocking effect is obtained with the presented GSH structure. Under the modulation light with a wavelength of 532 nm and a power of 60 mW, a modulation efficiency of 0.0275 dB µm-1 is achieved for light with a communication wavelength of 1.55 µm in the experiment. This modulator has the advantage of having a compact footprint, which may make it a candidate for achieving a highly integrated all-optical modulator.

Degradation of optical components in space

NASA Technical Reports Server (NTRS)

Blue, M. D.

1993-01-01

This report concerns two types of optical components: multilayer filters and mirrors, and self-scanned imaging arrays using charge coupled device (CCD) readouts. For the filters and mirrors, contamination produces a strong reduction in transmittance in the ultraviolet spectral region, but has little or no effect in the visible and infrared spectral regions. Soft substrates containing halides are unsatisfactory as windows or substrates. Materials choice for dielectric layers should also reflect such considerations. Best performance is also found for the harder materials. Compaction of the layers and interlayer diffusion causes a blue shift in center wavelength and loss of throughput. For sensors using CCD's, shifts in gate voltage and reductions in transfer efficiency occur. Such effects in CCD's are in accord with expectations of the effects of the radiation dose on the device. Except for optical fiber, degradation of CCD's represents the only ionizing-radiation induced effect on the Long Duration Exposure Facility (LDEF) optical systems components that has been observed.

Intermodal Parametric Frequency Conversion in Optical Fibers

NASA Astrophysics Data System (ADS)

Demas, Jeffrey D.

Lasers are an essential technology enabling countless fields of optics, however, their operation wavelengths are limited to isolated regions across the optical spectrum due to the need for suitable gain media. Parametric frequency conversion (PFC) is an attractive means to convert existing lasers to new colors using nonlinear optical interactions rather than the material properties of the host medium, allowing for the development of high power laser sources across the entire optical spectrum. PFC in bulk chi(2) crystals has led to the development of the optical parametric oscillator, which is currently the standard source for high power light at non-traditional wavelengths in the laboratory setting. Ideally, however, one could implement PFC in an optical fiber, thus leveraging the crucial benefits of a guided-wave geometry: alignment-free, compact, and robust operation. Four-wave mixing (FWM) is a nonlinear effect in optical fibers that can be used to convert frequencies, the major challenge being conservation of momentum, or phase matching, between the interacting light waves. Phase matching can be satisfied through the interaction of different spatial modes in a multi-mode fiber, however, previous demonstrations have been limited by mode stability and narrow-band FWM gain. Alternatively, phase matching within the fundamental mode can be realized in high-confinement waveguides (such as photonic crystal fibers), but achieving the anomalous waveguide dispersion necessary for phase matching at pump wavelengths near ˜1 mum (where the highest power fiber lasers emit) comes at the cost of reducing the effective area of the mode, thus limiting power-handling. Here, we specifically consider the class of Bessel-like LP0,m modes in step-index fibers. It has been shown that these modes can be selectively excited and guided stably for long lengths of fiber, and mode stability increases with mode order 'm'. The effective area of modes in these fibers can be very large (>6000 mum2 demonstrated) and is decoupled from dispersion, allowing for phase matching within a single mode in a power-scalable platform. Furthermore, step-index fibers can guide many different LP0,m modes, allowing access to a highly multi-moded basis set with which to study FWM interactions between different modes. In this thesis we develop techniques to excite, propagate, and characterize LP0,m modes in order to demonstrate FWM in two regimes: monomode interactions comprising waves all belonging to the same mode, and intermodal interactions between different modes. In the monomode regime we demonstrate parametric sources which operate at near-infrared wavelengths under-served by conventional fiber lasers, including 880, 974, 1173, and 1347 nm. The output pulses for these systems are ˜300 ps in duration and reach peak powers of ˜10 kW, representing, to the best our knowledge, the highest peak power fiber laser sources demonstrated at these wavelengths to date. In the intermodal regime, we demonstrate a cascade of FWM processes between different modes that lead to a series of discrete peaks in the visible portion of the spectrum, increasing monotonically in mode order from LP0,7 at 678 nm to LP0,16 at 443 nm. This cascade underscores the huge number of potential FWM interactions between different LP0,m modes available in a highly multi-mode fiber, which scale as N4 for N guided modes. Finally, we demonstrate a novel intermodal FWM process pumped between the LP0,4 and LP0,5 modes of a step-index fiber, which provides broadband FWM gain (63 nm at 1550 nm) while maintaining wavelength separations of nearly an octave (762 nm) - a result that cannot be replicated in the single-mode regime. We seed this process to generate a ˜10 kW, ˜300-ps pulsed fiber laser wavelength-tunable from 786-795 nm; representing a fiber analogue of the ubiquitous Ti:Sapphire laser.

Optical Fiber Sensors for Infrasonic Wind Noise Reduction and Earth Strain Measurement

NASA Astrophysics Data System (ADS)

DeWolf, Scott

Fiber-based interferometers provide the means to sense very small displacements over long baselines, and have the advantage of being nearly completely passive in their operation, making them particularly well suited for geophysical applications. This work presents the development and results from four new systems: one in atmospheric acoustics and three in Earth strain. Turbulent pressure fluctuations (wind noise) are a significant limiting factor in low-frequency atmospheric acoustic measurements. The Optical Fiber Infrasound Sensor (OFIS) provides an alternative to traditional infrasonic wind noise reduction (WNR) techniques by providing an instantaneous average over a large spatial extent. This study shows that linear OFISs ranging in length from 30 to 270 m provide a WNR of up to 30 dB in winds up to 5 m/s, in good agreement with a new analytical model. Arrays of optical fiber strainmeters were deployed to measure sediment compaction at two sites in Bangladesh. One array at Jamalganj (in the north) consists of 20, 40, 60, and 100 m long strainmeters, while the second near Khulna (in the south) also includes lengths of 80 and 300 m. Two years of weekly measurements show a clear seasonal signal and subsidence at both sites that is in reasonable agreement with collocated GPS receivers. A new 250-meter, interferometric vertical borehole strainmeter has been developed based completely on passive optical components. Details of the prototyping, design, and deployment at the Pinon Flat Observatory (PFO) are presented. Power spectra show an intertidal noise level of -130 dB (re. 1 epsilon/Hz), consistent within 1-3 dB between redundant components. Examination of its response to Earth tides and earthquakes relative to the areal strain recorded by an orthogonal pair of collocated, 730 m horizontal laser strainmeters yield a Poisson's ratio of 0.26. Two prototype horizontal strainmeters were also developed to explore the use of similar interferometric optical fiber technology for near-surface, long baseline strain measurement. Both instruments are shown to faithfully record earthquakes and yield very good estimates of the M2 tidal constituent, despite unexplained 2-8% amplitude discrepancies between the 90 and 180 m long instruments relative to the collocated laser strainmeter and each other.

Induction and quantification of collagen fiber alignment in a three-dimensional hydroxyapatite-collagen composite scaffold.

PubMed

Banglmaier, Richard F; Sander, Edward A; VandeVord, Pamela J

2015-04-01

Hydroxyapatite-collagen composite scaffolds are designed to serve as a regenerative load bearing replacement that mimics bone. However, the material properties of these scaffolds are at least an order of magnitude less than that of bone and subject to fail under physiological loading conditions. These scaffolds compositionally resemble bone but they do not possess important structural attributes such as an ordered arrangement of collagen fibers, which is a correlate to the mechanical properties in bone. Furthermore, it is unclear how much ordering of structure is satisfactory to mimic bone. Therefore, quantitative methods are needed to characterize collagen fiber alignment in these scaffolds for better correlation between the scaffold structure and the mechanical properties. A combination of extrusion and compaction was used to induce collagen fiber alignment in composite scaffolds. Collagen fiber alignment, due to extrusion and compaction, was quantified from polarized light microscopy images with a Fourier transform image processing algorithm. The Fourier transform method was capable of resolving the degree of collagen alignment from polarized light images. Anisotropy indices of the image planes ranged from 0.08 to 0.45. Increases in the degree of fiber alignment induced solely by extrusion (0.08-0.25) or compaction (0.25-0.44) were not as great as those by the combination of extrusion and compaction (0.35-0.45). Additional measures of randomness and fiber direction corroborate these anisotropy findings. This increased degree of collagen fiber alignment was induced in a preferred direction that is consistent with the extrusion direction and parallel with the compacted plane. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Development of A Chip-Scale Spectrometer for In Situ Characterization of Solar System Surfaces

NASA Astrophysics Data System (ADS)

Chanover, Nancy J.; Voelz, David; Cho, Sang-Yeon; Pelzman, Charles

2017-10-01

We discuss the development of a plasmonic spectrometer for in situ characterization of solar system surface and subsurface environments. The two goals of this project are to (1) quantitatively demonstrate that a plasmonic spectrometer can be used to rapidly acquire high signal-to-noise spectra between 0.5 - 1.0 microns at a spectral resolution suitable for unambiguous detection of spectral features indicative of volatiles and characteristic surface mineralogies, and (2) demonstrate that this class of spectrometer can be used in conjunction with optical fibers to access subsurface materials and vertically map the geochemistry and mineralogy of subsurface layers, thereby demonstrating that a plasmonic spectrometer is feasible in a low-mass, low-power, compact configuration. Our prototype spectrometer is comprised of a broadband lamp/source, a fiber optic system to illuminate the sample surface and collect the reflected light, a mosaic filter element based on plasmon resonance, and a focal plane array (FPA) detector. Our work thus far has been divided into two primary areas: (i) the development of the plasmon filter element and (ii) the construction of a testbed to explore the source, fiber system and focal plane array components of the system. We discuss our preliminary design studies of the plasmonic nanostructure prototypes to optimize the full-width half-maximum of the filter, and our fiber illumination and signal collection system.

Fiber-optic fringe projection with crosstalk reduction by adaptive pattern masking

NASA Astrophysics Data System (ADS)

Matthias, Steffen; Kästner, Markus; Reithmeier, Eduard

2017-02-01

To enable in-process inspection of industrial manufacturing processes, measuring devices need to fulfill time and space constraints, while also being robust to environmental conditions, such as high temperatures and electromagnetic fields. A new fringe projection profilometry system is being developed, which is capable of performing the inspection of filigree tool geometries, e.g. gearing elements with tip radii of 0.2 mm, inside forming machines of the sheet-bulk metal forming process. Compact gradient-index rod lenses with a diameter of 2 mm allow for a compact design of the sensor head, which is connected to a base unit via flexible high-resolution image fibers with a diameter of 1.7 mm. The base unit houses a flexible DMD based LED projector optimized for fiber coupling and a CMOS camera sensor. The system is capable of capturing up to 150 gray-scale patterns per second as well as high dynamic range images from multiple exposures. Owing to fiber crosstalk and light leakage in the image fiber, signal quality suffers especially when capturing 3-D data of technical surfaces with highly varying reflectance or surface angles. An algorithm is presented, which adaptively masks parts of the pattern to reduce these effects via multiple exposures. The masks for valid surface areas are automatically defined according to different parameters from an initial capture, such as intensity and surface gradient. In a second step, the masks are re-projected to projector coordinates using the mathematical model of the system. This approach is capable of reducing both inter-pixel crosstalk and inter-object reflections on concave objects while maintaining measurement durations of less than 5 s.

Modeling of mode-locked fiber lasers

NASA Astrophysics Data System (ADS)

Shaulov, Gary

This thesis presents the results of analytical and numerical simulations of mode-locked fiber lasers and their components: multiple quantum well saturable absorbers and nonlinear optical loop mirrors. Due to the growing interest in fiber lasers as a compact source of ultrashort pulses there is a need to develop a full understanding of the advantages and limitations of the different mode-locked techniques. The mode-locked fiber laser study performed in this thesis can be used to optimize the design and performance of mode-locked fiber laser systems. A group at Air Force Research Laboratory reported a fiber laser mode-locked by multiple quantum well (MQW) saturable absorber with stable pulses generated as short as 2 ps [21]. The laser cavity incorporates a chirped fiber Bragg grating as a dispersion element; our analysis showed that the laser operates in the soliton regime. Soliton perturbation theory was applied and conditions for stable pulse operation were investigated. Properties of MQW saturable absorbers and their effect on cavity dynamics were studied and the cases of fast and slow saturable absorbers were considered. Analytical and numerical results are in a good agreement with experimental data. In the case of the laser cavity with a regular fiber Bragg grating, the properties of MQW saturable absorbers dominate the cavity dynamics. It was shown that despite the lack of a soliton shaping mechanism, there is a regime in parameter space where stable or quasi-stable solitary waves solutions can exist. Further a novel technique of fiber laser mode-locking by nonlinear polarization rotation was proposed. Polarization rotation of vector solitons was simulated in a birefringent nonlinear optical loop mirror (NOLM) and the switching characteristics of this device was studied. It was shown that saturable absorber-like action of NOLM allows mode-locked operation of the two fiber laser designs. Laser cavity designs were proposed: figure-eight-type and sigma-type cavity.

High speed optical wireless data transmission system for particle sensors in high energy physics

NASA Astrophysics Data System (ADS)

Ali, W.; Corsini, R.; Ciaramella, E.; Dell'Orso, R.; Messineo, A.; Palla, F.

2015-08-01

High speed optical fiber or copper wire communication systems are frequently deployed for readout data links used in particle physics detectors. Future detector upgrades will need more bandwidth for data transfer, but routing requirements for new cables or optical fiber will be challenging due to space limitations. Optical wireless communication (OWC) can provide high bandwidth connectivity with an advantage of reduced material budget and complexity of cable installation and management. In a collaborative effort, Scuola Superiore Sant'Anna and INFN Pisa are pursuing the development of a free-space optical link that could be installed in a future particle physics detector or upgrade. We describe initial studies of an OWC link using the inner tracker of the Compact Muon Solenoid (CMS) detector as a reference architecture. The results of two experiments are described: the first to verify that the laser source transmission wavelength of 1550 nm will not introduce fake signals in silicon strip sensors while the second was to study the source beam diameter and its tolerance to misalignment. For data rates of 2.5 Gb/s and 10 Gb/s over a 10 cm working distance it was observed that a tolerance limit of ±0.25 mm to ±0.8 mm can be obtained for misaligned systems with source beam diameters of 0.38 mm to 3.5 mm, respectively.

Preliminary results of real-time in-vitro electronic speckle pattern interferometry (ESPI) measurements in otolaryngology

NASA Astrophysics Data System (ADS)

Conerty, Michelle D.; Castracane, James; Cacace, Anthony T.; Parnes, Steven M.; Gardner, Glendon M.; Miller, Mitchell B.

1995-05-01

Electronic Speckle Pattern Interferometry (ESPI) is a nondestructive optical evaluation technique that is capable of determining surface and subsurface integrity through the quantitative evaluation of static or vibratory motion. By utilizing state of the art developments in the areas of lasers, fiber optics and solid state detector technology, this technique has become applicable in medical research and diagnostics. Based on initial support from NIDCD and continued support from InterScience, Inc., we have been developing a range of instruments for improved diagnostic evaluation in otolaryngological applications based on the technique of ESPI. These compact fiber optic instruments are capable of making real time interferometric measurements of the target tissue. Ongoing development of image post- processing software is currently capable of extracting the desired quantitative results from the acquired interferometric images. The goal of the research is to develop a fully automated system in which the image processing and quantification will be performed in hardware in near real-time. Subsurface details of both the tympanic membrane and vocal cord dynamics could speed the diagnosis of otosclerosis, laryngeal tumors, and aid in the evaluation of surgical procedures.

High power tube solid-state laser with zigzag propagation of pump and laser beam

NASA Astrophysics Data System (ADS)

Savich, Michael

2015-02-01

A novel resonator and pumping design with zigzag propagation of pumping and laser beams permits to design an improved tube Solid State Laser (SSL), solving the problem of short absorption path to produce a high power laser beam (100 - 1000kW). The novel design provides an amplifier module and laser oscillator. The tube-shaped SSL includes a gain element fiber-optically coupled to a pumping source. The fiber optic coupling facilitates light entry at compound Brewster's angle of incidence into the laser gain element and uses internal reflection to follow a "zigzag" path in a generally spiral direction along the length of the tube. Optics are arranged for zigzag propagation of the laser beam, while the cryogenic cooling system is traditional. The novel method of lasing uses advantages of cylindrical geometry to reach the high volume of gain medium with compactness and structural rigidity, attain high pump density and uniformity, and reach a low threshold without excessive increase of the temperature of the crystal. The design minimizes thermal lensing and stress effects, and provides high gain amplification, high power extraction from lasing medium, high pumping and lasing efficiency and a high beam quality.

A compactly integrated laser-induced fluorescence detector for microchip electrophoresis.

PubMed

Li, Hai-Fang; Lin, Jin-Ming; Su, Rong-Guo; Uchiyama, Katsumi; Hobo, Toshiyuki

2004-06-01

A simple and easy-to-use integrated laser-induced fluorescence detector for microchip electrophoresis was constructed and evaluated. The fluid channels and optical fiber channels in the glass microchip were fabricated using standard photolithographic techniques and wet chemical etching. A 473 nm diode-pumped laser was used as the excitation source, and the collimation and collection optics and mirrors were discarded by using a multimode optical fiber to couple the excitation light straight into the microchannel and placing the microchip directly on the top of the photomultiplier tube. A combination of filter systems was incorporated into a poly(dimethylsiloxane) layer, which was reversibly sealed to the bottom of the microchip to eliminate the scattering excitation light reaching to the photomultiplier tube. Fluorescein/calcein samples were taken as model analytes to evaluate the performance with respect to design factors. The detection limits were 0.05 microM for fluorescein and 0.18 microM for calcein, respectively. The suitability of this simple detector for fluorescence detection was demonstrated by baseline separation of fluorescein isothiocyanate (FITC)-labeled arginine, phenylalanine, and glycine and FITC within 30 s at separation length of 3.8 cm and electrical field strength of 600 V/cm.

Single fiber temperature probe configuration using anti-Stokes luminescence from Cr:GdAlO3

NASA Astrophysics Data System (ADS)

Eldridge, Jeffrey I.

2018-06-01

Single-photon excitation of anti-Stokes-shifted emission from a thermographic phosphor allows operation of a luminescence decay-based single fiber temperature probe with negligible interference from background fiber-generated Raman scattering. While single fiber probe configurations for luminescence-based fiber optic thermometers offer advantages of simple design, compactness, and superior emission light collection efficiency, their effective use has been limited by interference from Raman scattering in the fiber probe and excitation delivery fiber that produces distortion of the luminescence decay that follows the excitation pulse. The near elimination of interference by background fiber-generated Raman scattering was demonstrated by incorporating a Cr-doped GdAlO3 (Cr:GdAlO3) thermographic phosphor as the sensing element at the end of a single fiber luminescence decay-based thermometer and detecting anti-Stokes-shifted luminescence centered at 542 or 593 nm produced by 695 nm excitation. Measurements were performed using both silica (up to 1150 °C) and single-crystal YAG (up to 1200 °C) fiber-based thermometers. Selection of emission detection centered at 542 nm greatly benefited the YAG fiber probe measurements by practically eliminating detection of otherwise significant luminescence from Cr3+ impurities in the YAG fiber. For both the silica and YAG fiber probes, the relative benefit of adopting single-photon excitation of anti-Stokes-shifted luminescence was evaluated by comparison with results obtained by conventional 532 nm excitation of Stokes-shifted luminescence.

Polarization-maintaining performance of large effective area, higher order modes fiber in a coiled configuration

NASA Astrophysics Data System (ADS)

Ahmad, Raja; Nicholson, Jeffrey W.; Abedin, Kazi S.; Westbrook, Paul S.; Headley, Clifford; Wisk, Patrick W.; Monberg, Eric M.; Yan, Man F.; DiGiovanni, David J.

2018-02-01

Scaling the power-level of fiber sources has many practical advantages, while also enabling fundamental studies on the light-matter interaction in amorphous guiding media. In order to scale the power-level of fiber-sources without encountering nonlinear impairments, a strategy is to increase the effective-area of the guided optical-mode. Increasing the effective-area of the fundamental mode in a fiber, however, presents the challenges of increased susceptibility to mode-distortion and effective-area-reduction under the influence of bends. Therefore, higher-order-mode (HOM) fibers, which guide light in large effective-area (Aeff) Bessel-like modes, are a good candidate for scaling the power-level of robust fiber-sources. Many applications of high-power fiber-sources also demand a deterministic control on the polarization-state of light. Furthermore, a polarization-maintaining (PM)-type HOM fiber can afford the added possibility of coherent-beam combination and polarization multiplexing of high-power fiber-lasers. Previously, we reported polarization-maintaining operation in a 1.3 m length of PM-HOM fiber that was held straight. The PM-HOM fiber guided Bessel-like modes with Aeff ranging from 1200-2800 μm2. In this work, we report, for the first time, that the polarization-extinction-ratio (PER) of the HOM exceeds 10 dB in an 8 m long fiber that is coiled down to a diameter of 40 cm. This opens a path towards compact and polarization-controlled high-power fiber-systems.

Modeling of fiber orientation in viscous fluid flow with application to self-compacting concrete

NASA Astrophysics Data System (ADS)

Kolařík, Filip; Patzák, Bořek

2013-10-01

In recent years, unconventional concrete reinforcement is of growing popularity. Especially fiber reinforcement has very wide usage in high performance concretes like "Self Compacting Concrete" (SCC). The design of advanced tailor-made structures made of SCC can take advantage of anisotropic orientation of fibers. Tools for fiber orientation predictions can contribute to design of tailor made structure and allow to develop casting procedures that enable to achieve the desired fiber distribution and orientation. This paper deals with development and implementation of suitable tool for prediction of fiber orientation in a fluid based on the knowledge of the velocity field. Statistical approach to the topic is employed. Fiber orientation is described by a probability distribution of the fiber angle.

Compact sub-nanosecond pulse seed source with diode laser driven by a high-speed circuit

NASA Astrophysics Data System (ADS)

Wang, Xiaoqian; Wang, Bo; Wang, Junhua; Cheng, Wenyong

2018-06-01

A compact sub-nanosecond pulse seed source with 1550 nm diode laser (DL) was obtained by employing a high-speed circuit. The circuit mainly consisted of a short pulse generator and a short pulse driver. The short pulse generator, making up of a complex programmable logic device (CPLD), a level translator, two programmable delay chips and an AND gate chip, output a triggering signal to control metal-oxide-semiconductor field-effect transistor (MOSFET) switch of the short pulse driver. The MOSFET switch with fast rising time and falling time both shorter than 1 ns drove the DL to emit short optical pulses. Performances of the pulse seed source were tested. The results showed that continuously adjustable repetition frequency ranging from 500 kHz to 100 MHz and pulse duration in the range of 538 ps to 10 ns were obtained, respectively. 537 μW output was obtained at the highest repetition frequency of 100 MHz with the shortest pulse duration of 538 ps. These seed pulses were injected into an fiber amplifier, and no optical pulse distortions were found.

On-line carbon balance of yeast fermentations using miniaturized optical sensors.

PubMed

Beuermann, Thomas; Egly, Dominik; Geoerg, Daniel; Klug, Kerris Isolde; Storhas, Winfried; Methner, Frank-Juergen

2012-03-01

Monitoring of microbiological processes using optical sensors and spectrometers has gained in importance over the past few years due to its advantage in enabling non-invasive on-line analysis. Near-infrared (NIR) and mid-infrared (MIR) spectrometer set-ups in combination with multivariate calibrations have already been successfully employed for the simultaneous determination of different metabolites in microbiological processes. Photometric sensors, in addition to their low price compared to spectrometer set-ups, have the advantage of being compact and are easy to calibrate and operate. In this work, the detection of ethanol and CO(2) in the exhaust gas during aerobic yeast fermentation was performed by two photometric gas analyzers, and dry yeast biomass was monitored using a fiber optic backscatter set-up. The optical sensors could be easily fitted to the bioreactor and exhibited high robustness during measuring. The ethanol content of the fermentation broth was monitored on-line by measuring the ethanol concentration in the fermentation exhaust and applying a conversion factor. The vapor/liquid equilibrium and the associated conversion factor strongly depend on the process parameter temperature but not on aeration and stirring rate. Dry yeast biomass was determined in-line by a backscattering signal applying a linear calibration. An on-line balance with a recovery rate of 95-97% for carbon was achieved with the use of three optical sensors (two infrared gas analyzers and one fiber optic backscatter set-up). Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Refractive index and temperature sensors based on no-core fiber cascaded with long period fiber grating

NASA Astrophysics Data System (ADS)

Zhang, Jianming; Pu, Shengli; Rao, Jie; Yao, Tianjun

2018-05-01

A kind of compact fibre-optic sensor based on no-core fibre (NCF) cascaded with a strong coupling long-period fibre grating (LPFG) is proposed and experimentally demonstrated. The sensing mechanism is based on the Mach-Zehnder-like interference between the core fundamental mode and cladding mode of the fibre structure. The NCF and LPFG are used as the mode exciter and combiner, respectively. Due to the particular properties of the strong coupling LPFG, the measurements of refractive index (RI) and temperature with high sensitivity are realized by monitoring the transmission spectrum with intensity and wavelength interrogation techniques, respectively. The achieved RI sensitivity reaches -580.269 dB/RIU in the range of 1.436-1.454 and the temperature sensitivity reaches 27.2 pm/°C.

Optical fiber tip interferometer gas pressure sensor based on anti-resonant reflecting guidance mechanism

NASA Astrophysics Data System (ADS)

Yang, Y. B.; Wang, D. N.; Xu, Ben; Wang, Z. K.

2018-05-01

We propose and demonstrate a gas pressure sensor based on an anti-resonant reflecting guidance (ARRG) mechanism in quartz capillary tube with an open cavity. The device is simple in fabrication by only fusion splicing a segment of capillary tube with single mode fiber. It has compact size, robust structure, convenient mode of operation, and high sensitivity of 4.278 nm/MPa. Moreover, as two Faby-Perot cavities exist in the device, which create the interference spectrum with several distinct resonance dips, a simultaneous gas pressure and temperature detection can be readily achieved by tracing two dip wavelengths. The error in the measurement due to the choice of different resonant dips can be effectively reduced by using the Fourier band pass filtering method.

Chemical, biochemical, and environmental fiber sensors III; Proceedings of the Meeting, Boston, MA, Sept. 4, 5, 1991

NASA Astrophysics Data System (ADS)

Lieberman, Robert A.

Various papers on chemical, biochemical, and environmental fiber sensors are presented. Individual topics addressed include: fiber optic pressure sensor for combustion monitoring and control, viologen-based fiber optic oxygen sensors, renewable-reagent fiber optic sensor for ocean pCO2, transition metal complexes as indicators for a fiber optic oxygen sensor, fiber optic pH measurements using azo indicators, simple reversible fiber optic chemical sensors using solvatochromic dyes, totally integrated optical measuring sensors, integrated optic biosensor for environmental monitoring, radiation dosimetry using planar waveguide sensors, optical and piezoelectric analysis of polymer films for chemical sensor characterization, source polarization effects in an optical fiber fluorosensor, lens-type refractometer for on-line chemical analysis, fiber optic hydrocarbon sensor system, chemical sensors for environmental monitoring, optical fibers for liquid-crystal sensing and logic devices, suitability of single-mode fluoride fibers for evanescent-wave sensing, integrated modules for fiber optic sensors, optoelectronic sensors based on narrowband A3B5 alloys, fiber Bragg grating chemical sensor.

Electrical source of pseudothermal light

NASA Astrophysics Data System (ADS)

Kuusela, Tom A.

2018-06-01

We describe a simple and compact electrical version of a pseudothermal light source. The source is based on electrical white noise whose spectral properties are tailored by analog filters. This signal is used to drive a light-emitting diode. The type of second-order coherence of the output light can be either Gaussian or Lorentzian, and the intensity distribution can be either Gaussian or non-Gaussian. The output light field is similar in all viewing angles, and thus, there is no need for a small aperture or optical fiber in temporal coherence analysis.

Fiber optic label-free biophotonic diagnostic tool for cardiovascular disease

NASA Astrophysics Data System (ADS)

Rius, Cristina; Ackermann, Tobias N.; Dorado, Beatriz; Muñoz-Berbel, Xavier; Andrés, Vicente; Llobera, Andreu

2015-06-01

A label-free compact method for performing photonic characterization of "healthy" versus "diseased" arteries has been developed. It permits the detection of atherosclerotic lesion in living mouse arteries. Using this prototype, we observed that the spectral response (photonic fingerprint, PIN) obtained from aortas of wild-type mice differs from the response of ApoE-KO mice fed with high-fat diet (an atheroprone mouse model). Benchmark of the results against gold standard was performed by staining the aortas with Oil-Red-O to visualize atherosclerotic plaques.

Development of a US Gravitational Wave Laser System for LISA

NASA Technical Reports Server (NTRS)

Camp, Jordan B.; Numata, Kenji

2015-01-01

A highly stable and robust laser system is a key component of the space-based LISA mission architecture.In this talk I will describe our plans to demonstrate a TRL 5 LISA laser system at Goddard Space Flight Center by 2016.The laser system includes a low-noise oscillator followed by a power amplifier. The oscillator is a low-mass, compact 10mW External Cavity Laser, consisting of a semiconductor laser coupled to an optical cavity, built by the laser vendorRedfern Integrated Optics. The amplifier is a diode-pumped Yb fiber with 2W output, built at Goddard. I will show noiseand reliability data for the full laser system, and describe our plans to reach TRL 5 by 2016.

Optimization of mid-IR generation from a periodically poled MgO doped stoichiometric lithium tantalate optical parametric oscillator with intracavity difference frequency mixing

NASA Astrophysics Data System (ADS)

Hatano, Hideki; Slater, Richard; Takekawa, Shunji; Kusano, Masahiro; Watanabe, Makoto

2017-07-01

We demonstrate 43% slope efficiency for generation of ∼3200 nm light, a wavelength considered to be ideal for laser induced ultrasound generation in carbon fiber reinforced plastic. High slope efficiency was obtained by optimizing crystal lengths, cavity length and mirror reflectivity using a two crystal optical parametric oscillator+difference frequency mixing (OPO+DFM) nonlinear wavelength conversion scheme. Mid-IR output >12 mJ was obtained from a 1064 nm Nd:YAG pump laser with 12 ns pulse width (FWHM) and containing pulse energy of 43 mJ. A compact, single temperature crystal oven is described along with some suggestions for improving the slope efficiency.

Concentric core optical fiber with multiple-mode signal transmission

DOEpatents

Muhs, J.D.

1997-05-06

A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion. 3 figs.

Concentric core optical fiber with multiple-mode signal transmission

DOEpatents

Muhs, Jeffrey D.

1997-01-01

A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion.

Ultra Compact Optical Pickup with Integrated Optical System

NASA Astrophysics Data System (ADS)

Nakata, Hideki; Nagata, Takayuki; Tomita, Hironori

2006-08-01

Smaller and thinner optical pickups are needed for portable audio-visual (AV) products and notebook personal computers (PCs). We have newly developed an ultra compact recordable optical pickup for Mini Disc (MD) that measures less than 4 mm from the disc surface to the bottom of the optical pickup, making the optical system markedly compact. We have integrated all the optical components into an objective lens actuator moving unit, while fully satisfying recording and playback performance requirements. In this paper, we propose an ultra compact optical pickup applicable to portable MD recorders.

Abrasion Resistance and Mechanical Properties of Waste-Glass-Fiber-Reinforced Roller-compacted Concrete

NASA Astrophysics Data System (ADS)

Yildizel, S. A.; Timur, O.; Ozturk, A. U.

2018-05-01

The potential use of waste glass fibers in roller-compacted concrete (RCC) was investigated with the aim to improve its performance and reduce environmental effects. The research was focused on the abrasion resistance and compressive and flexural strengths of the reinforced concrete relative to those of reference mixes without fibers. The freeze-thaw resistance of RCC mixes was also examined. It was found that the use of waste glass fibers at a rate of 2 % increased the abrasion resistance of the RCC mixes considerably.

Q-switched Erbium-doped fiber laser at 1600 nm for photoacoustic imaging application

PubMed Central

Zeng, Lvming; Chen, Zhongping; Kim, Chang-Seok

2016-01-01

We present a nanosecond Q-switched Erbium-doped fiber (EDF) laser system operating at 1600 nm with a tunable repetition rate from 100 kHz to 1 MHz. A compact fiber coupled, acousto-optic modulator-based EDF ring cavity was used to generate a nanosecond seed laser at 1600 nm, and a double-cladding EDF based power amplifier was applied to achieve the maximum average power of 250 mW. In addition, 12 ns laser pulses with the maximum pulse energy of 2.4 μJ were obtained at 100 kHz. Furthermore, the Stokes shift by Raman scattering over a 25 km long fiber was measured, indicating that the laser can be potentially used to generate the high repetition rate pulses at the 1.7 μm region. Finally, we detected the photoacoustic signal from a human hair at 200 kHz repetition rate with a pulse energy of 1.2 μJ, which demonstrates that a Q-switched Er-doped fiber laser can be a promising light source for the high speed functional photoacoustic imaging. PMID:27110032

Q-switched Erbium-doped fiber laser at 1600 nm for photoacoustic imaging application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piao, Zhonglie; Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, California 92612; Zeng, Lvming

We present a nanosecond Q-switched Erbium-doped fiber (EDF) laser system operating at 1600 nm with a tunable repetition rate from 100 kHz to 1 MHz. A compact fiber coupled, acousto-optic modulator-based EDF ring cavity was used to generate a nanosecond seed laser at 1600 nm, and a double-cladding EDF based power amplifier was applied to achieve the maximum average power of 250 mW. In addition, 12 ns laser pulses with the maximum pulse energy of 2.4 μJ were obtained at 100 kHz. Furthermore, the Stokes shift by Raman scattering over a 25 km long fiber was measured, indicating that the laser can be potentially used to generate the highmore » repetition rate pulses at the 1.7 μm region. Finally, we detected the photoacoustic signal from a human hair at 200 kHz repetition rate with a pulse energy of 1.2 μJ, which demonstrates that a Q-switched Er-doped fiber laser can be a promising light source for the high speed functional photoacoustic imaging.« less

Visible high power fiber coupled diode lasers

NASA Astrophysics Data System (ADS)

Köhler, Bernd; Drovs, Simon; Stoiber, Michael; Dürsch, Sascha; Kissel, Heiko; Könning, Tobias; Biesenbach, Jens; König, Harald; Lell, Alfred; Stojetz, Bernhard; Löffler, Andreas; Strauß, Uwe

2018-02-01

In this paper we report on further development of fiber coupled high-power diode lasers in the visible spectral range. New visible laser modules presented in this paper include the use of multi single emitter arrays @ 450 nm leading to a 120 W fiber coupled unit with a beam quality of 44 mm x mrad, as well as very compact modules with multi-W output power from 405 nm to 640 nm. However, as these lasers are based on single emitters, power scaling quickly leads to bulky laser units with a lot of optical components to be aligned. We also report on a new approach based on 450 nm diode laser bars, which dramatically reduces size and alignment effort. These activities were performed within the German government-funded project "BlauLas": a maximum output power of 80 W per bar has been demonstrated @ 450 nm. We show results of a 200 μm NA0.22 fiber coupled 35 W source @ 450 nm, which has been reduced in size by a factor of 25 compared to standard single emitter approach. In addition, we will present a 200 μm NA0.22 fiber coupled laser unit with an output power of 135 W.

Fiber Bragg grating interrogation using wavelength modulated tunable distributed feedback lasers and a fiber-optic Mach-Zehnder interferometer.

PubMed

Roy, Anirban; Chakraborty, Arup Lal; Jha, Chandan Kumar

2017-04-20

This paper demonstrates a technique of high-resolution interrogation of two fiber Bragg gratings (FBGs) with flat-topped reflection spectra centered on 1649.55 nm and 1530.182 nm with narrow line width tunable semiconductor lasers emitting at 1651.93 nm and 1531.52 nm, respectively. The spectral shift of the reflection spectrum in response to temperature and strain is accurately measured with a fiber-optic Mach-Zehnder interferometer that has a free spectral range of 0.0523 GHz and a broadband photodetector. Laser wavelength modulation and harmonic detection techniques are used to transform the gentle edges of the flat-topped FBG into prominent leading and trailing peaks that are up to five times narrower than the FBG spectrum. Either of these peaks can be used to accurately measure spectral shifts of the FBG reflection spectrum with a resolution down to a value of 0.47 pm. A digital signal processing board is used to measure the temperature-induced spectral shifts over the range of 30°C-80°C and strain-induced spectral shifts from 0  μϵ to 12,000  μϵ. The shift is linear in both cases with a temperature sensitivity of 12.8 pm/°C and strain sensitivity of 0.12  pm/μϵ. The distinctive feature of this technique is that it does not use an optical spectrum analyzer at any stage of its design or operation. It can be readily extended to all types of tunable diode lasers and is ideally suited for compact field instruments and for biomedical applications in stroke rehabilitation monitoring.

Linear FMCW Laser Radar for Precision Range and Vector Velocity Measurements

NASA Technical Reports Server (NTRS)

Pierrottet, Diego; Amzajerdian, Farzin; Petway, Larry; Barnes, Bruce; Lockhard, George; Rubio, Manuel

2008-01-01

An all fiber linear frequency modulated continuous wave (FMCW) coherent laser radar system is under development with a goal to aide NASA s new Space Exploration initiative for manned and robotic missions to the Moon and Mars. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed. Linear FMCW lidar has the capability of high-resolution range measurements, and when configured into a multi-channel receiver system it has the capability of obtaining high precision horizontal and vertical velocity measurements. Precision range and vector velocity data are beneficial to navigating planetary landing pods to the preselected site and achieving autonomous, safe soft-landing. The all-fiber coherent laser radar has several important advantages over more conventional pulsed laser altimeters or range finders. One of the advantages of the coherent laser radar is its ability to measure directly the platform velocity by extracting the Doppler shift generated from the motion, as opposed to time of flight range finders where terrain features such as hills, cliffs, or slopes add error to the velocity measurement. Doppler measurements are about two orders of magnitude more accurate than the velocity estimates obtained by pulsed laser altimeters. In addition, most of the components of the device are efficient and reliable commercial off-the-shelf fiber optic telecommunication components. This paper discusses the design and performance of a second-generation brassboard system under development at NASA Langley Research Center as part of the Autonomous Landing and Hazard Avoidance (ALHAT) project.

Magnetic focusing immunosensor for the detection of Salmonella typhimurium in foods

NASA Astrophysics Data System (ADS)

Pivarnik, Philip E.; Cao, He; Letcher, Stephen V.; Pierson, Arthur H.; Rand, Arthur G.

1999-01-01

From 1988 through 1992 Salmonellosis accounted for 27% of the total reported foodborne disease outbreaks and 57% of the outbreaks in which the pathogen was identified. The prevalence of Salmonellosis and the new requirements to monitor the organism as a marker in pathogen reduction programs will drive the need for rapid, on-site testing. A compact fiber optic fluorometer using a red diode laser as an excitation source and fiber probes for analyte detection has been constructed and used to measure Salmonella. The organisms were isolated with anti-Salmonella magnetic beads and were labeled with a secondary antibody conjugated to a red fluorescent dye. The response of the system was proportional to the concentration of Salmonella typhimurium from 3.2 X 105 colony forming units (CFU)/ml to 1.6 X 107 CFU/ml. The system was developed to utilize a fiber-optic magnetic focusing problem that attracted the magnetic microspheres to the surface of a sample chamber directly in front of the excitation and emission fibers. The signal obtained from a homogenous suspension of fluorescent magnetic microspheres was 9 to 10 picowatts. After focusing, the signal from the fluorescent labeled magnetic microspheres increased to 200 picowatts, approximately 20 times greater than the homogeneous suspension. The magnetic focusing assay detected 1.59 X 105 colony forming units/ml of Salmonella typhimurium cultured in growth media. The process of magnetic focusing in front of the fibers has the potential to reduce the background fluorescence from unbound secondary antibodies, eliminating several rinsing steps, resulting in a simple rapid assay.

Temporal laser pulse manipulation using multiple optical ring-cavities

NASA Technical Reports Server (NTRS)

Nguyen, Quang-Viet (Inventor); Kojima, Jun (Inventor)

2010-01-01

An optical pulse stretcher and a mathematical algorithm for the detailed calculation of its design and performance is disclosed. The optical pulse stretcher has a plurality of optical cavities, having multiple optical reflectors such that an optical path length in each of the optical cavities is different. The optical pulse stretcher also has a plurality of beam splitters, each of which intercepts a portion of an input optical beam and diverts the portion into one of the plurality of optical cavities. The input optical beam is stretched and a power of an output beam is reduced after passing through the optical pulse stretcher and the placement of the plurality of optical cavities and beam splitters is optimized through a model that takes into account optical beam divergence and alignment in the pluralities of the optical cavities. The optical pulse stretcher system can also function as a high-repetition-rate (MHz) laser pulse generator, making it suitable for use as a stroboscopic light source for high speed ballistic projectile imaging studies, or it can be used for high speed flow diagnostics using a laser light sheet with digital particle imaging velocimetry. The optical pulse stretcher system can also be implemented using fiber optic components to realize a rugged and compact optical system that is alignment free and easy to use.

Compact 2100 nm laser diode module for next-generation DIRCM

NASA Astrophysics Data System (ADS)

Dvinelis, Edgaras; Greibus, Mindaugas; TrinkÅ«nas, Augustinas; NaujokaitÄ--, Greta; Vizbaras, Augustinas; Vizbaras, Dominykas; Vizbaras, Kristijonas

2017-10-01

Compact high-power 2100 nm laser diode module for next-generation directional infrared countermeasure (DIRCM) systems is presented. Next-generation DIRCM systems require compact, light-weight and robust laser modules which could provide intense IR light emission capable of disrupting the tracking sensor of heat-seeking missile. Currently used solid-state and fiber laser solutions for mid-IR band are bulky and heavy making them difficult to implement in smaller form-factor DIRCM systems. Recent development of GaSb laser diode technology greatly improved optical output powers and efficiencies of laser diodes working in 1900 - 2450 nm band [1] while also maintaining very attractive size, weight, power consumption and cost characteristics. 2100 nm laser diode module presented in this work performance is based on high-efficiency broad emitting area GaSb laser diode technology. Each laser diode emitter is able to provide 1 W of CW output optical power with working point efficiency up to 20% at temperature of 20 °C. For output beam collimation custom designed fast-axis collimator and slow-axis collimator lenses were used. These lenses were actively aligned and attached using UV epoxy curing. Total 2 emitters stacked vertically were used in 2100 nm laser diode module. Final optical output power of the module goes up to 2 W at temperature of 20 °C. Total dimensions of the laser diode module are 35 x 25 x 16 mm (L x W x H) with a weight of 28 grams. Finally output beam is bore-sighted to mechanical axes of the module housing allowing for easy integration into next-generation DIRCM systems.

A Low-Cost and Portable Dual-Channel Fiber Optic Surface Plasmon Resonance System.

PubMed

Liu, Qiang; Liu, Yun; Chen, Shimeng; Wang, Fang; Peng, Wei

2017-12-04

A miniaturization and integration dual-channel fiber optic surface plasmon resonance (SPR) system was proposed and demonstrated in this paper. We used a yellow light-emitting diode (LED, peak wavelength 595 nm) and built-in web camera as a light source and detector, respectively. Except for the detection channel, one of the sensors was used as a reference channel to compensate nonspecific binding and physical absorption. We packaged the LED and surface plasmon resonance (SPR) sensors together, which are flexible enough to be applied to mobile devices as a compact and portable system. Experimental results show that the normalized intensity shift and refractive index (RI) of the sample have a good linear relationship in the RI range from 1.328 to 1.348. We used this sensor to monitor the reversible, specific interaction between lectin concanavalin A (Con A) and glycoprotein ribonuclease B (RNase B), which demonstrate its capabilities of specific identification and biochemical samples concentration detection. This sensor system has potential applications in various fields, such as medical diagnosis, public health, food safety, and environment monitoring.

Design and modeling of a prototype fiber scanning CARS endoscope

NASA Astrophysics Data System (ADS)

Veilleux, Isra"l.; Doucet, Michel; Coté, Patrice; Verreault, Sonia; Fortin, Michel; Paradis, Patrick; Leclair, Sébastien; Da Costa, Ralph S.; Wilson, Brian C.; Seibel, Eric; Mermut, Ozzy; Cormier, Jean-François

2010-02-01

An endoscope capable of Coherent Anti-Stokes Raman scattering (CARS) imaging would be of significant clinical value for improving early detection of endoluminal cancers. However, developing this technology is challenging for many reasons. First, nonlinear imaging techniques such as CARS are single point measurements thus requiring fast scanning in a small footprint if video rate is to be achieved. Moreover, the intrinsic nonlinearity of this modality imposes several technical constraints and limitations, mainly related to pulse and beam distortions that occur within the optical fiber and the focusing objective. Here, we describe the design and report modeling results of a new CARS endoscope. The miniature microscope objective design and its anticipated performance are presented, along with its compatibility with a new spiral scanningfiber imaging technology developed at the University of Washington. This technology has ideal attributes for clinical use, with its small footprint, adjustable field-of-view and high spatial-resolution. This compact hybrid fiber-based endoscopic CARS imaging design is anticipated to have a wide clinical applicability.

Factor XIII stiffens fibrin clots by causing fiber compaction.

PubMed

Kurniawan, N A; Grimbergen, J; Koopman, J; Koenderink, G H

2014-10-01

Factor XIII-induced cross-linking has long been associated with the ability of fibrin blood clots to resist mechanical deformation, but how FXIII can directly modulate clot stiffness is unknown. We hypothesized that FXIII affects the self-assembly of fibrin fibers by altering the lateral association between protofibrils. To test this hypothesis, we studied the cross-linking kinetics and the structural evolution of the fibers and clots during the formation of plasma-derived and recombinant fibrins by using light scattering, and the response of the clots to mechanical stresses by using rheology. We show that the lateral aggregation of fibrin protofibrils initially results in the formation of floppy fibril bundles, which then compact to form tight and more rigid fibers. The first stage is reflected in a fast (10 min) increase in clot stiffness, whereas the compaction phase is characterized by a slow (hours) development of clot stiffness. Inhibition of FXIII completely abrogates the slow compaction. FXIII strongly increases the linear elastic modulus of the clots, but does not affect the non-linear response at large deformations. We propose a multiscale structural model whereby FXIII-mediated cross-linking tightens the coupling between the protofibrils within a fibrin fiber, thus making the fiber stiffer and less porous. At small strains, fiber stiffening enhances clot stiffness, because the clot response is governed by the entropic elasticity of the fibers, but once the clot is sufficiently stressed, the modulus is independent of protofibril coupling, because clot stiffness is governed by individual protofibril stretching. © 2014 International Society on Thrombosis and Haemostasis.

Research on influence of different cover to the characteristic of FBG reflectance spectrum in vacuum thermal environment

NASA Astrophysics Data System (ADS)

Pei, Yifei; Zhang, Jingchuan; Zhang, Luosha; Liu, Yang; Zhang, Lina; Chen, Shiyu

2018-01-01

To satisfy the application of fiber grating sensor technology in high vacuum thermal environment, two different kinds of sleeve compactly single model fiber covered by acrylate and polyimide are researched. Influence of the cover to the characteristic of FBG reflectance spectrum in high vacuum thermal environment is analyzed and verified. First, transmission characteristic of single model fiber in high vacuum thermal environment is analyzed by solve the equation of heat conduction. Then, experimental program of influence on FBG reflection spectrum characteristics is designed and a hardware-in-the-loop detection platform is set up. Finally, the influence of temperature and vacuum on the reflection peak power of FBG in different coating single-mode transmission fiber under high vacuum thermal environment is studied and verified. Experimental results indicate that: when vacuum varied from normal pressure to 10-4Pa level and then return to normal pressure, temperature of two different coating single-mode transmission fiber dropped to -196 ° from room temperature and then returned to room temperature, after 224 hours, the peak power of the FBG reflectance spectrum did not change. It provided the theoretical and experimental basis for the application of optical fiber sensing technology in high vacuum (pressure about 10-4Pa level) and thermal environment (-196 ° 25 ° temperature cycle) .

Development of mechanical structure for the compact space IR camera MIRIS

NASA Astrophysics Data System (ADS)

Moon, Bongkon; Jeong, Woong-Seob; Cha, Sang-Mok; Park, Youngsik; Ree, Chang-Hee; Lee, Dae-Hee; Park, Sung-Joon; Nam, Uk-Won; Park, Jang-Hyun; Ka, Nung Hyun; Lee, Mi Hyun; Lee, Duk-Hang; Pyo, Jeonghyun; Rhee, Seung-Woo; Park, Jong-Oh; Lee, Hyung-Mok; Matsumoto, Toshio; Yang, Sun Choel; Han, Wonyong

2010-07-01

MIRIS is a compact near-infrared camera with a wide field of view of 3.67°×3.67° in the Korea Science and Technology Satellite 3 (STSAT-3). MIRIS will be launched warm and cool the telescope optics below 200K by pointing to the deep space on Sun-synchronous orbit. In order to realize the passive cooling, the mechanical structure was designed to consider thermal analysis results on orbit. Structural analysis was also conducted to ensure safety and stability in launching environments. To achieve structural and thermal requirements, we fabricated the thermal shielding parts such as Glass Fiber Reinforced Plastic (GFRP) pipe supports, a Winston cone baffle, aluminum-shield plates, a sunshade, a radiator and 30 layers of Multi Layer Insulation (MLI). These structures prevent the heat load from the spacecraft and the earth effectively, and maintain the temperature of the telescope optics within operating range. A micro cooler was installed in a cold box including a PICNIC detector and a filter-wheel, and cooled the detector down to a operating temperature range. We tested the passive cooling in the simulated space environment and confirmed that the required temperature of telescope can be achieved. Driving mechanism of the filter-wheel and the cold box structure were also developed for the compact space IR camera. Finally, we present the assembly procedures and the test result for the mechanical parts of MIRIS.

Development of a fiber optic pavement subgrade strain measurement system

NASA Astrophysics Data System (ADS)

Miller, Craig Emerson

2000-11-01

This dissertation describes the development of a fiber optic sensing system to measure strains within the soil subgrade of highway pavements resulting from traffic loads. The motivation to develop such a device include improvements to: (1)all phases of pavement design, (2)theoretical models used to predict pavement performance, and (3)pavement rehabilitation. The design of the sensing system encompasses selecting an appropriate transducer design as well as the development of optimal optical and demodulation systems. The first is spring based, which attempts to match its spring stiffness to that of the soil-data indicate it is not an optimal transducer design. The second transducer implements anchoring plates attached to two telescoping tubes which allows the soil to be compacted to a desired density between the plates to dictate the transducer's behavior. Both transducers include an extrinsic Fabry- Perot cavity to impose the soil strains onto a phase change of the optical signal propagating through the cavity. The optical system includes a low coherence source and allows phase modulation via path length stretching by adding a second interferometer in series with the transducer, resulting in a path matched differential interferometer. A digitally implemented synthetic heterodyne demodulator based on a four step phase stepping algorithm is used to obtain unambiguous soil strain information from the displacement of the Fabry-Perot cavity. The demodulator is calibrated and characterized by illuminating the transducer with a second long coherence source of different wavelength. The transducer using anchoring plates is embedded within cylindrical soil specimens of varying soil types and soil moisture contents. Loads are applied to the specimen and resulting strains are measured using the embedded fiber optic gage and LVDTs attached to the surface of the specimen. This experimental verification is substantiated using a finite element analysis to predict any differences between interior and surface strains in the specimens. The experimental data indicate 2-inch diameter anchoring plates embedded in soil close to its optimum moisture content allow for very accurate soil strain measurements.

Strength Analysis of Coconut Fiber Stabilized Earth for Farm Structures

NASA Astrophysics Data System (ADS)

Enokela, O. S.; P. O, Alada

2012-07-01

Investigation of the strength characteristic of soil from alluvial deposit of River Benue in makurdi stabilized with coconut fiber as a stabilizer was carried as local building material for farm structure. Processed coconut fibers were mixed with the soil at four different mix ratios of 1% fiber, 2% fiber, 3% fiber and 4% fiber by percentage weight with 0% fiber as control. Compaction test and compressive strength were carried out on the various stabilizing ratio. From the compaction test, the correlation between the maximum dry density and optimum moisture content is a second order polynomial with a coefficient of 63% obtained at1.91kg/m3and 20.0% respectively while the compressive strength test shows an optimum failure load of 8.62N/mm2 at 2%fibre:100% soil mix ratio at 2.16 maximum dry density.

Integration of high power laser diodes with microoptical components in a compact pumping source for visible fiber laser

NASA Astrophysics Data System (ADS)

Goering, Rolf; Hoefer, Bernd; Kraeplin, Anke; Schreiber, Peter; Kley, Ernst-Bernhard; Schmeisser, Volkmar

1999-04-01

A novel technique, the so-called skew ray imaging concept, has been developed for beam transformation of high power diode laser bars. It leads to beam circularization with optimum brightness conservation. This concept uses two key microoptical components: a fast axis collimator microlens (FAC) of high isoplanatism and a special array of beam deflecting elements, the number of which corresponds to the single emitter number of the diode laser. Using this concept of skew ray imaging in a modified form, prototypes of pumping sources for visible fiber laser have been developed and built up. Several watts of optical power have been focused into a small spot of 25 micrometers with a numerical aperture of 0.35. GRIN cylindrical microlenses with 0.1 mm focal length and diffractive blazed gratings as redirector have been used. The grating periods of the redirector sections have been between 8 and 100 (mu) M. They have been produced by e-beam direct writing in resist. After optimization of the fabrication process the diffraction efficiencies of al sections have been beyond 86 percent with good reproducibility. Special techniques have been sued for system integration. The FAC microlenses have been attached to a copper lens holder with a subsequent gluing process of the holder to the laser diode heatsink. A UV-curable adhesive with extremely low shrinkage has been selected. The redirector element has been integrated with an additional possibility for lateral adjustment in order to compensate minor residual walk-off effects of the microlens when the laser power is varied from zero to maximum. A very compact pumping source of 3 inches X 1 inch X 1 inch dimensions has been realized with 5 W optical power in the desired spot. First diode pumped fiber laser operation in the visible has been demonstrated with this source.

In vivo monitoring of glial scar proliferation on chronically implanted neural electrodes by fiber optical coherence tomography

PubMed Central

Xie, Yijing; Martini, Nadja; Hassler, Christina; Kirch, Robert D.; Stieglitz, Thomas; Seifert, Andreas; Hofmann, Ulrich G.

2014-01-01

In neural prosthetics and stereotactic neurosurgery, intracortical electrodes are often utilized for delivering therapeutic electrical pulses, and recording neural electrophysiological signals. Unfortunately, neuroinflammation impairs the neuron-electrode-interface by developing a compact glial encapsulation around the implants in long term. At present, analyzing this immune reaction is only feasible with post-mortem histology; currently no means for specific in vivo monitoring exist and most applicable imaging modalities can not provide information in deep brain regions. Optical coherence tomography (OCT) is a well established imaging modality for in vivo studies, providing cellular resolution and up to 1.2 mm imaging depth in brain tissue. A fiber based spectral domain OCT was shown to be capable of minimally invasive brain imaging. In the present study, we propose to use a fiber based spectral domain OCT to monitor the progression of the tissue's immune response through scar encapsulation progress in a rat animal model. A fine fiber catheter was implanted in rat brain together with a flexible polyimide microelectrode in sight both of which acts as a foreign body and induces the brain tissue immune reaction. OCT signals were collected from animals up to 12 weeks after implantation and thus gliotic scarring in vivo monitored for that time. Preliminary data showed a significant enhancement of the OCT backscattering signal during the first 3 weeks after implantation, and increased attenuation factor of the sampled tissue due to the glial scar formation. PMID:25191264

Optical stimulation of the prostate nerves: A potential diagnostic technique

NASA Astrophysics Data System (ADS)

Tozburun, Serhat

There is wide variability in sexual potency rates (9--86%) after nerve-sparing prostate cancer surgery due to limited knowledge of the location of the cavernous nerves (CN's) on the prostate surface, which are responsible for erectile function. Thus, preservation of the CN's is critical in preserving a man's ability to have spontaneous erections following surgery. Nerve-mapping devices, utilizing conventional Electrical Nerve Stimulation (ENS) techniques, have been used as intra-operative diagnostic tools to assist in preservation of the CN. However, these technologies have proven inconsistent and unreliable in identifying the CN's due to the need for physical contact, the lack of spatial selectivity, and the presence of electrical artifacts in measurements. Optical Nerve Stimulation (ONS), using pulsed infrared laser radiation, is studied as an alternative to ENS. The objective of this study is sevenfold: (1) to develop a laparoscopic laser probe for ONS of the CN's in a rat model, in vivo; (2) to demonstrate faster ONS using continuous-wave infrared laser radiation; (3) to describe and characterize the mechanism of successful ONS using alternative laser wavelengths; (4) to test a compact, inexpensive all-single-mode fiber configuration for optical stimulation of the rat CN studies; (5) to implement fiber optic beam shaping methods for comparison of Gaussian and flat-top spatial beam profiles during ONS; (6) to demonstrate successful ONS of CN's through a thin layer of fascia placed over the nerve and prostate gland; and (7) to verify the experimentally determined therapeutic window for safe and reliable ONS without thermal damage to the CN's by comparison with a computational model for thermal damage. A 5.5-Watt Thulium fiber laser operated at 1870 nm and two pigtailed, single mode, near-IR diode lasers (150-mW, 1455-nm laser and 500-mW, 1550-nm laser) were used for non-contact stimulation of the rat CN's. Successful laser stimulation, as measured by an intracavernous pressure (ICP) response in the penis, was achieved with the laser operating in CW mode. CW optical nerve stimulation provides a significantly faster ICP response time using a lower laser power laser than conventional pulsed stimulation. An all-single-mode fiber design was successfully tested in a rat model. The CN reached a threshold temperature of ˜ 42 °C, with response times as short as 3 s, and ICP responses in the rat penis of up to 50 mmHg compared to a baseline of 5--10 mmHg. Chemical etching of the distal single-mode-fiber tip produced a concave shape and transformed the Gaussian to a flat-top spatial beam profile, resulting in simplified alignment of the laser beam with the nerve. This novel, all-single-mode-fiber laser nerve stimulation system introduces several advantages including: (1) a less expensive and more compact ONS configuration; (2) elimination of alignment and cleaning bulk optical components; and (3) improved spatial beam profile for simplified alignment. For the fascia layers over the CN's (240--600 microm), the 1550 nm laser with an optical penetration depth of ˜ 930 microm in water was substituted for the 1455 nm laser. Successful ONS was achieved, for the first time, in fascia layers up to 450 microm thick which is critical for future clinical translation of this method for intra-operative identification and preservation of CN's during prostate cancer surgery. In order to define the upper limit of the therapeutic window for ONS of CN in a rat model, in vivo, identification of the thermal damage threshold for the CN after laser irradiation was investigated by direct comparison of the visible thermal damage data with a theoretical thermal damage calculation utilizing a standard Arrhenius integral model.

Adaptive optics full-field OCT: a resolution almost insensitive to aberrations (Conference Presentation)

NASA Astrophysics Data System (ADS)

Xiao, Peng; Fink, Mathias; Boccara, A. Claude

2016-03-01

A Full-Field OCT (FFOCT) setup coupled to a compact transmissive liquid crystal spatial light modulator (LCSLM) is used to induce or correct aberrations and simulate eye examinations. To reduce the system complexity, strict pupil conjugation was abandoned. During our work on quantifying the effect of geometrical aberrations on FFOCT images, we found that the image resolution is almost insensitive to aberrations. Indeed if the object channel PSF is distorted, its interference with the reference channel conserves the main feature of an unperturbed PSF with only a reduction of the signal level. This unique behavior is specific to the use of a spatially incoherent illumination. Based on this, the FFOCT image intensity was used as the metric for our wavefront sensorless correction. Aberration correction was first conducted on an USAF resolution target with the LSCLM as both aberration generator and corrector. A random aberration mask was induced, and the low-order Zernike Modes were corrected sequentially according to the intensity metric function optimization. A Ficus leaf and a fixed mouse brain tissue slice were also imaged to demonstrate the correction of sample self-induced wavefront distortions. After optimization, more structured information appears for the leaf imaging. And the high-signal fiber-like myelin fiber structures were resolved much more clearly after the whole correction process for mouse brain imaging. Our experiment shows the potential of this compact AO-FFOCT system for aberration correction imaging. This preliminary approach that simulates eyes aberrations correction also opens the path to a simple implementation of FFOCT adaptive optics for retinal examinations.

Compact Mach-Zehnder interferometer based on photonic crystal fiber and its application in switchable multi-wavelength fiber laser

NASA Astrophysics Data System (ADS)

Chen, Weiguo; Lou, Shuqin; Wang, Liwen; Li, Honglei; Guo, Tieying; Jian, Shuisheng

2009-08-01

The compact Mach-Zehnder interferometer is proposed by splicing a section of photonic crystal fiber (PCF) and two pieces of single mode fiber (SMF) with the air-holes of PCF intentionally collapsed in the vicinity of the splices. The depedence of the fringe spacing on the length of PCF is investigated. Based on the Mach-Zehnder interferometer as wavelength-selective filter, a switchable dual-wavelength fiber ring laser is demonstrated with a homemade erbiumdoped fiber amplifier (EDFA) as the gain medium at room temperature. By adjusting the states of the polarization controller (PC) appropriately, the laser can be switched among the stable single-and dual -wavelength lasing operations by exploiting polarization hole burning (PHB) effect.

Cell identification using Raman spectroscopy in combination with optical trapping and microfluidics

NASA Astrophysics Data System (ADS)

Krafft, Christoph; Dochow, Sebastian; Beleites, Claudia; Popp, Jürgen

2014-03-01

Cell identification by Raman spectroscopy has evolved to be an attractive complement to established optical techniques. Raman activated cell sorting (RACS) offers prospects to complement the widely applied fluorescence activated cell sorting. RACS can be realized by combination with optical traps and microfluidic devices. The progress of RACS is reported for a cellular model system that can be found in peripheral blood of tumor patients. Lymphocytes and erythrocytes were extracted from blood samples. Breast carcinoma derived tumor cells (MCF-7, BT-20) and acute myeloid leukemia cells (OCI-AML3) were grown in cell cultures. First, Raman images were collected from dried cells on calcium fluoride slides. Support vector machines (SVM) classified 99.7% of the spectra to the correct cell type. Second, a 785 nm laser was used for optical trapping of single cells in aqueous buffer and for excitation of the Raman spectrum. SVM distinguished 1210 spectra of tumor and normal cells with a sensitivity of >99.7% and a specificity of >99.5%. Third, a microfluidic glass chip was designed to inject single cells, modify the flow speed, accommodate fibers of an optical trap and sort single cells after Raman based identification with 514 nm for excitation. Forth, the microfluidic chip was fabricated by quartz which improved cell identification results with 785 nm excitation. Here, partial least squares discriminant analysis gave classification rates of 98%. Finally, a Raman-on-chip approach was developed that integrates fibers for trapping, Raman excitation and signal detection in a single compact unit.

Optimal arrangements of fiber optic probes to enhance the spatial resolution in depth for 3D reflectance diffuse optical tomography with time-resolved measurements performed with fast-gated single-photon avalanche diodes

NASA Astrophysics Data System (ADS)

Puszka, Agathe; Di Sieno, Laura; Dalla Mora, Alberto; Pifferi, Antonio; Contini, Davide; Boso, Gianluca; Tosi, Alberto; Hervé, Lionel; Planat-Chrétien, Anne; Koenig, Anne; Dinten, Jean-Marc

2014-02-01

Fiber optic probes with a width limited to a few centimeters can enable diffuse optical tomography (DOT) in intern organs like the prostate or facilitate the measurements on extern organs like the breast or the brain. We have recently shown on 2D tomographic images that time-resolved measurements with a large dynamic range obtained with fast-gated single-photon avalanche diodes (SPADs) could push forward the imaged depth range in a diffusive medium at short source-detector separation compared with conventional non-gated approaches. In this work, we confirm these performances with the first 3D tomographic images reconstructed with such a setup and processed with the Mellin- Laplace transform. More precisely, we investigate the performance of hand-held probes with short interfiber distances in terms of spatial resolution and specifically demonstrate the interest of having a compact probe design featuring small source-detector separations. We compare the spatial resolution obtained with two probes having the same design but different scale factors, the first one featuring only interfiber distances of 15 mm and the second one, 10 mm. We evaluate experimentally the spatial resolution obtained with each probe on the setup with fast-gated SPADs for optical phantoms featuring two absorbing inclusions positioned at different depths and conclude on the potential of short source-detector separations for DOT.

Metal-Coated Optical Fibers for High Temperature Applications

NASA Technical Reports Server (NTRS)

Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

1996-01-01

This poster will highlight on-going research at the Virginia Tech Fiber & Electro-Optics Research Center (FEORC) in the area of thin films on optical fibers. Topics will include the sputter deposition of metals and metal; alloys onto optical fiber and fiber optic sensors for innovative applications. Specific information will be available on thin film fiber optic hydrogen sensors, corrosion sensors, and metal-coated optical fiber for high temperature aerospace applications.

The Level 0 Pixel Trigger system for the ALICE experiment

NASA Astrophysics Data System (ADS)

Aglieri Rinella, G.; Kluge, A.; Krivda, M.; ALICE Silicon Pixel Detector project

2007-01-01

The ALICE Silicon Pixel Detector contains 1200 readout chips. Fast-OR signals indicate the presence of at least one hit in the 8192 pixel matrix of each chip. The 1200 bits are transmitted every 100 ns on 120 data readout optical links using the G-Link protocol. The Pixel Trigger System extracts and processes them to deliver an input signal to the Level 0 trigger processor targeting a latency of 800 ns. The system is compact, modular and based on FPGA devices. The architecture allows the user to define and implement various trigger algorithms. The system uses advanced 12-channel parallel optical fiber modules operating at 1310 nm as optical receivers and 12 deserializer chips closely packed in small area receiver boards. Alternative solutions with multi-channel G-Link deserializers implemented directly in programmable hardware devices were investigated. The design of the system and the progress of the ALICE Pixel Trigger project are described in this paper.