Longitudinal residual stresses in boron fibers

NASA Technical Reports Server (NTRS)

Behrendt, D. R.

1976-01-01

A method of measuring the longitudinal residual stress distribution in boron fibers is presented. The residual stresses in commercial CVD boron on tungsten fibers of 102, 142, and 203 microns (4, 5.6, and 8 mil) diameters were determined. Results for the three sizes show a compressive stress at the surface 800 to -1400 MN/sq m 120 to -200 ksi), changing monotonically to a region of tensile stress within the boron. At approximately 25 percent of the original radius, the stress reaches a maximum tensile 600 to 1000 MN/sq m(90 to 150 ksi) and then decreases to compressive near the tungsten boride core. The core itself is under a compressive stress of approximately -1300 MN/sq m (-190 ksi). The effects of surface removal on core residual stress and core-initiated fracture are discussed.

A flexible tactile sensitive sheet using a hetero-core fiber optic sensor

NASA Astrophysics Data System (ADS)

Fujino, S.; Yamazaki, H.; Hosoki, A.; Watanabe, K.

2014-05-01

In this report, we have designed a tactile sensitive sheet based on a hetero-core fiber-optic sensor, which realize an areal sensing by using single sensor potion in one optical fiber line. Recently, flexible and wide-area tactile sensing technology is expected to applied to acquired biological information in living space and robot achieve long-term care services such as welfare and nursing-care and humanoid technology. A hetero-core fiber-optic sensor has several advantages such as thin and flexible transmission line, immunity to EMI. Additionally this sensor is sensitive to moderate bending actions with optical loss changes and is independent of temperature fluctuation. Thus, the hetero-core fiber-optic sensor can be suitable for areal tactile sensing. We measure pressure characteristic of the proposed sensitive sheet by changing the pressure position and pinching characteristic on the surface. The proposed tactile sensitive sheet shows monotonic responses on the whole sensitive sheet surface although different sensitivity by the position is observed at the sensitive sheet surface. Moreover, the tactile sensitive sheet could sufficiently detect the pinching motion. In addition, in order to realize the discrimination between pressure and pinch, we fabricated a doubled-over sensor using a set of tactile sensitive sheets, which has different kinds of silicon robbers as a sensitive sheet surface. In conclusion, the flexible material could be given to the tactile sensation which is attached under proposed sensitive sheet.

Processing and characterization of polycrystalline YAG (Yttrium Aluminum Garnet) core-clad fibers

NASA Astrophysics Data System (ADS)

Kim, Hyun Jun; Fair, Geoff E.; Potticary, Santeri A.; O'Malley, Matthew J.; Usechak, Nicholas G.

2014-06-01

Polycrystalline YAG fiber has recently attracted considerable attention for the role it could play as a fiber-laser gain media. This primarily due to its large surface-to-volume ratio, high stimulated Brillouin scattering threshold, and its high thermal conductivity; all of which are superior to that of silica-glass fibers. As a consequence, techniques which enable the fabrication of poly- and single-crystalline YAG fibers have recently been the focus of a number of efforts. In this work we have endeavored to reduce the scattering loss of polycrystalline-YAG-core fibers while simultaneously demonstrating optical gain by enhancing our processing techniques using feedback from mechanical testing and through the development of a technique to encase doped YAG-core fibers with un-doped YAG claddings. To this end we have recently fabricated fibers with both core and claddings made up of polycrystalline YAG and subsequently confirmed that they indeed guide light. In this paper, the processes leading to the fabrication of these fibers will be discussed along with their characterization.

Effect of surface treatments on the bond strength of CAD/CAM fiberglass posts

PubMed Central

Garcia, Paula-Pontes; da Costa, Rogério-Goulart; Garcia, André-Vivan; Gonzaga, Carla-Castiglia; da Cunha, Leonardo-Fernandes; Rezende, Carlos-Eduardo-Edwards

2018-01-01

Background There is no ideal protocol for the surface treatment of fiber posts, especially when using a computer-aided design/computer-aided manufacturing (CAD/CAM) experimental fiberglass block. The purpose of this study was to evaluate the bond strength of a CAD/CAM customized glass fiber post and core after applying different surface treatment techniques. Material and Methods Forty premolars were prepared to receive a customized CAD/CAM glass-fiber post and core obtained from an experimental block of glass fiber and epoxy resin. The specimens were randomly distributed in 4 groups (n=10) according to the post and core surface treatment: ETH - 70% ethanol; HP - 24% hydrogen peroxide for 1 minute; ETH/S - 70% ethanol + silane; HP/S - 24% hydrogen peroxide + silane. The universal adhesive containing silane was applied on the posts and prepared post spaces in all groups. The posts were cemented using dual cure resin cement. The specimens were stored in distilled water at 37°C for 24 h, cut (two slices of 1 mm for each root third - coronal, middle, and apical) and subjected to push-out test (0.5 mm/min). Data was subjected to two-way ANOVA (surface treatment and root third) and Tukey’s test (α=0,05). Results There was no significant difference of bond strength values among groups, regardless the surface treatment (p >0.05). There was significant difference on bond strength values for the different root thirds (p<0.05) (coronal>middle=apical). Conclusions The different surface treatment and application of additional silane in the CAD/CAM customized glass-fiber post and core does not interfere on bond strength values. The root dentin third interfered on the bond strength, with higher values for the coronal third. Key words:Post and core technique, cad/cam, shear strength, hydrogen peroxide. PMID:29930778

Core-Shell Composite Fibers for High-Performance Flexible Supercapacitor Electrodes.

PubMed

Lu, Xiaoyan; Shen, Chen; Zhang, Zeyang; Barrios, Elizabeth; Zhai, Lei

2018-01-31

Core-shell nanofibers containing poly(acrylic acid) (PAA) and manganese oxide nanoparticles as the core and polypyrrole (PPy) as the shell were fabricated through electrospinning the solution of PAA and manganese ions (PAA/Mn 2+ ). The obtained nanofibers were stabilized by Fe 3+ through the interaction between Fe 3+ ions and carboxylate groups. Subsequent oxidation of Mn 2+ by KMnO 4 produced uniform manganese dioxide (MnO 2 ) nanoparticles in the fibers. A PPy shell was created on the fibers by immersing the fibers in a pyrrole solution where the Fe 3+ ions in the fiber polymerized the pyrrole on the fiber surfaces. In the MnO 2 @PAA/PPy core-shell composite fibers, MnO 2 nanoparticles function as high-capacity materials, while the PPy shell prevents the loss of MnO 2 during the charge/discharge process. Such a unique structure makes the composite fibers efficient electrode materials for supercapacitors. The gravimetric specific capacity of the MnO 2 @PAA/PPy core-shell composite fibers was 564 F/g based on cyclic voltammetry curves at 10 mV/s and 580 F/g based on galvanostatic charge/discharge studies at 5 A/g. The MnO 2 @PAA/PPy core-shell composite fibers also present stable cycling performance with 100% capacitance retention after 5000 cycles.

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, S.M.; Sharma, S.K.

1988-11-01

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber having a metal coating on at least a portion of a light transmissive core. The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the absorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode may function as a working electrode of an electrochemical cell while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface. 6 figs.

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, S.M.; Sharma, S.K.

1987-11-30

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber having a metal coating on at least a portion of a light transmissive core. The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the adsorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode may function as a working electrode of an electrochemical cell while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface. 6 figs.

Conductive cable fibers with insulating surface prepared by co-axial electrospinning of multi-walled nanotubes and cellulose

PubMed Central

Miyauchi, Minoru; Miao, Jianjun; Simmons, Trevor J.; Lee, Jong-Won; Doherty, Thomas V.; Dordick, Jonathan S.; Linhardt, Robert J.

2010-01-01

A core-sheath of multi-walled carbon nanotube (MWNT)-cellulose fibers of diameters from several hundreds nm to several µm were prepared by co-axial electrospinning from a non-valatile, non-flammable ionic liquid (IL) solvent, 1-methyl-3-methylimidazolium acetate ([EMIM][Ac]). MWNTs were dispersed in IL to form a gel solution. This gel core solution was electrospun surrounded by a sheath solution of cellulose disolved in the same IL. Electrospun fibers were collected in a coagulation bath containing ethanol-water to completely remove the IL and dried to form a core-sheath MWNT-cellulose fibers having a cable structure with a conductive core and insulating sheath. Enzymatic treatment of a portion of a mat of these fibers with cellulase selectively removed the cellulose sheath exposing the MWNT core for connection to an electrode. These MWNT-cellulose fiber mats demonstrated excellent conductivity due to a conductive pathway of bundleled MWNTs. Fiber mat conductivity increased with increasing ratio of MWNT in the fibers with a maximum conductivity of 10.7 S/m obtained at 45 wt% MWNT loading. PMID:20690644

Conductive cable fibers with insulating surface prepared by coaxial electrospinning of multiwalled nanotubes and cellulose.

PubMed

Miyauchi, Minoru; Miao, Jianjun; Simmons, Trevor J; Lee, Jong-Won; Doherty, Thomas V; Dordick, Jonathan S; Linhardt, Robert J

2010-09-13

Core-sheath multiwalled carbon nanotube (MWNT)-cellulose fibers of diameters from several hundreds of nanometers to several micrometers were prepared by coaxial electrospinning from a nonvolatile, nonflammable ionic liquid (IL) solvent, 1-methyl-3-methylimidazolium acetate ([EMIM][Ac]). MWNTs were dispersed in IL to form a gel solution. This gel core solution was electrospun surrounded by a sheath solution of cellulose dissolved in the same IL. Electrospun fibers were collected in a coagulation bath containing ethanol-water to remove the IL completely and dried to form core-sheath MWNT-cellulose fibers having a cable structure with a conductive core and insulating sheath. Enzymatic treatment of a portion of a mat of these fibers with cellulase selectively removed the cellulose sheath exposing the MWNT core for connection to an electrode. These MWNT-cellulose fiber mats demonstrated excellent conductivity because of a conductive pathway of bundled MWNTs. Fiber mat conductivity increased with increasing ratio of MWNT in the fibers with a maximum conductivity of 10.7 S/m obtained at 45 wt % MWNT loading.

Response of Metal Core Piezoelectric Fibers to Unsteady Airflows

NASA Astrophysics Data System (ADS)

Qiu, J. H.; Ji, H. L.; Zhu, K. J.; Park, M. J.

In the previous study, possible applications of metal core piezoelectric fibers with a diameter of 200 to 250 µm as bionic airflow sensors mimicking the flow sensitive receptor hairs of crickets have been proposed. This study aims to investigate the dynamic responses of the metal core piezoelectric fibers to unsteady airflow. The metal core piezoelectric fiber is half coated on the outer surface and is used in the bending mode. Wind tunnel tests were carried out and the output voltage of the fiber under the excitation of the unsteady aerodynamic force during flow acceleration and deceleration was measured when the wind tunnel was suddenly closed or opened by a shutter. The relationship between the maximum voltage and the steady-state velocity and that between the voltage and the acceleration of flow were also obtained.

Application of Diffuse Reflectance FT-IR Spectroscopy for the Surface Study of Kevlar Fibers

NASA Astrophysics Data System (ADS)

Chatzi, E. G.; Ishida, H.; Koenig, J. L.

1985-12-01

The surfaces of Kevlar-49 aramid fibers, being used in high-performance composite materials, have been characterized by diffuse reflectance Fourier transform infrared (FT-IR) spectroscopy. Enhancement of the surface selectivity of the technique has been achieved using KBr overlayers. The water absorbed by both the skin and the core of the fibers has been characterized by using this technique and the accessibility of the fiber functional groups has been evaluated.

Rare-earth-doped optical-fiber core deposition using full vapor-phase SPCVD process

NASA Astrophysics Data System (ADS)

Barnini, A.; Robin, T.; Cadier, B.; Aka, G.; Caurant, D.; Gotter, T.; Guyon, C.; Pinsard, E.; Guitton, P.; Laurent, A.; Montron, R.

2017-02-01

One key parameter in the race toward ever-higher power fiber lasers remains the rare earth doped optical core quality. Modern Large Mode Area (LMA) fibers require a fine radial control of the core refractive index (RI) close to the silica level. These low RI are achieved with multi-component materials that cannot be readily obtained using conventional solution doping based Modified Chemical Vapor Deposition (MCVD) technology. This paper presents a study of such optical material obtained through a full-vapor phase Surface Plasma Chemical Vapor Deposition (SPCVD). The SPCVD process generates straight glassy films on the inner surface of a thermally regulated synthetic silica tube under vacuum. The first part of the presented results points out the feasibility of ytterbium-doped aluminosilicate fibers by this process. In the second part we describe the challenge controlling the refractive index throughout the core diameter when using volatile fluorine to create efficient LMA fiber profiles. It has been demonstrated that it is possible to counter-act the loss of fluorine at the center of the core by adjusting the core composition locally. Our materials yielded, when used in optical fibers with numerical apertures ranging from 0.07 to 0.09, power conversion efficiency up to 76% and low background losses below 20 dB/km at 1100nm. Photodarkening has been measured to be similar to equivalent MCVD based fibers. The use of cerium as a co-dopant allowed for a complete mitigation of this laser lifetime detrimental effect. The SPCVD process enables high capacity preforms and is particularly versatile when it comes to radial tailoring of both rare earth doping level and RI. Large core diameter preforms - up to 4mm - were successfully produced.

Techniques for increasing boron fiber fracture strain

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.

1977-01-01

Improvement in the strain-to-failure of CVD boron fibers is shown possible by contracting the tungsten boride core region and its inherent flaws. The results of three methods are presented in which etching and thermal processing techniques were employed to achieve core flaw contraction by internal stresses available in the boron sheath. After commercially and treatment induced surface flaws were removed from 203 micrometers (8 mil) fibers, the core flaw was observed to be essentially the only source of fiber fracture. Thus, fiber strain-to-failure was found to improve by an amount equal to the treatment induced contraction on the core flaw. Commercial feasibility considerations suggest as the most cost effective technique that method in which as-produced fibers are given a rapid heat treatment above 700 C. Preliminary results concerning the contraction kinetics and fracture behavior observed are presented and discussed both for high vacuum and argon gas heat treatment environments.

Fabrication and photoluminescence properties of graphite fiber/ZnO nanorod core-shell structures.

PubMed

Liu, Xianbin; Du, Hejun; Liu, Bo; Wang, Jianxiong; Sun, Xiao Wei; Sun, Handong

2011-08-01

Graphite fiber/ZnO nanorod core-shell structures were synthesized by thermal evaporation process. The core-shell hybrid architectures were comprised of ZnO nanorods grown on the surface of graphite fiber. In addition, Hollow ZnO hierarchical structure can be obtained by oxidizing the graphite fiber. Room temperature photoluminescence (PL) of the as-made graphite fiber/ZnO nanorod structures shows two UV peaks at around 3.274 eV and 3.181 eV. The temperature-dependent photoluminescence spectra demonstrate the two UV emissions are attributed to the intrinsic optical transitions and extrinsic defect-related emissions in ZnO. These hybrid structures may be used as the building block for fabrication of nanodevices.

Nd:YAG-laser-based time-domain reflectometry measurements of the intrinsic reflection signature from PMMA fiber splices

NASA Astrophysics Data System (ADS)

Lawson, Christopher M.; Michael, Robert R., Jr.; Dressel, Earl M.; Harmony, David W.

1991-12-01

Optical time domain reflectometry (OTDR) measurements have been performed on polished polymethylmethacrylate (PMMA) plastic fiber splices. After the dominant splice reflection sources due to surface roughness, inexact index matching, and fiber core misalignment were eliminated, an intrinsic OTDR signature 3 - 8 dB above the Rayleigh backscatter floor remained with all tested fibers. This minimum splice reflectivity exhibits characteristics that are consistent with sub-surface polymer damage and can be used for detection of PMMA fiber splices.

Liquid droplet sensing using twisted optical fiber couplers fabricated by hydrofluoric acid flow etching

NASA Astrophysics Data System (ADS)

Son, Gyeongho; Jung, Youngho; Yu, Kyoungsik

2017-04-01

We report a directional-coupler-based refractive index sensor and its cost-effective fabrication method using hydrofluoric acid droplet wet-etching and surface-tension-driven liquid flows. The proposed fiber sensor consists of a pair of twisted tapered optical fibers with low excess losses. The fiber cores in the etched microfiber region are exposed to the surrounding medium for efficient interaction with the guided light. We observe that the etching-based low-loss fiber-optic sensors can measure the water droplet volume by detecting the refractive index changes of the surrounding medium around the etched fiber core region.

Method for the preparation of carbon fiber from polyolefin fiber precursor

DOEpatents

Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

2017-11-28

Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

Plasmonic structure: fiber grating formed by gold nanorods on a tapered fiber.

PubMed

Trevisanutto, J O; Linhananta, A; Das, G

2016-12-15

The authors demonstrated the fabrication of a fiber Bragg grating-like plasmonic nanostructure on the surface of a tapered optical fiber using gold nanorods (GNRs). A multimode optical fiber with core and cladding diameters of 105 and 125 μm, respectively, was used to make a tapered fiber using a dynamic etching process. The tip diameter was ∼100  nm. Light from a laser was coupled to the untapered end of the fiber, which produced a strong evanescent field around the tapered section of the fiber. The gradient force due to the evanescent field trapped the GNRs on the surface of the tapered fiber. The authors explored possible causes of the GNR distribution. The plasmonic structure will be a good candidate for sensing based on surface enhanced Raman scattering.

Selective pH-Responsive Core-Sheath Nanofiber Membranes for Chem/Bio/Med Applications: Targeted Delivery of Functional Molecules.

PubMed

Han, Daewoo; Steckl, Andrew J

2017-12-13

Core-sheath fibers using different Eudragit materials were successfully produced, and their controlled multi-pH responses have been demonstrated. Core-sheath fibers made of Eudragit L 100 (EL100) core and Eudragit S 100 (ES100) sheath provide protection and/or controlled release of core material at pH 6 by adjusting the sheath thickness (controlled by the flow rate of source polymer solution). The thickest sheath (∼250 nm) provides the least core release ∼1.25%/h, while the thinnest sheath (∼140 nm) provides much quicker release ∼16.75%/h. Furthermore, switching core and sheath material dramatically altered the pH response. Core-sheath fibers made of ES100 core and EL100 sheath can provide a consistent core release rate, while the sheath release rate becomes higher as the sheath layer becomes thinner. For example, the thinnest sheath (∼120 nm) provides a core and sheath release ratio of 1:2.5, while the thickest sheath (∼200 nm) shows only a ratio of 1:1.7. All core-sheath Eudragit fibers show no noticeable release at pH 5, while they are completely dissolved at pH 7. Extremely high surface area in the porous network of the fiber membranes provides much faster (>30 times) response to external pH changes as compared to that of equivalent cast films.

Method for the preparation of carbon fiber from polyolefin fiber precursor, and carbon fibers made thereby

DOEpatents

Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

2015-08-04

Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

Enhanced chemiluminescent detection scheme for trace vapor sensing in pneumatically-tuned hollow core photonic bandgap fibers.

PubMed

Stolyarov, Alexander M; Gumennik, Alexander; McDaniel, William; Shapira, Ofer; Schell, Brent; Sorin, Fabien; Kuriki, Ken; Benoit, Gilles; Rose, Aimee; Joannopoulos, John D; Fink, Yoel

2012-05-21

We demonstrate an in-fiber gas phase chemical detection architecture in which a chemiluminescent (CL) reaction is spatially and spectrally matched to the core modes of hollow photonic bandgap (PBG) fibers in order to enhance detection efficiency. A peroxide-sensitive CL material is annularly shaped and centered within the fiber's hollow core, thereby increasing the overlap between the emission intensity and the intensity distribution of the low-loss fiber modes. This configuration improves the sensitivity by 0.9 dB/cm compared to coating the material directly on the inner fiber surface, where coupling to both higher loss core modes and cladding modes is enhanced. By integrating the former configuration with a custom-built optofluidic system designed for concomitant controlled vapor delivery and emission measurement, we achieve a limit-of-detection of 100 parts per billion (ppb) for hydrogen peroxide vapor. The PBG fibers are produced by a new fabrication method whereby external gas pressure is used as a control knob to actively tune the transmission bandgaps through the entire visible range during the thermal drawing process.

Proximal fiber tip damage during Holmium:YAG and thulium fiber laser ablation of kidney stones

NASA Astrophysics Data System (ADS)

Wilson, Christopher R.; Hardy, Luke A.; Irby, Pierce B.; Fried, Nathaniel M.

2016-02-01

The Thulium fiber laser (TFL) is being studied as an alternative to Holmium:YAG laser for lithotripsy. TFL beam originates within an 18-μm-core thulium doped silica fiber, and its near single mode, Gaussian beam profile enables transmission of higher laser power through smaller fibers than possible during Holmium laser lithotripsy. This study examines whether TFL beam profile also reduces proximal fiber tip damage compared to Holmium laser multimodal beam. TFL beam at wavelength of 1908 nm was coupled into 105-μm-core silica fibers, with 35-mJ energy, 500-μs pulse duration, and pulse rates of 50-500 Hz. For each pulse rate, 500,000 pulses were delivered. Magnified images of proximal fiber surfaces were taken before and after each trial. For comparison, 20 single-use, 270-μm-core fibers were collected after clinical Holmium laser lithotripsy procedures using standard settings (600 mJ, 350 μs, 6 Hz). Total laser energy, number of laser pulses, and laser irradiation time were recorded, and fibers were rated for damage. For TFL studies, output power was stable, and no proximal fiber damage was observed after delivery of 500,000 pulses at settings up to 35 mJ, 500 Hz, and 17.5 W average power. In contrast, confocal microscopy images of fiber tips after Holmium lithotripsy showed proximal fiber tip degradation in all 20 fibers. The proximal fiber tip of a 105-μm-core fiber transmitted 17.5 W of TFL power without degradation, compared to degradation of 270-μm-core fibers after transmission of 3.6 W of Holmium laser power. The smaller and more uniform TFL beam profile may improve fiber lifetime, and potentially reduce costs for the surgical disposables as well.

Photonic Crystal Fiber-Based Surface Plasmon Resonance Sensor with Selective Analyte Channels and Graphene-Silver Deposited Core

PubMed Central

Rifat, Ahmmed A.; Mahdiraji, G. Amouzad; Chow, Desmond M.; Shee, Yu Gang; Ahmed, Rajib; Adikan, Faisal Rafiq Mahamd

2015-01-01

We propose a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs). Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber’s properties and sensing performance are performed using the finite element method (FEM). The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU−1) with resolution as high as 2.4 × 10−5 RIU. Using the wavelength interrogation method, a maximum refractive index (RI) sensitivity of 3000 nm/RIU in the sensing range of 1.46–1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor’s footprint. PMID:25996510

Coaxial Electrospinning and Characterization of Core-Shell Structured Cellulose Nanocrystal Reinforced PMMA/PAN Composite Fibers

PubMed Central

Li, Chao; Li, Qingde; Ni, Xiaohui; Liu, Guoxiang; Cheng, Wanli; Han, Guangping

2017-01-01

A modified coaxial electrospinning process was used to prepare composite nanofibrous mats from a poly(methyl methacrylate) (PMMA) solution with the addition of different cellulose nanocrystals (CNCs) as the sheath fluid and polyacrylonitrile (PAN) solution as the core fluid. This study investigated the conductivity of the as-spun solutions that increased significantly with increasing CNCs addition, which favors forming uniform fibers. This study discussed the effect of different CNCs addition on the morphology, thermal behavior, and the multilevel structure of the coaxial electrospun PMMA + CNCs/PAN composite nanofibers. A morphology analysis of the nanofibrous mats clearly demonstrated that the CNCs facilitated the production of the composite nanofibers with a core-shell structure. The diameter of the composite nanofibers decreased and the uniformity increased with increasing CNCs concentrations in the shell fluid. The composite nanofibrous mats had the maximum thermal decomposition temperature that was substantially higher than electrospun pure PMMA, PAN, as well as the core-shell PMMA/PAN nanocomposite. The BET (Brunauer, Emmett and Teller) formula results showed that the specific surface area of the CNCs reinforced core-shell composite significantly increased with increasing CNCs content. The specific surface area of the composite with 20% CNCs loading rose to 9.62 m2/g from 3.76 m2/g for the control. A dense porous structure was formed on the surface of the electrospun core-shell fibers. PMID:28772933

Fabrication of a polyvinylidene difluoride fiber with a metal core and its application as directional air flow sensor

NASA Astrophysics Data System (ADS)

Bian, Yixiang; Liu, Rongrong; Hui, Shen

2016-09-01

We fabricated a sensitive air flow detector that mimic the sensing mechanism found at the tail of some insects. [see Y. Yang, A. Klein, H. Bleckmann and C. Liu, Appl. Phys. Lett. 99(2) (2011); J. J. Heys, T. Gedeon, B. C. Knott and Y. Kim, J. Biomech. 41(5), 977 (2008); J. Tao and X. Yu, Smart Mat. Struct. 21(11) (2012)]. Our bionic airflow sensor uses a polyvinylidene difluoride (PVDF) microfiber with a molybdenum core which we produced with the hot extrusion tensile method. The surface of the fiber is partially coated with conductive silver adhesive that serve as surface electrodes. A third electrode, the metal core is used to polarize polyvinylidene difluoride (PVDF) under the surface electrodes. The cantilever beam structure of the prepared symmetric electrodes of metal core piezoelectric fiber (SMPF) is used as the artificial hair airflow sensor. The surface electrodes are used to measure output voltage. Our theoretical and experimental results show that the SMPF responds fast to air flow changes, the output charge has an exponential correlation with airflow velocity and a cosine relation with the direction of airflow. Our bionic airflow sensor with directional sensing ability can also measure air flow amplitude. [see H. Droogendijk, R. G. P. Sanders and G. J. M. Krijnen, New J. Phys. 15 (2013)]. By using two surface electrodes, our sensing circuit further improves sensitivity.

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, Stanley M.; Sharma, Shiv K.

1988-01-01

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber (13, 13a to 13e) having a metal coating (22, 22a to 22e) on at least a portion of a light transmissive core (17, 17a to 17d). The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the absorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector (16, 16d, 16e) analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode (13e) may function as a working electrode of an electrochemical cell (53) while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface.

An in-line Mach-Zehnder Interferometer Using Thin-core Fiber for Ammonia Gas Sensing With High Sensitivity

NASA Astrophysics Data System (ADS)

Huang, Xinyue; Li, Xueming; Yang, Jianchun; Tao, Chuanyi; Guo, Xiaogang; Bao, Hebin; Yin, Yanjun; Chen, Huifei; Zhu, Yuhua

2017-04-01

Ammonia is an important indicator among environmental monitoring parameters. In this work, thin-core fiber Mach-Zehnder interferometer deposited with poly (acrylic acid) (PAA), poly (allyamine hydrochloride) (PAH) and single-walled carbon nanotubes (SWCNTs-COOH) sensing film for the detection of ammonia gas has been presented. The thin-core fiber modal interferometer was made by fusion splicing a small section of thin-core fiber (TCF) between two standard single mode fibers (SMF). A beam propagation method (BPM) is employed for the design of proposed interferometer and numerical simulation. Based on the simulation results, interferometer with a length of 2 cm of thin-core fiber is fabricated and experimentally studied. (PAH/PAA)2 + [PAH/(PAA + SWCNTs-COOH)]8 film is deposited on the outer surface of thin-core fiber via layer-by-layer (LbL) self-assembly technique. The gas sensor coated with (PAH/PAA)2 + [PAH/(PAA + SWCNTs-COOH)]8 film towards NH3 gas exposure at concentrations range from 1 to 960 ppm are analyzed and the sensing capability is demonstrated by optical spectrum analyzer (OSA). Experimental results show that the characteristic wavelength shift has an approximately linear relationship in the range 1-20 ppm, which is in accordance with the numerical simulation. Thus, this paper reveals the potential application of this sensor in monitoring low concentration NH3 gas.

Optical fiber head for providing lateral viewing

DOEpatents

Everett, Matthew J.; Colston, Billy W.; James, Dale L.; Brown, Steve; Da Silva, Luiz

2002-01-01

The head of an optical fiber comprising the sensing probe of an optical heterodyne sensing device includes a planar surface that intersects the perpendicular to axial centerline of the fiber at a polishing angle .theta.. The planar surface is coated with a reflective material so that light traveling axially through the fiber is reflected transverse to the fiber's axial centerline, and is emitted laterally through the side of the fiber. Alternatively, the planar surface can be left uncoated. The polishing angle .theta. must be no greater than 39.degree. or must be at least 51.degree.. The emitted light is reflected from adjacent biological tissue, collected by the head, and then processed to provide real-time images of the tissue. The method for forming the planar surface includes shearing the end of the optical fiber and applying the reflective material before removing the buffer that circumscribes the cladding and the core.

Solution blow spun spinel ferrite and highly porous silica nanofibers

USDA-ARS?s Scientific Manuscript database

The novelty of this work is the production of nano- and submicrometric silica and spinel-ferrite fibers using the solution blow spinning (SBS) method. A pseudo-core-shell method for the production of large surface area silica fibers is also reported. Silica fibers present mean diameters and specific...

Bent-core fiber structure: Experimental and theoretical studies of fiber stability

NASA Astrophysics Data System (ADS)

Bailey, C.; Gartland, E.; Jakli, A.

2007-03-01

Recent studies have shown that bent core liquid crystals in the B7 and B2 phases can form stable freestanding fibers with a so called ``jelly-roll'' layer configuration, which means that the smectic layers would be arranged in concentric cylindrical shells. This configuration shows layer curvature is necessary for fiber stability. Classically this effect would destabilize the fiber configuration because of the energy cost of layer distortions and surface tension. We propose a model that can predict fiber stability in the experimentally observed range of a few micrometers, by assuming that layer curvature can be stabilized by including a term dealing with the linear divergence of the polarization direction if the polarization is allowed to have a component normal to the smectic layers. We show that this term can stabilize the fiber configuration if its strength is larger than the surface tension. We also propose an entropic model to explain the strength of this term by considering steric effects. Finally we will take results from this model and apply them to better understand experimental findings of bent-core fibers. Financial support by NSF FRG under contract DMS-0456221. Prof. Daniel Phillips, Particia Bauman and Jie Shen at Purdue Univ., Prof. Maria Carme Calderer at Univ. of Minnesota, and Prof. Jonathan Selinger at Kent State Univ. Liou Qiu and Dr. O.D. Lavrentovich, Characterization Facilities, Liquid Crystal Institute, Kent State Univ. Julie Kim and Dr. Quan Li, Chemical Synthesis Facilities, Liquid Crystal Institute, Kent State Univ.

U-Shaped and Surface Functionalized Polymer Optical Fiber Probe for Glucose Detection.

PubMed

Azkune, Mikel; Ruiz-Rubio, Leire; Aldabaldetreku, Gotzon; Arrospide, Eneko; Pérez-Álvarez, Leyre; Bikandi, Iñaki; Zubia, Joseba; Vilas-Vilela, Jose Luis

2017-12-25

In this work we show an optical fiber evanescent wave absorption probe for glucose detection in different physiological media. High selectivity is achieved by functionalizing the surface of an only-core poly(methyl methacrylate) (PMMA) polymer optical fiber with phenilboronic groups, and enhanced sensitivity by using a U-shaped geometry. Employing a supercontinuum light source and a high-resolution spectrometer, absorption measurements are performed in the broadband visible light spectrum. Experimental results suggest the feasibility of such a fiber probe as a low-cost and selective glucose detector.

An in-fiber integrated optofluidic device based on an optical fiber with an inner core.

PubMed

Yang, Xinghua; Yuan, Tingting; Teng, Pingping; Kong, Depeng; Liu, Chunlan; Li, Entao; Zhao, Enming; Tong, Chengguo; Yuan, Libo

2014-06-21

A new kind of optofluidic in-fiber integrated device based on a specially designed hollow optical fiber with an inner core is designed. The inlets and outlets are built by etching the surface of the optical fiber without damaging the inner core. A reaction region between the end of the fiber and a solid point obtained after melting is constructed. By injecting samples into the fiber, the liquids can form steady microflows and react in the region. Simultaneously, the emission from the chemiluminescence reaction can be detected from the remote end of the optical fiber through evanescent field coupling. The concentration of ascorbic acid (AA or vitamin C, Vc) is determined by the emission intensity of the reaction of Vc, H2O2, luminol, and K3Fe(CN)6 in the optical fiber. A linear sensing range of 0.1-3.0 mmol L(-1) for Vc is obtained. The emission intensity can be determined within 2 s at a total flow rate of 150 μL min(-1). Significantly, this work presents information for the in-fiber integrated optofluidic devices without spatial optical coupling.

Gold nanoparticle-based plasmonic random fiber laser

NASA Astrophysics Data System (ADS)

Hu, Zhijia; Liang, Yunyun; Xie, Kang; Gao, Pengfei; Zhang, Douguo; Jiang, Haiming; Shi, Fan; Yin, Leicheng; Gao, Jiangang; Ming, Hai; Zhang, Qijin

2015-03-01

We have reported the realization of a plasmonic random fiber laser based on the localized surface plasmonic resonance of gold nanoparticles (NPs) in the liquid core optical fiber. The liquid core material contains a dispersive solution of gold NPs and laser dye pyrromethene 597 in toluene. It was experimentally proved that the fluorescence quenching of the dye is restrained in the optical fiber, which is considered one of the main sources of loss in the traditional laser system. Meanwhile, the random lasing can be more easily obtained in the random laser system with more overlap between the plasmonic resonance of the gold NPs and the photoluminescence spectrum of the dye molecules.

An in-line Mach-Zehnder Interferometer Using Thin-core Fiber for Ammonia Gas Sensing With High Sensitivity

PubMed Central

Huang, Xinyue; Li, Xueming; Yang, Jianchun; Tao, Chuanyi; Guo, Xiaogang; Bao, Hebin; Yin, Yanjun; Chen, Huifei; Zhu, Yuhua

2017-01-01

Ammonia is an important indicator among environmental monitoring parameters. In this work, thin-core fiber Mach-Zehnder interferometer deposited with poly (acrylic acid) (PAA), poly (allyamine hydrochloride) (PAH) and single-walled carbon nanotubes (SWCNTs-COOH) sensing film for the detection of ammonia gas has been presented. The thin-core fiber modal interferometer was made by fusion splicing a small section of thin-core fiber (TCF) between two standard single mode fibers (SMF). A beam propagation method (BPM) is employed for the design of proposed interferometer and numerical simulation. Based on the simulation results, interferometer with a length of 2 cm of thin-core fiber is fabricated and experimentally studied. (PAH/PAA)2 + [PAH/(PAA + SWCNTs-COOH)]8 film is deposited on the outer surface of thin-core fiber via layer-by-layer (LbL) self-assembly technique. The gas sensor coated with (PAH/PAA)2 + [PAH/(PAA + SWCNTs-COOH)]8 film towards NH3 gas exposure at concentrations range from 1 to 960 ppm are analyzed and the sensing capability is demonstrated by optical spectrum analyzer (OSA). Experimental results show that the characteristic wavelength shift has an approximately linear relationship in the range 1–20 ppm, which is in accordance with the numerical simulation. Thus, this paper reveals the potential application of this sensor in monitoring low concentration NH3 gas. PMID:28378783

Facile preparation of polymer microspheres and fibers with a hollow core and porous shell for oil adsorption and oil/water separation

NASA Astrophysics Data System (ADS)

Gao, Jiefeng; Song, Xin; Huang, Xuewu; Wang, Ling; Li, Bei; Xue, Huaiguo

2018-05-01

Non-solvent assisted electrospinning was proposed for fabricating Polymethylmethacrylate (PMMA) microspheres and fibers with a hollow core and porous shell, which could be used for oil adsorption and oil/water separation. Propanediol was chosen as the non-solvent because of its high surface tension and viscosity as well as large phase separation tendency with polymer, which was beneficial to the formation of both the hollow core and porous shell during the electrospinning. With the increase of the polymer solution concentration, the microsphere gradually evolved to the bead-on-string geometry and finally to a continuous fiber form, indicating the transition from electro-spraying to electrospinning. The hollow core and dense surface pores enhanced the hydrophobicity, oleophilicity, permeability, and specific surface area of the fibers, and hence imparted the fibrous mat a high oil adsorption capacity. When the porous hollow microspheres were electro-sprayed onto the stainless steel mesh followed by the PDMS modification, the modified mesh became super-hydrophobic and super-oleophilic with the contact angle of 153° and sliding angle of 4°. The as-prepared mesh showed rapid oil/water separation with high efficiency and excellent recycling performance. The flux for separation of oil/water mixture could reach as high as 11,000 L m-2 h-1. This facile non-solvent assisted electrospinning method provides a new avenue for preparation of multifunctional porous materials which possess potential applications in large-scale oil/water separation.

Effect of core diameter and surface treatment on the retention of resin composite cores to prefabricated endodontic posts.

PubMed

Artopoulou, Ioli-Ioanna; O'Keefe, Kathy L; Powers, John M

2006-01-01

With advances in adhesive dentistry and current emphasis on esthetic restorations, dowel systems have been developed to take advantage of these new techniques. Of interest when using these systems is the interaction between core materials and post materials. This investigation compared the tensile retentive force of two resin composite core materials to two metallic and one non-metallic prefabricated endodontic posts. Two dimensions of core build-up and two post-surface treatments were tested. One hundred twenty posts (stainless steel, titanium alloy, and glass fiber-impregnated resin) were secured in a jig with 4 mm of the post extending into a cylindrical matrix. The matrix formed cylinders with diameters of 3 and 5 mm into which resin composite was inserted. The posts were treated or not treated with a bonding agent. After storage for 24 hours at 100% humidity, five specimens per condition were tested in an Instron testing machine at a crosshead speed of 0.5 mm/min. Failure loads were recorded in kilograms and failure modes were observed under light microscopy (40 x). Four-way analysis of variance and multiple comparison testing were used to compare means at the 0.05 level of significance. The means and standard deviations of tensile loads were calculated. All variables were significant in either main effects or interactions ( p<0.05). Fisher's PLSD intervals for post, core, treatment, and diameter were 2.0, 1.6, 1.6, and 1.6 kg, respectively. In most cases, the retentive force recorded for metallic posts was higher than that of glass fiber posts. Titanium posts had higher retentive forces than did the stainless steel posts. For metallic posts, 5-mm cores provided higher forces than 3-mm cores. In the glass fiber group, core diameter was not significant. For core materials, Build-It gave higher results with stainless steel posts, and FluoroCore gave higher results with the titanium ones. The surface treatment results were mixed. In the metallic post groups the adhesive failure data ranged between 80% and 100%, whereas in the glass fiber post groups, adhesive failures ranged between 60% and 70%. Within the limitations of this study, the metallic post groups always provided higher tensile retentive forces, with the titanium post groups showing higher retentive forces than the stainless steel ones. In the glass fiber post groups, different core diameters did not affect retention values.

Effect of Surface Coverage of Gold Nanoparticles on the Refractive Index Sensitivity in Fiber-Optic Nanoplasmonic Sensing.

PubMed

Wu, Wei-Te; Chen, Chien-Hsing; Chiang, Chang-Yue; Chau, Lai-Kwan

2018-05-31

A simple theoretical model was developed to analyze the extinction spectrum of gold nanoparticles (AuNPs) on the fiber core and glass surfaces in order to aid the determination of the surface coverage and surface distribution of the AuNPs on the fiber core surface for sensitivity optimization of the fiber optic particle plasmon resonance (FOPPR) sensor. The extinction spectrum of AuNPs comprises of the interband absorption of AuNPs, non-interacting plasmon resonance (PR) band due to isolated AuNPs, and coupled PR band of interacting AuNPs. When the surface coverage is smaller than 12.2%, the plasmon coupling effect can almost be ignored. This method is also applied to understand the refractive index sensitivity of the FOPPR sensor with respect to the non-interacting PR band and the coupled PR band. In terms of wavelength sensitivity at a surface coverage of 18.6%, the refractive index sensitivity of the coupled PR band (205.5 nm/RIU) is greater than that of the non-interacting PR band (349.1 nm/RIU). In terms of extinction sensitivity, refractive index sensitivity of the coupled PR band (-3.86/RIU) is similar to that of the non-interacting PR band (-3.93/RIU). Both maximum wavelength and extinction sensitivities were found at a surface coverage of 15.2%.

Supermodes in Coupled Multi-Core Waveguide Structures

DTIC Science & Technology

2016-04-01

and therefore can be treated as linear polarization (LP) modes. In essence, the LP modes are scalar approximations of the vector mode fields and contain...field, including the discovery of optical discrete solitons , Bragg and vector solitons in fibers, nonlinear surface waves, and the discovery of self...increased for an isolated core, it can guide high-order modes. For optical fibers with low re- fractive index contrast, the vector modes are weakly guided

An interferometer having fused optical fibers, and apparatus and method using the interferometer

NASA Technical Reports Server (NTRS)

Hellbaum, Richard F. (Inventor); Claus, Richard O. (Inventor); Murphy, Kent A. (Inventor); Gunther, Michael F. (Inventor)

1992-01-01

An interferometer includes a first optical fiber coupled to a second optical fiber by fusing. At a fused portion, the first and second optical fibers are cut to expose respective cores. The cut or fused end of the first and second optical fibers is arranged to oppose a diaphragm or surface against which a physical phenomenon such as pressure or stress, is applied. In a first embodiment, a source light which is generally single-mode monochromatic, coherent light, is input to the first optical fiber and by evanescence, effectively crosses to the second optical fiber at the fused portion. Source light from the second optical fiber is reflected by the diaphragm or surface, and received at the second optical fiber to generate an output light which has an intensity which depends upon interference of reference light based on the source light, and the reflected light reflected from the diaphragm or surface. The intensity of the output light represents a positional relationship or displacement between the interferometer and the diaphragm or surface.

Microstructured optical fiber photonic wires with subwavelength core diameter.

PubMed

Lizé, Yannick; Mägi, Eric; Ta'eed, Vahid; Bolger, Jeremy; Steinvurzel, Paul; Eggleton, Benjamin

2004-07-12

We demonstrate fabrication of robust, low-loss silica photonic wires using tapered microstructured silica optical fiber. The fiber is tapered by a factor of fifty while retaining the internal structure and leaving the air holes completely open. The air holes isolate the core mode from the surrounding environment, making it insensitive to surface contamination and contact leakage, suggesting applications as nanowires for photonic circuits . We describe a transition between two different operation regimes of our photonic wire from the embedded regime, where the mode is isolated from the environment, to the evanescent regime, where more than 70% of the mode intensity can propagate outside of the fiber. Interesting dispersion and nonlinear properties are identified.

Multicore photonic crystal fiber force meters

NASA Astrophysics Data System (ADS)

Reimlinger, M.; Colalillo, A.; Coompson, J.; Wynne, R.

2011-04-01

A silica based three core photonic crystal fiber (PCF) force meter with fast response times (<30μs) for low wind speed detection is presented. Results are provided for PCF structures containing cores with varied lattice spacing. Force meters with high spatial resolution (sample regions <10cm) specially outfitted for extreme environmental conditions are of interest to both industry and basic research institutions. The featured PCF force meter exhibited sensitivities that agreed with theoretical predictions that are useful for the detection of minimum displacements for wind speeds <30m/s. The results of this investigation are relevant to civil engineering applications including urban sensing technologies that involve air quality monitoring. The deflection of the PCF detection interface was measured as a function of the fiber deflection or the applied force (e.g. wind speed). The three core PCF has a core diameter of 3.9μm, outer diameter of 132.5μm and 7.56μm core-core spacing. A 4cm length of the PCF is attached to the surface of a thin metal beam. One end of the PCF section is fusion spliced to a single mode fiber (SMF) at the fiber input. The remaining fiber end is coupled to a CCD camera with a lens at the PCF output. The applied force deflects the supported PCF such that the intensity distribution of the optical field for the multiple cores changes as a function of displacement. Experimental results from static deflection measurements are in agreement with coupled-mode theory and simple beam deflection theory models.

Photogrammetric Verification of Fiber Optic Shape Sensors on Flexible Aerospace Structures

NASA Technical Reports Server (NTRS)

Moore, Jason P.; Rogge, Matthew D.; Jones, Thomas W.

2012-01-01

Multi-core fiber (MCF) optic shape sensing offers the possibility of providing in-flight shape measurements of highly flexible aerospace structures and control surfaces for such purposes as gust load alleviation, flutter suppression, general flight control and structural health monitoring. Photogrammetric measurements of surface mounted MCF shape sensing cable can be used to quantify the MCF installation path and verify measurement methods.

Electrospun nanofibers: Formation, characterization, and evaluation for nerve tissue engineering applications

NASA Astrophysics Data System (ADS)

Zander, Nicole E.

The effects of fiber alignment and surface chemistry, including the covalent attachment and physical adsorption of the extracellular matrix (ECM) proteins laminin and collagen, on the neurite outgrowth of neuron-like PC12 cells were examined. Neuron-like PC12 cells responded to fiber orientation, and were successfully contact-guided by aligned electrospun nanofibers. In addition, fibers with attached protein, either physically adsorbed or covalently attached, improved neurite outgrowth lengths. Furthermore, aligning the fibers and attaching the ECM protein laminin, in particular, significantly improved neurite outgrowth over randomly oriented fibers with laminin. Since this research suggested that protein concentration on the fibers was the dominant driving force for improved neurite outgrowth, the effect of protein concentration, incorporated onto the surface of the nanofibers, on neurite outgrowth was examined. Two ways to control protein concentration on the fibers were explored—the variation of the fiber-protein reaction time and the variation of the protein soaking solution concentration. In addition, analytical methods to quantify the concentration of protein, as well as the protein coverage, on the surface of the fibers were developed. Although most of the fiber mats had multilayer protein coverage, and hence physically adsorbed proteins which could potentially mean a loss in bioactivity, the neuron-like PC12 cell neurites responded in a dose-dependent manner with increased neurite lengths on scaffolds with higher protein concentrations. The work was extended further by forming protein gradients on the fiber mats in hopes of locally directing neurite outgrowth and orientation. Fiber mats with both linear gradients (continuous change in protein concentration) and step gradients (six regions of uniform protein coverage, with protein concentration increasing from region to region) were fabricated and analyzed. The step gradients formed in the aligned fiber direction showed the most promise for use in cell culture assays. While surface chemistry and topography are important, porosity of the scaffold is also critical to control cellular infiltration and tissue formation. To enhance the porosity of our electrospun nanofiber scaffolds and improve the infiltration of cells, two methods were explored to control porosity. In the first method, the scaffold polymer polycaprolactone was co-electrospun with a sacrificial polymer polyethylene oxide, which was removed after the bi-component fiber mat was formed. In doing so, the void space was increased. In the second method, the spinning solution concentration of polycaprolactone was varied to control fiber diameter and porosity. The second method proved to be more effective at improving the cellular infiltration of PC12 cells. Two orders of magnitude range of fiber diameters were achieved, and nearly full infiltration of PC12 cells was observed for the mats with the highest porosity. The pore sizes of these mats were on the order of the size of the cell bodies (approximately 6-10 µm). Although the majority of this work focuses on using conventional electrospinning to generate solid-core fibers, core-shell fibers, have many applications in tissue engineering, among other fields. We explored an efficient way to generate these fibers from an emulsion solution using a conventional electrospinning apparatus. We characterized the fibers using an atomic force microscope (AFM) elastic modulus mapping technique, along with AFM phase imaging, angle-resolved x-ray photoelectron spectroscopy and thermal gravimetric analysis, to determine the chemical and molar composition of the core and shell layers. This work presents novel analytical techniques for the characterization of core-shell nanofibers in order to better predict and understand their material properties. (Abstract shortened by UMI.).

Interaction and dispersion of waveguide modes in an optical fiber with microirregularities of the core surface

NASA Astrophysics Data System (ADS)

Zadorin, A. S.; Kruglov, R. S.; Surkova, G. A.

2012-08-01

A self-consistent linear model is proposed for the transformation of the average intensity of the mode spectrum I( z) of the waveguide field in a multimode optical fiber with a stepped refractive index profile and the core having a rough surface. The model is based on the concept of the intermodal dispersion matrix of an elementary segment of the fiber, ∆, whose elements characterize the mutual transfer of energy between the waveguide modes, as well as their conversion to radiation modes on the specified interval. On this basis, the features of the transformation of the mode spectrum I( z) in a multimode optical fiber with a stepped refractive index profile are considered that is due to the effects of multiple dispersion of the signal by the stochastic irregularities of the duct. The effect of self-filtering of I( z) is described that results in the formation of a stable (normalized) distribution I*. The features of the normalization of the radiative damping of a group of modes I i ( z) in an optical fiber are considered.

Low concentration biomolecular detection using liquid core photonic crystal fiber (LCPCF) SERS sensor

NASA Astrophysics Data System (ADS)

Shi, Chao; Zhang, Yi; Gu, Claire; Seballos, Leo; Zhang, Jin Z.

2008-02-01

This work demonstrates the use of a highly sensitive Liquid Core Photonic Crystal Fiber (LCPCF) Surface Enhanced Raman Scattering (SERS) sensor in detecting biological and biochemical molecules. The Photonic Crystal Fiber (PCF) probe was prepared by carefully sealing the cladding holes using a fusion splicer while leaving the central hollow core open, which ensures that the liquid mixture of the analyte and silver nanoparticles only fills in the hollow core of the PCF, therefore preserving the photonic bandgap. The dependence of the SERS signal on the excitation power and sample concentration was fully characterized using Rhodamine 6G (R6G) molecules. The result shows that the LCPCF sensor has significant advantages over flat surface SERS detections at lower concentrations. This is attributed to the lower absorption at lower concentration leading to a longer effective interaction length inside the LCPCF, which in turn, results in a stronger SERS signal. Several biomolecules, such as Prostate Specific Antigen (PSA) and alpha-synuclein, which are indicators of prostate cancer and Parkinson's disease, respectively, and fail to be detected directly, are successfully detected by the LCPCF sensor. Our results demonstrate the potential of the LCPCF SERS sensor for biomedical detection at low concentrations.

Microsurgical anatomy of the central core of the brain.

PubMed

Ribas, Eduardo Carvalhal; Yağmurlu, Kaan; de Oliveira, Evandro; Ribas, Guilherme Carvalhal; Rhoton, Albert

2017-12-22

OBJECTIVE The purpose of this study was to describe in detail the cortical and subcortical anatomy of the central core of the brain, defining its limits, with particular attention to the topography and relationships of the thalamus, basal ganglia, and related white matter pathways and vessels. METHODS The authors studied 19 cerebral hemispheres. The vascular systems of all of the specimens were injected with colored silicone, and the specimens were then frozen for at least 1 month to facilitate identification of individual fiber tracts. The dissections were performed in a stepwise manner, locating each gray matter nucleus and white matter pathway at different depths inside the central core. The course of fiber pathways was also noted in relation to the insular limiting sulci. RESULTS The insular surface is the most superficial aspect of the central core and is divided by a central sulcus into an anterior portion, usually containing 3 short gyri, and a posterior portion, with 2 long gyri. It is bounded by the anterior limiting sulcus, the superior limiting sulcus, and the inferior limiting sulcus. The extreme capsule is directly underneath the insular surface and is composed of short association fibers that extend toward all the opercula. The claustrum lies deep to the extreme capsule, and the external capsule is found medial to it. Three fiber pathways contribute to form both the extreme and external capsules, and they lie in a sequential anteroposterior disposition: the uncinate fascicle, the inferior fronto-occipital fascicle, and claustrocortical fibers. The putamen and the globus pallidus are between the external capsule, laterally, and the internal capsule, medially. The internal capsule is present medial to almost all insular limiting sulci and most of the insular surface, but not to their most anteroinferior portions. This anteroinferior portion of the central core has a more complex anatomy and is distinguished in this paper as the "anterior perforated substance region." The caudate nucleus and thalamus lie medial to the internal capsule, as the most medial structures of the central core. While the anterior half of the central core is related to the head of the caudate nucleus, the posterior half is related to the thalamus, and hence to each associated portion of the internal capsule between these structures and the insular surface. The central core stands on top of the brainstem. The brainstem and central core are connected by several white matter pathways and are not separated from each other by any natural division. The authors propose a subdivision of the central core into quadrants and describe each in detail. The functional importance of each structure is highlighted, and surgical approaches are suggested for each quadrant of the central core. CONCLUSIONS As a general rule, the internal capsule and its vascularization should be seen as a parasagittal barrier with great functional importance. This is of particular importance in choosing surgical approaches within this region.

Optical fiber nanoprobe preparation for near-field optical microscopy by chemical etching under surface tension and capillary action.

PubMed

Mondal, Samir K; Mitra, Anupam; Singh, Nahar; Sarkar, S N; Kapur, Pawan

2009-10-26

We propose a technique of chemical etching for fabrication of near perfect optical fiber nanoprobe (NNP). It uses photosensitive single mode optical fiber to etch in hydro fluoric (HF) acid solution. The difference in etching rate for cladding and photosensitive core in HF acid solution creates capillary ring along core-cladding boundary under a given condition. The capillary ring is filled with acid solution due to surface tension and capillary action. Finally it creates near perfect symmetric tip at the apex of the fiber as the height of the acid level in capillary ring decreases while width of the ring increases with continuous etching. Typical tip features are short taper length (approximately 4 microm), large cone angle (approximately 38 degrees ), and small probe tip dimension (<100 nm). A finite difference time domain (FDTD) analysis is also presented to compare near field optics of the NNP with conventional nanoprobe (CNP). The probe may be ideal for near field optical imaging and sensor applications.

Mesoporous coaxial titanium nitride-vanadium nitride fibers of core-shell structures for high-performance supercapacitors.

PubMed

Zhou, Xinhong; Shang, Chaoqun; Gu, Lin; Dong, Shanmu; Chen, Xiao; Han, Pengxian; Li, Lanfeng; Yao, Jianhua; Liu, Zhihong; Xu, Hongxia; Zhu, Yuwei; Cui, Guanglei

2011-08-01

In this study, titanium nitride-vanadium nitride fibers of core-shell structures were prepared by the coaxial electrospinning, and subsequently annealed in the ammonia for supercapacitor applications. These core-shell (TiN-VN) fibers incorporated mesoporous structure into high electronic conducting transition nitride hybrids, which combined higher specific capacitance of VN and better rate capability of TiN. These hybrids exhibited higher specific capacitance (2 mV s(-1), 247.5 F g(-1)) and better rate capability (50 mV s(-1), 160.8 F g(-1)), which promise a good candidate for high-performance supercapacitors. It was also revealed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) characterization that the minor capacitance fade originated from the surface oxidation of VN and TiN.

Fiber optic evanescent wave (FOEW) microbial sensor for dental application

NASA Astrophysics Data System (ADS)

Kishen, Anil; John, M. S.; Chen, Jun-Wei; Lim, Chu S.; Hu, Xiao; Asundi, Anand K.

2001-10-01

In this work a new approach based on the fiber Optic Evanescent Wave (FOEW) Spectroscopy is developed for the effective determination of dental caries activity in human saliva. The biosensor design utilized the exponentially decaying wave that extends to the lower index region of the optical fiber's core-cladding interface. In order to achieve this, a short length of the cladding is removed and the fiber core surface is coated with a porous glass medium using sol-gel technique. The acidogenic profile resulting from the Streptococcus mutans activity in the human saliva is monitored using an indicator, which was encapsulated within the porous coating. These investigations display the potential benefits of FOEW based microbial sensor to monitor caries activity in human saliva.

The Nature of Accelerating Modes in PBG Fibers

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

Noble, TRobert J.; /SLAC

Transverse magnetic (TM) modes with phase velocities at or just below the speed of light, c, are intended to accelerate relativistic particles in hollow-core, photonic band gap (PBG) fibers. These are so-called 'surface defect modes', being lattice modes perturbed by the defect to have their frequencies shifted into the band gap, and they can have any phase velocity. PBG fibers also support so-called 'core defect modes' which are characterized as having phase velocities always greater than c and never cross the light line. In this paper we explore the nature of these two classes of accelerating modes and compare theirmore » properties.« less

Fiber Tracts of the Medial and Inferior Surfaces of the Cerebrum.

PubMed

Baydin, Serhat; Gungor, Abuzer; Tanriover, Necmettin; Baran, Oguz; Middlebrooks, Erik H; Rhoton, Albert L

2017-02-01

Fiber dissection studies of the cerebrum have focused on the lateral surface. No comparable detailed studies have been done on the medial and inferior surfaces. The object of this study was to examine the fiber tracts, cortical, and subcortical structures of the medial and inferior aspects of the brain important in planning operative approaches along the interhemispheric fissure, parafalcine area, and basal surfaces of the cerebrum. Twenty formalin-fixed human hemispheres (10 brains) were examined by fiber dissection technique under ×6-×40 magnifications. The superior longitudinal fasciculus I, cingulum, inferior longitudinal fasciculus, uncinate fasciculus, optic radiations, tapetum, and callosal fibers were dissected step by step from medial to lateral, exposing the nucleus accumbens, subthalamic nucleus, red nucleus, and central midline structures (fornix, stria medullaris, and stria terminalis). Finally, the central core structures were dissected from medial to lateral. Understanding the fiber network underlying the medial and inferior aspects of the brain is important in surgical planning for approaches along the interhemispheric fissure, parafalcine area, and basal surfaces of the cerebrum. Copyright © 2016. Published by Elsevier Inc.

Improved Fabrication of Ceramic Matrix Composite/Foam Core Integrated Structures

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.

2009-01-01

The use of hybridized carbon/silicon carbide (C/SiC) fabric to reinforce ceramic matrix composite face sheets and the integration of such face sheets with a foam core creates a sandwich structure capable of withstanding high-heatflux environments (150 W/cm2) in which the core provides a temperature drop of 1,000 C between the surface and the back face without cracking or delamination of the structure. The composite face sheet exhibits a bilinear response, which results from the SiC matrix not being cracked on fabrication. In addition, the structure exhibits damage tolerance under impact with projectiles, showing no penetration to the back face sheet. These attributes make the composite ideal for leading edge structures and control surfaces in aerospace vehicles, as well as for acreage thermal protection systems and in high-temperature, lightweight stiffened structures. By tailoring the coefficient of thermal expansion (CTE) of a carbon fiber containing ceramic matrix composite (CMC) face sheet to match that of a ceramic foam core, the face sheet and the core can be integrally fabricated without any delamination. Carbon and SiC are woven together in the reinforcing fabric. Integral densification of the CMC and the foam core is accomplished with chemical vapor deposition, eliminating the need for bond-line adhesive. This means there is no need to separately fabricate the core and the face sheet, or to bond the two elements together, risking edge delamination during use. Fibers of two or more types are woven together on a loom. The carbon and ceramic fibers are pulled into the same pick location during the weaving process. Tow spacing may be varied to accommodate the increased volume of the combined fiber tows while maintaining a target fiber volume fraction in the composite. Foam pore size, strut thickness, and ratio of face sheet to core thickness can be used to tailor thermal and mechanical properties. The anticipated CTE for the hybridized composite is managed by the choice of constituents, varying fiber tow sizes and constituent part ratios. This structural concept provides high strength and stiffness at low density 1.06 g/cm3 in panels tested. Varieties of face sheet constructions are possible, including variations in fiber type and weave geometry. The integrated structures possible with this composite could eliminate the need for non-load-bearing thermal protection systems on top of a structural component. The back sheet can readily be integrated to substructures through the incorporation of ribs. This would eliminate weight and cost for aerospace missions.

Liquid-core photonic crystal fiber platform for raman scattering measurements of microliter analyte solutions

NASA Astrophysics Data System (ADS)

Han, Yun; Oo, Maung Khaing; Zhu, Yinian; Sukhishvili, Svetlana; Xiao, Limin; Demokan, M. Süleyman; Jin, Wei; Du, Henry

2007-09-01

We have explored the use of index-guiding liquid-core photonic crystal fiber (LC-PCF) as a platform for sensing and measurements of analyte solutions of minute volume by normal and surface-enhanced Raman scattering (SERS). The index-guiding LC-PCF was fabricated by selectively sealing via fusion splicing the cladding air channels of a hollow-core PCF (HC-PCF) while leaving the center core open at both ends of the fiber. The center core of the resultant fiber was subsequently filled with water-ethanol solution mixtures at various ethanol concentrations for normal Raman scattering measurements and with water-thiocynate solutions containing Ag nanoparticle aggregates for SERS detection of thiocynate at trace concentrations. The light-guiding nature in the solution phase inside the LC-PCF allows direct and strong light-field overlap with the solution phase over the entire length of the PCF (~30 cm). This detection scheme also dramatically reduces the contribution of silica to Raman spectral background, compared with the solid-core counterpart, thus its potential interference in spectral analysis. These features attribute to ready normal Raman measurements of water, ethanol, and water (99 vol.%)-ethanol (1 vol.%) solutions as well as sensitive and reproducible SERS detection of ~10 ppb thiocynate in water, all at a volume of ~0.1 μL.

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.

Miniaturized fiber-optic Michelson-type interferometric sensors

NASA Technical Reports Server (NTRS)

Murphy, Kent A.; Miller, William V., III; Tran, Tuan A.; Vengsarkar, Ashish M.; Claus, Richard O.

1991-01-01

A novel, miniaturized Michelson-type fiber-optic interferometric sensor that is relatively insensitive to temperature drifts is presented. A fused-biconical tapered coupler is cleaved immediately after the coupled length and polished down to the region of the fused cladding, but short of the interaction region. The end of one core is selectively coated with a reflective surface and is used as the reference arm; the other core serves as the sensing arm. The detection of surface acoustic waves, microdisplacements, and magnetic fields is reported. The sensor is shown to be highly stable in comparison to a classic homodyne, uncompensated Michelson interferometer, and signal-to-noise ratios of 65 dB have been obtained.

Ultrashort polarization splitter based on dual-core photonic crystal fibers with gold wire

NASA Astrophysics Data System (ADS)

Xu, Qiang; Zhao, Ya; Xia, Houping; Lin, Shebao; Zhang, Yani

2018-04-01

An ultrashort polarization splitter based on dual-core photonic crystal fibers with gold wire has been proposed. Based on the beam propagation method with anisotropic perfectly matched layers, its polarization splitter coupling length, coupling length ratio, extinction ratio (ER), and bandwidth are numerically investigated. When the gold thread is filled in the fiber, the surface of the gold wire will produce the surface plasmon polaritons, which has certain influence on the beam propagation. A polarization splitter with shorter length and greater working bandwidth can be obtained by filling the gold wire. Numerical results demonstrate that the polarization splitter possesses extremely the length of 290 μm and high ER of -56.5 dB at the wavelength of 1.55 μm. Moreover, the polarization splitter is proposed to achieve ER better than -10 dB and a bandwidth of 19.2 nm.

Preparation and characterization of amphiphilic triblock terpolymer-based nanofibers as antifouling biomaterials.

PubMed

Cho, Youngjin; Cho, Daehwan; Park, Jay Hoon; Frey, Margaret W; Ober, Christopher K; Joo, Yong Lak

2012-05-14

Antifouling surfaces are critical for the good performance of functional materials in various applications including water filtration, medical implants, and biosensors. In this study, we synthesized amphiphilic triblock terpolymers (tri-BCPs, coded as KB) and fabricated amphiphilic nanofibers by electrospinning of solutions prepared by mixing the KB with poly(lactic acid) (PLA) polymer. The resulting fibers with amphiphilic polymer groups exhibited superior antifouling performance to the fibers without such groups. The adsorption of bovine serum albumin (BSA) on the amphiphilic fibers was about 10-fold less than that on the control surfaces from PLA and PET fibers. With the increase of the KB content in the amphiphilic fibers, the resistance to adsorption of BSA was increased. BSA was released more easily from the surface of the amphiphilic fibers than from the surface of hydrophobic PLA or PET fibers. We have also investigated the structural conformation of KB in fibers before and after annealing by contact angle measurements, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and coarse-grained molecular dynamics (CGMD) simulation to probe the effect of amphiphilic chain conformation on antifouling. The results reveal that the amphiphilic KB was evenly distributed within as-spun hybrid fibers, while migrated toward the core from the fiber surface during thermal treatment, leading to the reduction in antifouling. This suggests that the antifouling effect of the amphiphilic fibers is greatly influenced by the arrangement of amphiphilic groups in the fibers.

Optical fiber humidity sensor based on evanescent-wave scattering.

PubMed

Xu, Lina; Fanguy, Joseph C; Soni, Krunal; Tao, Shiquan

2004-06-01

The phenomenon of evanescent-wave scattering (EWS) is used to design an optical-fiber humidity sensor. Porous solgel silica (PSGS) coated on the surface of a silica optical-fiber core scatters evanescent waves that penetrate the coating layer. Water molecules in the gas phase surrounding the optical fiber can be absorbed into the inner surface of the pores of the porous silica. The absorbed water molecules form a thin layer of liquid water on the inner surface of the porous silica and enhance the EWS. The amount of water absorbed into the PSGS coating is in dynamic equilibrium with the water-vapor pressure in the gas phase. Therefore the humidity in the air can be quantitatively determined with fiber-optic EWS caused by the PSGS coating. The humidity sensor reported here is fast in response, reversible, and has a wide dynamic range. The possible interference caused by EWS to an optical-fiber gas sensor with a reagent-doped PSGS coating as a transducer is also discussed.

Inert Welding/Brazing Gas Filters and Dryers

NASA Technical Reports Server (NTRS)

Goudy, Jerry

2009-01-01

The use of hybridized carbon/silicon carbide (C/SiC) fabric to reinforce ceramic matrix composite face sheets and the integration of such face sheets with a foam core creates a sandwich structure capable of withstanding high-heat-flux environments (150 W/sq cm) in which the core provides a temperature drop of 1,000 C between the surface and the back face without cracking or delamination of the structure. The composite face sheet exhibits a bilinear response, which results from the SiC matrix not being cracked on fabrication. In addition, the structure exhibits damage tolerance under impact with projectiles, showing no penetration to the back face sheet. These attributes make the composite ideal for leading-edge structures and control surfaces in aerospace vehicles, as well as for acreage thermal protection systems and in high-temperature, lightweight stiffened structures. By tailoring the coefficient of thermal expansion (CTE) of a carbon fiber containing ceramic matrix composite (CMC) face sheet to match that of a ceramic foam core, the face sheet and the core can be integrally fabricated without any delamination. Carbon and SiC are woven together in the reinforcing fabric. Integral densification of the CMC and the foam core is accomplished with chemical vapor deposition, eliminating the need for bond-line adhesive. This means there is no need to separately fabricate the core and the face sheet, or to bond the two elements together, risking edge delamination during use. Fibers of two or more types are woven together on a loom. The carbon and ceramic fibers are pulled into the same "pick" location during the weaving process. Tow spacing may be varied to accommodate the increased volume of the combined fiber tows while maintaining a target fiber volume fraction in the composite. Foam pore size, strut thickness, and ratio of face sheet to core thickness can be used to tailor thermal and mechanical properties. The anticipated CTE for the hybridized composite is managed by the choice of constituents, varying fiber tow sizes and constituent part ratios. This structural concept provides high strength and stiffness at low density 1.06 g/cu cm in panels tested. Varieties of face sheet constructions are possible, including variations in fiber type and weave geometry. The integrated structures possible with this composite could eliminate the need for non-load-bearing thermal protection systems on top of a structural component. The back sheet can readily be integrated to substructures through the incorporation of ribs. This would eliminate weight and cost for aerospace missions.

Microstructured optical fibers for gas sensing systems

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

Challener, William Albert; Choudhury, Niloy; Palit, Sabarni

2017-10-17

Microstructured optical fiber (MOF) includes a cladding extending a length between first and second ends. The cladding includes an inner porous microstructure that at least partially surrounds a hollow core. A perimeter contour of the hollow core has a non-uniform radial distance from a center axis of the cladding such that first segments of the cladding along the perimeter contour have a shorter radial distance from the center axis relative to second segments of the cladding along the perimeter contour. The cladding receives and propagates light energy through the hollow core, and the inner porous microstructure substantially confines the lightmore » energy within the hollow core. The cladding defines at least one port hole that extends radially from an exterior surface of the cladding to the hollow core. Each port hole penetrates the perimeter contour of the hollow core through one of the second segments of the cladding.« less

All fiber passively Q-switched laser

DOEpatents

Soh, Daniel B. S.; Bisson, Scott E

2015-05-12

Embodiments relate to an all fiber passively Q-switched laser. The laser includes a large core doped gain fiber having a first end. The large core doped gain fiber has a first core diameter. The laser includes a doped single mode fiber (saturable absorber) having a second core diameter that is smaller than the first core diameter. The laser includes a mode transformer positioned between a second end of the large core doped gain fiber and a first end of the single mode fiber. The mode transformer has a core diameter that transitions from the first core diameter to the second core diameter and filters out light modes not supported by the doped single mode fiber. The laser includes a laser cavity formed between a first reflector positioned adjacent the large core doped gain fiber and a second reflector positioned adjacent the doped single mode fiber.

Photonic crystal fiber temperature sensor with high sensitivity based on surface plasmon resonance

NASA Astrophysics Data System (ADS)

Wu, Junjun; Li, Shuguang; shi, Min; Feng, Xinxing

2018-07-01

A high sensitivity photonic crystal fiber (PCF) temperature sensor based on surface plasmon resonance is proposed and evaluated using the finite element method. Besides, the coupling phenomenon is studied. The gold layer deposited on the polishing surface of D-shape PCF is used as the metal to stimulate surface plasma, which can improves the sensitivity. Through exquisite design, the birefringence of the fiber is improved, which makes the loss of y-polarization far greater than the loss of x-polarization. The D-shape fiber avoids filling metal and liquid into the air-holes, which can contact with fluid directly to feel temperature. When the phase matching condition is satisfied, the core mode will couple with the surface plasma mode. The resonance position of y-polarization is very sensitive to the temperature change. The simulation shows that the PCF has high sensitivity of 36.86 nm/°C in y-polarization and wide detection that from 10 °C to 85 °C.

PMMA/PS coaxial electrospinning: a statistical analysis on processing parameters

NASA Astrophysics Data System (ADS)

Rahmani, Shahrzad; Arefazar, Ahmad; Latifi, Masoud

2017-08-01

Coaxial electrospinning, as a versatile method for producing core-shell fibers, is known to be very sensitive to two classes of influential factors including material and processing parameters. Although coaxial electrospinning has been the focus of many studies, the effects of processing parameters on the outcomes of this method have not yet been well investigated. A good knowledge of the impacts of processing parameters and their interactions on coaxial electrospinning can make it possible to better control and optimize this process. Hence, in this study, the statistical technique of response surface method (RSM) using the design of experiments on four processing factors of voltage, distance, core and shell flow rates was applied. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), oil immersion and Fluorescent microscopy were used to characterize fiber morphology. The core and shell diameters of fibers were measured and the effects of all factors and their interactions were discussed. Two polynomial models with acceptable R-squares were proposed to describe the core and shell diameters as functions of the processing parameters. Voltage and distance were recognized as the most significant and influential factors on shell diameter, while core diameter was mainly under the influence of core and shell flow rates besides the voltage.

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.

Sol-gel processing to form doped sol-gel monoliths inside hollow core optical fiber and sol-gel core fiber devices made thereby

NASA Technical Reports Server (NTRS)

Shaw, Harry C. (Inventor); Ott, Melanie N. (Inventor); Manuel, Michele V. (Inventor)

2002-01-01

A process of fabricating a fiber device includes providing a hollow core fiber, and forming a sol-gel material inside the hollow core fiber. The hollow core fiber is preferably an optical fiber, and the sol-gel material is doped with a dopant. Devices made in this manner includes a wide variety of sensors.

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.

Fast and Exact Fiber Surfaces for Tetrahedral Meshes.

PubMed

Klacansky, Pavol; Tierny, Julien; Carr, Hamish; Zhao Geng

2017-07-01

Isosurfaces are fundamental geometrical objects for the analysis and visualization of volumetric scalar fields. Recent work has generalized them to bivariate volumetric fields with fiber surfaces, the pre-image of polygons in range space. However, the existing algorithm for their computation is approximate, and is limited to closed polygons. Moreover, its runtime performance does not allow instantaneous updates of the fiber surfaces upon user edits of the polygons. Overall, these limitations prevent a reliable and interactive exploration of the space of fiber surfaces. This paper introduces the first algorithm for the exact computation of fiber surfaces in tetrahedral meshes. It assumes no restriction on the topology of the input polygon, handles degenerate cases and better captures sharp features induced by polygon bends. The algorithm also allows visualization of individual fibers on the output surface, better illustrating their relationship with data features in range space. To enable truly interactive exploration sessions, we further improve the runtime performance of this algorithm. In particular, we show that it is trivially parallelizable and that it scales nearly linearly with the number of cores. Further, we study acceleration data-structures both in geometrical domain and range space and we show how to generalize interval trees used in isosurface extraction to fiber surface extraction. Experiments demonstrate the superiority of our algorithm over previous work, both in terms of accuracy and running time, with up to two orders of magnitude speedups. This improvement enables interactive edits of range polygons with instantaneous updates of the fiber surface for exploration purpose. A VTK-based reference implementation is provided as additional material to reproduce our results.

In Situ Hydrothermally Grown TiO2@C Core-Shell Nanowire Coating for Highly Sensitive Solid Phase Microextraction of Polycyclic Aromatic Hydrocarbons.

PubMed

Wang, Fuxin; Zheng, Juan; Qiu, Junlang; Liu, Shuqin; Chen, Guosheng; Tong, Yexiang; Zhu, Fang; Ouyang, Gangfeng

2017-01-18

Nanostructured materials have great potential for solid phase microextraction (SPME) on account of their tiny size, distinct architectures and superior physical and chemical properties. Herein, a core-shell TiO 2 @C fiber for SPME was successfully fabricated by the simple hydrothermal reaction of a titanium wire and subsequent amorphous carbon coating. The readily hydrothermal procedure afforded in situ synthesis of TiO 2 nanowires on a titanium wire and provided a desirable substrate for further coating of amorphous carbon. Benefiting from the much larger surface area of subsequent TiO 2 and good adsorption property of the amorphous carbon coating, the core-shell TiO 2 @C fiber was utilized for the SPME device for the first time and proved to have better performance in extraction of polycyclic aromatic hydrocarbons. In comparison to the polydimethylsiloxane (PDMS) and PDMS/divinylbenzene (DVB) fiber for commercial use, the TiO 2 @C fiber obtained gas chromatography responses 3-8 times higher than those obtained by the commercial 100 μm PDMS and 1-9 times higher than those obtained by the 65 μm PDMS/DVB fiber. Under the optimized extraction conditions, the low detection limits were obtained in the range of 0.4-7.1 ng L -1 with wider linearity in the range of 10-2000 ng L -1 . Moreover, the fiber was successfully used for the determination of polycyclic aromatic hydrocarbons in Pearl River water, which demonstrated the applicability of the core-shell TiO 2 @C fiber.

Selenium semiconductor core optical fibers

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

Tang, G. W.; Qian, Q., E-mail: qianqi@scut.edu.cn; Peng, K. L.

2015-02-15

Phosphate glass-clad optical fibers containing selenium (Se) semiconductor core were fabricated using a molten core method. The cores were found to be amorphous as evidenced by X-ray diffraction and corroborated by Micro-Raman spectrum. Elemental analysis across the core/clad interface suggests that there is some diffusion of about 3 wt % oxygen in the core region. Phosphate glass-clad crystalline selenium core optical fibers were obtained by a postdrawing annealing process. A two-cm-long crystalline selenium semiconductor core optical fibers, electrically contacted to external circuitry through the fiber end facets, exhibit a three times change in conductivity between dark and illuminated states. Suchmore » crystalline selenium semiconductor core optical fibers have promising utility in optical switch and photoconductivity of optical fiber array.« less

Coaxial fiber supercapacitor using all-carbon material electrodes.

PubMed

Le, Viet Thong; Kim, Heetae; Ghosh, Arunabha; Kim, Jaesu; Chang, Jian; Vu, Quoc An; Pham, Duy Tho; Lee, Ju-Hyuck; Kim, Sang-Woo; Lee, Young Hee

2013-07-23

We report a coaxial fiber supercapacitor, which consists of carbon microfiber bundles coated with multiwalled carbon nanotubes as a core electrode and carbon nanofiber paper as an outer electrode. The ratio of electrode volumes was determined by a half-cell test of each electrode. The capacitance reached 6.3 mF cm(-1) (86.8 mF cm(-2)) at a core electrode diameter of 230 μm and the measured energy density was 0.7 μWh cm(-1) (9.8 μWh cm(-2)) at a power density of 13.7 μW cm(-1) (189.4 μW cm(-2)), which were much higher than the previous reports. The change in the cyclic voltammetry characteristics was negligible at 180° bending, with excellent cycling performance. The high capacitance, high energy density, and power density of the coaxial fiber supercapacitor are attributed to not only high effective surface area due to its coaxial structure and bundle of the core electrode, but also all-carbon materials electrodes which have high conductivity. Our coaxial fiber supercapacitor can promote the development of textile electronics in near future.

Trace hydrogen sulfide gas sensor based on tungsten sulfide membrane-coated thin-core fiber modal interferometer

NASA Astrophysics Data System (ADS)

Deng, Dashen; Feng, Wenlin; Wei, Jianwei; Qin, Xiang; Chen, Rong

2017-11-01

A novel fiber-optic hydrogen sulfide sensor based on a thin-core Mach-Zehnder fiber modal interferometer (TMZFI) is demonstrated and fabricated. This in-line interferometer is composed of a short section of thin-core fiber sandwiched between two standard single mode fibers, and the fast response to hydrogen sulfide is achieved via the construction of tungsten sulfide film on the outside surface of the TMZFI using the dip-coating and calcination technique. The fabricated sensing nanofilm is characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) spectrometer, Fourier transform infrared (FTIR) and spectroscopic analysis technology, etc. Experimental results showed that the WS2 sensing film has a hexagonal structure with a compact and porous morphology. The XPS and FTIR indicate that the existence of two elements (W and S) is demonstrated. With the increasing concentration of hydrogen sulfide, the interference spectra appear blue shift. In addition, a high sensitivity of 18.37 pm/ppm and a good linear relationship are obtained within a measurement range from 0 to 80 ppm. In addition, there is an excellent selectivity for H2S, which has also been proved by the surface adsorption energy results of tungsten sulfide with four gases (H2S, N2, O2 and CO2) by using the density functional theory calculations. This interferometer has the advantages of simple structure, high sensitivity and easy manufacture, and could be used in the safety monitoring field of hydrogen sulfide gas.

Optical fiber sensor having an active core

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

1993-01-01

An optical fiber is provided. The fiber is comprised of an active fiber core which produces waves of light upon excitation. A factor ka is identified and increased until a desired improvement in power efficiency is obtained. The variable a is the radius of the active fiber core and k is defined as 2 pi/lambda wherein lambda is the wavelength of the light produced by the active fiber core. In one embodiment, the factor ka is increased until the power efficiency stabilizes. In addition to a bare fiber core embodiment, a two-stage fluorescent fiber is provided wherein an active cladding surrounds a portion of the active fiber core having an improved ka factor. The power efficiency of the embodiment is further improved by increasing a difference between the respective indices of refraction of the active cladding and the active fiber core.

Label-Free Quantitative Immunoassay of Fibrinogen in Alzheimer Disease Patient Plasma Using Fiber Optical Surface Plasmon Resonance

NASA Astrophysics Data System (ADS)

Kim, Jisoo; Kim, SeJin; Nguyen, Tan Tai; Lee, Renee; Li, Tiehua; Yun, Changhyun; Ham, Youngeun; An, Seong Soo A.; Ju, Heongkyu

2016-05-01

We present a real-time quantitative immunoassay to detect fibrinogen in the blood plasma of Alzheimer's disease patients using multimode fiber optical sensors in which surface plasmon resonance (SPR) was employed. Nanometer-thick bimetals including silver and aluminum were coated onto the core surface of the clad-free part (5 cm long) of the fiber for SPR excitation at the He-Ne laser wavelength of 632.8 nm. The histidine-tagged peptide was then coated on the metal surface to immobilize the fibrinogen antibody for the selective capture of fibrinogen among the proteins in the patient blood plasma. The SPR fiber optical sensor enabled quantitative detection of concentrations of fibrinogen from the different human patient blood at a detection limit of ˜20 ng/ml. We also observed a correlation in the fibrinogen concentration measurement between enzyme-linked immunosorbent assay and our SPR fiber-based sensors. This suggests that the presented SPR fiber-based sensors that do not rely on the use of labels such as fluorophores can be used for a real-time quantitative assay of a specific protein such as fibrinogen in a human blood that is known to contain many other kinds of proteins together.

Single mode fiber and twin-core fiber connection technique for in-fiber integrated interferometer

NASA Astrophysics Data System (ADS)

Yuan, Tingting; Zhang, Xiaotong; Guan, Chunying; Yang, Xinghua; Yuan, Libo

2015-09-01

A novel twin-core fiber connector has been made by two side-polished fibers. By using side polishing technique, we present a connector based on the twin-core fiber (TCF) and two D-shaped single-core fibers. After simple alignment and splicing, all fiber miniaturizing connector can be obtained. Two cores can operate independently and are non-interfering. The coupling loss of this connector is low and the fabrication technologies are mature. The connector device could be used for sensors or particle trapping.

Fiber optic hydrogen sensor

DOEpatents

Buchanan, B.R.; Prather, W.S.

1991-01-01

Apparatus and method for detecting a chemical substance by exposing an optic fiber having a core and a cladding to the chemical substance so that the chemical substance can be adsorbed onto the surface of the cladding. The optic fiber is coiled inside a container having a pair of valves for controlling the entrance and exit of the substance. Light from a light source is received by one end of the optic fiber, preferably external to the container, and carried by the core of the fiber. Adsorbed substance changes the transmissivity of the fiber as measured by a spectrophotometer at the other end, also preferably external to the container. Hydrogen is detected by the absorption of infrared light carried by an optic fiber with a silica cladding. Since the adsorption is reversible, a sensor according to the present invention can be used repeatedly. Multiple positions in a process system can be monitored using a single container that can be connected to each location to be monitored so that a sample can be obtained for measurement, or, alternatively, containers can be placed near each position and the optic fibers carrying the partially-absorbed light can be multiplexed for rapid sequential reading, by a single spectrophotometer.

Fiber optic hydrogen sensor

DOEpatents

Buchanan, B.R.; Prather, W.S.

1992-10-06

An apparatus and method are described for detecting a chemical substance by exposing an optic fiber having a core and a cladding to the chemical substance so that the chemical substance can be adsorbed onto the surface of the cladding. The optic fiber is coiled inside a container having a pair of valves for controlling the entrance and exit of the substance. Light from a light source is received by one end of the optic fiber, preferably external to the container, and carried by the core of the fiber. Adsorbed substance changes the transmissivity of the fiber as measured by a spectrophotometer at the other end, also preferably external to the container. Hydrogen is detected by the absorption of infrared light carried by an optic fiber with a silica cladding. Since the adsorption is reversible, a sensor according to the present invention can be used repeatedly. Multiple positions in a process system can be monitored using a single container that can be connected to each location to be monitored so that a sample can be obtained for measurement, or, alternatively, containers can be placed near each position and the optic fibers carrying the partially-absorbed light can be multiplexed for rapid sequential reading by a single spectrophotometer. 4 figs.

Fiber optic hydrogen sensor

DOEpatents

Buchanan, Bruce R.; Prather, William S.

1992-01-01

An apparatus and method for detecting a chemical substance by exposing an optic fiber having a core and a cladding to the chemical substance so that the chemical substance can be adsorbed onto the surface of the cladding. The optic fiber is coiled inside a container having a pair of valves for controlling the entrance and exit of the substance. Light from a light source is received by one end of the optic fiber, preferably external to the container, and carried by the core of the fiber. Adsorbed substance changes the transmissivity of the fiber as measured by a spectrophotometer at the other end, also preferably external to the container. Hydrogen is detected by the absorption of infrared light carried by an optic fiber with a silica cladding. Since the adsorption is reversible, a sensor according to the present invention can be used repeatedly. Multiple positions in a process system can be monitored using a single container that can be connected to each location to be monitored so that a sample can be obtained for measurement, or, alternatively, containers can be placed near each position and the optic fibers carrying the partially-absorbed light can be multiplexed for rapid sequential reading by a single spectrophotometer.

Mode instability in a Yb-doped stretched core fiber

NASA Astrophysics Data System (ADS)

Xia, N.; Yoo, S.

2017-02-01

In this work we present the theoretical study of transverse mode instability (TMI) in ytterbium (Yb)-doped rectangular core fibers with different core aspect ratios using the fast Fourier transform (FFT) beam propagation method (BPM). As expected, the rectangular core fiber with larger aspect ratio (AR.) offers more efficient heat dissipation than a circular core fiber. However, it is found that the rectangular core fiber does not benefit from the better heat dissipation to suppress the TMI when compared to the circular core counterpart. The temperature building in the rectangular core fiber decreases by up to 24.6% with a 10:1 aspect ratio core, while threshold pump power drops by up to 38.3% when compared with a circular core fiber with the same core area. Our study reveals that a smaller effective refractive index difference between modes and a weaker gain saturation effect compensate the thermal advantage from more efficient heat dissipation.

Effect of ultraviolet light irradiation period on bond strengths between fiber-reinforced composite post and core build-up composite resin.

PubMed

Asakawa, Yuya; Takahashi, Hidekazu; Iwasaki, Naohiko; Kobayashi, Masahiro

2014-01-01

The aim of the present study was to characterize the effects of the ultraviolet light (UV) irradiation period on the bond strength of fiber-reinforced composite (FRC) posts to core build-up resin. Three types of FRC posts were prepared using polymethyl methacrylate, urethane dimethacrylate, and epoxy resin. The surfaces of these posts were treated using UV irradiation at a distance of 15 mm for 0 to 600 s. The pull-out bond strength was measured and analyzed with the Dunnett's comparison test (α=0.05). The bond strengths of the post surfaces without irradiation were 6.9 to 7.4 MPa; those after irradiation were 4.2 to 26.1 MPa. The bond strengths significantly increased after 15 to 120-s irradiation. UV irradiation on the FRC posts improved the bond strengths between the FRC posts and core build-up resin regardless of the type of matrix resin.

Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

PubMed

Huang, Zhulin; Lei, Xing; Liu, Ye; Wang, Zhiwei; Wang, Xiujuan; Wang, Zhaoming; Mao, Qinghe; Meng, Guowen

2015-08-12

Optical fiber-Raman devices integrated with plasmonic nanostructures have promising potentials for in situ probing remote liquid samples and biological samples. In this system, the fiber probe is required to simultaneously demonstrate stable surface enhanced Raman scattering (SERS) signals and high sensitivity toward the target species. Here we demonstrate a generic approach to integrate presynthesized plasmonic nanostructures with tapered fiber probes that are prepared by a dipping-etching method, through reversed electrostatic attraction between the silane couple agent modified silica fiber probe and the nanostructures. Using this approach, both negatively and positively charged plasmonic nanostructures with various morphologies (such as Au nanosphere, Ag nanocube, Au nanorod, Au@Ag core-shell nanorod) can be stably assembled on the tapered silica fiber probes. Attributed to the electrostatic force between the plasmonic units and the fiber surface, the nanostructures do not disperse in liquid samples easily, making the relative standard deviation of SERS signals as low as 2% in analyte solution. Importantly, the detection sensitivity of the system can be optimized by adjusting the cone angle (from 3.6° to 22°) and the morphology of nanostructures assembled on the fiber. Thus, the nanostructures-sensitized optical fiber-Raman probes show great potentials in the applications of SERS-based environmental detection of liquid samples.

High sensitivity refractive index sensor based on a tapered small core single-mode fiber structure.

PubMed

Liu, Dejun; Mallik, Arun Kumar; Yuan, Jinhui; Yu, Chongxiu; Farrell, Gerald; Semenova, Yuliya; Wu, Qiang

2015-09-01

A high sensitivity refractive index (RI) sensor based on a tapered small core single-mode fiber (SCSMF) structure sandwiched between two traditional single-mode fibers (SMF28) is reported. The microheater brushing technique was employed to fabricate the tapered fiber structures with different waist diameters of 12.5, 15.0, and 18.8 μm. Experiments demonstrate that the fiber sensor with a waist diameter of 12.5 μm offers the best sensitivity of 19212.5  nm/RIU (RI unit) in the RI range of 1.4304 to 1.4320. All sensors fabricated in this Letter show good linearity in terms of the spectral wavelength shift versus changes in RI. Furthermore, the sensor with the best sensitivity to RI was also used to measure relative humidity (RH) without any coating materials applied to the fiber surface. Experimental results show that the spectral wavelength shift changes exponentially as the RH varies from 60% to 95%. A maximum sensitivity of 18.3 nm per relative humidity unit (RHU) was achieved in the RH range of 90.4% to 94.5% RH.

Development of SPR temperature sensor using Au/TiO2 on hetero-core optical fiber

NASA Astrophysics Data System (ADS)

Kitagawa, Sho; Yamazaki, Hiroshi; Hosoki, Ai; Nishiyama, Michiko; Watanabe, Kazuhiro

2016-03-01

This paper describes a novel temperature sensor based on a hetero-core structured fiber optic surface plasmon resonance (SPR) sensor with multi-layer thin film of gold (Au) and titanium dioxide (TiO2). Temperature condition is an essential parameter in chemical plants for avoiding fire accident and controlling qualities of chemical substances. Several fiber optic temperature sensors have been developed for some advantages such as immunity to electromagnetic interference, corrosion resistance and no electrical leakage. The proposed hetero-core fiber optic SPR sensor detects temperature condition by measuring slight refractive index changes of TiO2 which has a large thermo-optic coefficient. We experimentally confirmed that the SPR resonant wavelength in the hetero-core SPR sensor with coating an Au film which slightly depended on temperature changes in the range from 20 °C to 80 °C. In addition, it was experimentally shown that the proposed SPR temperature sensor with multi-layer film of Au and TiO2 had the SPR resonant wavelength shift of 1.6 nm due to temperature change from -10 °C to 50 °C. As a result, a series of experiments successfully demonstrated that the proposed sensor was able to detect temperature directly depending on the thermo-optic effect of TiO2.

Tunable ultra-broadband polarization filter based on three-core resonance of the fluid-infiltrated and gold-coated photonic crystal fiber

NASA Astrophysics Data System (ADS)

Liu, Yingchao; Chen, Hailiang; Ma, Mingjian; Zhang, Wenxun; Wang, Yujun; Li, Shuguang

2018-03-01

We propose a tunable ultra-broadband polarization filter based on three-core resonance of the fluid-infiltrated and gold-coated high birefringent photonic crystal fiber (HB-PCF). Gold film was applied to the inner walls of two cladding air holes and surface plasmon polaritons were generated on its surface. The two gold-coated cladding air holes acted as two defective cores. As the phase matching condition was satisfied, light transmitted in the fiber core and coupled to the two defective cores. The three-core PCF supported three super modes in two orthogonal polarization directions. The coupling characteristics among these modes were investigated using the finite-element method. We found that the coupling wavelengths and strength between these guided modes can be tuned by altering the structural parameters of the designed HB-PCF, such as the size of the voids, thickness of the gold-films and liquid infilling pattern. Under the optimized structural parameters, a tunable broadband polarization filter was realized. For one liquid infilling pattern, we obtained a broadband polarization filter which filtered out the light in y-polarization direction at the wavelength of 1550 nm. For another liquid infilling pattern, we filtered out light in the x-polarization direction at the wavelength of 1310 nm. Our studies on the designed HB-PCF made contributions to the further devising of tunable broadband polarization filters, which are extensively used in telecommunication and sensor systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505175 and 61475134) and the Natural Science Foundation of Hebei Province (Grant Nos. F2017203110 and F2017203193).

Fiber-Type Random Laser Based on a Cylindrical Waveguide with a Disordered Cladding Layer.

PubMed

Zhang, Wei Li; Zheng, Meng Ya; Ma, Rui; Gong, Chao Yang; Yang, Zhao Ji; Peng, Gang Ding; Rao, Yun Jiang

2016-05-25

This letter reports a fiber-type random laser (RL) which is made from a capillary coated with a disordered layer at its internal surface and filled with a gain (laser dye) solution in the core region. This fiber-type optical structure, with the disordered layer providing randomly scattered light into the gain region and the cylindrical waveguide providing confinement of light, assists the formation of random lasing modes and enables a flexible and efficient way of making random lasers. We found that the RL is sensitive to laser dye concentration in the core region and there exists a fine exponential relationship between the lasing intensity and particle concentration in the gain solution. The proposed structure could be a fine platform of realizing random lasing and random lasing based sensing.

Influence of high power 405 nm multi-mode and single-mode diode laser light on the long-term stability of fused silica fibers

NASA Astrophysics Data System (ADS)

Gonschior, C. P.; Klein, K.-F.; Sun, T.; Grattan, K. T. V.

2012-04-01

As the demand for high power fiber-coupled violet laser systems increases existing problems remain. The typical power of commercially available diode lasers around 400 nm is in the order of 100 to 300 mW, depending on the type of laser. But in combination with the small core of single-mode fibers reduced spot sizes are needed for good coupling efficiencies, leading to power densities in the MW/cm2 range. We investigated the influence of 405 nm laser light irradiation on different fused silica fibers and differently treated end-faces. The effect of glued-and-polished, cleaved-and-clamped and of cleaved-and-fusion-arc-treated fiber end-faces on the damage rate and behavior are presented. In addition, effects in the deep ultra-violet were determined spectrally using newest spectrometer technology, allowing the measurement of color centers around 200 nm in small core fibers. Periodic surface structures were found on the proximal end-faces and were investigated concerning generation control parameters and composition. The used fiber types range from low-mode fiber to single-mode and polarization-maintaining fiber. For this investigation 405 nm single-mode or multi-mode diode lasers with 150 mW or 300 mW, respectively, were employed.

Nanostructural evolution during emission of CsI-coated carbon fiber cathodes

NASA Astrophysics Data System (ADS)

Drummy, Lawrence F.; Apt, Scott; Shiffler, Don; Golby, Ken; LaCour, Matt; Maruyama, Benji; Vaia, Richard A.

2010-06-01

Carbon-based nanofiber and microfiber cathodes exhibit very low voltages for the onset of electron emission, and thus provide exciting opportunities for applications ranging from high power microwave sources to field emission displays. CsI coatings have been experimentally shown to lower the work function for emission from the fiber tips, although little is known about the microstructure of the fibers themselves in their as-received state, after coating with CsI, or after being subjected to high voltage cycling. Longitudinal cross sections of the original, unused CsI-coated fibers produced by focused ion beam lift-out revealed a nanostructured graphitic core surrounded by an amorphous carbon shell with submicron sized islands of crystalline CsI on the outer surface. Aberration-corrected high resolution electron microscopy (HREM) of the fiber core achieved 0.10 nm resolution, with the graphite (200) clearly visible in digital fast Fourier transformations of the 2-4 nm highly ordered graphitic domains. As the cathode fibers are cycled at high voltage, HREM demonstrates that the graphitic ordering of the core increases with the number of cycles, however the structure and thickness of the amorphous carbon layer remains unchanged. These results are consistent with micro-Raman measurements of the fiber disordered/graphitic (D/G) band ratios. After high voltage cycling, a uniform ˜100 nm film at the fiber tip was evident in both bright field transmission electron microscopy (TEM) and high angle annular dark field scanning TEM (STEM). Low-dose electron diffraction techniques confirmed the amorphous nature of this film, and STEM with elemental mapping via x-ray energy dispersive spectroscopy indicates this layer is composed of CsIO. The oxidative evolution of tip composition and morphology due to impurities in the chamber, along with increased graphitization of the fiber core, contributes to changes in emission behavior with cycling.

Supercontinuum generation covering the entire 0.4-5 µm transmission window in a tapered ultra-high numerical aperture all-solid fluorotellurite fiber

NASA Astrophysics Data System (ADS)

Jia, Z. X.; Yao, C. F.; Jia, S. J.; Wang, F.; Wang, S. B.; Zhao, Z. P.; Liao, M. S.; Qin, G. S.; Hu, L. L.; Ohishi, Y.; Qin, W. P.

2018-02-01

Enormous efforts have been made to realize supercontinuum (SC) generation covering the entire transmission window of fiber materials for their wide applications in many fields. Here we demonstrate ultra-broadband SC generation from 400 to 5140 nm in a tapered ultra-high numerical aperture (NA) all-solid fluorotellurite fiber pumped by a 1560 nm mode-locked fiber laser. The fluorotellurite fibers are fabricated using a rod-in-tube method. The core and cladding materials are TeO2-BaF2-Y2O3- and TeO2-modified fluoroaluminate glasses, respectively, which have large refractive index contrast and similar thermal expansion coefficients and softening temperatures. The NA at 3200 nm of the fluorotellurite fiber is about 1.11. Furthermore, tapered fluorotellurite fibers are prepared using an elongation machine. SC generation covering the entire 0.4-5 µm transmission window is achieved in a tapered fluorotellurite fiber for a pumping peak power of ~10.5 kW through synergetic control of dispersion, nonlinearity, confinement loss and other unexpected effects (e.g. the attachment of dust or water to the surface of the fiber core) of the fiber. Our results show that tapered ultra-high NA all-solid soft glass fibers have a potential for generating SC light covering their entire transmission window.

Sigma 1 protein of mammalian reoviruses extends from the surfaces of viral particles

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

Furlong, D.B.; Nibert, M.L.; Fields, B.N.

1988-01-01

Electron microscopy revealed structures consisting of long fibers topped with knobs extending from the surfaces of virions of mammalian reoviruses. The morphology of these structures was reminiscent of the fiber protein of adenovirus. Fibers were also seen extending from the reovirus top component and intermediate subviral particles but not from cores, suggesting that the fibers consist of either the ..mu..1C or sigma1 outer capsid protein. Amino acid sequence analysis predicts that the reovirus cell attachment protein sigma1 contains an extended fiber domain. When sigma1 protein was released from viral particles with mild heat and subsequently obtained in isolation, it wasmore » found to have a morphology identical to that of the fiber structures seen extending from the viral particles. The identification of an extended form of sigma1 has important implications for its function in cell attachment. Other evidence suggest that sigma1 protein may occur in virions in both an extended and an unextended state.« less

Microstructured Optical Fiber-based Biosensors: Reversible and Nanoliter-Scale Measurement of Zinc Ions.

PubMed

Heng, Sabrina; McDevitt, Christopher A; Kostecki, Roman; Morey, Jacqueline R; Eijkelkamp, Bart A; Ebendorff-Heidepriem, Heike; Monro, Tanya M; Abell, Andrew D

2016-05-25

Sensing platforms that allow rapid and efficient detection of metal ions would have applications in disease diagnosis and study, as well as environmental sensing. Here, we report the first microstructured optical fiber-based biosensor for the reversible and nanoliter-scale measurement of metal ions. Specifically, a photoswitchable spiropyran Zn(2+) sensor is incorporated within the microenvironment of a liposome attached to microstructured optical fibers (exposed-core and suspended-core microstructured optical fibers). Both fiber-based platforms retains high selectivity of ion binding associated with a small molecule sensor, while also allowing nanoliter volume sampling and on/off switching. We have demonstrated that multiple measurements can be made on a single sample without the need to change the sensor. The ability of the new sensing platform to sense Zn(2+) in pleural lavage and nasopharynx of mice was compared to that of established ion sensing methodologies such as inductively coupled plasma mass spectrometry (ICP-MS) and a commercially available fluorophore (Fluozin-3), where the optical-fiber-based sensor provides a significant advantage in that it allows the use of nanoliter (nL) sampling when compared to ICP-MS (mL) and FluoZin-3 (μL). This work paves the way to a generic approach for developing surface-based ion sensors using a range of sensor molecules, which can be attached to a surface without the need for its chemical modification and presents an opportunity for the development of new and highly specific ion sensors for real time sensing applications.

Suspended core subwavelength fibers: towards practical designs for low-loss terahertz guidance.

PubMed

Rozé, Mathieu; Ung, Bora; Mazhorova, Anna; Walther, Markus; Skorobogatiy, Maksim

2011-05-09

In this work we report two designs of subwavelength fibers packaged for practical terahertz wave guiding. We describe fabrication, modeling and characterization of microstructured polymer fibers featuring a subwavelength-size core suspended in the middle of a large porous outer cladding. This design allows convenient handling of the subwavelength fibers without distorting their modal profile. Additionally, the air-tight porous cladding serves as a natural enclosure for the fiber core, thus avoiding the need for a bulky external enclosure for humidity-purged atmosphere. Fibers of 5 mm and 3 mm in outer diameters with a 150 µm suspended solid core and a 900 µm suspended porous core respectively, were obtained by utilizing a combination of drilling and stacking techniques. Characterization of the fiber optical properties and the subwavelength imaging of the guided modes were performed using a terahertz near-field microscopy setup. Near-field imaging of the modal profiles at the fiber output confirmed the effectively single-mode behavior of such waveguides. The suspended core fibers exhibit transmission from 0.10 THz to 0.27 THz (larger core), and from 0.25 THz to 0.51 THz (smaller core). Due to the large fraction of power that is guided in the holey cladding, fiber propagation losses as low as 0.02 cm(-1) are demonstrated specifically for the small core fiber. Low-loss guidance combined with the core isolated from environmental perturbations make these all-dielectric fibers suitable for practical terahertz imaging and sensing applications. © 2011 Optical Society of America

[INVITED] Porphyrin-nanoassembled fiber-optic gas sensor fabrication: Optimization of parameters for sensitive ammonia gas detection

NASA Astrophysics Data System (ADS)

Korposh, Sergiy; Kodaira, Suguru; Selyanchyn, Roman; Ledezma, Francisco H.; James, Stephen W.; Lee, Seung-Woo

2018-05-01

Highly sensitive fiber-optic ammonia gas sensors were fabricated via layer-by-layer deposition of poly(diallyldimethylammonium chloride) (PDDA) and tetrakis(4-sulfophenyl)porphine (TSPP) onto the surface of the core of a hard-clad multimode fiber that was stripped of its polymer cladding. The effects of film thickness, length of sensing area, and depth of evanescent wave penetration were investigated to clearly understand the sensor performance. The sensitivity of the fiber-optic sensor to ammonia was linear in the concentration range of 0.5-50 ppm and the response and recovery times were less than 3 min, with a limit of detection of 0.5 ppm, when a ten-cycle PDDA/TSPP film was assembled on the surface of the core along a 1 cm-long stripped section of the fiber. The sensor's response towards ammonia was also checked under different relative humidity conditions and a simple statistical data treatment approach, principal component analysis, demonstrated the feasibility of ammonia sensing in environmental relative humidity ranging from dry 7% to highly saturated 80%. Penetration depths of the evanescent wave for the optimal sensor configuration were estimated to be 30 and 33 nm at wavelengths of 420 and 706 nm, which are in a good agreement with the thickness of the 10-cycle deposited film (ca. 30 nm).

Optical fiber sensor having a sol-gel fiber core and a method of making

DOEpatents

Tao, Shiquan; Jindal, Rajeev; Winstead, Christopher; Singh, Jagdish P.

2006-06-06

A simple, economic wet chemical procedure is described for making sol-gel fibers. The sol-gel fibers made from this process are transparent to ultraviolet, visible and near infrared light. Light can be guided in these fibers by using an organic polymer as a fiber cladding. Alternatively, air can be used as a low refractive index medium. The sol-gel fibers have a micro pore structure which allows molecules to diffuse into the fiber core from the surrounding environment. Chemical and biochemical reagents can be doped into the fiber core. The sol-gel fiber can be used as a transducer for constructing an optical fiber sensor. The optical fiber sensor having an active sol-gel fiber core is more sensitive than conventional evanescent wave absorption based optical fiber sensors.

Controlled chemical modification of the internal surface of photonic crystal fibers for application as biosensitive elements

NASA Astrophysics Data System (ADS)

Pidenko, Sergey A.; Burmistrova, Natalia A.; Pidenko, Pavel S.; Shuvalov, Andrey A.; Chibrova, Anastasiya A.; Skibina, Yulia S.; Goryacheva, Irina Y.

2016-10-01

Photonic crystal fibers (PCF) are one of the most promising materials for creation of constructive elements for bio-, drug and contaminant sensing based on unique optical properties of the PCF as effective nanosized optical signal collectors. In order to provide efficient and controllable binding of biomolecules, the internal surface of glass hollow core photonic crystal fibers (HC-PCF) has been chemically modified with silanol groups and functionalized with (3-aminopropyl) triethoxysilane (APTES). The shift of local maxima in the HC-PCF transmission spectrum has been selected as a signal for estimating the amount of silanol groups on the HC-PCF inner surface. The relationship between amount of silanol groups on the HC-PCF inner surface and efficiency of following APTES functionalization has been evaluated. Covalent binding of horseradish peroxidase (chosen as a model protein) on functionalized PCF inner surface has been performed successively, thus verifying the possibility of creating a biosensitive element.

Evaluation of Contemporary Holmium Laser Fibers for Performance Characteristics.

PubMed

Lusch, Achim; Heidari, Emon; Okhunov, Zhamshid; Osann, Kathryn; Landman, Jaime

2016-05-01

Several holmium:YAG laser fibers for urologic applications are currently commercially available. We compared contemporary holmium laser fibers with different core sizes for performance characteristics, including energy transmission, fiber failure, fiber flexibility, and core diameter. Single-use fibers from Cook, Boston Scientific, and Storz were tested in small (200 and 272/273 μm), medium (365 μm), and large (550 and 940/1000 μm) core sizes. Fibers were tested in straight and deflected configurations. All fibers were evaluated for flexibility, true fiber diameter, energy transmission, and fiber failure. For energy transmission, fibers were tested at a pulse energy of 1 J and a frequency of 10 Hz for 30 seconds. All tests were performed on a 30 W holmium laser. For the small core fibers, Storz, Cook OptiLite, and Smart Sync had the smallest core diameter (p < 0.005). In the large core group, Cook OptiLite and Boston Scientific AccuMax showed the smallest diameter. Among the small core fibers, Storz and Cook Smart Sync showed a significant higher deflection, whereas in the 550 μm group, Boston Scientific AccuMax and Cook Smart Sync were the most flexible fibers. In the large and medium core groups, Boston Scientific AccuMax showed superior energy transmission (p = 0.007 and p = 0.001, respectively), whereas in the small core group, there was no significant difference between the fibers, except for 272/3 μm (Storz was inferior compared with the competitors [p < 0.0005]). For fiber failure, Storz, Cook OptiLite, and BS AccuTrac completed all testing without failing (200 μm, bending radius <0.5 cm). In the 365 μm group, Cook OptiLite showed superior results, whereas in the large core group, Boston Scientific AccuMax was superior. Performance characteristics differ significantly between different laser fiber diameters and manufacturers, and fiber choice should depend on specific surgical requirements. There is a trend for less fiber fracture at long pulse, high energy, and low frequency, but this finding will require further investigation.

Surface plasmon resonance based fiber optic detection of chlorine utilizing polyvinylpyrolidone supported zinc oxide thin films.

PubMed

Tabassum, Rana; Gupta, Banshi D

2015-03-21

A highly sensitive chlorine sensor for an aqueous medium is fabricated using an optical fiber surface plasmon resonance (OFSPR) system. An OFSPR-based chlorine sensor is designed with a multilayer-type platform by zinc oxide (ZnO) and polyvinylpyrollidone (PVP) film morphology manipulations. Among all the methodologies of transduction reported in the field of solid state chemical and biochemical sensing, our attention is focused on the Kretschmann configuration optical fiber sensing technique using the mechanism of surface plasmon resonance. The optical fiber surface plasmon resonance (SPR) chlorine sensor is developed using a multimode optical fiber with the PVP-supported ZnO film deposited over a silver-coated unclad core of the fiber. A spectral interrogation mode of operation is used to characterize the sensor. In an Ag/ZnO/PVP multilayer system, the absorption of chlorine in the vicinity of the sensing region is performed by the PVP layer and the zinc oxide layer enhances the shift in resonance wavelength. It is, experimentally, demonstrated that the SPR wavelength shifts nonlinearly towards the red side of the visible region with an increase in the chlorine concentration in an aqueous medium while the sensitivity of the sensor decreases linearly with an increase in the chlorine concentration. As the proposed sensor utilizes an optical fiber, it possesses the additional advantages of fiber such as less signal degradation, less susceptibility to electromagnetic interference, possibility of remote sensing, probe miniaturization, probe re-usability, online monitoring, small size, light weight and low cost.

Experimental implementation of fiber optic bundle array wide FOV free space optical communications receiver.

PubMed

Brown, Andrea M; Hahn, Daniel V; Brown, David M; Rolander, Nathan W; Bair, Chun-Huei; Sluz, Joseph E

2012-06-20

A gimbal-free wide field-of-regard (FOR) optical receiver has been built in a laboratory setting for proof-of-concept testing. Multiple datasets are presented that examine the overall FOR of the system and the receiver's ability to track and collect a signal from a moving source. The design is not intended to compete with traditional free space optical communication systems, but rather offer an alternative design that minimizes the number and complexity of mechanical components required at the surface of a small mobile platform. The receiver is composed of a micro-lens array and hexagonal bundles of large core optical fibers that route the optical signal to remote detectors and electronics. Each fiber in the bundle collects power from a distinct solid angle of space and a piezo-electric transducer is used to translate the micro-lens array and optimize coupling into a given fiber core in the bundle. The micro-lens to fiber bundle design is scalable, modular, and can be replicated in an array to increase aperture size.

Distributed gas detection system and method

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

Challener, William Albert; Palit, Sabarni; Karp, Jason Harris

A distributed gas detection system includes one or more hollow core fibers disposed in different locations, one or more solid core fibers optically coupled with the one or more hollow core fibers and configured to receive light of one or more wavelengths from a light source, and an interrogator device configured to receive at least some of the light propagating through the one or more solid core fibers and the one or more hollow core fibers. The interrogator device is configured to identify a location of a presence of a gas-of-interest by examining absorption of at least one of themore » wavelengths of the light at least one of the hollow core fibers.« less

Characterization of exposures to nanoscale particles and fibers during solid core drilling of hybrid carbon nanotube advanced composites.

PubMed

Bello, Dhimiter; Wardle, Brian L; Zhang, Jie; Yamamoto, Namiko; Santeufemio, Christopher; Hallock, Marilyn; Virji, M Abbas

2010-01-01

This work investigated exposures to nanoparticles and nanofibers during solid core drilling of two types of advanced carbon nanotube (CNT)-hybrid composites: (1) reinforced plastic hybrid laminates (alumina fibers and CNT); and (2) graphite-epoxy composites (carbon fibers and CNT). Multiple real-time instruments were used to characterize the size distribution (5.6 nm to 20 microm), number and mass concentration, particle-bound polyaromatic hydrocarbons (b-PAHs), and surface area of airborne particles at the source and breathing zone. Time-integrated samples included grids for electron microscopy characterization of particle morphology and size resolved (2 nm to 20 microm) samples for the quantification of metals. Several new important findings herein include generation of airborne clusters of CNTs not seen during saw-cutting of similar composites, fewer nanofibers and respirable fibers released, similarly high exposures to nanoparticles with less dependence on the composite thickness, and ultrafine (< 5 nm) aerosol originating from thermal degradation of the composite material.

Diffractive optics development using a modified stack-and-draw technique.

PubMed

Pniewski, Jacek; Kasztelanic, Rafal; Nowosielski, Jedrzej M; Filipkowski, Adam; Piechal, Bernard; Waddie, Andrew J; Pysz, Dariusz; Kujawa, Ireneusz; Stepien, Ryszard; Taghizadeh, Mohammad R; Buczynski, Ryszard

2016-06-20

We present a novel method for the development of diffractive optical elements (DOEs). Unlike standard surface relief DOEs, the phase shift is introduced through a refractive index variation achieved by using different types of glass. For the fabrication of DOEs we use a modified stack-and-draw technique, originally developed for the fabrication of photonic crystal fibers, resulting in a completely flat element that is easy to integrate with other optical components. A proof-of-concept demonstration of the method is presented-a two-dimensional binary optical phase grating in the form of a square chessboard with a pixel size of 5 μm. Two types of glass are used: low refractive index silicate glass NC21 and high refractive index lead-silicate glass F2. The measured diffraction characteristics of the fabricated component are presented and it is shown numerically and experimentally that such a DOE can be used as a fiber interconnector that couples light from a small-core fiber into the several cores of a multicore fiber.

Flexural properties, morphology and bond strength of fiber-reinforced posts: influence of post pretreatment.

PubMed

Braga, Neilor Mateus Antunes; Souza-Gabriel, Aline Evangelista; Messias, Danielle Cristine Furtado; Rached-Junior, Fuad Jacob Abi; Oliveira, Camila Fávero; Silva, Ricardo Gariba; Silva-Sousa, Yara T Corrêa

2012-01-01

The aim of this study was to assess the influence of surface pretreatments of fiber-reinforced posts on flexural strength (FS), modulus of elasticity (ME) and morphology of these posts, as well as the bond strength (BS) between posts and core material. Fifty-two fiber posts (smooth and serrated) were assigned to 4 groups (n=13): no treatment (control), 10% hydrogen peroxide (HP) for 10 min (HP-10), 24% HP for 1 min (HP-24) and airborne-particle abrasion (Al(2)O(3)). To evaluate FS and ME, a 3-point bending test was performed. Three posts of each group were examined by scanning electron microscopy. Composite resin was used as the core build-up and samples were sectioned to obtain microtensile sticks. Data were analyzed by ANOVA and Tukey's test (α=0.05). For FS, significant differences were observed between posts type and surface pretreatment (p<0.05), with the highest means for the smooth posts. Al2O3 provided higher FS than HP-24. Al(2)O(3) promoted higher ME than HP-24 and control. SEM images revealed partial dissolution of the resin matrix in all treated groups. The smooth posts had higher BS and FS than serrated posts (p<0.05). Mechanical properties of the glass fiber posts and the bond strength between posts and composite material were not altered by the surface treatments, except for airborne-particle abrasion that increased the post elastic modulus.

Method and apparatus for enhanced evanescent fluorescence and color filtering using a high refractive index thin film coating

DOEpatents

Kao, Hung Pin; Schoeniger, Joseph; Yang, Nancy

2001-01-01

A technique for increasing the excitation and collection of evanescent fluorescence radiation emanating from a fiber optic sensor having a high refractive index (n.sub.r), dielectric thin film coating has been disclosed and described. The invention comprises a clad optical fiber core whose cladding is removed on a distal end, the distal end coated with a thin, non-porous, titanium dioxide sol-gel coating. It has been shown that such a fiber will exhibit increased fluorescence coupling due in part by 1) increasing the intensity of the evanescent field at the fiber core surface by a constructive interference effect on the propagating light, and 2) increasing the depth of penetration of the field in the sample. The interference effect created by the thin film imposes a wavelength dependence on the collection of the fluorescence and also suggests a novel application of thin films for color filtering as well as increasing collected fluorescence in fiber sensors. Collected fluorescence radiation increased by up to 6-fold over that of a bare fused silica fiber having a numerical aperture (N.A.) of O.6.

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.

Fiber optic laser rod

DOEpatents

Erickson, G.F.

1988-04-13

A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.

Optimization of GRIN lenses coupling system for twin-core fiber interconnection with single core fibers

NASA Astrophysics Data System (ADS)

Chen, Gongdai; Deng, Hongchang; Yuan, Libo

2018-07-01

We aim at a more compact, flexible, and simpler core-to-fiber coupling approach, optimal combinations of two graded refractive index (GRIN) lenses have been demonstrated for the interconnection between a twin-core single-mode fiber and two single-core single-mode fibers. The optimal two-lens combinations achieve an efficient core-to-fiber separating coupling and allow the fibers and lenses to coaxially assemble. Finally, axial deviations and transverse displacements of the components are discussed, and the latter increases the coupling loss more significantly. The gap length between the two lenses is designed to be fine-tuned to compensate for the transverse displacement, and the good linear compensation relationship contributes to the device manufacturing. This approach has potential applications in low coupling loss and low crosstalk devices without sophisticated alignment and adjustment, and enables the channel separating for multicore fibers.

Three-dimensional topographic fiber tract anatomy of the cerebrum.

PubMed

Yagmurlu, Kaan; Vlasak, Alexander L; Rhoton, Albert L

2015-06-01

The fiber tracts of the cerebrum may be a more important determinant of resection limits than the cortex. Better knowledge of the 3-dimensional (3-D) anatomic organization of the fiber pathways is important in planning safe and accurate surgery for lesions within the cerebrum. To examine the topographic anatomy of fiber tracts and subcortical gray matter of the human cerebrum and their relationships with consistent cortical, ventricular, and nuclear landmarks. Twenty-five formalin-fixed human brains and 4 whole cadaveric heads were examined by fiber dissection technique and ×6 to ×40 magnification. The fiber tracts and central core structures, including the insula and basal ganglia, were examined and their relationships captured in 3-D photography. The depth between the surface of the cortical gyri and selected fiber tracts was measured. The topographic relationships of the important association, projection, and commissural fasciculi within the cerebrum and superficial cortical landmarks were identified. Important landmarks with consistent relationships to the fiber tracts were the cortical gyri and sulci, limiting sulci of the insula, nuclear masses in the central core, and lateral ventricles. The fiber tracts were also organized in a consistent pattern in relation to each other. The anatomic findings are briefly compared with functional data from clinicoradiological analysis and intraoperative stimulation of fiber tracts. An understanding of the 3-D anatomic organization of the fiber tracts of the brain is essential in planning safe and accurate cerebral surgery.

Single-mode annular chirally-coupled core fibers for fiber lasers

NASA Astrophysics Data System (ADS)

Zhang, Haitao; Hao, He; He, Linlu; Gong, Mali

2018-03-01

Chirally-coupled core (CCC) fiber can transmit single fundamental mode and effectively suppresses higher-order mode (HOM) propagation, thus improve the beam quality. However, the manufacture of CCC fiber is complicated due to its small side core. To decrease the manufacture difficulty in China, a novel fiber structure is presented, defined as annular chirally-coupled core (ACCC) fiber, replacing the small side core by a larger side annulus. In this paper, we designed the fiber parameters of this new structure, and demonstrated that the new structure has a similar property of single mode with traditional CCC fiber. Helical coordinate system was introduced into the finite element method (FEM) to analyze the mode field in the fiber, and the beam propagation method (BPM) was employed to analyze the influence of the fiber parameters on the mode loss. Based on the result above, the fiber structure was optimized for efficient single-mode transmission, in which the core diameter is 35 μm with beam quality M2 value of 1.04 and an optical to optical conversion efficiency of 84%. In this fiber, fundamental mode propagates in an acceptable loss, while the HOMs decay rapidly.

A direction detective asymmetrical twin-core fiber curving sensor

NASA Astrophysics Data System (ADS)

An, Maowei; Geng, Tao; Yang, Wenlei; Zeng, Hongyi; Li, Jian

2015-10-01

Long period fiber gratings (LPFGs), which can couple the core mode to the forward propagating cladding modes of a fiber and have the advantage of small additional loss, no backward reflection, small size, which is widely used in optical fiber sensors and optical communication systems. LPFG has different fabricating methods, in order to write gratings on the twin-core at the same time effectively, we specially choose electric heating fused taper system to fabricate asymmetric dual-core long period fiber grating, because this kind of method can guarantee the similarity of gratings on the twin cores and obtain good geometric parameters of LPFG, such as cycle, cone waist. Then we use bending test platform to conduct bending test for each of the core of twin-core asymmetric long period fiber grating. Experiments show that: the sensitivity of asymmetrical twin-core long period fiber grating's central core under bending is -5.47nm·m, while the sensitivity of asymmetric twin-core long period fiber grating partial core changed with the relative position of screw micrometer. The sensitivity at 0°, 30°, 90° direction is -4.22nm·m, -9.84nm·m, -11.44nm·m respectively. The experiment results strongly demonstrate the properties of rim sensing of asymmetrical twin-core fiber gratings which provides the possibility of simultaneously measuring the bending magnitude and direction and solving the problem of cross sensing when multi-parameter measuring. In other words, we can detect temperature and bend at the same time by this sensor. As our knowledge, it is the first time simultaneously measuring bend and temperature using this structure of fiber sensors.

Measurements of gas temperatures at 100 kHz within the annulus of a rotating detonation engine

NASA Astrophysics Data System (ADS)

Rein, Keith D.; Roy, Sukesh; Sanders, Scott T.; Caswell, Andrew W.; Schauer, Frederick R.; Gord, James R.

2017-03-01

Cycle-resolved measurements of H2O temperatures and number densities taken within the detonation channel of a hydrogen—air rotating detonation engine (RDE) at a 100 kHz repetition rate using laser absorption spectroscopy are presented. The laser source used is an MEMS-tunable Vertical-Cavity Surface Emitting laser which scans from 1330 to 1360 nm. Optical access into and out of the RDE is achieved using a dual-core fiber optic. Light is pitched into the RDE through a sapphire window via a single-mode core, retroreflected off the mirror-polished inner radius of the RDE annulus, and collected with the multi-mode fiber core. The resulting absorption spectra are used to determine gas temperatures as a function of time. These measurements allow characterization of the transient-temperature response of the RDE.

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.

A study of bending effect on the femtosecond-pulse inscribed fiber Bragg gratings in a dual-core fiber

NASA Astrophysics Data System (ADS)

Yakushin, Sergey S.; Wolf, Alexey A.; Dostovalov, Alexandr V.; Skvortsov, Mikhail I.; Wabnitz, Stefan; Babin, Sergey A.

2018-07-01

Fiber Bragg gratings with different reflection wavelengths have been inscribed in different cores of a dual-core fiber section. The effect of fiber bending on the FBG reflection spectra has been studied. Various interrogation schemes are presented, including a single-end scheme based on a cross-talk between the cores that uses only standard optical components. Simultaneous interrogation of the FBGs in both cores allows to achieve a bending sensitivity of 12.8 pm/m-1, being free of temperature and strain influence. The technology enables the development of real-time bending sensors with high spatial resolution based on series of FBGs with different wavelength inscribed along the multi-core fiber.

Quasi-homogeneous partial coherent source modeling of multimode optical fiber output using the elementary source method

NASA Astrophysics Data System (ADS)

Fathy, Alaa; Sabry, Yasser M.; Khalil, Diaa A.

2017-10-01

Multimode fibers (MMF) have many applications in illumination, spectroscopy, sensing and even in optical communication systems. In this work, we present a model for the MMF output field assuming the fiber end as a quasi-homogenous source. The fiber end is modeled by a group of partially coherent elementary sources, spatially shifted and uncorrelated with each other. The elementary source distribution is derived from the far field intensity measurement, while the weighting function of the sources is derived from the fiber end intensity measurement. The model is compared with practical measurements for fibers with different core/cladding diameters at different propagation distances and for different input excitations: laser, white light and LED. The obtained results show normalized root mean square error less than 8% in the intensity profile in most cases, even when the fiber end surface is not perfectly cleaved. Also, the comparison with the Gaussian-Schell model results shows a better agreement with the measurement. In addition, the complex degree of coherence, derived from the model results, is compared with the theoretical predictions of the modified Van Zernike equation showing very good agreement, which strongly supports the assumption that the large core MMF could be considered as a quasi-homogenous source.

Nonlinear optics in hollow-core photonic bandgap fibers.

PubMed

Bhagwat, Amar R; Gaeta, Alexander L

2008-03-31

Hollow-core photonic-bandgap fibers provide a new geometry for the realization and enhancement of many nonlinear optical effects. Such fibers offer novel guidance and dispersion properties that provide an advantage over conventional fibers for various applications. In this review we summarize the nonlinear optics experiments that have been performed using these hollow-core fibers.

Fabrication and characterization of chalcogenide polarization-maintaining fibers based on extrusion

NASA Astrophysics Data System (ADS)

Jiang, Ling; Wang, Xunsi; Guo, Fangxia; Wu, Bo; Zhao, Zheming; Mi, Nan; Li, Xing; Dai, Shixun; Liu, Zijun; Nie, Qiuhua; Wang, Rongping

2017-12-01

The fabrication and characterization of IR chalcogenide polarization-maintaining (PM) step-index optical fibers with elliptical-core and 1-in-line-core have been reported for the first time. An improved isolated co-extrusion method was used to fabricate these core-shaped PM fibers. The elliptical core had a horizontal radius of a = 3.66 μm, vertical radius of b = 1.83 μm and the 1-in-line core of a = 4.83 μm, b = 1.42 μm, respectively. Single-mode PM beam spots were observed for the elliptical-core and 1-in-line-core fibers in the near-field energy distributions. The highest values of birefringence of the elliptical-core and 1-in-line-core fibers are 2.09 × 10-4 at 2.7 μm and 3.272 × 10-4 at 2.8 μm, respectively. The extinction ratios of -3.7 dB and -2 dB were achieved in fibers of 0.5 m long with elliptical-core and 1-in-line-core, respectively.

Oxidation-induced contraction and strengthening of boron fibers

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.; Wagner, T. C.

1981-01-01

An investigation of the physical and mechanical effects of thermal treatment in a controlled oxygen-argon atmosphere on boron fibers is reported, with attention to the optimization of such treatment as a secondary processing method for improvement of fiber strength. The strengthening mechanism is comprised of an oxidation-induced axial contraction of the fiber, accompanied by axial compression of strength-limiting flaws within the fiber's tungsten boride core. It was found that after an oxidation contraction of 0.3% near 900 C, and a slight surface etch near 100 C, the average tensile strength of 203-micron fibers increased from 500 to 800 ksi. Various physical observations are used to develop mechanistic models of oxidation, contraction, and the formation of new flaws in the boron sheath at contractions greater than 0.3%.

Fabricating and strengthening the carbon nanotube/copper composite fibers with high strength and high electrical conductivity

NASA Astrophysics Data System (ADS)

Han, Baoshuai; Guo, Enyu; Xue, Xiang; Zhao, Zhiyong; Li, Tiejun; Xu, Yanjin; Luo, Liangshun; Hou, Hongliang

2018-05-01

Combining the excellent properties of carbon nanotube (CNT) and copper, CNT/Cu composite fibers were fabricated by physical vapor deposition (PVD) and rolling treatment. Dense and continuous copper film (∼2 μm) was coated on the surface of the CNT fibers by PVD, and rolling treatment was adopt to strengthen the CNT/Cu composite fibers. After the rolling treatment, the defects between the Cu grains and the CNT bundles were eliminated, and the structure of both the copper film and the core CNT fibers were optimized. The rolled CNT/Cu composite fibers possess high tensile effective strength (1.01 ± 0.13 GPa) and high electrical conductivity ((2.6 ± 0.3) × 107 S/m), and thus, this material may become a promising wire material.

Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability.

PubMed

Park, Joung-Man; Kim, Dae-Sik; Kim, Sung-Ryong

2003-08-15

Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes.

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.

On the design of composite protein-quantum dot biomaterials via self-assembly.

PubMed

Majithia, Ravish; Patterson, Jan; Bondos, Sarah E; Meissner, Kenith E

2011-10-10

Incorporation of nanoparticles during the hierarchical self-assembly of protein-based materials can impart function to the resulting composite materials. Herein we demonstrate that the structure and nanoparticle distribution of composite fibers are sensitive to the method of nanoparticle addition and the physicochemical properties of both the nanoparticle and the protein. Our model system consists of a recombinant enhanced green fluorescent protein-Ultrabithorax (EGFP-Ubx) fusion protein and luminescent CdSe-ZnS core-shell quantum dots (QDs), allowing us to optically assess the distribution of both the protein and nanoparticle components within the composite material. Although QDs favorably interact with EGFP-Ubx monomers, the relatively rough surface morphology of composite fibers suggests EGFP-Ubx-QD conjugates impact self-assembly. Indeed, QDs templated onto EGFP-Ubx film post-self-assembly can be subsequently drawn into smooth composite fibers. Additionally, the QD surface charge impacts QD distribution within the composite material, indicating that surface charge plays an important role in self-assembly. QDs with either positively or negatively charged coatings significantly enhance fiber extensibility. Conversely, QDs coated with hydrophobic moieties and suspended in toluene produce composite fibers with a heterogeneous distribution of QDs and severely altered fiber morphology, indicating that toluene severely disrupts Ubx self-assembly. Understanding factors that impact the protein-nanoparticle interaction enables manipulation of the structure and mechanical properties of composite materials. Since proteins interact with nanoparticle surface coatings, these results should be applicable to other types of nanoparticles with similar chemical groups on the surface.

Dual-core optical fiber based strain sensor for remote sensing in hard-to-reach areas

NASA Astrophysics Data System (ADS)

MÄ kowska, Anna; Szostkiewicz, Łukasz; Kołakowska, Agnieszka; Budnicki, Dawid; Bieńkowska, Beata; Ostrowski, Łukasz; Murawski, Michał; Napierała, Marek; Mergo, Paweł; Nasiłowski, Tomasz

2017-10-01

We present research on optical fiber sensors based on microstructured multi-core fiber. Elaborated sensor can be advantageously used in hard-to-reach areas by taking advantage of the fact, that optical fibers can play both the role of sensing elements and they can realize signal delivery. By using the sensor, it is possible to increase the level of the safety in the explosive endangered areas, e.g. in mine-like objects. As a base for the strain remote sensor we use dual-core fibers. The multi-core fibers possess a characteristic parameter called crosstalk, which is a measure of the amount of signal which can pass to the adjacent core. The strain-sensitive area is made by creating the tapered section, in which the level of crosstalk is changed. Due to this fact, we present broadened conception of fiber optic sensor designing. Strain measurement is realized thanks to the fact, that depending on the strain applied, the power distribution between the cores of dual-core fibers changes. Principle of operation allows realization of measurements both in wavelength and power domain.

Shape Sensing Using a Multi-Core Optical Fiber Having an Arbitrary Initial Shape in the Presence of Extrinsic Forces

NASA Technical Reports Server (NTRS)

Rogge, Matthew D. (Inventor); Moore, Jason P. (Inventor)

2014-01-01

Shape of a multi-core optical fiber is determined by positioning the fiber in an arbitrary initial shape and measuring strain over the fiber's length using strain sensors. A three-coordinate p-vector is defined for each core as a function of the distance of the corresponding cores from a center point of the fiber and a bending angle of the cores. The method includes calculating, via a controller, an applied strain value of the fiber using the p-vector and the measured strain for each core, and calculating strain due to bending as a function of the measured and the applied strain values. Additionally, an apparent local curvature vector is defined for each core as a function of the calculated strain due to bending. Curvature and bend direction are calculated using the apparent local curvature vector, and fiber shape is determined via the controller using the calculated curvature and bend direction.

Optical cross-talk and surface characterization of SERS nanoimaging bundle substrates

NASA Astrophysics Data System (ADS)

Kiser, John B.; Cullum, Brian M.

2010-04-01

Due to the narrow vibrational bandwidths and unique molecular fingerprints, Raman spectroscopy can be an information rich transduction technique for chemical imaging. Dynamic systems are often difficult to measure using spontaneous Raman due to the relatively weak scattering cross-sections. Using a Raman enhancement mechanism such as surface enhanced Raman scattering (SERS), exposure times can be reduced to a reasonable level for dynamic imaging, due to the increased Raman signal intensity. This paper will discuss the development of a novel SERS substrate, fabricated on the tips of fiber-optic imaging bundles, which can be integrated into a multispectral imaging system for non-scanning chemical imaging. These substrates are fabricated by mechanically tapering a polished fiber optic imaging bundle consisting of 30,000 individual elements; producing 100-nm or smaller diameter core elements on the distal tip. Chemical etching with hydrofluoric acid creates uniform cladding spikes onto which a SERS active metal is vacuum deposited, forming the SERS active surface. By varying the size of the silver islands deposited on the cladding peaks active, surface plasmons can be tuned to various excitation frequencies. The surface of these tapered fiber optic probes will be evaluated by analysis of the SERS signal, location and shape of the active surface plasmons. The cross talk between the fiber elements will also be evaluated.

Core-to-core uniformity improvement in multi-core fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Lindley, Emma; Min, Seong-Sik; Leon-Saval, Sergio; Cvetojevic, Nick; Jovanovic, Nemanja; Bland-Hawthorn, Joss; Lawrence, Jon; Gris-Sanchez, Itandehui; Birks, Tim; Haynes, Roger; Haynes, Dionne

2014-07-01

Multi-core fiber Bragg gratings (MCFBGs) will be a valuable tool not only in communications but also various astronomical, sensing and industry applications. In this paper we address some of the technical challenges of fabricating effective multi-core gratings by simulating improvements to the writing method. These methods allow a system designed for inscribing single-core fibers to cope with MCFBG fabrication with only minor, passive changes to the writing process. Using a capillary tube that was polished on one side, the field entering the fiber was flattened which improved the coverage and uniformity of all cores.

Liquid-filled hollow core microstructured polymer optical fiber.

PubMed

Cox, F M; Argyros, A; Large, M C J

2006-05-01

Guidance in a liquid core is possible with microstructured optical fibers, opening up many possibilities for chemical and biochemical fiber-optic sensing. In this work we demonstrate how the bandgaps of a hollow core microstructured polymer optical fiber scale with the refractive index of liquid introduced into the holes of the microstructure. Such a fiber is then filled with an aqueous solution of (-)-fructose, and the resulting optical rotation measured. Hence, we show that hollow core microstructured polymer optical fibers can be used for sensing, whilst also fabricating a chiral optical fiber based on material chirality, which has many applications in its own right.

More than threefold expansion of highly nonlinear photonic crystal fiber cores for low-loss fusion splicing.

PubMed

Chen, Z; Xiong, C; Xiao, L M; Wadsworth, W J; Birks, T A

2009-07-15

We have formed low-loss fusion splices from highly nonlinear (HNL) photonic crystal fibers (PCFs) with small cores and high air-filling fractions to fibers with much larger mode field diameters (MFDs). The PCF core was locally enlarged by the controlled collapse of holes around the core while keeping other holes open. The fiber was then cleaved at the enlarged core and spliced to the large MFD fiber with a conventional electric arc fusion splicer. Splice losses as low as 0.36 dB were achieved between a PCF and a standard single-mode fiber (SMF) with MFDs of 1.8 microm and 5.9 microm, respectively.

Particle levitation and guidance in hollow-core photonic crystal fiber.

PubMed

Benabid, Fetah; Knight, J; Russell, P

2002-10-21

We report the guidance of dry micron-sized dielectric particles in hollow core photonic crystal fiber. The particles were levitated in air and then coupled to the air-core of the fiber using an Argon ion laser beam operating at a wavelength of 514 nm. The diameter of the hollow core of the fiber is 20 m . A laser power of 80 mW was sufficient to levitate a 5 m diameter polystyrene sphere and guide it through a ~150 mm long hollow-core crystal photonic fiber. The speed of the guided particle was measured to be around 1 cm/s.

Fusion splice between tapered inhibited coupling hypocycloid-core Kagome fiber and SMF.

PubMed

Zheng, Ximeng; Debord, Benoît; Vincetti, Luca; Beaudou, Benoît; Gérôme, Frédéric; Benabid, Fetah

2016-06-27

We report for the first time on tapering inhibited coupling (IC) hypocycloid-core shape Kagome hollow-core photonic crystal fibers whilst maintaining their delicate core-contour negative curvature with a down-ratio as large as 2.4. The transmission loss of down-tapered sections reaches a figure as low as 0.07 dB at 1550 nm. The tapered IC fibers are also spliced to standard SMF with a total insertion loss of 0.48 dB. These results show that all-fiber photonic microcells with the ultra-low loss hypocycloid core-contour Kagome fibers is now possible.

Controllable Construction of Core-Shell Polymer@Zeolitic Imidazolate Frameworks Fiber Derived Heteroatom-Doped Carbon Nanofiber Network for Efficient Oxygen Electrocatalysis.

PubMed

Zhao, Yingxuan; Lai, Qingxue; Zhu, Junjie; Zhong, Jia; Tang, Zeming; Luo, Yan; Liang, Yanyu

2018-05-01

Designing rational nanostructures of metal-organic frameworks based carbon materials to promote the bifunctional catalytic activity of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desired but still remains a great challenge. Herein, an in situ growth method to achieve 1D structure-controllable zeolitic imidazolate frameworks (ZIFs)/polyacrylonitrile (PAN) core/shell fiber (PAN@ZIFs) is developed. Subsequent pyrolysis of this precursor can obtain a heteroatom-doped carbon nanofiber network as an efficient bifunctional oxygen electrocatalyst. The electrocatalytic performance of derived carbon nanofiber is dominated by the structures of PAN@ZIFs fiber, which is facilely regulated by efficiently controlling the nucleation and growth process of ZIFs on the surface of polymer fiber as well as optimizing the components of ZIFs. Benefiting from the core-shell structures with appropriate dopants and porosity, as-prepared catalysts show brilliant bifunctional ORR/OER catalytic activity and durability. Finally, the rechargeable Zn-air battery assembled from the optimized catalyst (CNF@Zn/CoNC) displays a peak power density of 140.1 mW cm -2 , energy density of 878.9 Wh kg Zn -1 , and excellent cyclic stability over 150 h, giving a promising performance in realistic application. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diode-Pumped Thulium (Tm)/Holmium (Ho) Composite Fiber 2.1-Micrometers Laser

DTIC Science & Technology

2015-09-01

composite fiber laser of holmium-core and thulium-doped cladding . The composite fiber was optically pumped by an 803-nm fiber coupled diode source and was...4 odd and 5 even modes were exclusive to the core and first cladding . As the Tm laser modes are excluded from lasing in the second (undoped...of the Tm-doped clad /Ho-doped core fiber laser . In particular, calculations of the model overlap of the cladding modes with the core have been

Grafting methyl acrylic onto carbon fiber via Diels-Alder reaction for excellent mechanical and tribological properties of phenolic composites

NASA Astrophysics Data System (ADS)

Fei, Jie; Duan, Xiao; Luo, Lan; Zhang, Chao; Qi, Ying; Li, Hejun; Feng, Yongqiang; Huang, Jianfeng

2018-03-01

Carbon fibers (CFs) were grafted with methyl acrylic via Diels-Alder reaction at the different oil bath temperature effectively creating a carboxyl functionalized surface. The effect of grafting temperature on the surface morphology and functional groups of carbon fibers were investigated by FTIR, Raman spectroscopy, XPS and SEM respectively. The results showed that the optimal grafting temperature was 80 °C, and the relative surface coverage by carboxylic acid groups increased from an initial 5.16% up to 19.30% significantly improved the chemical activity without damaging the skin and core region of the carbon fibers. Mechanical property tests indicated that the shear and tensile strength of the sample with the grafting temperature of 80 °C (CFRP-3) increased obviously by 90.3% and 78.7%, respectively, compared with the pristine carbon fibers reinforced composite. Further, the sample CFRP-3 exhibited higher and more stable friction coefficient and improved wear resistance, while the wear rate decreased 52.7%, from 10.8 × 10-6 to 5.1 × 10-6 mm3/N m. The present work shows that grafting methyl acrylic via Diels-Alder reaction could be a highly efficient and facile method to functionalize carbon fibers for advanced composites.

Optical fiber sensors for damage analysis in aerospace materials

NASA Technical Reports Server (NTRS)

Schindler, Paul; May, Russell; Claus, Richard

1995-01-01

Under this grant, fiber optic sensors were investigated for use in the nondestructive evaluation of aging aircraft. Specifically, optical fiber sensors for detection and location of impacts on a surface, and for detection of corrosion in metals were developed. The use of neural networks was investigated for determining impact location by processing the output of a network of fiberoptic strain sensors distributed on a surface. This approach employs triangulation to determine location by comparing the arrival times at several sensors, of the acoustic signal generated by the impact. For this study, a neural network simulator running on a personal computer was used to train a network using a back-propagation algorithm. Fiber optic extrinsic Fabry-Perot interferometer (EFPI) strain sensors are attached to or embedded in the surface, so that stress waves emanating from an impact can be detected. The ability of the network to determine impact location by time-or-arrival of acoustic signals was assessed by comparing network outputs with actual experimental results using impacts on a panel instrumented with optical fiber sensors. Using the neural network to process the sensor outputs, the impact location can be inferred to centimeter range accuracy directly from the arrival time data. In addition, the network can be trained to determine impact location, regardless of material anisotropy. Results demonstrate that a back-propagation network identifies impact location for an anisotropic graphite/bismaleimide plate with the same accuracy as that for an isotropic aluminum plate. Two different approaches were investigated for the development of fiber optic sensors for corrosion detection in metals, both utilizing optical fiber sensors with metal coatings. In the first approach, an extrinsic Fabry-Perot interferometric fiber optic strain sensor was placed under tensile stress, and while in the resulting strained position, a thick coating of metal was applied. Due to an increase in the quantity of material, the sensor does not return to its original position upon removal of the applied stress, and some residual strain is maintained within the sensor element. As the metal thickness decreases due to corrosion, this strain is released, providing the sensing mechanism for corrosion detection. In the second approach, photosensitive optical fibers with long period Bragg gratings in the core were coated with metal. The Bragg gratings serve to couple core modes at discrete wavelengths to cladding modes. Since cladding modes interact with the metal coating surrounding the fiber cladding, the specific wavelengths coupled from core to cladding depend on the refractive index of the metal coating. Therefore, as the metal corrodes, the resulting change in index of the coating may be measured by measuring the change in wavelength of the coupled mode. Results demonstrate that both approaches can be successfully used to track the loss in metal coating on the optical fiber sensors due to corrosion.

PMMA/PS coaxial electrospinning: core-shell fiber morphology as a function of material parameters

NASA Astrophysics Data System (ADS)

Rahmani, Shahrzad; Arefazar, Ahmad; Latifi, Masoud

2017-03-01

Core-shell fibers of polymethyl methacrylate (PMMA) and polystyrene (PS) have been successfully electrospun by coaxial electrospinning. To evaluate the influence of the solvent on the final fiber morphology, four types of organic solvents were used in the shell solution while the core solvent was preserved. Morphological observations with scanning electron microscopy, transmission electron microscopy and optical microscopy revealed that both core and shell solvent properties were involved in the final fiber morphology. To explain this involvement, alongside a discussion of the Bagley solubility graph of PS and PMMA, a novel criterion based on solvent physical properties was introduced. A theoretical model based on the momentum conservation principle was developed and applied for describing the dependence of the core and shell diameters to their solvent combinations. Different concentrations of core and shell were also investigated in the coaxial electrospinning of PMMA/PS. The core-shell fiber morphologies with different core and shell concentrations were compared with their single electrospun fibers.

Experimental Tests on the Composite Foam Sandwich Pipes Subjected to Axial Load

NASA Astrophysics Data System (ADS)

Li, Feng; Zhao, QiLin; Xu, Kang; Zhang, DongDong

2015-12-01

Compared to the composite thin-walled tube, the composite foam sandwich pipe has better local flexural rigidity, which can take full advantage of the high strength of composite materials. In this paper, a series of composite foam sandwich pipes with different parameters were designed and manufactured using the prefabricated polyurethane foam core-skin co-curing molding technique with E-glass fabric prepreg. The corresponding axial-load compressive tests were conducted to investigate the influence factors that experimentally determine the axial compressive performances of the tubes. In the tests, the detailed failure process and the corresponding load-displacement characteristics were obtained; the influence rules of the foam core density, surface layer thickness, fiber ply combination and end restraint on the failure modes and ultimate bearing capacity were studied. Results indicated that: (1) the fiber ply combination, surface layer thickness and end restraint have a great influence on the ultimate load bearing capacity; (2) a reasonable fiber ply combination and reliable interfacial adhesion not only optimize the strength but also transform the failure mode from brittle failure to ductile failure, which is vital to the fully utilization of the composite strength of these composite foam sandwich pipes.

Optical fibers and Fluorosensors having improved power efficiency and methods of producing same

NASA Technical Reports Server (NTRS)

Egalon, Claudio O. (Inventor); Rogowski, Robert S. (Inventor)

1993-01-01

Optical fibers may have applications including fluorosensors which sense the concentration of an analyte. Like communication fibers, these fluorosensors are modeled using a weakly guiding approximation which is only effective when the difference between the respective refractive indices of the fiber core and surrounding cladding are minimal. An optical fiber fluorosensor is provided having a portion of a fiber core which is surrounded by an active cladding which is permeable by the analyte to be sensed and containing substances which emit light waves upon excitation. A remaining portion of the fiber core is surrounded by a guide cladding which guides these light waves to a sensor which detects the intensity of waves, which is a function of the analyte concentration. Contrary to conventional weakly guiding principles, the difference between the respective indices of refraction of the fiber core is surrounded by an active cladding which is thin enough such that its index of refraction is effectively that of the surrounding atmosphere, thereby the atmosphere guides the injective indices of the fiber core and the cladding results in an unexpected increase in the power efficiency of the fiber core.

Single-mode fiber laser based on core-cladding mode conversion.

PubMed

Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

2008-02-15

A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

LiNbO3 Cylinder Fiber

NASA Technical Reports Server (NTRS)

2004-01-01

We have successfully fabricate optical fiber with a thin layer of LiNbO3 at the boundary of the glass core and dear glass cladding. The construction of this fiber is based on our successful Semiconductor Cylinder Fibers (SCF). A schematic representation of a LiNbO3 Cylinder Fiber is shown. These fibers can be used as light modulators, sonar detectors and in other applications. The core diameter of the fiber is sufficiently small compared to the light wavelength and the indices of refraction of the core and cladding glasses are sufficiently close in value so that there is sufficient light at the core cladding boundary to interact with the LiNbO3 layer. This fiber functions best when just a single light mode propagates through the fiber. The idea for a LiNbO3 Cylinder Fiber came from Dr. Tracee Jamison of NASA. The optical properties of LiNbO3 can be changed with strain or the application of an electric field. Thus these fibers can be used as acoustic sensors as for example in a sonar. They can also be used as electric field operated light modulators. However, for this application the fibers would be made with a cross section in the form of a 'D'. The core with its surrounding LiNbO, layer would be close to the flat portion of the 'D' shaped fiber. Two metal contacts would be deposited on the flat portion of the fiber on either side of the core. A voltage applied across these contacts will result in an electric field in the core region that can be used for modulating the optical properties of the LiNbO, layer. To our knowledge this is the first ever LiNbO, Cylinder Fiber made.

LiNbO3 Cylinder Fiber

NASA Technical Reports Server (NTRS)

Kornreich, Philip

2004-01-01

We have successfully fabricate optical fiber with a thin layer of LiNbO3 at the boundary of the glass core and clear glass cladding. The construction of this fiber is based on our successful Semiconductor Cylinder Fibers (SCF). A schematic representation of a LiN bo, Cylinder Fiber. These fibers can be used as light modulators, sonar detectors and in other applications. The core diameter of the fiber is sufficiently small compared to the light wavelength and the indices of refraction of the core and cladding glasses are sufficiently close in value so that there is sufficient light at the core cladding boundary to interact with the LiNbO3 layer. This fiber functions best when just a single light mode propagates through the fiber. The idea for a LiNbO3 Cylinder Fiber came from Dr. Tracee Jamison of NASA. The optical properties of LiNbO3 can be changed with strain or the application of an electric field. Thus these fibers can be used as acoustic sensors as for example in a sonar. They can also be used as electric field operated light modulators. However, for this application the fibers would be made with a cross section in the form of a "D". The core with its surrounding LiNbO, layer would be close to the flat portion of the "D" shaped fiber. Two metal contacts would be deposited on the flat portion of the fiber on either side of the core. A voltage applied across these contacts will result in an electric field in the core region that can be used for modulating the optical properties of the LiNbO3 layer. To our knowledge this is the first ever LiNbO3 Cylinder Fiber made.

Hollow Core Optical Fiber Gas Lasers: Toward Novel and Practical Systems in Fused Silica

DTIC Science & Technology

2017-05-18

Hollow core Optically pumped Fiber Gas LASer’s (HOFGLAS’s) based on population inversion combine advantages of fiber lasers such as long interaction...polarization dependent fiber properties. Preliminary experiments were performed toward simultaneous lasing in the visible and near infrared; lasing in...words) Hollow core Optically pumped Fiber Gas LASer’s (HOFGLAS’s) based on population inversion combine advantages of fiber lasers such as long

A high-sensitivity fiber-optic evanescent wave sensor with a three-layer structure composed of Canada balsam doped with GeO2.

PubMed

Zhong, Nianbing; Zhao, Mingfu; Zhong, Lianchao; Liao, Qiang; Zhu, Xun; Luo, Binbin; Li, Yishan

2016-11-15

In this paper, we present a high-sensitivity polymer fiber-optic evanescent wave (FOEW) sensor with a three-layer structure that includes bottom, inter-, and surface layers in the sensing region. The bottom layer and inter-layer are POFs composed of standard cladding and the core of the plastic optical fiber, and the surface layer is made of dilute Canada balsam in xylene doped with GeO2. We examine the morphology of the doped GeO2, the refractive index and composition of the surface layer and the surface luminous properties of the sensing region. We investigate the effects of the content and morphology of the GeO2 particles on the sensitivity of the FOEW sensors by using glucose solutions. In addition, we examine the response of sensors incubated with staphylococcal protein A plus mouse IgG isotype to goat anti-mouse IgG solutions. Results indicate very good sensitivity of the three-layer FOEW sensor, which showed a 3.91-fold improvement in the detection of the target antibody relative to a conventional sensor with a core-cladding structure, and the novel sensor showed a lower limit of detection of 0.2ng/l and a response time around 320s. The application of this high-sensitivity FOEW sensor can be extended to biodefense, disease diagnosis, biomedical and biochemical analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

[The experiment research on solution refractive index sensor based on tilted fiber Bragg grating].

PubMed

Jiang, Qi; Lü, Dan-Dan; Yu, Ming-Hao; Kang, Li-Min; Ouyang, Jun

2013-12-01

The present paper analyzes the sensor's basic principle of the bare tilted fiber Bragg grating (TFBG) and surface plasmon resonance sensor (SPR) that deposited nanoscale gold-coating on the surface of the cladding. We simulated the transmission spectrums and some order cladding mode of TFBG in different concentration solutions by Integration and optical fiber grating software OptiGrating. So by the graphic observation and data analysis, a preliminary conclusion was got that in a certain sensing scope, the cladding modes of TFBG shift slightly to right with the increasing the solution refractive index(SRI),and the relation between resonance peak caused by the coupling of core mode and a certain cladding mode and the SRI was linear. Then the 45 nm thick gold coating was deposited on the surface of the TFBG cladding in a small-scale sputtering chamber KYKY SBC-12, and thermal field scanning electron microscopy presents that the effect of gold-coating was satisfactory to a certain extent in terms of microscopic level. The refractive index(RI) sensing experiments of different concentration solutions of NaCI, MgCI2, CaCI2 were carried out using bare and gold deposited TFBG. The RI sensing characteristics of both bare and gold deposited TFBGs respectively were studied by experiments. Meanwhile, it proved the conclusion that the cladding modes of TFBG drifted to right gradually when the SRI was increasing and the relations between resonance peak caused by the coupling of core mode and a certain cladding mode and the SRI were linear. And by quantitative analysis, we know that SPR sensor with the deposited namoscale gold layer on the surface of cladding enhanced the RI sensitivity dramatically by 2 to 500 nm RIU-1 which is 200 to 300 times larger than that of the bare tilted fiber Bragg grating approximately. The degrees of linear fittings of resonance peak caused by the coupling of core mode and a certain cladding mode and SRI of bare and gold-coating deposited SPR sensor are very good and both of them reach up to more than 0. 99.

Tapered polysilicon core fibers for nonlinear photonics.

PubMed

Suhailin, Fariza H; Shen, Li; Healy, Noel; Xiao, Limin; Jones, Maxwell; Hawkins, Thomas; Ballato, John; Gibson, Ursula J; Peacock, Anna C

2016-04-01

We propose and demonstrate a novel approach to obtaining small-core polysilicon waveguides from the silicon fiber platform. The fibers were fabricated via a conventional drawing tower method and, subsequently, tapered down to achieve silicon core diameters of ∼1  μm, the smallest optical cores for this class of fiber to date. Characterization of the material properties have shown that the taper process helps to improve the local crystallinity of the silicon core, resulting in a significant reduction in the material loss. By exploiting the combination of small cores and low losses, these tapered fibers have enabled the first observation of nonlinear transmission within a polycrystalline silicon waveguide of any type. As the fiber drawing method is highly scalable, it opens a route for the development of low-cost and flexible nonlinear silicon photonic systems.

Study on micro-bend light transmission performance of novel liquid-core optical fiber

NASA Astrophysics Data System (ADS)

Ma, Junyan; Zhao, Zhimin; Wang, Kaisheng; Guo, Linfeng

2007-01-01

With the increasing development of material technology and electronic integration technology, optical fiber and its using in smart structure have become hot in the field of material research. And liquid-core optical fiber is a special kind of optical fiber, which is made using liquid material as core and polymer material as optical layer and protective covering, and it has the characteristics of large core diameter, high numerical aperture, large-scope and efficient spectrum transmission and long life for using. So the liquid-core optical fiber is very suitable for spectrum cure, ultraviolet solidification, fluorescence detection, criminal investigation and evidence obtainment, etc, and especially as light transfer element in some new structures for the measurement of some signals, such as concentration, voltage, temperature, light intensity and so on. In this paper, the novel liquid-core optical fiber is self-made, and then through the test of its light transmission performance in free state, the relation between axial micro-bend and light-intensity loss are presented. When the liquid-core optical fiber is micro-bent axially, along with the axial displacement's increase, output power of light is reducing increasingly, and approximately has linear relation to micro-displacement in a range. According to the results liquid-core fiber-optic micro-bend sensor can be designed to measure micro-displacement of the tested objects. Experimental data and analysis provide experimental basis for further application of liquid-core optical fiber.

Properties of polyurethane foam/coconut coir fiber as a core material and as a sandwich composites component

NASA Astrophysics Data System (ADS)

Azmi, M. A.; Abdullah, H. Z.; Idris, M. I.

2013-12-01

This research focuses on the fabrication and characterization of sandwich composite panels using glass fiber composite skin and polyurethane foam reinforced coconut coir fiber core. The main objectives are to characterize the physical and mechanical properties and to elucidate the effect of coconut coir fibers in polyurethane foam cores and sandwich composite panels. Coconut coir fibers were used as reinforcement in polyurethane foams in which later were applied as the core in sandwich composites ranged from 5 wt% to 20 wt%. The physical and mechanical properties found to be significant at 5 wt% coconut coir fiber in polyurethane foam cores as well as in sandwich composites. It was found that composites properties serve better in sandwich composites construction.

Development of a core sheath process for production of oxide fibers

NASA Technical Reports Server (NTRS)

Freske, S.

1972-01-01

Improvements were sought in an oxide fiber of a core sheath configuration intended for structural applications at 2000 F (1093 C). Discontinuities in the core were eliminated by using core materials other than pure alumina, and continuous core sheath fibers were produced. In the case of some core materials, the continuous sections were sufficiently long for applications in short fiber composites. Creep at 2000 F (1093 C) was found to be due, in most cases, to breaks in the core, allowing the glass sheath to creep. Evidence was obtained indicating that a closer match between the thermal expansion coefficient of the sheath and the core would greatly improve the strength.

Shape sensing using multi-core fiber optic cable and parametric curve solutions.

PubMed

Moore, Jason P; Rogge, Matthew D

2012-01-30

The shape of a multi-core optical fiber is calculated by numerically solving a set of Frenet-Serret equations describing the path of the fiber in three dimensions. Included in the Frenet-Serret equations are curvature and bending direction functions derived from distributed fiber Bragg grating strain measurements in each core. The method offers advantages over prior art in that it determines complex three-dimensional fiber shape as a continuous parametric solution rather than an integrated series of discrete planar bends. Results and error analysis of the method using a tri-core optical fiber is presented. Maximum error expressed as a percentage of fiber length was found to be 7.2%.

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.

Stack-and-Draw Manufacture Process of a Seven-Core Optical Fiber for Fluorescence Measurements

NASA Astrophysics Data System (ADS)

Samir, Ahmed; Batagelj, Bostjan

2018-01-01

Multi-core, optical-fiber technology is expected to be used in telecommunications and sensory systems in a relatively short amount of time. However, a successful transition from research laboratories to industry applications will only be possible with an optimized design and manufacturing process. The fabrication process is an important aspect in designing and developing new multi-applicable, multi-core fibers, where the best candidate is a seven-core fiber. Here, the basics for designing and manufacturing a single-mode, seven-core fiber using the stack-and-draw process is described for the example of a fluorescence sensory system.

Controlled core removal from a D-shaped optical fiber.

PubMed

Markos, Douglas J; Ipson, Benjamin L; Smith, Kevin H; Schultz, Stephen M; Selfridge, Richard H; Monte, Thomas D; Dyott, Richard B; Miller, Gregory

2003-12-20

The partial removal of a section of the core from a continuous D-shaped optical fiber is presented. In the core removal process, selective chemical etching is used with hydrofluoric (HF) acid. A 25% HF acid solution removes the cladding material above the core, and a 5% HF acid solution removes the core. A red laser with a wavelength of 670 nm is transmitted through the optical fiber during the etching. The power transmitted through the optical fiber is correlated to the etch depth by scanning electron microscope imaging. The developed process provides a repeatable method to produce an optical fiber with a specific etch depth.

Plasmonic Optical Fiber-Grating Immunosensing: A Review

PubMed Central

Loyez, Médéric; Caucheteur, Christophe

2017-01-01

Plasmonic immunosensors are usually made of a noble metal (in the form of a film or nanoparticles) on which bioreceptors are grafted to sense analytes based on the antibody/antigen or other affinity mechanism. Optical fiber configurations are a miniaturized counterpart to the bulky Kretschmann prism and allow easy light injection and remote operation. To excite a surface plasmon (SP), the core-guided light is locally outcoupled. Unclad optical fibers were the first configurations reported to this end. Among the different architectures able to bring light in contact with the surrounding medium, a great quantity of research is today being conducted on metal-coated fiber gratings photo-imprinted in the fiber core, as they provide modal features that enable SP generation at any wavelength, especially in the telecommunication window. They are perfectly suited for use with cost-effective high-resolution interrogators, allowing both a high sensitivity and a low limit of detection to be reached in immunosensing. This paper will review recent progress made in this field with different kinds of gratings: uniform, tilted and eccentric short-period gratings as well as long-period fiber gratings. Practical cases will be reported, showing that such sensors can be used in very small volumes of analytes and even possibly applied to in vivo diagnosis. PMID:29186871

Plasmonic Optical Fiber-Grating Immunosensing: A Review.

PubMed

Guo, Tuan; González-Vila, Álvaro; Loyez, Médéric; Caucheteur, Christophe

2017-11-26

Plasmonic immunosensors are usually made of a noble metal (in the form of a film or nanoparticles) on which bioreceptors are grafted to sense analytes based on the antibody/antigen or other affinity mechanism. Optical fiber configurations are a miniaturized counterpart to the bulky Kretschmann prism and allow easy light injection and remote operation. To excite a surface plasmon (SP), the core-guided light is locally outcoupled. Unclad optical fibers were the first configurations reported to this end. Among the different architectures able to bring light in contact with the surrounding medium, a great quantity of research is today being conducted on metal-coated fiber gratings photo-imprinted in the fiber core, as they provide modal features that enable SP generation at any wavelength, especially in the telecommunication window. They are perfectly suited for use with cost-effective high-resolution interrogators, allowing both a high sensitivity and a low limit of detection to be reached in immunosensing. This paper will review recent progress made in this field with different kinds of gratings: uniform, tilted and eccentric short-period gratings as well as long-period fiber gratings. Practical cases will be reported, showing that such sensors can be used in very small volumes of analytes and even possibly applied to in vivo diagnosis.

High Sensitive Temperature Sensor Using a Liquid-core Optical Fiber with Small Refractive Index Difference Between Core and Cladding Materials.

PubMed

Xu, Yonghao; Chen, Xianfeng; Zhu, Yu

2008-03-17

An intensive temperature sensor based on a liquid-core optical fiber has been demonstrated for the measuring the temperature of the environment. The core of fiber is filled with a mixture of toluene and chloroform in order to make the refractive index of the liquid-core and the cladding of the fiber close. The experiment shows that a temperature sensitivity of about 5 dB/K and a tunable temperature range (from 20 o C to 60 o C) can be achieved. Based on the dielectric-clad liquid core fiber model, a simulation was carried out and the calculated results were in good accord with the experimental measurement.

Thermoresponsive Cellulose Acetate-Poly(N-isopropylacrylamide) Core-Shell Fibers for Controlled Capture and Release of Moisture.

PubMed

Thakur, Neha; Sargur Ranganath, Anupama; Sopiha, Kostiantyn; Baji, Avinash

2017-08-30

In this study, we used core-shell electrospinning to fabricate cellulose acetate-poly(N-isopropylacrylamide) (CA-PNIPAM) fibrous membranes and demonstrated the ability of these fibers to capture water from a high humid atmosphere and release it when thermally stimulated. The wettability of the fibers was controlled by using thermoresponsive PNIPAM as the shell layer. Scanning electron and fluorescence microscopes are used to investigate the microstructure of the fibers and confirm the presence of the core and shell phases within the fibers. The moisture capturing and releasing ability of these core-shell CA-PNIPAM fibers was compared with those of the neat CA and neat PNIPAM fibers at room temperature as well as at an elevated temperature. At room temperature, the CA-PNIPAM core-shell fibers are shown to have the maximum moisture uptake capacity among the three samples. The external temperature variations which trigger the moisture response behavior of these CA-PNIPAM fibers fall within the range of typical day and night cycles of deserts, demonstrating the potential use of these fibers for water harvesting applications.

"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.

Post-inscription tuning of multicore fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Lindley, Emma Y.; Min, Seong-sik; Leon-Saval, Sergio G.; Bland-Hawthorn, Joss

2016-07-01

Fiber Bragg gratings are used in astronomy for their ability to suppress narrow atmospheric emission lines of temporally varying brightness before the light is dispersed. These gratings can only operate in a single-mode fiber as the suppressed wavelength depends on mode velocity in the core. Recent experiments with fibers containing multiple single-moded cores have demonstrated the potential for inscribing identical gratings across all cores in a single pass. We have already improved the uniformity of gratings in 7-core fibers via modifications to the writing process; further progress can be achieved by tuning the gratings of the outer and inner cores relative to one another. Our eventual goal is to make the entire fiber suppress one wavelength to a depth of 30 dB or greater. By coating the fiber in a heat-conductive material with a high expansion coefficient, we can examine the effects of temperature and strain on the spectral response of each core. In this paper we present methods and results from experiments concerning the post-write tuning of gratings in multicore fibers.

Mode coupling in 340 μm GeO2 doped core-silica clad optical fibers

NASA Astrophysics Data System (ADS)

Djordjevich, Alexandar; Savović, Svetislav

2017-03-01

The state of mode coupling in 340 μm GeO2 doped core-silica clad optical fibers is investigated in this article using the power flow equation. The coupling coefficient in this equation was first tuned such that the equation could correctly reconstruct previously reported measured output power distributions. It was found that the GeO2 doped core-silica clad optical fiber showed stronger mode coupling than both, glass and popular plastic optical fibers. Consequently, the equilibrium as well as steady state mode distributions were achieved at shorter fiber lengths in GeO2 doped core-silica clad optical fibers.

Excitation efficiency of an optical fiber core source

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.; Tai, Alan C.

1992-01-01

The exact field solution of a step-index profile fiber is used to determine the excitation efficiency of a distribution of sources in the core of an optical fiber. Previous results of a thin-film cladding source distribution to its core source counterpart are used for comparison. The behavior of power efficiency with the fiber parameters is examined and found to be similar to the behavior exhibited by cladding sources. It is also found that a core-source fiber is two orders of magnitude more efficient than a fiber with a bulk distribution of cladding sources. This result agrees qualitatively with previous ones obtained experimentally.

Laser beam uniformity and stability using homogenizer-based fiber optic launch method: square core fiber delivery

NASA Astrophysics Data System (ADS)

Lizotte, Todd E.

2011-03-01

Over the years, technological achievements within the laser medical diagnostic, treatment, and therapy markets have led to ever increasing requirements for greater control of critical laser beam parameters. Increased laser power/energy stabilization, temporal and spatial beam shaping and flexible laser beam delivery systems with ergonomic focusing or imaging lens systems are sought by leading medical laser system producers. With medical procedures that utilize laser energy, there is a constant emphasis on reducing adverse effects that come about by the laser itself or its optical system, but even when these variables are well controlled the medical professional will still need to deal with the multivariate nature of the human body. Focusing on the variables that can be controlled, such as accurate placement of the laser beam where it will expose a surface being treated as well as laser beam shape and uniformity is critical to minimizing adverse conditions. This paper covers the use of fiber optic beam delivery as a means of defining the beam shape (intensity/power distribution uniformity) at the target plane as well as the use of fiber delivery as a means to allow more flexible articulation of the laser beam over the surface being treated. The paper will present a new concept of using a square core fiber beam delivery design utilizing a unique micro lens array (MLA) launch method that improves the overall stability of the system, by minimizing the impact of the laser instability. The resulting performance of the prototype is presented to demonstrate its stability in comparison to simple lens launch techniques, with an emphasis on homogenization and articulated fiber delivery.

Oil sorption by lignocellulosic fibers

Treesearch

Beom-Goo Lee; James S. Han; Roger M. Rowell

1999-01-01

The oil sorption capacities of cotton fiber, kenaf bast fiber, kenaf core fiber, and moss fiber were compared after refining, extraction, and reduction in particle sizes. The tests were conducted on diesel oil in a pure form. Cotton fiber showed the highest capacity, followed by kenaf core and bast fibers. Wetting, extraction, and reduction in particle size all...

A Coherent Fiber for an Airborne Heterodyne Sensor.

DTIC Science & Technology

1982-04-01

17 4 TlBr /KRS-5 fiber showing irregular core shape . ....... ... 20 5 Enlargement of fiber cross section showing highly irregular core...21 6 TIBr/KRS-5 billet after extrusion ...... ............. 22 7 Side view of TlBr /KRS-5 fiber extruded at high...material. The composite billet is then extruded into fiber. Our composite billets were made of TlBr /KRS-5 and KRS-6/TlCl (clad/core). The extruded

Coilable Crystalline Fiber (CCF) Lasers and their Scalability

DTIC Science & Technology

2014-03-01

Fibers: Double-Clad Design Concept of Tm:YAG-Core Fiber and Mode Simulation. Proc. SPIE 2012, 8237 , 82373M. 8. Beach, R. J.; Mitchell, S. C...Dubinskii, M. True Crystalline Fibers: Double-Clad LMA Design Concept of Tm:YAG-Core Fiber and Mode Simulation. Proc. of SPIE 2012, 8237 , 82373M-1...Tm:YAG-Core Fiber and Mode Simulation. Proc. SPIE 8237 , 82373M, 2012. 8. Beach, R. J.; Mitchell, S. C.; Meissner, H. E.; Meissner, O. R.; Krupke, W

Improved Optical Fiber Chemical Sensors

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1994-01-01

Calculations, based on exact theory of optical fiber, have shown how to increase optical efficiency sensitivity of active-core, step-index-profile optical-fiber fluorosensor. Calculations result of efforts to improve efficiency of optical-fiber chemical sensor of previous concept described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525). Optical fiber chemical detector of enhanced sensitivity made in several configurations. Portion of fluorescence or chemiluminescence generated in core, and launched directly into bound electromagnetic modes that propagate along core to photodetector.

Innovative use of wood-plastic-composites (WPC) as a core material in the sandwich injection molding process

NASA Astrophysics Data System (ADS)

Moritzer, Elmar; Martin, Yannick

2016-03-01

The demand for materials based on renewable raw materials has risen steadily in recent years. With society's increasing interest for climate protection and sustainability, natural-based materials such as wood-plastic-composites (WPC) have gained market share thanks to their positive reputation. Due to advantages over unreinforced plastics such as cost reduction and weight savings it is possible to use WPC in a wide area of application. Additionally, an increase in mechanical properties such as rigidity and strength is achieved by the fibers compared to unreinforced polymers. The combination of plastic and wood combines the positive properties of both components in an innovative material. Despite the many positive properties of wood-plastic-composite, there are also negative characteristics that prevent the use of WPC in many product areas, such as automotive interiors. In particular, increased water intake, which may result in swelling of near-surface particles, increased odor emissions, poor surface textures and distortion of the components are unacceptable for many applications. The sandwich injection molding process can improve this situation by eliminating the negative properties of WPC by enclosing it with a pure polymer. In this case, a layered structure of skin and core material is produced, wherein the core component is completely enclosed by the skin component. The suitability of WPC as the core component in the sandwich injection molding has not yet been investigated. In this study the possibilities and limitations of the use of WPC are presented. The consideration of different fiber types, fiber contents, skin materials and its effect on the filling behavior are the focus of the presented analysis.

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

Group delay spread analysis of coupled-multicore fibers: A comparison between weak and tight bending conditions

NASA Astrophysics Data System (ADS)

Fujisawa, Takeshi; Saitoh, Kunimasa

2017-06-01

Group delay spread of coupled three-core fiber is investigated based on coupled-wave theory. The differences between supermode and discrete core mode models are thoroughly investigated to reveal applicability of both models for specific fiber bending condition. A macrobending with random twisting is taken into account for random modal mixing in the fiber. It is found that for weakly bent condition, both supermode and discrete core mode models are applicable. On the other hand, for strongly bent condition, the discrete core mode model should be used to account for increased differential modal group delay for the fiber without twisting and short correlation length, which were experimentally observed recently. Results presented in this paper indicate the discrete core mode model is superior to the supermode model for the analysis of coupled-multicore fibers for various bent condition. Also, for estimating GDS of coupled-multicore fiber, it is critically important to take into account the fiber bending condition.

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.

Performance comparison of a fiber optic communication system based on optical OFDM and an optical OFDM-MIMO with Alamouti code by using numerical simulations

NASA Astrophysics Data System (ADS)

Serpa-Imbett, C. M.; Marín-Alfonso, J.; Gómez-Santamaría, C.; Betancur-Agudelo, L.; Amaya-Fernández, F.

2013-12-01

Space division multiplexing in multicore fibers is one of the most promise technologies in order to support transmissions of next-generation peta-to-exaflop-scale supercomputers and mega data centers, owing to advantages in terms of costs and space saving of the new optical fibers with multiple cores. Additionally, multicore fibers allow photonic signal processing in optical communication systems, taking advantage of the mode coupling phenomena. In this work, we numerically have simulated an optical MIMO-OFDM (multiple-input multiple-output orthogonal frequency division multiplexing) by using the coded Alamouti to be transmitted through a twin-core fiber with low coupling. Furthermore, an optical OFDM is transmitted through a core of a singlemode fiber, using pilot-aided channel estimation. We compare the transmission performance in the twin-core fiber and in the singlemode fiber taking into account numerical results of the bit-error rate, considering linear propagation, and Gaussian noise through an optical fiber link. We carry out an optical fiber transmission of OFDM frames using 8 PSK and 16 QAM, with bit rates values of 130 Gb/s and 170 Gb/s, respectively. We obtain a penalty around 4 dB for the 8 PSK transmissions, after 100 km of linear fiber optic propagation for both singlemode and twin core fiber. We obtain a penalty around 6 dB for the 16 QAM transmissions, with linear propagation after 100 km of optical fiber. The transmission in a two-core fiber by using Alamouti coded OFDM-MIMO exhibits a better performance, offering a good alternative in the mitigation of fiber impairments, allowing to expand Alamouti coded in multichannel systems spatially multiplexed in multicore fibers.

High Power Spark Delivery System Using Hollow Core Kagome Lattice Fibers

PubMed Central

Dumitrache, Ciprian; Rath, Jordan; Yalin, Azer P.

2014-01-01

This study examines the use of the recently developed hollow core kagome lattice fibers for delivery of high power laser pulses. Compared to other photonic crystal fibers (PCFs), the hollow core kagome fibers have larger core diameter (~50 µm), which allows for higher energy coupling in the fiber while also maintaining high beam quality at the output (M2 = 1.25). We have conducted a study of the maximum deliverable energy versus laser pulse duration using a Nd:YAG laser at 1064 nm. Pulse energies as high as 30 mJ were transmitted for 30 ns pulse durations. This represents, to our knowledge; the highest laser pulse energy delivered using PCFs. Two fiber damage mechanisms were identified as damage at the fiber input and damage within the bulk of the fiber. Finally, we have demonstrated fiber delivered laser ignition on a single-cylinder gasoline direct injection engine. PMID:28788155

High power 938 nanometer fiber laser and amplifier

DOEpatents

Dawson, Jay W [Livermore, CA; Liao, Zhi Ming [Pleasanton, CA; Beach, Raymond J [Livermore, CA; Drobshoff, Alexander D [Livermore, CA; Payne, Stephen A [Castro Valley, CA; Pennington, Deanna M [Livermore, CA; Hackenberg, Wolfgang [Munich, DE; Calia, Domenico Bonaccini [Garching, DE; Taylor, Luke [Montauban de Bretagne, FR

2006-05-02

An optical fiber amplifier includes a length of silica optical fiber having a core doped with neodymium, a first cladding and a second cladding each with succeeding lower refractive indices, where the first cladding diameter is less than 10 times the diameter of the core. The doping concentration of the neodymium is chosen so that the small signal absorption for 816 nm light traveling within the core is less than 15 dB/m above the other fiber losses. The amplifier is optically pumped with one laser into the fiber core and with another laser into the first cladding.

Ho3+-doped AlF3-TeO2-based glass fibers for 2.1 µm laser applications

NASA Astrophysics Data System (ADS)

Wang, S. B.; Jia, Z. X.; Yao, C. F.; Ohishi, Y.; Qin, G. S.; Qin, W. P.

2017-05-01

Ho3+-doped AlF3-TeO2-based glass fibers based on AlF3-BaF2-CaF2-YF3-SrF2-MgF2-TeO2 glasses are fabricated by using a rod-in-tube method. The glass rod including a core and a thick cladding layer is prepared by using a suction method, where the thick cladding layer is used to protect the core from the effect of surface crystallization during the fiber drawing. By inserting the glass rod into a glass tube, the glass fibers with relatively low loss (~2.3 dB m-1 @ 1560 nm) are prepared. By using a 38 cm long Ho3+-doped AlF3-TeO2-based glass fiber as the gain medium and a 1965 nm fiber laser as the pump source, 2065 nm lasing is obtained for a threshold pump power of ~220 mW. With further increasing the pump power to ~325 mW, the unsaturated output power of the 2065 nm laser is about 82 mW and the corresponding slope efficiency is up to 68.8%. The effects of the gain fiber length on the lasing threshold, the slope efficiency, and the operating wavelength are also investigated. Our experimental results show that Ho3+-doped AlF3-TeO2-based glass fibers are promising gain media for 2.1 µm laser applications.

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.

Multiphoton endoscopy based on a mode-filtered single-mode fiber

NASA Astrophysics Data System (ADS)

Moon, Sucbei; Liu, Gangjun; Chen, Zhongping

2011-03-01

We present a new low-nonlinearity fiber of mode-filtered large-core fiber for flexible beam delivery of intense pulsed light aiming at multi-photon endoscopy application. A multimode fiber of a large core diameter (20 μm) equips a mode filtering means in the middle of the fiber link to suppress the high-order modes selectively. A large effective core area of ~200 μm2 has been achieved at 0.8-μm and 1.0-μm bands. This is 8 times larger than the core area of a conventional SMF used for those spectral bands. Various advantages of our large-mode area fiber will be demonstrated and discussed in this report.

Thulium fiber laser ablation of kidney stones using a 50-μm-core silica optical fiber

NASA Astrophysics Data System (ADS)

Blackmon, Richard L.; Hutchens, Thomas C.; Hardy, Luke A.; Wilson, Christopher R.; Irby, Pierce B.; Fried, Nathaniel M.

2015-01-01

Our laboratory is currently studying the experimental thulium fiber laser (TFL) as a potential alternative laser lithotripter to the gold standard, clinical Holmium:YAG laser. We have previously demonstrated the efficient coupling of TFL energy into fibers as small as 100-μm-core-diameter without damage to the proximal end. Although smaller fibers have a greater tendency to degrade at the distal tip during lithotripsy, fiber diameters (≤200 μm) have been shown to increase the saline irrigation rates through the working channel of a flexible ureteroscope, to maximize the ureteroscope deflection, and to reduce the stone retropulsion during laser lithotripsy. In this study, a 50-μm-core-diameter, 85-μm-outer-diameter, low-OH silica fiber is characterized for TFL ablation of human calcium oxalate monohydrate urinary stones, ex vivo. The 50-μm-core fiber consumes approximately 30 times less cross-sectional area inside the single working channel of a ureteroscope than the standard 270-μm-core fiber currently used in the clinic. The ureteroscope working channel flow rate, including the 50-μm fiber, decreased by only 10% with no impairment of ureteroscope deflection. The fiber delivered up to 15.4±5.9 W under extreme bending (5-mm-radius) conditions. The stone ablation rate measured 70±22 μg/s for 35-mJ-pulse-energy, 500-μs-pulse-duration, and 50-Hz-pulse-rate. Stone retropulsion and fiber burnback averaged 201±336 and 3000±2600 μm, respectively, after 2 min. With further development, thulium fiber laser lithotripsy using ultra-small, 50-μm-core fibers may introduce new integration and miniaturization possibilities and potentially provide an alternative to conventional Holmium:YAG laser lithotripsy using larger fibers.

Electrochromic properties of polyaniline-coated fiber webs for tissue engineering applications.

PubMed

Beregoi, Mihaela; Busuioc, Cristina; Evanghelidis, Alexandru; Matei, Elena; Iordache, Florin; Radu, Mihaela; Dinischiotu, Anca; Enculescu, Ionut

2016-08-30

By combining the electrospinning method advantages (high surface-to-volume ratio, controlled morphology, varied composition and flexibility for the resulting structures) with the electrical activity of polyaniline, a new core-shell-type material with potential applications in the field of artificial muscles was synthesized. Thus, a poly(methylmethacrylate) solution was electrospun in optimized conditions to obtain randomly oriented polymer fiber webs. Further, a gold layer was sputtered on their surface in order to make them conductive and improve the mechanical properties. The metalized fiber webs were then covered with a PANI layer by in situ electrochemical polymerization starting from aniline and using sulphuric acid as oxidizing agent. By applying a small voltage on PANI-coated fiber webs in the presence of an electrolyte, the oxidation state of PANI changes, which is followed by the device color modification. The morphological, electrical and biological properties of the resulting multilayered material were also investigated. Copyright © 2015 Elsevier B.V. All rights reserved.

Thulium fiber laser lithotripsy using tapered fibers.

PubMed

Blackmon, Richard L; Irby, Pierce B; Fried, Nathaniel M

2010-01-01

The Thulium fiber laser has recently been tested as a potential alternative to the Holmium:YAG laser for lithotripsy. This study explores use of a short taper for expanding the Thulium fiber laser beam at the distal tip of a small-core fiber. Thulium fiber laser radiation with a wavelength of 1,908 nm, 10 Hz pulse rate, 70 mJ pulse energy, and 1-millisecond pulse duration was delivered through a 2-m-length fiber with 150-microm-core-input-end, 300-microm-core-output-end, and 5-mm-length taper, in contact with human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n = 10 each). Stone mass loss, stone crater depths, fiber transmission losses, fiber burn-back, irrigation rates, and deflection through a flexible ureteroscope were measured for the tapered fiber and compared with conventional fibers. After delivery of 1,800 pulses through the tapered fiber, mass loss measured 12.7+/-2.6 mg for UA and 7.2+/-0.8 mg COM stones, comparable to conventional 100-microm-core fibers (12.6+/-2.5 mg for UA and 6.8+/-1.7 mg for COM stones). No transmission losses or burn-back occurred for the tapered fiber after 36,000 pulses, while a conventional 150-microm fiber experienced significant tip degradation after only 1,800 pulses. High irrigation rates were measured with the tapered fiber inserted through the working port of a flexible ureteroscope without hindering its deflection, mimicking that of a conventional 150 microm fiber. The short tapered distal fiber tip allows expansion of the laser beam, resulting in decreased fiber tip damage compared to conventional small-core fibers, without compromising fiber bending, stone vaporization efficiency, or irrigation rates.

High-power picosecond pulse delivery through hollow core photonic band gap fibers

NASA Astrophysics Data System (ADS)

Michieletto, Mattia; Johansen, Mette M.; Lyngsø, Jens K.; Lægsgaard, Jesper; Bang, Ole; Alkeskjold, Thomas T.

2016-03-01

We demonstrated robust and bend insensitive fiber delivery of high power laser with diffraction limited beam quality for two different kinds of hollow core band gap fibers. The light source for this experiment consists of ytterbium-doped double clad fiber aeroGAIN-ROD-PM85 in a high power amplifier setup. It provided 22ps pulses with a maximum average power of 95W, 40MHz repetition rate at 1032nm (~2.4μJ pulse energy), with M2 <1.3. We determined the facet damage threshold for a 7-cells hollow core photonic bandgap fiber and showed up to 59W average power output for a 5 meters fiber. The damage threshold for a 19-cell hollow core photonic bandgap fiber exceeded the maximum power provided by the light source and up to 76W average output power was demonstrated for a 1m fiber. In both cases, no special attention was needed to mitigate bend sensitivity. The fibers were coiled on 8 centimeters radius spools and even lower bending radii were present. In addition, stimulated rotational Raman scattering arising from nitrogen molecules was measured through a 42m long 19 cell hollow core fiber.

Pressure-assisted melt-filling and optical characterization of Au nano-wires in microstructured fibers.

PubMed

Lee, H W; Schmidt, M A; Russell, R F; Joly, N Y; Tyagi, H K; Uebel, P; Russell, P St J

2011-06-20

We report a novel splicing-based pressure-assisted melt-filling technique for creating metallic nanowires in hollow channels in microstructured silica fibers. Wires with diameters as small as 120 nm (typical aspect ration 50:1) could be realized at a filling pressure of 300 bar. As an example we investigate a conventional single-mode step-index fiber with a parallel gold nanowire (wire diameter 510 nm) running next to the core. Optical transmission spectra show dips at wavelengths where guided surface plasmon modes on the nanowire phase match to the glass core mode. By monitoring the side-scattered light at narrow breaks in the nanowire, the loss could be estimated. Values as low as 0.7 dB/mm were measured at resonance, corresponding to those of an ultra-long-range eigenmode of the glass-core/nanowire system. By thermal treatment the hollow channel could be collapsed controllably, permitting creation of a conical gold nanowire, the optical properties of which could be monitored by side-scattering. The reproducibility of the technique and the high optical quality of the wires suggest applications in fields such as nonlinear plasmonics, near-field scanning optical microscope tips, cylindrical polarizers, optical sensing and telecommunications.

Modification of the internal surface of photonic crystal fibers with Ag and Au nanoparticles for application as sensor elements

NASA Astrophysics Data System (ADS)

Pidenko, Pavel S.; Borzov, Victor M.; Savenko, Olga A.; Skaptsov, Alexander A.; Skibina, Yulia S.; Goryacheva, Irina Yu.; Rusanova, Tatiana Yu.

2017-03-01

Photonic crystal fibers (PCFs) are one of the most promising materials for biosensors construction due to their unique optical properties. The modification of PCF by noble metal nanoparticles (NPs) provides the SPR and SERS signal detection where as the application amino group-containing compounds allows efficient binding of biomolecules. In this work the internal surface of glass hollow core photonic crystal fibers (HC-PCFs) has been modified Ag and Au nanoparticles using three different approaches. PCFs were treated by: 1) mixture of NPs and precursors for silanization (tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES)); 2) alternately deposition of polyelectrolytes and NPs, 3) mixture of chitosan with NPs. The shift of local maxima in the HC-PCF transmission spectrum has been selected as a signal for estimating the amount of NPs on the HC-PCF inner surface. The most efficient techniques were the chitosan application for Ag NPs and silanization for Au NPs. The obtaining PCFs could be useful for creating biosensitive elements.

Fusion splicing small-core photonic crystal fibers and single-mode fibers by repeated arc discharges.

PubMed

Xiao, Limin; Jin, Wei; Demokan, M S

2007-01-15

We demonstrate a novel method for low-loss splicing small-core photonic crystal fibers (PCFs) and single-mode fibers (SMFs) by repeated arc discharges using a conventional fusion splicer. An optimum mode field match at the interface of PCF-SMF and an adiabatic mode field variation in the longitudinal direction of the small-core PCF can be achieved by repeated arc discharges applied over the splicing joint to gradually collapse the air holes of the small-core PCF. This method is simple and offers a practical solution for light coupling between small-core PCFs and SMFs.

Fusion splicing small-core photonic crystal fibers and single-mode fibers by repeated arc discharges

NASA Astrophysics Data System (ADS)

Xiao, Limin; Jin, Wei; Demokan, M. S.

2007-01-01

We demonstrate a novel method for low-loss splicing small-core photonic crystal fibers (PCFs) and single-mode fibers (SMFs) by repeated arc discharges using a conventional fusion splicer. An optimum mode field match at the interface of PCF-SMF and an adiabatic mode field variation in the longitudinal direction of the small-core PCF can be achieved by repeated arc discharges applied over the splicing joint to gradually collapse the air holes of the small-core PCF. This method is simple and offers a practical solution for light coupling between small-core PCFs and SMFs.

Distributed sensing of Composite Over-wrapped Pressure Vessel using Fiber-Bragg Gratings at Ambient and Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Grant, Joseph

2005-01-01

Fiber Bragg gratings are use to monitor the structural properties of composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in laminate structure. The fiber Bragg sensors are both embedded within the composite laminates and bonded to the surface of the vessel with varying orientations with respect to the carbon fiber in the epoxy matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 2800 psi. This is done at both ambient and cryogenic temperatures using water and liquid nitrogen. The recorded response is compared with the response from conventional strain gauge also present on the vessel. Additionally, several vessels were tested that had been damaged to simulate different type of events, such as cut tow, delimitation and impact damage.

Distributed Sensing of Composite Over-wrapped Pressure Vessel Using Fiber-Bragg Gratings at Ambient and Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Grant, Joseph

2004-01-01

Fiber Bragg gratings are use to monitor the structural properties of composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in laminate structure. The fiber Bragg sensors are both embedded within the composite laminates and bonded to the surface of the vessel with varying orientations with respect to the carbon fiber in the epoxy matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 2800 psi. This is done at both ambient and cryogenic temperatures using water and liquid nitrogen. The recorded response is compared with the response from conventional strain gauge also present on the vessel. Additionally, several vessels were tested that had been damaged to simulate different type of events, such as cut tow, delimitation and impact damage.

Novel bidirectional optical subassembly with embedded filter, 45-degree angle polished fiber cladding and etched fiber core

NASA Astrophysics Data System (ADS)

Lee, Seihyoung; Lim, Kwon-Seob; Lee, Jong Jin; Kang, Hyun Seo

2009-10-01

The optical wavelength-division-multiplex filter for bidirectional optical subassembly (BOSA) is embedded to the fiber core, which results in simplicity of the BOSA module. The fiber cladding is 45-deg angle polished to receive a downstream signal. The core is etched by a femtosecond laser to have a normal core facet and to transmit an upstream signal. The downstream signal, which is core mode, is coupled to the cladding mode by the long-period fiber grating and then detected by a photodiode by means of the total internal reflection effect at the 45-deg angle polished cladding facet. The measured transmitted and received coupling efficiencies are 27.3 and 43.8%, respectively.

Using of fiber-array diagnostic to measure the propagation of fast axial ionization wave during breakdown of electrically exploding tungsten wire in vacuum.

PubMed

Shi, Huantong; Zou, Xiaobing; Wang, Xinxin

2017-12-01

The physical process of electrical explosion of wires in vacuum is featured with the surface discharge along the wire, which generates the corona plasma layer and terminates the Joule heating of the wire core. In this paper, a fiber-array probe was designed to directly measure the radiation of surface arc with spatial and temporal resolution. The radiation of the exploding wire was casted to the section of an optical-fiber-array by a lens and transmitted to PIN diodes and finally collected with an oscilloscope. This probe enables direct diagnostics of the evolution of surface discharge with high temporal resolution and certain spatial resolution. The radiation of a tungsten wire driven by a positive current pulse was measured, and results showed that surface discharge initiates near the cathode and propagates toward the anode with a speed of 7.7 ± 1.6 mm/ns; further estimations showed that this process is responsible for the "conical" structure of the exploding wire.

Using of fiber-array diagnostic to measure the propagation of fast axial ionization wave during breakdown of electrically exploding tungsten wire in vacuum

NASA Astrophysics Data System (ADS)

Shi, Huantong; Zou, Xiaobing; Wang, Xinxin

2017-12-01

The physical process of electrical explosion of wires in vacuum is featured with the surface discharge along the wire, which generates the corona plasma layer and terminates the Joule heating of the wire core. In this paper, a fiber-array probe was designed to directly measure the radiation of surface arc with spatial and temporal resolution. The radiation of the exploding wire was casted to the section of an optical-fiber-array by a lens and transmitted to PIN diodes and finally collected with an oscilloscope. This probe enables direct diagnostics of the evolution of surface discharge with high temporal resolution and certain spatial resolution. The radiation of a tungsten wire driven by a positive current pulse was measured, and results showed that surface discharge initiates near the cathode and propagates toward the anode with a speed of 7.7 ± 1.6 mm/ns; further estimations showed that this process is responsible for the "conical" structure of the exploding wire.

Tellurite microstructure fibers with small hexagonal core for supercontinuum generation.

PubMed

Liao, Meisong; Chaudhari, Chitrarekha; Qin, Guanshi; Yan, Xin; Suzuki, Takenobu; Ohishi, Yasutake

2009-07-06

Tellurite glass microstructure fibers with a 1 microm hexagonal core were fabricated successfully by accurately controlling the temperature field in the fiber-drawing process. The diameter ratio of holey region to core (DRHC) for the fiber can be adjusted freely in the range of 1-20 by pumping a positive pressure into the holes when drawing fiber, which provides much freedom in engineering the chromatic dispersion. With the increase of DRHC from 3.5 to 20, the zero dispersion wavelengths were shifted several hundred nanometers, the cutoff wavelength due to confinement loss was increased from 1600 nm to 3800 nm, and the nonlinear coefficient gamma was increased from 3.9 to 5.7 W(-1)/m. Efficient visible emissions due to third harmonic generation were found for fibers with a DRHC of 10 and 20 under the 1557 nm pump of a femtosecond fiber laser. One octave flattened supercontinuum spectrum was generated from fibers with a DRHC of 3.5, 10 and 20 by the 1064 nm pump of a picosecond fiber laser. To the best of our knowledge, we have for the first time fabricated a hexagonal core fiber by soft glass with such a small core size, and have demonstrated a large influence of the holey region on the dispersion, nonlinear coefficient and supercontinuum generation for such fiber.

Opportunities to Enhance Multimode Fiber Links by Application of Overfilled Launch

NASA Astrophysics Data System (ADS)

Onlagic, Denis

2005-11-01

This paper investigates possibilities for the practical design of high-performance multimode fibers (MMFs) that can provide bandwidths in excess of 10 GHz ...km in an overfilled regime of operation. Analysis of standard MMF in an overfilled launch demonstrates that the theoretical bandwidth limitations arise from the influence of cladding on the propagation of the highest order modes. Practical MMF profile designs that overcome this problem are investigated. The standard 50-and 62.5- μm fiber profiles are redesigned first to allow for the performance in an overfilled launch with the differential mode delays (DMDs) below 0.055 and 0.250 ns/km, respectively. It is shown that such fibers can exhibit the same or better theoretical bandwidth in an overfilled launch when compared to standard fiber under restricted launch. Elimination of the need for the restricted mode launch in high-performance multimode transmission systems can improve reliability issues and can relax the range of tolerance requirements imposed on terminal equipment, optical components, and link installation. Furthermore, MMFs that can be operated in an overfilled launched are compatible with emerging vertical cavity surface emitting laser (VCSEL) wavelength division multiplexing (WDM) array technologies. A successfully controlled higher order mode DMD also allows for the reduction of MMF core size and mit Delta that can be beneficial for low-cost high-performance single-channel links. It is demonstrated that properly designed reduced core fibers can achieve theoretical DMDs in the range of 0.005-0.02 ns/km. The bend loss properties of redesigned fibers are investigated in detail, showing that the proposed modifications do not lead to significant degradation of bend loss performance. Moreover, they can be manufactured at considerably lower cost while utilizing commercially readily available low-cost VCSELs. Even where the theoretical limit is not achieved by practical fiber making, the reduced core size and mit Delta MMF can provide higher production yield, lower cost, and higher average bandwidth.

Reduced thermal sensitivity of hybrid air-core photonic band-gap fiber ring resonator

NASA Astrophysics Data System (ADS)

Feng, Li-shuang; Wang, Kai; Jiao, Hong-chen; Wang, Jun-jie; Liu, Dan-ni; Yang, Zhao-hua

2018-01-01

A novel hybrid air-core photonic band-gap fiber (PBF) ring resonator with twin 90° polarization-axis rotated splices is proposed and demonstrated. Frist, we measure the temperature dependent birefringence coefficient of air-core PBF and Panda fiber. Experimental results show that the relative temperature dependent birefringence coefficient of air-core PBF is 1.42×10-8/°C, which is typically 16 times less than that of Panda fiber. Then, we extract the geometry profile of air-core PBF from scanning electron microscope (SEM) images. Numerical modal is built to distinguish the fast axis and slow axis in the fiber. By precisely setting the length difference in air-core PBF and Panda fiber between two 90° polarization-axis rotated splicing points, the hybrid air-core PBF ring resonator is constructed, and the finesse of the resonator is 8.4. Environmental birefringence variation induced by temperature change can be well compensated, and experimental results show an 18-fold reduction in thermal sensitivity, compared with resonator with twin 0° polarization-axis rotated splices.

Design and analysis of three-layer-core optical fiber

NASA Astrophysics Data System (ADS)

Zheng, Siwen; Liu, Yazhuo; Chang, Guangjian

2018-03-01

A three-layer-core single-mode large-mode-area fiber is investigated. The three-layer structure in the core, which is composed of a core-index layer, a cladding-index layer, and a depression-index layer, could achieve a large effective area Aeff while maintaining an ultralow bending loss without deteriorating cutoff behaviors. The single-mode large mode area of 100 to 330 μm2 could be achieved in the fiber. The effective area Aeff can be further enlarged by adjusting the layer parameters. Furthermore, the bending property could be improved in this three-layer-core structure. The bending loss could decrease by 2 to 4 orders of magnitude compared with the conventional step-index fiber with the same Aeff. These characteristics of three-layer-core fiber suggest that it can be used in large-mode-area wide-bandwidth high-capacity transmission or high-power optical fiber laser and amplifier in optical communications, which could be used for the basic physical layer structure of big data storage, reading, calculation, and transmission applications.

Hollow-Core Photonic Band Gap Fibers for Particle Acceleration

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

Noble, Robert J.; Spencer, James E.; /SLAC

Photonic band gap (PBG) dielectric fibers with hollow cores are being studied both theoretically and experimentally for use as laser driven accelerator structures. The hollow core functions as both a longitudinal waveguide for the transverse-magnetic (TM) accelerating fields and a channel for the charged particles. The dielectric surrounding the core is permeated by a periodic array of smaller holes to confine the mode, forming a photonic crystal fiber in which modes exist in frequency pass-bands, separated by band gaps. The hollow core acts as a defect which breaks the crystal symmetry, and so-called defect, or trapped modes having frequencies inmore » the band gap will only propagate near the defect. We describe the design of 2-D hollow-core PBG fibers to support TM defect modes with high longitudinal fields and high characteristic impedance. Using as-built dimensions of industrially-made fibers, we perform a simulation analysis of the first prototype PBG fibers specifically designed to support speed-of-light TM modes.« less

Development of an optical fiber SERS microprobe for minimally invasive sensing applications

NASA Astrophysics Data System (ADS)

Mamun, Md Abdullah Al; Juodkazis, Saulius; Mahadevan-Jansen, Anita; Stoddart, Paul R.

2018-02-01

Numerous potential biomedical sensing applications of surface-enhanced Raman scattering (SERS) have been reported, but its practical use has been limited by the lack of a robust sensing platform. Optical fiber SERS probes show great promise, but are limited by the prominent silica Raman background, which requires the use of bulky optics for filtering the signal collection and excitation delivery paths. In the present study, a SERS microprobe has been designed and developed to eliminate the bottlenecks outlined above. For efficient excitation and delivery of the SERS signal, both hollow core photonic crystal fiber and double clad fiber have been investigated. While the hollow core fiber was still found to have excessive silica background, the double clad fiber allows efficient signal collection via the multi-mode inner cladding. A micro filtering mechanism has been designed, which can be integrated into the tip of the optical fiber SERS probe, providing filtering to suppress silica Raman background and thus avoiding the need for bulky optics. The design also assists in the efficient collection of SERS signal from the sample by rejecting Rayleigh scattered light from the sample. Optical fiber cleaving using ultra-short laser pulses was tested for improved control of the fiber tip geometry. With this miniaturized and integrated filtering mechanism, it is expected that the developed probe will promote the use of SERS for minimally invasive biomedical monitoring and sensing applications in future. The probe could potentially be placed inside a small gauge hypodermic needle and would be compatible with handheld portable spectrometers.

Scalable Manufacturing of Metal Micro/Nanowires and Applications by Thermal Fiber Drawing Method

NASA Astrophysics Data System (ADS)

Hwang, Injoo

The objective of this study is to better understand the fundamental principal of the thermal fiber drawing process with metal-core preforms. This would enable us to overcome the fundamental limits of current thermal drawing techniques by tuning material properties of core metals and interactions between core and cladding materials using nanoparticles. Metal micro/nanowires with controlled size, aspect ratio and spatial configurations of core and cladding materials exhibit extraordinary mechanical, thermal, electrical and optical properties. These metal micro/nanowires can be utilized for widespread applications such as: thermoelectric, conductive electrode and plasmonic photonic crystal fibers. Thermal fiber drawing method has emerged as an advanced scalable manufacturing technique for micro/nanowires production due to its unique characteristics that allow mass production of continuous and arbitrary designed wires. It is of tremendous scientific and technical interests to conduct a fundamental study on thermal fiber drawing methods and to break the current limits of the crystalline metal core thermal fiber drawing process. In this study, metal core was fabricated by cold compaction of the Zinc (Zn)-Tungsten Carbide (WC) nanopowders. Our characterizations through scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) showed that WC nanoparticle are uniformly dispersed in Zn matrix. The effects of WC nanoparticles on the mechanical properties and degradation rate in Zn-WC nanocomposites were carefully analyzed by tensile, compressive, hardness, degradation and viscosity tests. Metallic stents are commonly used to expand blood vessels that have been narrowed by plaque buildup (atherosclerosis). Fabrication difficulty and other constrains of metallic stents result in high cost. Zn-WC nanocomposite microwires were controllably drawn for stent struts with a diameter of 200 ?m. Characterizations by the tensile and degradation tests of Zn-WC nanocomposite microwires validate the eligibility for stent fabrication. Single cell Zn-WC nanocomposite stents were fabricated by braiding thermally drawn Zn-WC nanocomposite microwires on a weaving stage built by 3D printing. Zn-WC nanocomposite stents with an inner diameter of 2 mm was expanded up to 10 mm without recoil by a catheter, which is thin tube inserted into human body serving in a broad range of functions. For the purpose of in vivo test, Zn-WC nanocomposite stents were deployed in a pig by percutaneous coronary intervention method (angioplasty with stent). The surgery under fluoroscopy that continuous X-ray beam is passed through the body part being examined. X-ray opaque Zn-WC nanocomposite stents were distinctly shown to be expanded by a catheter and remained without bounce back through the whole procedure. The Zn-WC nanocomposite stents were extracted from the pig a month later and studied for the degradability by SEM and EDS mapping analysis. SEM images of Zn-WC stents showed that the degradation of the stents was uniformly proceeded on the surface without fractures. While the Zn-WC nanocomposite stents stayed inside the vessel, good endothelializations between the Zn-WC stents and surrounding cell tissues as well as no acute pathological problems were discovered from this study. One of the current challenges of thermal fiber drawing process for crystalline metal nanowires is low aspect ratio (< 10,000). A molten metal nanowire in a cladding material breaks up into shorter nanowires or smaller droplets due to Plateau-Rayleigh instability. It was experimentally and theoretically shown that molten liquid tends to minimize their surface area by virtue of surface tensions. The Tomotika model introduced the relation among instability time, viscosities of core and cladding materials, the wavelength and diameter of the core fluid, and interfacial energy between core and cladding materials as specifying the Plateau-Rayleigh instability [1]. The instability time was impeded by high viscosity of the Zn-WC nanocomposite core material while the preform of Zn-WC nanocomposite was thermally drawn by the stack-and-draw method. Consequently, high aspect ratio (> 1,500,000) of Zn-WC nanocomposite nanowires that are 200 nm in diameter and up to 31 cm length were achieved. Herein, we present that WC nanoparticles decreased interfacial energy between metal and glass due to its inherent characteristic such as partly metallic bonding. As a result, the nanoparticle can play the role of anchors to prevent breakage by capillary instability in nanoscale thermal fiber drawing process. Zn-WC nanocomposite nanowires surrounded by borosilicate glass were shown through the TEM (transmission electron microscope) diffraction patterns. By the electrical resistance test, not onlythe electrical resistance and but also the continuity of the Zn-WC nanocomposite nanowires was presented. (Abstract shortened by ProQuest.).

ANSYS-based birefringence property analysis of side-hole fiber induced by pressure and temperature

NASA Astrophysics Data System (ADS)

Zhou, Xinbang; Gong, Zhenfeng

2018-03-01

In this paper, we theoretically investigate the influences of pressure and temperature on the birefringence property of side-hole fibers with different shapes of holes using the finite element analysis method. A physical mechanism of the birefringence of the side-hole fiber is discussed with the presence of different external pressures and temperatures. The strain field distribution and birefringence values of circular-core, rectangular-core, and triangular-core side-hole fibers are presented. Our analysis shows the triangular-core side-hole fiber has low temperature sensitivity which weakens the cross sensitivity of temperature and strain. Additionally, an optimized structure design of the side-hole fiber is presented which can be used for the sensing application.

Fiber laser with combined feedback of core and cladding modes assisted by an intracavity long-period grating.

PubMed

Sáez-Rodriguez, D; Cruz, J L; Díez, A; Andrés, M V

2011-05-15

We present a fiber laser made in a single piece of conventional doped-core fiber that operates by combined feedback of the fundamental core mode LP((0,1)) and the high-order cladding mode LP((0,10)). The laser is an all-fiber structure that uses two fiber Bragg gratings and a long-period grating to select the modes circulating in the cavity; the laser emits at the coupling wavelength between the core mode LP((0,1)) and the counterpropagating cladding mode LP((0,10)) in the Bragg gratings. This work demonstrates the feasibility of high-order mode fiber lasers assisted by long-period gratings. © 2011 Optical Society of America

Optical Sensing using Fiber Bragg Gratings for Monitoring Structural Damage in Composite Over-Wrapped Vessels

NASA Technical Reports Server (NTRS)

Grant, Joseph

2005-01-01

Composite Over-Wrap Vessels are widely used in the aerospace community. They are made of thin-walled bottles that are over wrapped with high strength fibers embedded in a matrix material. There is a strong drive to reduce the weight of space borne vehicles and thus pushes designers to adopt COPVs that are over wrapped with graphite fibers embedded in its epoxy matrix. Unfortunately, this same fiber-matrix configuration is more susceptible to impact damage than others and to make matters worse; there is a regime where impacts that damage the over wrap leave no visible scar on the COPV surface. In this paper FBG sensors are presented as a means of monitoring and detecting these types of damage. The FBG sensors are surface mounted to the COPVs and optically interrogated to explore the structural properties of these composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in the composite matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 4500 psi. A Fiber Optic Demodulation System built by Blue Road Research, is used for interrogation of the Bragg gratings.

Supercontinuum generation through DNA-filled hollow core fiber for broadband absorption spectroscopy

NASA Astrophysics Data System (ADS)

Cho, Youngho; Park, Byeongho; Oh, Juyeong; Seo, Min Ah; Lee, Kwanil; Kim, Chulki; Lee, Taikjin; Woo, Deok Ha; Lee, Seok; Kim, Hyung Min; Lee, Hyuk Jae; Oh, Kyunghwan; Yeom, Dong-Il; Park, Sung Ha; Kim, Jae Hun

2015-07-01

In this study, we successfully generated the large bandwidth of supercontinuum spectra through hollow fibers filled with DNA. Also, by observing that spectra bandwidth was the widest in the order of the hollow core fiber filled with DNA modified by copper ion, the hollow core fiber with only DNA, and the bulk hollow core fiber, we demonstrated that DNA material modified with copper ions can further enhance the spectral bandwidth of supercontinuum. As a result, we anticipate that the SCG as a broadband light source can be used in analytical methods to demonstrate a wide range of biological and environmental questions.

The truth about laser fiber diameters.

PubMed

Kronenberg, Peter; Traxer, Olivier

2014-12-01

To measure the various diameters of laser fibers from various manufacturers and compare them with the advertised diameter. Fourteen different unused laser fibers from 6 leading manufacturers with advertised diameters of 200, 270, 272, 273, 365, and 400 μm were measured by light microscopy. The outer diameter (including the fiber coating, cladding, and core), cladding diameter (including the cladding and the fiber core), and core diameter were measured. Industry representatives of the manufacturers were interviewed about the diameter of their fibers. For all fibers, the outer and cladding diameters differed significantly from the advertised diameter (P <.00001). The outer diameter, which is of most practical relevance for urologists, exhibited a median increase of 87.3% (range, 50.7%-116.7%). The outer, cladding, and core diameters of fibers with equivalent advertised diameters differed by up to 180, 100, and 78 μm, respectively. Some 200-μm fibers had larger outer diameters than the 270- to 273-μm fibers. All packaging material and all laser fibers lacked clear and precise fiber diameter information labels. Of 12 representatives interviewed, 8, 3, and 1 considered the advertised diameter to be the outer, the cladding, and the core diameter, respectively. Representatives within the same company frequently gave different answers. This study suggests that, at present, there is a lack of uniformity between laser fiber manufacturers, and most of the information conveyed to urologists regarding laser fiber diameter may be incorrect. Because fibers larger than the advertised laser fibers are known to influence key interventional parameters, this misinformation can have surgical repercussions. Copyright © 2014 Elsevier Inc. All rights reserved.

Cross talk analysis in multicore optical fibers by supermode theory.

PubMed

Szostkiewicz, Lukasz; Napierala, Marek; Ziolowicz, Anna; Pytel, Anna; Tenderenda, Tadeusz; Nasilowski, Tomasz

2016-08-15

We discuss the theoretical aspects of core-to-core power transfer in multicore fibers relying on supermode theory. Based on a dual core fiber model, we investigate the consequences of this approach, such as the influence of initial excitation conditions on cross talk. Supermode interpretation of power coupling proves to be intuitive and thus may lead to new concepts of multicore fiber-based devices. As a conclusion, we propose a definition of a uniform cross talk parameter that describes multicore fiber design.

Transversely polarized source cladding for an optical fiber

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

1994-01-01

An optical fiber comprising a fiber core having a longitudinal symmetry axis is provided. An active cladding surrounds a portion of the fiber core and comprises light-producing sources which emit light in response to chemical or light excitation. The cladding sources are oriented transversely with respect to the longitudinal axis of the fiber core. This polarization results in a superior power efficiency compared to active cladding sources that are randomly polarized or longitudinally polarized parallel with the longitudinal symmetry axis.

A multicore optical fiber for distributed sensing

NASA Astrophysics Data System (ADS)

Sun, Xiaoguang; Li, Jie; Burgess, David T.; Hines, Mike; Zhu, Beyuan

2014-06-01

With advancements in optical fiber technology, the incorporation of multiple sensing functionalities within a single fiber structure opens the possibility to deploy dielectric, fully distributed, long-length optical sensors in an extremely small cross section. To illustrate the concept, we designed and manufactured a multicore optical fiber with three graded-index (GI) multimode (MM) cores and one single mode (SM) core. The fiber was coated with both a silicone primary layer and an ETFE buffer for high temperature applications. The fiber properties such as geometry, crosstalk and attenuation are described. A method for coupling the signal from the individual cores into separate optical fibers is also presented.

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.

Multibeam Interferometer Using a Photonic Crystal Fiber with Two Asymmetric Cores for Torsion, Strain and Temperature Sensing

PubMed Central

Naeem, Khurram; Kwon, Il-Bum; Chung, Youngjoo

2017-01-01

We present a fiber-optic multibeam Mach-Zehnder interferometer (m-MZI) for simultaneous multi-parameter measurement. The m-MZI is comprised of a section of photonic crystal fiber integrated with two independent cores of distinct construction and birefringence properties characterized for torsion, strain and temperature sensing. Due to the presence of small core geometry and use of a short fiber length, the sensing device demonstrates inter-modal interference in the small core alongside the dominant inter-core interference between the cores for each of the orthogonal polarizations. The output spectrum of the device is characterized by the three-beam interference model and is polarization-dependent. The two types of interferometers present in the fiber m-MZI exhibit distinct sensitivities to torsion, strain and temperature for different polarizations, and matrix coefficients allowing simultaneous measurement of the three sensing parameters are proposed in experiment. PMID:28085046

Efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser.

PubMed

Wang, P; Cooper, L J; Sahu, J K; Clarkson, W A

2006-01-15

A novel approach to achieving robust single-spatial-mode operation of cladding-pumped fiber lasers with multimode cores is reported. The approach is based on the use of a fiber geometry in which the core has a helical trajectory within the inner cladding to suppress laser oscillation on higher-order modes. In a preliminary proof-of-principle study, efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser with a 30 microm diameter core and a numerical aperture of 0.087 has been demonstrated. The laser yielded 60.4 W of output at 1043 nm in a beam with M2 < 1.4 for 92.6 W launched pump power from a diode stack at 976 nm. The slope efficiency at pump powers well above threshold was approximately 84%, which compares favorably with the slope efficiencies achievable with conventional straight-core Yb-doped double-clad fiber lasers.

Hollow fiber surface plasmon resonance sensor for the detection of liquid with high refractive index.

PubMed

Liu, Bing-Hong; Jiang, Yong-Xiang; Zhu, Xiao-Song; Tang, Xiao-Li; Shi, Yi-Wei

2013-12-30

A new kind of surface plasmon resonance (SPR) sensor based on silver-coated hollow fiber (HF) structure for the detection of liquids with high refractive index (RI) is presented. Liquid sensed medium with high RI is filled in the hollow core of the HF and its RI can be detected by measuring the transmission spectra of the HF SPR sensor. The designed sensors with different silver thicknesses are fabricated and the transmission spectra for filled liquids with different RI are measured to investigate the performances of the sensors. Theoretical analysis is also carried out to evaluate the performance. The simulation results agree well with the experimental results. Factors that might affect sensitivity and detection accuracy of the sensor are discussed. The highest sensitivity achieved is 6,607 nm/RIU, which is comparable to the sensitivities of the other reported fiber SPR sensors.

Simple immunoglobulin G sensor based on thin core single-mode fiber

NASA Astrophysics Data System (ADS)

Zheng, Yingfang; Lang, Tingting; Shen, Tingting; Shen, Changyu

2018-03-01

In this paper, a simple fiber biosensor (FOB) for immunoglobulin G (IgG) detection is designed and experimentally verified. The FOB is constructed by a 20 mm long thin core single-mode fiber (TCSMF) sandwiched between two single-mode optical fibers (SMFs). First, the refractive index (RI) sensitivity of the fiber structures is calculated by the beam propagation method. The refractive index sensing experiment is performed using different concentrations of glycerol solutions, and the experimental results are mostly consistent with the simulation predictions. The experimental RI sensitivity increases with the surrounding RI and reaches 82.7 nm/RIU. Then the surface of the FOB is functionalized by APTES for covalent bonding. The human IgG and goat anti-human IgG are chosen as a bioconjugated pair to examine the bio-sensing effectiveness of this FOB. The sensitivity of IgG detection is determined to be 10.4 nm/(mg/ml). And the serum IgG concentration in normal adults lies within the range of 6-16 mg/ml (Worsfold et al., 1985), so the sensor is applicable to human IgG monitoring. The specificity of the FOB is also verified by a contrast experiment conducted using rabbit immunoglobulin G. The proposed FOB is simple, low loss, cost-effective, and can be used for various biological and chemical applications.

The impact of surface-polish on the angular and wavelength dependence of fiber focal ratio degradation

NASA Astrophysics Data System (ADS)

Eigenbrot, Arthur D.; Bershady, Matthew A.; Wood, Corey M.

2012-09-01

We present measurements of how multimode fiber focal-ratio degradation (FRD) and throughput vary with levels of fiber surface polish from 60 to 0.5 micron grit. Measurements used full-beam and laser injection methods at wavelengths between 0.4 and 0.8 microns on 17 meter lengths of Polymicro FBP 300 and 400 μm core fiber. Full-beam injection probed input focal-ratios between f/3 and f/13.5, while laser injection allowed us to isolate FRD at discrete injection angles up to 17 degrees (f/1.6 marginal ray). We find (1) FRD effects decrease as grit size decreases, with the largest gains in beam quality occurring at grit sizes above 5 μm (2) total throughput increases as grit size decreases, reaching 90% at 790 nm with the finest polishing levels; (3) total throughput is higher at redder wavelengths for coarser polishing grit, indicating surface-scattering as the primary source of loss. We also quantify the angular dependence of FRD as a function of polishing level. Our results indicate that a commonly adopted micro-bending model for FRD is a poor descriptor of the observed phenomenon.

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

A simple method for evacuating, refilling and connectorizing hollow-core photonic crystal fiber for use asgas reference cell is proposed and demonstrated. It relies on torch-sealing a quartz filling tube connected to amechanical splice between regular and hollow-core fibers.

Partially degradable fibers and microvascular materials formed from the fibers

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

Dong, Hefei; Pety, Stephen J.; Sottos, Nancy R.

A partially degradable polymeric fiber includes a thermally degradable polymeric core and a coating surrounding at least a portion of the core. The thermally degradable polymeric core includes a polymeric matrix including a poly(hydroxyalkanoate), and a metal selected from the group consisting of an alkali earth metal and a transition metal, in the core polymeric matrix. The concentration of the metal in the polymeric matrix is at least 0.1 wt %. The partially degradable polymeric fiber may be used to form a microvascular system containing one or more microfluidic channels.

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.

Co-axial Electrospun Polyacrylonitrile-Poly(methylmethacrylate) Nanofibers: Atomic Force Microscopy and Compositional Characterization

PubMed Central

Zander, N.E.; Strawhecker, K.E.; Orlicki, J.A.; Rawlett, A.M.; Beebe, T.P.

2011-01-01

Poly(methylmethacrylate) (PMMA)- Polyacrylonitrile (PAN) fibers were prepared using a conventional single-nozzle electrospinning technique. The as-spun fibers exhibited core-shell morphology as verified by transmission electron microscopy (TEM) and atomic force microscopy (AFM). AFM-phase and modulus mapping images of the fiber cross-section and x-ray photoelectron spectroscopy (XPS) analysis indicated PAN formed the shell and PMMA the core material. XPS, thermal gravimetric analysis (TGA), and elemental analysis were used to determine fiber compositional information. Soaking the fibers in solvent demonstrated removal of the core material, generating hollow PAN fibers. PMID:21928836

Supercontinuum generation and analysis in extruded suspended-core As2S3 chalcogenide fibers

NASA Astrophysics Data System (ADS)

Si, Nian; Sun, Lihong; Zhao, Zheming; Wang, Xunsi; Zhu, Qingde; Zhang, Peiqing; Liu, Shuo; Pan, Zhanghao; Liu, Zijun; Dai, Shixun; Nie, Qiuhua

2018-02-01

Compared with the traditional fluoride fibers and tellurite fibers that can work in the near-infrared region, suspended-core fibers based on chalcogenide glasses have wider transmitting regions and higher nonlinear coefficients, thus the mid-infrared supercontinuum generations can be achieved easily. Rather than adopting the traditional fabrication technique of hole-drilling and air filling, we adopted a totally novel extrusion technique to fabricate As2S3 suspended-core fibers with four holes, and its mid-infrared supercontinuum generation was investigated systematically by integrating theoretical simulation and empirical results. The generalized nonlinear SchrÖdinger equation was used to simulate the supercontinuum generation in the As2S3 suspended-core fibers. The simulated supercontinuum generation in the As2S3 suspended-core fibers with different pump wavelengths (2-5 µm), increasing powers (0.3-4 kW), and various fiber lengths (1-50 cm) was obtained by a simulative software, MATLAB. The experimental results of supercontinuum generation via femtosecond optical parametric amplification (OPA) were recorded by changing fiber lengths (5-25 cm), pump wavelengths (2.9-5 µm), and pump powers (10-200 kW). The simulated consulting spectra are consistent with the experimental results of supercontinuum generation only if the fiber loss is sufficiently low.

Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding

PubMed Central

Li, Rui; Zhou, Hui; Wei, Wei; Wang, Chen; Sun, Ying Chun; Gao, Ping

2015-01-01

The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber) posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber) post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilyl)ethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future. PMID:26066349

Passively mode-locked fiber laser based on a hollow-core photonic crystal fiber filled with few-layered graphene oxide solution.

PubMed

Liu, Zhi-Bo; He, Xiaoying; Wang, D N

2011-08-15

We demonstrate a nanosecond-pulse erbium-doped fiber laser that is passively mode locked by a hollow-core photonic crystal fiber filled with few-layered graphene oxide solution. Owing to the good solution processing capability of few-layered graphene oxide, which can be filled into the core of a hollow-core photonic crystal fiber through a selective hole filling process, a graphene saturable absorber can be successfully fabricated. The output pulses obtained have a center wavelength, pulse width, and repetition rate of 1561.2 nm, 4.85 ns, and 7.68 MHz, respectively. This method provides a simple and efficient approach to integrate the graphene into the optical fiber system. © 2011 Optical Society of America

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

Respiration and body movement analysis during sleep in bed using hetero-core fiber optic pressure sensors without constraint to human activity.

PubMed

Nishyama, Michiko; Miyamoto, Mitsuo; Watanabe, Kazuhiro

2011-01-01

We describe respiration monitoring in sleep using hetero-core fiber optic pressure sensors. The proposed hetero-core fiber optic sensor is highly sensitive to macrobending as a result of the core diameter difference due to stable single-mode transmission. Pressure sensors based on hetero-core fiber optics were fabricated to have a high sensitivity to small pressure changes resulting from minute body motions, such as respiration, during sleep and large pressure changes, such as those caused by a rollover. The sensors are installed in a conventional bed. The pressure characteristic performance of all the fabricated hetero-core fiber optic pressure sensors is found to show a monotonic response with weight changes. A respiration monitoring test in seven subjects efficiently demonstrates the effective use of eight hetero-core pressure sensors installed in a bed. Additionally, even in the case of different body postures, such as lying on one's side, a slight body movement due to respiration is detected by the hetero-core pressure sensors.

Respiration and body movement analysis during sleep in bed using hetero-core fiber optic pressure sensors without constraint to human activity

NASA Astrophysics Data System (ADS)

Nishyama, Michiko; Miyamoto, Mitsuo; Watanabe, Kazuhiro

2011-01-01

We describe respiration monitoring in sleep using hetero-core fiber optic pressure sensors. The proposed hetero-core fiber optic sensor is highly sensitive to macrobending as a result of the core diameter difference due to stable single-mode transmission. Pressure sensors based on hetero-core fiber optics were fabricated to have a high sensitivity to small pressure changes resulting from minute body motions, such as respiration, during sleep and large pressure changes, such as those caused by a rollover. The sensors are installed in a conventional bed. The pressure characteristic performance of all the fabricated hetero-core fiber optic pressure sensors is found to show a monotonic response with weight changes. A respiration monitoring test in seven subjects efficiently demonstrates the effective use of eight hetero-core pressure sensors installed in a bed. Additionally, even in the case of different body postures, such as lying on one's side, a slight body movement due to respiration is detected by the hetero-core pressure sensors.

Improving the mechanical performance of wood fiber reinforced bio-based polyurethane foam

NASA Astrophysics Data System (ADS)

Chang, Li-Chi

Because of the environmental impact of fossil fuel consumption, soybean-based polyurethane (PU) foam has been developed as an alternative to be used as the core in structural insulated panels (SIPs). Wood fibers can be added to enhance the resistance of foam against bending and buckling in compression. The goal of this work is to study the effect of three modifications: fiber surface treatment, catalyst choice, and mixing method on the compression performance of wood fiber-reinforced PU foam. Foams were made with a free-rising process. The compression performance of the foams was measured and the foams were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray computed tomography (CT). The foam reinforced with alkali-treated fibers had improved compression performance. The foams made with various catalysts shared similar performance. The foam made using a mechanical stirrer contained well-dispersed fibers but the reinforcing capability of the fibers was reduced.

Optical bandwidth in coupling: the multicore photonic switch.

PubMed

Attard, Alfred E

2003-05-20

In the present study, the bandwidth of a photonic switch described previously [Appl. Opt. 37,2296 (1998); 38, 3239 (1999)] is evaluated. First the optical bandwidth is evaluated for coupling between two fiber-core waveguides, in which the cores are embedded within the same cladding. Then the coupling bandwidth is determined for a fiber-core-to-slab-core waveguide, in which the cores are embedded within the same cladding. These bandwidths are then compared and contrasted with the bandwidths of the photonic switch, which consists of two fiber cores and a control waveguide. Two configurations of the photonic switch are considered: one in which the control waveguide is a fiber core and one in which the control waveguide is a slab core. For the photonic switch, the bandwidth characteristics are more complicated than for the coupled pairs, and these characteristics are discussed in detail.

Model of a thin film optical fiber fluorosensor

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1991-01-01

The efficiency of core-light injection from sources in the cladding of an optical fiber is modeled analytically by means of the exact field solution of a step-profile fiber. The analysis is based on the techniques by Marcuse (1988) in which the sources are treated as infinitesimal electric currents with random phase and orientation that excite radiation fields and bound modes. Expressions are developed based on an infinite cladding approximation which yield the power efficiency for a fiber coated with fluorescent sources in the core/cladding interface. Marcuse's results are confirmed for the case of a weakly guiding cylindrical fiber with fluorescent sources uniformly distributed in the cladding, and the power efficiency is shown to be practically constant for variable wavelengths and core radii. The most efficient fibers have the thin film located at the core/cladding boundary, and fibers with larger differences in the indices of refraction are shown to be the most efficient.

Extremely small-core photonic crystal fiber fusion splicing with a single-mode fiber

NASA Astrophysics Data System (ADS)

Tiburcio, Bruno D.; Fernandes, Gil M.; Pinto, Armando N.

2013-11-01

We present a low-loss fusion splicing of a non-linear photonic-crystal fiber (NL-PCF) with a single-mode fiber (SMF), helped by an intermediate fiber, using a electric-arc splicer. We also analysed the splice loss between SMF and intermediate fiber, as a function of the electrical discharge duration, to achieve a low-loss transition between SMF and intermediate fiber, through a thermally expanded core splice (TEC). The NL-PCF has a external cladding diameter of 105 μm, a core diameter of 1.7 μm and mode-field diameter (MFD) of 1.5 μm. We also performed mechanical strength tests to verify the robustness of the splice joints obtained.

Multimode optical fiber

DOEpatents

Bigot-Astruc, Marianne; Molin, Denis; Sillard, Pierre

2014-11-04

A depressed graded-index multimode optical fiber includes a central core, an inner depressed cladding, a depressed trench, an outer depressed cladding, and an outer cladding. The central core has an alpha-index profile. The depressed claddings limit the impact of leaky modes on optical-fiber performance characteristics (e.g., bandwidth, core size, and/or numerical aperture).

High temperature, flexible, fiber-preform seal

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M. (Inventor); Strocky, Paul J. (Inventor)

1992-01-01

A seal is mounted in a rectangular groove in a movable structural panel. The seal comprises a fiber preform constructed of multiple layers of fiber having a uniaxial core. Helical fibers are wound over the core. The fibers are of materials capable of withstanding high temperatures and are both left-hand and right-hand wound. An outer layer wrapped over said helical fibers prevents abrasion damage.

Novel intercore-cladding lithium niobate thin film coated MOEMS fiber sensor/modulator

NASA Technical Reports Server (NTRS)

Jamlson, Tracee L.; Konreich, Phillip; Yu, Chung

2005-01-01

A MOEMS fiber modulator/sensor is fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125-micron fibers. Such a MOEMS modulator design is expected to enhance existing lithium niobate undersea acousto-optic sound wave detectors. In our proposed version, the lithium niobate thin film alters the ordinary silica core/cladding boundary conditions such that, when a stress or strain is applied to the fiber, the core light confinement factor changes, leading to modulation of fiber light transmission. Test results of the lithium niobate embedded fiber with a 1550-nm, 4-mW laser source revealed a reduction in light transmission with applied tension. As a comparison, using the same laser source, an ordinary silica core/cladding fiber did not exhibit any reduction in transmitted light when the same strain was applied. Further experimental work and theoretical analysis is ongoing.

Endoscopic sensing of alveolar pH.

PubMed

Choudhury, D; Tanner, M G; McAughtrie, S; Yu, F; Mills, B; Choudhary, T R; Seth, S; Craven, T H; Stone, J M; Mati, I K; Campbell, C J; Bradley, M; Williams, C K I; Dhaliwal, K; Birks, T A; Thomson, R R

2017-01-01

Previously unobtainable measurements of alveolar pH were obtained using an endoscope-deployable optrode. The pH sensing was achieved using functionalized gold nanoshell sensors and surface enhanced Raman spectroscopy (SERS). The optrode consisted of an asymmetric dual-core optical fiber designed for spatially separating the optical pump delivery and signal collection, in order to circumvent the unwanted Raman signal generated within the fiber. Using this approach, we demonstrate a ~100-fold increase in SERS signal-to-fiber background ratio, and demonstrate multiple site pH sensing with a measurement accuracy of ± 0.07 pH units in the respiratory acini of an ex vivo ovine lung model. We also demonstrate that alveolar pH changes in response to ventilation.

The effect of macro-bending on power confinement factor in single mode fibers

NASA Astrophysics Data System (ADS)

Waluyo, T. B.; Bayuwati, D.; Mulyanto, I.

2018-03-01

One of the methods to determine the macro-bending effect in a single mode fiber is by calculating its power loss coefficient. We describe an alternative method by using the equation of fractional power in the fiber core. Knowing the fiber parameters such as its core radius, refractive indexes, and operating wavelength; we can calculate the V-number and the fractional power in the core. Because the value of the fiber refractive indexes and the propagation constant are affected by bending, we can calculate the value of the fractional power in the core as a function of the bending radius. We calculate the fractional power in the core of an SMF28 and SM600 fiber and, to verify our calculation, we measure its transmission loss using an optical spectrum analyzer. Our calculations and experimental results showed that for SMF28 fiber, there is about 4% power loss due to bending at 633 nm, about 8% at 1310 nm, about 20% at 1550 nm, and about 60% at 1064 nm. For SM600 fiber, there is about 6% power loss due to bending at 633 nm, about 11% at 850 nm, and this fiber is not suitable for operating wavelength beyond 1000 nm.

A multi-core fiber based interferometer for high temperature sensing

NASA Astrophysics Data System (ADS)

Zhou, Song; Huang, Bo; Shu, Xuewen

2017-04-01

In this paper, we have verified and implemented a Mach-Zehnder interferometer based on seven-core fiber for high temperature sensing application. This proposed structure is based on a multi-mode-multi-core-multi-mode fiber structure sandwiched by a single mode fiber. Between the single-mode and multi-core fiber, a 3 mm long multi-mode fiber is formed for lead-in and lead-out light. The basic operation principle of this device is the use of multi-core modes, single-mode and multi-mode interference coupling is also utilized. Experimental results indicate that this interferometer sensor is capable of accurate measurements of temperatures up to 800 °C, and the temperature sensitivity of the proposed sensor is as high as 170.2 pm/°C, which is much higher than the current existing MZI based temperature sensors (109 pm/°C). This type of sensor is promising for practical high temperature applications due to its advantages including high sensitivity, simple fabrication process, low cost and compactness.

Multi-channel measurement for hetero-core optical fiber sensor by using CMOS camera

NASA Astrophysics Data System (ADS)

Koyama, Yuya; Nishiyama, Michiko; Watanabe, Kazuhiro

2015-07-01

Fiber optic smart structures have been developed over several decades by the recent fiber optic sensor technology. Optical intensity-based sensors, which use LD or LEDs, can be suitable for the monitor system to be simple and cost effective. In this paper, a novel fiber optic smart structure with human-like perception has been demonstrated by using intensity-based hetero-core optical fiber sensors system with the CMOS detector. The optical intensity from the hetero-core optical fiber bend sensor is obtained as luminance spots indicated by the optical power distributions. A number of optical intensity spots are simultaneously readout by taking a picture of luminance pattern. To recognize the state of fiber optic smart structure with the hetero-core optical fibers, the template matching process is employed with Sum of Absolute Differences (SAD). A fiber optic smart glove having five optic fiber nerves have been employed to monitor hand postures. Three kinds of hand postures have been recognized by means of the template matching process. A body posture monitoring has also been developed by placing the wearable hetero-core optical fiber bend sensors on the body segments. In order for the CMOS system to be a human brain-like, the luminescent spots in the obtained picture were arranged to make the pattern corresponding to the position of body segments. As a result, it was successfully demonstrated that the proposed fiber optic smart structure could recognize eight kinds of body postures. The developed system will give a capability of human brain-like processing to the existing fiber optic smart structures.

Photonic crystal fiber modal interferometer based on thin-core-fiber mode exciter.

PubMed

Miao, Yinping; Ma, Xixi; Wu, Jixuan; Song, Binbin; Zhang, Hao; Liu, Bo; Yao, Jianquan

2015-11-10

A thin-core-fiber excited photonic crystal fiber modal interferometer has been proposed and experimentally demonstrated. By employing a thin-core fiber as the mode exciter, both of the core and cladding modes propagate in the photonic crystal fiber and interfere with each other. The experimental results show that the transmission dips corresponding to different-order modes have various strain responses with opposite shift directions. The strain sensitivity could be improved to 58.57  pm/με for the applied strain from 0 to 491 με by utilizing the wavelength interval between the dips with opposite shift directions. Moreover, due to the pure silica property of the employed photonic crystal fiber, the proposed fiber modal interferometer exhibits a low-temperature sensitivity of about 0.56  pm/°C within a temperature range from 26.4°C (room temperature) to 70°C. Additionally, the proposed fiber modal interferometer has several advantages, such as good stability, compact structure, and simple fabrication. Therefore, it is more applicable for strain measurement with reducing temperature cross-sensitivity.

Improvement of optical damage in specialty fiber at 266 nm wavelength

NASA Astrophysics Data System (ADS)

Tobisch, T.; Ohlmeyer, H.; Zimmermann, H.; Prein, S.; Kirchhof, J.; Unger, S.; Belz, M.; Klein, K.-F.

2014-02-01

Improved multimode UV-fibers with core diameters ranging from 70 to 600 μm diameter have been manufactured based on novel preform modifications and fiber processing techniques. Only E'-centers at 214 nm and NBOHC at 260 nm are generated in these fibers. A new generation of inexpensive laser-systems have entered the market and generated a multitude of new and attractive applications in the bio-life science, chemical and material processing field. However, for example pulsed 355 nm Nd:YAG lasers generate significant UV-damages in commercially available fibers. For lower wavelengths, no results on suitable multi-mode or low-mode fibers with high UV resistance at 266 nm wavelength (pulsed 4th harmonic Nd:YAG laser) have been published. In this report, double-clad fibers with 70 μm or 100 μm core diameter and a large claddingto- core ratio will be recommended. Laser-induced UV-damages will be compared between these new fiber type and traditional UV fibers with similar core sizes. Finally, experimental results will be cross compared against broadband cw deuterium lamp damage standards.

Experimental investigation of inter-core crosstalk tolerance of MIMO-OFDM/OQAM radio over multicore fiber system.

PubMed

He, Jiale; Li, Borui; Deng, Lei; Tang, Ming; Gan, Lin; Fu, Songnian; Shum, Perry Ping; Liu, Deming

2016-06-13

In this paper, the feasibility of space division multiplexing for optical wireless fronthaul systems is experimentally demonstrated by implementing high speed MIMO-OFDM/OQAM radio signals over 20km 7-core fiber and 0.4m wireless link. Moreover, the impact of optical inter-core crosstalk in multicore fibers on the proposed MIMO-OFDM/OQAM radio over fiber system is experimentally evaluated in both SISO and MIMO configurations for comparison. The experimental results show that the inter-core crosstalk tolerance of the proposed radio over fiber system can be relaxed to -10 dB by using the proposed MIMO-OFDM/OQAM processing. These results could guide high density multicore fiber design to support a large number of antenna modules and a higher density of radio-access points for potential applications in 5G cellular system.

Fiber-Optic SPR Immunosensors Tailored To Target Epithelial Cells through Membrane Receptors.

PubMed

Malachovská, Viera; Ribaut, Clotilde; Voisin, Valérie; Surin, Mathieu; Leclère, Philippe; Wattiez, Ruddy; Caucheteur, Christophe

2015-06-16

We report, for the first time, the use of a surface plasmon resonance (SPR) fiber-optic immunosensor for selective cellular detection through membrane protein targeting. The sensor architecture lies on gold-coated tilted fiber Bragg gratings (Au-coated TFBGs) photoimprinted in the fiber core via a laser technique. TFBGs operate in the near-infrared wavelength range at ∼1550 nm, yielding optical and SPR sensing characteristics that are advantageous for the analyses of cellular bindings and technical compatibility with relatively low-cost telecommunication-grade measurement devices. In this work, we take consider their numerous assets to figure out their ability to selectively detect intact epithelial cells as analytes in cell suspensions in the range of 2-5 × 10(6) cells mL(-1). For this, the probe was first thermally annealed to ensure a strong adhesion of the metallic coating to the fiber surface. Its surface was then functionalized with specific monoclonal antibodies via alkanethiol self-assembled monolayers (SAMs) against extracellular domain of epidermal growth factor receptors (EGFRs) and characterized by peak force tapping atomic force microscopy. A differential diagnosis has been demonstrated between two model systems. The developed immunosensors were able to monitor, in real time, the specific attachment of single intact cells in concentrations from 3 × 10(6) cells mL(-1). Such results confirm that the developed probe fits the lab-on-fiber technology and has the potential to be used as a disposable device for in situ and real-time clinical diagnosis.

U-bent plastic optical fiber based plasmonic biosensor for nucleic acid detection

NASA Astrophysics Data System (ADS)

Gowri, A.; Sai, V. V. R.

2017-05-01

This study presents the development of low cost, rapid and highly sensitive plasmonic sandwich DNA biosensor using U-bent plastic optical fiber (POF) probes with high evanescent wave absorbance sensitivity and gold nanoparticles (AuNP) as labels. Plastic optical fiber (PMMA core and fluorinated polymer as cladding) offer ease in machinability and handling due to which optimum U-bent geometry (with fiber and bend diameter of 0.5 and 1.5 mm respectively) for high sensitivity could be achieved. A sensitive fiber optic DNA biosensor is realized by (i) modifying the PMMA surface using ethylenediamine (EDA) in order to maximize the immobilization of capture oligonucleotides (ONs) and (ii) conjugating probe ONs to AuNP labels of optimum size ( 35 nm) with high extinction coefficient and optimal ON surface density. The sandwich hybridization assay on U-bent POF probes results in increase in optical absorbance through the probe with increase in target ON concentration due to the presence of increased number of AuNPs. The absorbance of light passing through the U-bent probe due to the presence of AuNP labels on its surface as result of sandwich DNA hybridization is measured using a halogen lamp and a fiber optic spectrometer. A picomolar limit of detection of target ON (0.2 pM or 1 pg/ml or 5 attomol in 25 μL) is achieved with this biosensing scheme, indicating its potential for the development of a highly sensitive DNA biosensor.

Hybrid porous core low loss dispersion flattened fiber for THz propagation

NASA Astrophysics Data System (ADS)

Ali, Sharafat; Ahmed, Nasim; Aljunid, Syed; Ahmad, Badlishah

2016-11-01

This manuscript represents a novel porous core fiber design for Terahertz (THz) propagation with low loss and near zero flat dispersion properties. In this proposed fiber a hexagonal arrangement is used as cladding structure and a hybrid core containing circular and triangular designs is used as the central porous region. The Effective Material Loss (EML), confinement loss and bending loss are investigated for the proposed fiber along with dispersion characteristics. Simulation results show a very low EML of 0.01944 cm-1 at 1 THz operating frequency with negligible confinement and bending loss. The proposed novel porous design shows 0.55 THz range near zero flat dispersion of ±0.05 ps/THz/cm at 0.95 ps/THz/cm. The reported design consists of only circular shaped air holes with proper core diameter and porosity to simplify the fabrication process. The newly proposed hybrid design in the porous core region can be considered as an improved edition in the research of THz porous core fibers.

Neural networks within multi-core optic fibers

PubMed Central

Cohen, Eyal; Malka, Dror; Shemer, Amir; Shahmoon, Asaf; Zalevsky, Zeev; London, Michael

2016-01-01

Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a conceptual design for in-fiber optical neural networks. Neurons and synapses are realized as individual silica cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in erbium-doped cores mimics synaptic interactions. We simulated three-layered feed-forward neural networks and explored their capabilities. Simulations suggest that networks can differentiate between given inputs depending on specific configurations of amplification; this implies classification and learning capabilities. Finally, we tested experimentally our basic neuronal elements using fibers, couplers, and amplifiers, and demonstrated that this configuration implements a neuron-like function. Therefore, devices similar to our proposed multi-core fiber could potentially serve as building blocks for future large-scale small-volume optical artificial neural networks. PMID:27383911

Neural networks within multi-core optic fibers.

PubMed

Cohen, Eyal; Malka, Dror; Shemer, Amir; Shahmoon, Asaf; Zalevsky, Zeev; London, Michael

2016-07-07

Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a conceptual design for in-fiber optical neural networks. Neurons and synapses are realized as individual silica cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in erbium-doped cores mimics synaptic interactions. We simulated three-layered feed-forward neural networks and explored their capabilities. Simulations suggest that networks can differentiate between given inputs depending on specific configurations of amplification; this implies classification and learning capabilities. Finally, we tested experimentally our basic neuronal elements using fibers, couplers, and amplifiers, and demonstrated that this configuration implements a neuron-like function. Therefore, devices similar to our proposed multi-core fiber could potentially serve as building blocks for future large-scale small-volume optical artificial neural networks.

Investigation of cladding and coating stripping methods for specialty optical fibers

NASA Astrophysics Data System (ADS)

Lee, Jung-Ryul; Dhital, Dipesh; Yoon, Dong-Jin

2011-03-01

Fiber optic sensing technology is used extensively in several engineering fields, including smart structures, health and usage monitoring, non-destructive testing, minimum invasive sensing, safety monitoring, and other advanced measurement fields. A general optical fiber consists of a core, cladding, and coating layers. Many sensing principles require that the cladding or coating layer should be removed or modified. In addition, since different sensing systems are needed for different types of optical fibers, it is very important to find and sort out the suitable cladding or coating removal method for a particular fiber. This study focuses on finding the cladding and coating stripping methods for four recent specialty optical fibers, namely: hard polymer-clad fiber, graded-index plastic optical fiber, copper/carbon-coated optical fiber, and aluminum-coated optical fiber. Several methods, including novel laser stripping and conventional chemical and mechanical stripping, were tried to determine the most suitable and efficient technique. Microscopic investigation of the fiber surfaces was used to visually evaluate the mechanical reliability. Optical time domain reflectometric signals of the successful removal cases were investigated to further examine the optical reliability. Based on our results, we describe and summarize the successful and unsuccessful methods.

Detection of amino acid neurotransmitters by surface enhanced Raman scattering and hollow core photonic crystal fiber

NASA Astrophysics Data System (ADS)

Tiwari, Vidhu S.; Khetani, Altaf; Monfared, Ali Momenpour T.; Smith, Brett; Anis, Hanan; Trudeau, Vance L.

2012-03-01

The present work explores the feasibility of using surface enhanced Raman scattering (SERS) for detecting the neurotransmitters such as glutamate (GLU) and gamma-amino butyric acid (GABA). These amino acid neurotransmitters that respectively mediate fast excitatory and inhibitory neurotransmission in the brain, are important for neuroendocrine control, and upsets in their synthesis are also linked to epilepsy. Our SERS-based detection scheme enabled the detection of low amounts of GLU (10-7 M) and GABA (10-4 M). It may complement existing techniques for characterizing such kinds of neurotransmitters that include high-performance liquid chromatography (HPLC) or mass spectrography (MS). This is mainly because SERS has other advantages such as ease of sample preparation, molecular specificity and sensitivity, thus making it potentially applicable to characterization of experimental brain extracts or clinical diagnostic samples of cerebrospinal fluid and saliva. Using hollow core photonic crystal fiber (HC-PCF) further enhanced the Raman signal relative to that in a standard cuvette providing sensitive detection of GLU and GABA in micro-litre volume of aqueous solutions.

Miniature ball-tip optical fibers for use in thulium fiber laser ablation of kidney stones

NASA Astrophysics Data System (ADS)

Wilson, Christopher R.; Hardy, Luke A.; Kennedy, Joshua D.; Irby, Pierce B.; Fried, Nathaniel M.

2016-01-01

Optical fibers, consisting of 240-μm-core trunk fibers with rounded, 450-μm-diameter ball tips, are currently used during Holmium:YAG laser lithotripsy to reduce mechanical damage to the inner lining of the ureteroscope working channel during fiber insertion and prolong ureteroscope lifetime. Similarly, this study tests a smaller, 100-μm-core fiber with 300-μm-diameter ball tip during thulium fiber laser (TFL) lithotripsy. TFL was operated at a wavelength of 1908 nm, with 35-mJ pulse energy, 500-μs pulse duration, and 300-Hz pulse rate. Calcium oxalate/phosphate stone samples were weighed, laser procedure times were measured, and ablation rates were calculated for ball tip fibers, with comparison to bare tip fibers. Photographs of ball tips were taken before and after each procedure to track ball tip degradation and determine number of procedures completed before need for replacement. A high speed camera also recorded the cavitation bubble dynamics during TFL lithotripsy. Additionally, saline irrigation rates and ureteroscope deflection were measured with and without the presence of TFL fiber. There was no statistical difference (P>0.05) between stone ablation rates for single-use ball tip fiber (1.3±0.4 mg/s) (n=10), multiple-use ball tip fiber (1.3±0.5 mg/s) (n=44), and conventional single-use bare tip fibers (1.3±0.2 mg/s) (n=10). Ball tip durability varied widely, but fibers averaged greater than four stone procedures before failure, defined by rapid decline in stone ablation rates. Mechanical damage at the front surface of the ball tip was the limiting factor in fiber lifetime. The small fiber diameter did not significantly impact ureteroscope deflection or saline flow rates. The miniature ball tip fiber may provide a cost-effective design for safe fiber insertion through the ureteroscope working channel and into the ureter without risk of instrument damage or tissue perforation, and without compromising stone ablation efficiency during TFL lithotripsy.

Stimulated Raman scattering in AsSe2-As2S5 microstructured optical fiber

NASA Astrophysics Data System (ADS)

Gao, Weiqing; Ni, Chenquan; Xu, Qiang; Li, Xue; Chen, Xiangcai; Chen, Li; Wen, Zhenqiang; Cheng, Tonglei; Xue, Xiaojie; Suzuki, Takenobu; Ohishi, Yasutake

2017-02-01

We demonstrate the effects of stimulated Raman scattering (SRS) in the all-solid-core chalcogenide microstructured optical fibers (MOFs) with AsSe2 core and As2S5 cladding, which are fabricated by the rod-in-tube drawing technique. The core diameters of the MOFs are 6.3 (Fiber I), 3.0 (Fiber II), 2.6 (Fiber III) and 2.2 (Fiber IV) μm, respectively. The chromatic dispersion of the fundamental mode in Fibers I-IV is simulated by the full-vectorial mode solver technique. The first-order Stokes wave is investigated in the fibers with different core diameters pumped by the picosecond pulses at 1958 nm. In Fiber I, no obvious Raman peak is observed with the pump power increasing, because the effective nonlinearity is not high. In Fiber II, a Raman Stokes peak at 2065 nm begins to emerge at the pump power of 110 mW. The conversion efficiency is as weak as -36.6 dB at 150 mW pumping. In Fiber III, the first-order Raman peak at 2060 nm begins to emerge at 40 mW pumping. The conversion efficiency is -15.0 dB, which is 21.6 dB higher than that in Fiber II. In Fiber IV, the Stokes peak at 2070 nm begins to appear at 56 mW pumping. The maximum conversion efficiency of the first-order Stokes wave is obtained in the MOF with the core diameter of 2.6 μm. The evolution of the first-order Stokes wave with pump power and fiber length is investigated. This is the first demonstration of Raman effects in the AsSe2-As2S5 MOF, to the best of our knowledge.

Wide range optofluidically tunable multimode interference fiber laser

NASA Astrophysics Data System (ADS)

Antonio-Lopez, J. E.; Sanchez-Mondragon, J. J.; LiKamWa, P.; May-Arrioja, D. A.

2014-08-01

An optofluidically tunable fiber laser based on multimode interference (MMI) effects with a wide tuning range is proposed and demonstrated. The tunable mechanism is based on an MMI fiber filter fabricated using a special fiber known as no-core fiber, which is a multimode fiber (MMF) without cladding. Therefore, when the MMI filter is covered by liquid the optical properties of the no-core fiber are modified, which allow us to tune the peak wavelength response of the MMI filter. Rather than applying the liquid on the entire no-core fiber, we change the liquid level along the no-core fiber, which provides a highly linear tuning response. In addition, by selecting the adequate refractive index of the liquid we can also choose the tuning range. We demonstrate the versatility of the optofluidically tunable MMI filter by wavelength tuning two different gain media, erbium doped fiber and a semiconductor optical amplifier, achieving tuning ranges of 55 and 90 nm respectively. In both cases, we achieve side-mode suppression ratios (SMSR) better than 50 dBm with output power variations of less than 0.76 dBm over the whole tuning range.

Effect of controlling recrystallization from the melt on the residual stress and structural properties of the Silica-clad Ge core fiber

NASA Astrophysics Data System (ADS)

Zhao, Ziwen; Cheng, Xueli; He, Ting; Xue, Fei; Zhang, Wei; Chen, Na; Wen, Jianxiang; Zeng, Xianglong; Wang, Tingyun

2017-09-01

Effect of controlling recrystallization from the melt (1000 °C) on the residual stress and structural properties of a Ge core fiber via molten core drawing (MCD) method is investigated. Ge core fibers is investigated using Raman spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD). Compared with the as-drawn Ge fiber, the Raman peak of the recrystallized Ge fiber shift from 300 cm-1 to 300.6 cm-1 and full width at half maximum (FWHM) decreased from 5.36 cm-1 to 4.48 cm-1. The Ge crystal grains which sizes are of 200-600 nm were formed during the process of recrystallization; the XRD peak of (1 1 1) plane is observed after recrystallization. These results show that controlling recrystallization allows the release of the thermal stress, and improvement of the crystal quality of Ge core.

Two-mode elliptical-core weighted fiber sensors for vibration analysis

NASA Technical Reports Server (NTRS)

Vengsarkar, Ashish M.; Murphy, Kent A.; Fogg, Brian R.; Miller, William V.; Greene, Jonathan A.; Claus, Richard O.

1992-01-01

Two-mode, elliptical-core optical fibers are demonstrated in weighted, distributed and selective vibration-mode-filtering applications. We show how appropriate placement of optical fibers on a vibrating structure can lead to vibration mode filtering. Selective vibration-mode suppression on the order of 10 dB has been obtained using tapered two-mode, circular-core fibers with tapering functions that match the second derivatives of the modes of vibration to be enhanced. We also demonstrate the use of chirped, two-mode gratings in fibers as spatial modal sensors that are equivalents of shaped piezoelectric sensors.

High-beam quality, high-efficiency laser based on fiber with heavily Yb(3+)-doped phosphate core and silica cladding.

PubMed

Egorova, O N; Semjonov, S L; Medvedkov, O I; Astapovich, M S; Okhrimchuk, A G; Galagan, B I; Denker, B I; Sverchkov, S E; Dianov, E M

2015-08-15

We have fabricated and tested a composite fiber with an Yb(3+)-doped phosphate glass core and silica cladding. Oscillation with a slope efficiency of 74% was achieved using core pumping at 976 nm with fiber lengths of 48-90 mm in a simple laser configuration, where the cavity was formed by a high-reflectivity Bragg grating and the cleaved fiber end. The measured M(2) factors were as low as 1.05-1.22 even though the fiber was multimode at the lasing wavelength.

Seven-core neodymium-doped phosphate all-solid photonic crystal fibers

NASA Astrophysics Data System (ADS)

Wang, Longfei; He, Dongbing; Feng, Suya; Yu, Chunlei; Hu, Lili; Chen, Danping

2016-01-01

We demonstrate a single-mode seven-core Nd-doped phosphate photonic crystal fiber with all-solid structure with an effective mode field diameter of 108 μm. The multicore fiber is first theoretically investigated through the finite-difference time-domain method. Then the in-phase mode is selected experimentally by a far-field mode-filtering method. The obtained in-phase mode has 7 mrad mode field divergences, which approximately agrees with the predicted 5.6 mrad in seven-core fiber. Output power of 15.5 W was extracted from a 25 cm fiber with slope efficiency of 57%.

Development and characterization of coaxially electrospun gelatin coated poly (3-hydroxybutyric acid) thin films as potential scaffolds for skin regeneration.

PubMed

Nagiah, Naveen; Madhavi, Lakshmi; Anitha, R; Anandan, C; Srinivasan, Natarajan Tirupattur; Sivagnanam, Uma Tirichurapalli

2013-10-01

The morphology of fibers synthesized through electrospinning has been found to mimic extracellular matrix. Coaxially electrospun fibers of gelatin (sheath) coated poly (3-hydroxybutyric acid) (PHB) (core) was developed using 2,2,2 trifluoroethanol(TFE) and 1,1,1,3,3,3 hexafluoro-2-propanol(HFIP) as solvents respectively. The coaxial structure and coating of gelatin with PHB fibers was confirmed through transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Thermal stability of the coaxially electrospun fibers was analyzed using thermogravimetric analysis(TGA), differential scanning calorimetry(DSC) and differential thermogravimetric analysis(DTA). Complete evaporation of solvent and gelatin grafting over PHB fibers was confirmed through attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR). The coaxially electrospun fibers exhibited competent tensile properties for skin regeneration with high surface area and porosity. In vitro degradation studies proved the stability of fibers and its potential applications in tissue engineering. The fibers supported the growth of human dermal fibroblasts and keratinocytes with normal morphology indicating its potential as a scaffold for skin regeneration. © 2013.

Axial contraction in etched optical fiber due to internal stress reduction.

PubMed

Lim, Kok-Sing; Yang, Hang-Zhou; Chong, Wu-Yi; Cheong, Yew-Ken; Lim, Chin-Hong; Ali, Norfizah M; Ahmad, Harith

2013-02-11

When an optical fiber is dipped in an etching solution, the internal stress profile in the fiber varies with the fiber diameter. We observed a physical contraction as much as 0.2% in the fiber axial dimension when the fiber was reduced from its original diameter to ~6 µm through analysis using high resolution microscope images of the grating period of an etched FBG at different fiber diameters. This axial contraction is related to the varying axial stress profile in the fiber when the fiber diameter is reduced. On top of that, the refractive index of fiber core increases with reducing fiber diameter due to stress-optic effect. The calculated index increment is as much as 1.8 × 10(-3) at the center of fiber core after the diameter is reduced down to ~6 µm. In comparison with the conventional model that assumes constant grating period and neglects the variation in stress-induced index change in fiber core, our proposed model indicates a discrepancy as much as 3nm in Bragg wavelength at a fiber diameter of ~6 µm.

Studies on low-loss coupling of non-node anti-resonant hollow-core fiber and tapered fiber

NASA Astrophysics Data System (ADS)

Zhang, Naiqian; Wang, Zefeng; Liu, Wenbo; Xi, Xiaoming

2017-10-01

Up to now, near almost optical fiber gas lasers employ/adopt the scheme of free-space coupling, which increases the difficulty to adjust the optical path, and has poor stability. All-fiber structure fiber-gas lasers are important development directions in the future. We established the numerical model of SMF-28 type tapered single-mode fiber and non-node hollow-core fiber. When the SMF-28 type single-mode fiber has a waist diameter of 40μm when the light source is LP01 fundamental mode with 1550nm wavelength, the mode field diameter is the largest. Meanwhile, we simulated that the equivalent mode field diameter of non-node anti-resonant hollow-core fiber is about 75μm at the same 1550nm wavelength light source. Then, we use different waist diameters of SMF-28 type tapered fibers injected to the non-node anti-resonant hollow-core fiber in simulation and experiments. In the scheme of the single-ended low-loss coupling, the simulation results indicate that the best waist diameter of tapered fiber is 40μm, and the calculated maximum coupling efficiency is 83.55%. Meanwhile, the experimental result of maximum coupling efficiency is 80.74% when the best waist diameter of tapered fiber is also 40μm. As for the double-ended low-loss coupling, the calculated maximum coupling efficiency is near 83.38%.

RGB generation by four-wave mixing in small-core holey fibers

NASA Astrophysics Data System (ADS)

Horak, Peter; Dupriez, Pascal; Poletti, Francesco; Petrovich, Marco N.; Jeong, Yoonchan; Nilsson, Johan; Richardson, David J.; Payne, David N.

2007-09-01

We report the generation of white light comprising red, green, and blue spectral bands from a frequency-doubled fiber laser in submicron-sized cores of microstructured holey fibers. Picosecond pulses of green light are launched into a single suspended core of a silica holey fiber where energy is transferred by an efficient four-wave mixing process into a red and blue sideband whose wavelengths are fixed by birefringent phase matching due to a slight asymmetry of the structure arising during the fiber fabrication. Numerical models of the fiber structure and of the nonlinear processes confirm our interpretation. Finally, we discuss power scaling and limitations of this white light source.

High-efficiency (6 + 1) × 1 pump-signal combiner based on low-deformation and high-precision alignment fabrication

NASA Astrophysics Data System (ADS)

Zou, Shuzhen; Chen, Han; Yu, Haijuan; Sun, Jing; Zhao, Pengfei; Lin, Xuechun

2017-12-01

We demonstrate a new method for fabricating a (6 + 1) × 1 pump-signal combiner based on the reduction of signal fiber diameter by corrosion. This method avoids the mismatch loss of the splice between the signal fiber and the output fiber caused by the signal fiber taper processing. The optimum radius of the corroded signal fiber was calculated according to the analysis of the influence of the cladding thickness on the laser propagating in the fiber core. Besides, we also developed a two-step splicing method to complete the high-precision alignment between the signal fiber core and the output fiber core. A high-efficiency (6 + 1) × 1 pump-signal combiner was produced with an average pump power transmission efficiency of 98.0% and a signal power transmission efficiency of 97.7%, which is well suitable for application to high-power fiber laser system.

Surface plasmon resonance-based fiber-optic hydrogen gas sensor utilizing palladium supported zinc oxide multilayers and their nanocomposite.

PubMed

Tabassum, Rana; Gupta, Banshi D

2015-02-10

We analyze surface plasmon resonance-based fiber-optic sensor for sensing of small concentrations of hydrogen gas in the visible region of the electromagnetic spectrum. One of the two probes considered has multilayers of zinc oxide (ZnO) and palladium (Pd) while the other has layer of their composite over a silver coated unclad core of the fiber. The analysis is carried out for different volume fractions of palladium nanoparticles dispersed in zinc oxide host material in the nanocomposite layer. For the analysis, a Maxwell-Garnett model is adopted for calculating the dielectric function of a ZnO:Pd nanocomposite having nanoparticles of dimensions smaller than the wavelength of radiation used. The effects of the volume fraction of the nanoparticles in the nanocomposite and the thickness of the nanocomposite layer on the figure of merit of the sensor have been studied. The film thickness of the layer and the volume fraction of nanoparticles in the ZnO:Pd nanocomposite layer have been optimized to achieve the maximum value of the figure of merit of the sensor. It has been found that the figure of merit of the sensing probe coated with ZnO:Pd nanocomposite is more than twofold of the sensing probe coated with multilayers of Pd and ZnO over a silver coated unclad core of the fiber; hence, the sensor with a nanocomposite layer works better than that with multilayers of zinc oxide and palladium. The sensor can be used for online monitoring and remote sensing of hydrogen gas.

Photonic crystal fiber heat sensors

NASA Astrophysics Data System (ADS)

Twigg, S.; Coompson, J.; Colalillo, A.; Wynne, R.

2011-04-01

A sensing configuration based on commercially available triple-core photonic crystal fiber (PCF) for the image-based collection of thermal information is presented. Detection of thermal phenomena on the micro and nano scale is important for monitoring thermodynamic processes including cooling mechanisms for industry and basic research in both civil and mechanical systems. The thermal characteristics of the PCF combined with coupled-mode theory principles are used to construct a three core PCF with a 1-D core arrangement to simultaneously measure heat flux and temperature. The PCF sensor demonstrated high detection sensitivity (<1°C) and fast response times (<30μs), which is a significant improvement to current commercial standards. PCFs are specialty optical fibers that contain carefully spaced micronsized cavities that provide extraordinary waveguide characteristics not demonstrated by standard optical fiber. The three core PCF has a core diameter of 3.9μm, outer diameter of 132.5μm and varied inter core spacing. A single mode fiber is fusion spliced with the multi-core PCF such that the optical field is confined and launched into the PCF core. The output end of the fiber is inspected and imaged with a CCD camera. A 25mm section of the PCF is surrounded by a guarded hotplate configuration to control the thermal conditions for sensor characterization. Evanescent wave coupling occurs whereby power is transferred from the central core to a neighboring core. Minimum detection sensitivities of 0.2 °C were recorded. Theoretical sensitivities on the order of 10-2 °C are possible. Experimental results were in agreement with coupled-mode theoretical results.

Single-Crystal Germanium Core Optoelectronic Fibers

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

Ji, Xiaoyu; Page, Ryan L.; Chaudhuri, Subhasis

Synthesis and fabrication of high-quality, small-core single-crystal germanium fibers that are photosensitive at the near-infrared and have low optical losses ≈1 dB cm-1 at 2 μm are reported. These fibers have potential applications in fiber-based spectroscopic imaging, nonlinear optical devices, and photodetection at the telecommunication wavelengths.

Intricate Estimation and Assessment of Surface Conditioning of Posts to improve Interfacial Adhesion in Post-core Restorations: An in vitro Study.

PubMed

Gupta, Priyanka; Sharma, Amil; Pathak, Vivek K; Mankeliya, Saurabh; Bhardwaj, Shivanshu; Dhanare, Poorvasha

2017-12-01

Post and core restorations are routinely used for restoring grossly decayed tooth structures. Various chemical agents are known to affect the interfacial adhesions between the post and the core. Hence, we planned the present study to evaluate the effect of various post-surface treatments on the interfacial strength between the posts and composite materials that are used for building up the core portion. The present study included assessment of the effect of surface conditioning of posts on the interfacial adhesion in post-core restorations. A total of 80 clear post-tapers were included and were divided broadly into four study groups based on the type of chemical testing protocols used. Various chemical treatments included alkaline potassium permanganate, hydrogen peroxide, and phosphoric acid. The fourth group was the control group. The composite core material was used for building up the core. Testing of the tensile load was done on a universal testing machine. All the results were analyzed by the Statistical Package for the Social Sciences (SPSS) software. The highest bond strength was observed in the study group treated with alkaline potassium permanganate, while the lowest was observed in the control group followed by the hydrogen peroxide group. While comparing the mean bond strength in between various study groups, significant results were obtained. Chemical treatment protocol significantly alters the mean bond strength of the post and core restoration. Potassium permanganate significantly increases the bond strength between the fiber post and core restoration.

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.

Photonic Crystal Fiber Mach-Zehnder Interferometer for Refractive Index Sensing

PubMed Central

Wang, Jian-Neng; Tang, Jaw-Luen

2012-01-01

We report on a refractive index sensor using a photonic crystal fiber (PCF) interferometer which was realized by fusion splicing a short section of PCF (Blaze Photonics, LMA-10) between two standard single mode fibers. The fully collapsed air holes of the PCF at the spice regions allow the coupling of PCF core and cladding modes that makes a Mach-Zehnder interferometer. The transmission spectrum exhibits sinusoidal interference pattern which shifts differently when the cladding/core surface of the PCF is immersed with different RI of the surrounding medium. Experimental results using wavelength-shift interrogation for sensing different concentrations of sucrose solution show that a resolution of 1.62 × 10−4–8.88 × 10−4 RIU or 1.02 × 10−4–9.04 × 10−4 RIU (sensing length for 3.50 or 5.00 cm, respectively) was achieved for refractive indices in the range of 1.333 to 1.422, suggesting that the PCF interferometer are attractive for chemical, biological, biochemical sensing with aqueous solutions, as well as for civil engineering and environmental monitoring applications. PMID:22736988

Photonic crystal fiber Mach-Zehnder interferometer for refractive index sensing.

PubMed

Wang, Jian-Neng; Tang, Jaw-Luen

2012-01-01

We report on a refractive index sensor using a photonic crystal fiber (PCF) interferometer which was realized by fusion splicing a short section of PCF (Blaze Photonics, LMA-10) between two standard single mode fibers. The fully collapsed air holes of the PCF at the spice regions allow the coupling of PCF core and cladding modes that makes a Mach-Zehnder interferometer. The transmission spectrum exhibits sinusoidal interference pattern which shifts differently when the cladding/core surface of the PCF is immersed with different RI of the surrounding medium. Experimental results using wavelength-shift interrogation for sensing different concentrations of sucrose solution show that a resolution of 1.62 × 10(-4)-8.88 × 10(-4) RIU or 1.02 × 10(-4)-9.04 × 10(-4) RIU (sensing length for 3.50 or 5.00 cm, respectively) was achieved for refractive indices in the range of 1.333 to 1.422, suggesting that the PCF interferometer are attractive for chemical, biological, biochemical sensing with aqueous solutions, as well as for civil engineering and environmental monitoring applications.

A fiber optic temperature sensor based on multi-core microstructured fiber with coupled cores for a high temperature environment

NASA Astrophysics Data System (ADS)

Makowska, A.; Markiewicz, K.; Szostkiewicz, L.; Kolakowska, A.; Fidelus, J.; Stanczyk, T.; Wysokinski, K.; Budnicki, D.; Ostrowski, L.; Szymanski, M.; Makara, M.; Poturaj, K.; Tenderenda, T.; Mergo, P.; Nasilowski, T.

2018-02-01

Sensors based on fiber optics are irreplaceable wherever immunity to strong electro-magnetic fields or safe operation in explosive atmospheres is needed. Furthermore, it is often essential to be able to monitor high temperatures of over 500°C in such environments (e.g. in cooling systems or equipment monitoring in power plants). In order to meet this demand, we have designed and manufactured a fiber optic sensor with which temperatures up to 900°C can be measured. The sensor utilizes multi-core fibers which are recognized as the dedicated medium for telecommunication or shape sensing, but as we show may be also deployed advantageously in new types of fiber optic temperature sensors. The sensor presented in this paper is based on a dual-core microstructured fiber Michelson interferometer. The fiber is characterized by strongly coupled cores, hence it acts as an all-fiber coupler, but with an outer diameter significantly wider than a standard fused biconical taper coupler, which significantly increases the coupling region's mechanical reliability. Owing to the proposed interferometer imbalance, effective operation and high-sensitivity can be achieved. The presented sensor is designed to be used at high temperatures as a result of the developed low temperature chemical process of metal (copper or gold) coating. The hermetic metal coating can be applied directly to the silica cladding of the fiber or the fiber component. This operation significantly reduces the degradation of sensors due to hydrolysis in uncontrolled atmospheres and high temperatures.

All-fiber Faraday Devices Based on Terbium-doped Fiber

NASA Astrophysics Data System (ADS)

Sun, Lei

Surface damage is one of the most problematic power limits in high-power fiber laser systems. All-fiber Faraday components are demonstrated as a solution to this problem, since they can be completely fusion-spliced into existing systems, eliminating all glass-air interfaces. Beam filamentation due to self-focusing places another limit on the peak power attainable from fiber laser systems. The limits imposed by this phenomenon are analyzed for the first time. The concept of an effective Verdet constant is proposed and experimentally validated. The effective Verdet constant of light propagation in a fiber includes contributions from the materials in both the core and the cladding. It is measured in a 25-wt% terbium-doped-core phosphate fiber to be --6.2 rad/(Tm) at 1053 nm, which is six times larger than silica fiber. The result agrees well with Faraday rotation theory in optical fiber. 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 4cm-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 27x 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 crystals 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°. An all-fiber optical magnetic field sensor is also demonstrated. It consists of a fiber Faraday rotator and a fiber polarizer. The fiber Faraday rotator uses a 2-cm-long section of 56-wt%-terbium-doped silicate fiber with a Verdet constant of -24.5 rad/(Tm) at 1053 nm. The fiber polarizer is Corning SP1060 single-polarization fiber. The sensor has a sensitivity of 0.49 rad/T and can measure magnetic fields from 0.02 to 3.2 T. An all-fiber wavelength-tunable laser based on Faraday rotation is proposed. It consists of an all-fiber wavelength-tunable filter in a conventional fiber laser cavity. The filter includes a fiber polarizer and a fiber Faraday mirror in which a chirped fiber Bragg grating is directly written onto the 65-wt% terbium fiber. The ytterbium-doped fiber in the laser is gain flattened using a. 1030/1090 rim WDM filter, resulting a net gain ripple that is measured to he less than 0.2 dB from 1047 to 1060 nm. The wavelength tuning range of the resulting fiber laser is therefore expected to be in this 1047 to 1060 nm range. Filamentation is one of the nonlinear peak-power-threshold limits in high-power fiber lasers. Starting from the paraxial wave equation, an analytic expression for the filamentation threshold in fiber lasers is derived using a perturbation method. The occurrence of filamentation is determined by the larger of two thresholds, one of perturbative gain and one of spatial confinement. The threshold value is around a few megawatts, depending on the parameters of the fiber.

Exposed-core chalcogenide microstructured optical fibers for chemical sensing

NASA Astrophysics Data System (ADS)

Troles, Johann; Toupin, Perrine; Brilland, Laurent; Boussard-Plédel, Catherine; Bureau, Bruno; Cui, Shuo; Mechin, David; Adam, Jean-Luc

2013-05-01

Chemical bonds of most of the molecules vibrate at a frequency corresponding to the near or mid infrared field. It is thus of a great interest to develop sensitive and portable devices for the detection of specific chemicals and biomolecules for various applications in health, the environment, national security and so on. Optical fibers define practical sensing tools. Chalcogenide glasses are known for their transparency in the infrared optical range and their ability to be drawn as fibers. They are consequently good candidates to be used in biological/chemical sensing. For that matter, in the past decade, chalcogenide glass fibers have been successfully implemented in evanescent wave spectroscopy experiments, for the detection of bio-chemical species in various fields of applications including microbiology and medicine, water pollution and CO2 detection. Different types of fiber can be used: single index fibers or microstructured fibers. Besides, in recent years a new configuration of microstructured fibers has been developed: microstructured exposed-core fibers. This design consists of an optical fiber with a suspended micron-scale core that is partially exposed to the external environment. This configuration has been chosen to elaborate, using the molding method, a chalcogenide fiber for chemical species detection. The sensitivity of this fiber to detect molecules such as propan-2-ol and acetone has been compared with those of single index fibers. Although evanescent wave absorption is inversely proportional to the fiber diameter, the result shows that an exposed-core fiber is much more sensitive than a single index fiber having a twice smaller external diameter.

Application of Negative Curvature Hollow-Core Fiber in an Optical Fiber Sensor Setup for Multiphoton Spectroscopy

PubMed Central

Stawska, Hanna Izabela; Mazur, Leszek Mateusz; Kosolapov, Alexey; Kolyadin, Anton; Bereś-Pawlik, Elżbieta

2017-01-01

In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of (680–750) nm, making it well suited for the purpose of multiphoton excitation of biological fluorophores. Employing 1.5 m of this fiber in a simple, all-fiber sensor setup allows us to perform multiphoton experiments without any dispersion compensation methods. Multiphoton excitation of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) with this fiber shows a 6- and 9-fold increase, respectively, in the total fluorescence signal collected when compared with the commercial solution in the form of a hollow-core photonic band gap fiber (HCPBF). To the author’s best knowledge, this is the first time an NCHCF was used in an optical-fiber sensor setup for multiphoton fluorescence experiments. PMID:28984838

Application of Negative Curvature Hollow-Core Fiber in an Optical Fiber Sensor Setup for Multiphoton Spectroscopy.

PubMed

Popenda, Maciej Andrzej; Stawska, Hanna Izabela; Mazur, Leszek Mateusz; Jakubowski, Konrad; Kosolapov, Alexey; Kolyadin, Anton; Bereś-Pawlik, Elżbieta

2017-10-06

In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of (680-750) nm, making it well suited for the purpose of multiphoton excitation of biological fluorophores. Employing 1.5 m of this fiber in a simple, all-fiber sensor setup allows us to perform multiphoton experiments without any dispersion compensation methods. Multiphoton excitation of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) with this fiber shows a 6- and 9-fold increase, respectively, in the total fluorescence signal collected when compared with the commercial solution in the form of a hollow-core photonic band gap fiber (HCPBF). To the author's best knowledge, this is the first time an NCHCF was used in an optical-fiber sensor setup for multiphoton fluorescence experiments.

Rydberg excitation of cold atoms inside a hollow-core fiber

NASA Astrophysics Data System (ADS)

Langbecker, Maria; Noaman, Mohammad; Kjærgaard, Niels; Benabid, Fetah; Windpassinger, Patrick

2017-10-01

We report on a versatile, highly controllable hybrid cold Rydberg atom fiber interface, based on laser cooled atoms transported into a hollow-core kagome crystal fiber. Our experiments demonstrate the feasibility of exciting cold Rydberg atoms inside a hollow-core fiber and we study the influence of the fiber on Rydberg electromagnetically induced transparency (EIT) signals. Using a temporally resolved detection method to distinguish between excitation and loss, we observe two different regimes of the Rydberg excitations: one EIT regime and one regime dominated by atom loss. These results are a substantial advancement towards future use of our system for quantum simulation or information.

Wide angle near-field optical probes by reverse tube etching.

PubMed

Patanè, S; Cefalì, E; Arena, A; Gucciardi, P G; Allegrini, M

2006-04-01

We present a simple modification of the tube etching process for the fabrication of fiber probes for near-field optical microscopy. It increases the taper angle of the probe by a factor of two. The novelty is that the fiber is immersed in hydrofluoric acid and chemically etched in an upside-down geometry. The tip formation occurs inside the micrometer tube cavity formed by the polymeric jacket. By applying this approach, called reverse tube etching, to multimode fibers with 200/250 microm core/cladding diameter, we have fabricated tapered regions featuring high surface smoothness and average cone angles of approximately 30 degrees . A simple model based on the crucial role of the gravity in removing the etching products, explains the tip formation process.

Endoscopic sensing of alveolar pH

PubMed Central

Choudhury, D.; Tanner, M. G.; McAughtrie, S.; Yu, F.; Mills, B.; Choudhary, T. R.; Seth, S.; Craven, T. H.; Stone, J. M.; Mati, I. K.; Campbell, C. J.; Bradley, M.; Williams, C. K. I.; Dhaliwal, K.; Birks, T. A.; Thomson, R. R.

2016-01-01

Previously unobtainable measurements of alveolar pH were obtained using an endoscope-deployable optrode. The pH sensing was achieved using functionalized gold nanoshell sensors and surface enhanced Raman spectroscopy (SERS). The optrode consisted of an asymmetric dual-core optical fiber designed for spatially separating the optical pump delivery and signal collection, in order to circumvent the unwanted Raman signal generated within the fiber. Using this approach, we demonstrate a ~100-fold increase in SERS signal-to-fiber background ratio, and demonstrate multiple site pH sensing with a measurement accuracy of ± 0.07 pH units in the respiratory acini of an ex vivo ovine lung model. We also demonstrate that alveolar pH changes in response to ventilation. PMID:28101415

In-Situ Three-Dimensional Shape Rendering from Strain Values Obtained Through Optical Fiber Sensors

NASA Technical Reports Server (NTRS)

Chan, Hon Man (Inventor); Parker, Jr., Allen R. (Inventor)

2015-01-01

A method and system for rendering the shape of a multi-core optical fiber or multi-fiber bundle in three-dimensional space in real time based on measured fiber strain data. Three optical fiber cores arc arranged in parallel at 120.degree. intervals about a central axis. A series of longitudinally co-located strain sensor triplets, typically fiber Bragg gratings, are positioned along the length of each fiber at known intervals. A tunable laser interrogates the sensors to detect strain on the fiber cores. Software determines the strain magnitude (.DELTA.L/L) for each fiber at a given triplet, but then applies beam theory to calculate curvature, beading angle and torsion of the fiber bundle, and from there it determines the shape of the fiber in s Cartesian coordinate system by solving a series of ordinary differential equations expanded from the Frenet-Serrat equations. This approach eliminates the need for computationally time-intensive curve-tilting and allows the three-dimensional shape of the optical fiber assembly to be displayed in real-time.

Composite material hollow antiresonant fibers.

PubMed

Belardi, Walter; De Lucia, Francesco; Poletti, Francesco; Sazio, Pier J

2017-07-01

We study novel designs of hollow-core antiresonant fibers comprising multiple materials in their core-boundary membrane. We show that these types of fibers still satisfy an antiresonance condition and compare their properties to those of an ideal single-material fiber with an equivalent thickness and refractive index. As a practical consequence of this concept, we discuss the first realization and characterization of a composite silicon/glass-based hollow antiresonant fiber.

Effect of waist diameter and twist on tapered asymmetrical dual-core fiber MZI filter.

PubMed

Liu, Yan; Li, Yang; Yan, Xiaojun; Li, Weidong

2015-10-01

A compact in-fiber Mach-Zehnder interferometer (MZI) filter fabricated from custom-designed asymmetrical dual-core fiber is numerically analyzed in detail and experimentally verified. The asymmetrical dual-core fiber has core diameters and a core pitch of 6.9, 6, and 19.9 μm, respectively. The fiber tapering technique is introduced to fuse the originally uncoupled cores into strong coupling tapered regions. The length and diameter of the waist region have a close impact on the splitting ratio, which further affects the spectral properties of the MZI filter. The field evolution with varied waist parameters is characterized by the finite element method and beam propagation method. Repeatable comb filters with ∼15  dB extinction ratio are successfully achieved under the guidance of simulated optimum conditions. The twist-induced circular birefringence gives rise to a retardance that causes the spectral shifts of the MZI filter. The theoretical and experimental results confirm that the relative wavelength shift is proportional to the retardance, which follows a sinc function in the limit of a large twist rate.

Multipoint fiber-optic laser-ultrasonic actuator based on fiber core-opened tapers.

PubMed

Tian, Jiajun; Dong, Xiaolong; Gao, Shimin; Yao, Yong

2017-11-27

In this study, a novel fiber-optic, multipoint, laser-ultrasonic actuator based on fiber core-opened tapers (COTs) is proposed and demonstrated. The COTs were fabricated by splicing single-mode fibers using a standard fiber splicer. A COT can effectively couple part of a core mode into cladding modes, and the coupling ratio can be controlled by adjusting the taper length. Such characteristics are used to obtain a multipoint, laser-ultrasonic actuator with balanced signal strength by reasonably controlling the taper lengths of the COTs. As a prototype, we constructed an actuator that generated ultrasound at four points with a balanced ultrasonic strength by connecting four COTs with coupling ratios of 24.5%, 33.01%, 49.51%, and 87.8% in a fiber link. This simple-to-fabricate, multipoint, laser-ultrasonic actuator with balanced ultrasound signal strength has potential applications in fiber-optic ultrasound testing technology.

Modeling of Thermal Phase Noise in a Solid Core Photonic Crystal Fiber-Optic Gyroscope.

PubMed

Song, Ningfang; Ma, Kun; Jin, Jing; Teng, Fei; Cai, Wei

2017-10-26

A theoretical model of the thermal phase noise in a square-wave modulated solid core photonic crystal fiber-optic gyroscope has been established, and then verified by measurements. The results demonstrate a good agreement between theory and experiment. The contribution of the thermal phase noise to the random walk coefficient of the gyroscope is derived. A fiber coil with 2.8 km length is used in the experimental solid core photonic crystal fiber-optic gyroscope, showing a random walk coefficient of 9.25 × 10 -5 deg/√h.

Structure modeling and manufacturing PCFs for the range of 2-25 μm

NASA Astrophysics Data System (ADS)

Lvov, Alexandr; Salimgareev, Dmitrii; Korsakov, Michail; Korsakov, Alexandr; Zhukova, Liya

2017-11-01

Photostable and flexible materials transparent at the wide spectral range are necessary for the development of optical fiber units. Solid solutions of silver and monadic thallium halides are the most suitable crystal media for this purpose. The goal of our research was the search of optimum structure for the fibers with a single mode operation and a rather large core diameter. We modelled fiber structures (solid-core, hollow-core, active-core PCF) with various ratio of inserts diameters and increments between the inserts, basing on two crystal systems: AgCl-AgBr and AgBr-TlI. Then we chose the single mode fiber structure and manufactured it by means of extrusion.

Orientation-Dependent Displacement Sensor Using an Inner Cladding Fiber Bragg Grating.

PubMed

Yang, Tingting; Qiao, Xueguang; Rong, Qiangzhou; Bao, Weijia

2016-09-11

An orientation-dependent displacement sensor based on grating inscription over a fiber core and inner cladding has been demonstrated. The device comprises a short piece of multi-cladding fiber sandwiched between two standard single-mode fibers (SMFs). The grating structure is fabricated by a femtosecond laser side-illumination technique. Two well-defined resonances are achieved by the downstream both core and cladding fiber Bragg gratings (FBGs). The cladding resonance presents fiber bending dependence, together with a strong orientation dependence because of asymmetrical distribution of the "cladding" FBG along the fiber cross-section.

Transmission of laser pulses with high output beam quality using step-index fibers having large cladding

DOEpatents

Yalin, Azer P; Joshi, Sachin

2014-06-03

An apparatus and method for transmission of laser pulses with high output beam quality using large core step-index silica optical fibers having thick cladding, are described. The thick cladding suppresses diffusion of modal power to higher order modes at the core-cladding interface, thereby enabling higher beam quality, M.sup.2, than are observed for large core, thin cladding optical fibers. For a given NA and core size, the thicker the cladding, the better the output beam quality. Mode coupling coefficients, D, has been found to scale approximately as the inverse square of the cladding dimension and the inverse square root of the wavelength. Output from a 2 m long silica optical fiber having a 100 .mu.m core and a 660 .mu.m cladding was found to be close to single mode, with an M.sup.2=1.6. Another thick cladding fiber (400 .mu.m core and 720 .mu.m clad) was used to transmit 1064 nm pulses of nanosecond duration with high beam quality to form gas sparks at the focused output (focused intensity of >100 GW/cm.sup.2), wherein the energy in the core was <6 mJ, and the duration of the laser pulses was about 6 ns. Extending the pulse duration provided the ability to increase the delivered pulse energy (>20 mJ delivered for 50 ns pulses) without damaging the silica fiber.

Optical fiber sensors based on nanostructured coatings fabricated by means of the layer-by-layer electrostatic self-assembly method

NASA Astrophysics Data System (ADS)

Arregui, Francisco J.; Matías, Ignacio R.; Claus, Richard O.

2007-07-01

The Layer-by-Layer Electrostatic Self-Assembly (ESA) method has been successfully used for the design and fabrication of nanostructured materials. More specifically, this technique has been applied for the deposition of thin films on optical fibers with the purpose of fabricating different types of optical fiber sensors. In fact, optical fiber sensors for measuring humidity, temperature, pH, hydrogen peroxide, glucose, volatile organic compounds or even gluten have been already experimentally demonstrated. The versatility of this technique allows the deposition of these sensing coatings on flat substrates and complex geometries as well. For instance, nanoFabry-Perots and microgratings have been formed on cleaved ends of optical fibers (flat surfaces) and also sensing coatings have been built onto long period gratings (cylindrical shape), tapered fiber ends (conical shape), biconically tapered fibers or even the internal side of hollow core fibers. Among the different materials used for the construction of these sensing nanostructured coatings, diverse types such as polymers, inorganic semiconductors, colorimetric indicators, fluorescent dyes, quantum dots or even biological elements as enzymes can be found. This technique opens the door to the fabrication of new types of optical fiber sensors.

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.

Multi-kW single fiber laser based on an extra large mode area fiber design

NASA Astrophysics Data System (ADS)

Langner, Andreas; Such, Mario; Schötz, Gerhard; Just, Florian; Leich, Martin; Schwuchow, Anka; Grimm, Stephan; Zimer, Hagen; Kozak, Marcin; Wedel, Björn; Rehmann, Georg; Bachert, Charley; Krause, Volker

2012-02-01

The quality of Yb-doped fused bulk silica produced by sintering of Yb-doped fused silica granulates has improved greatly in the past five years [1 - 4]. In particular, the refractive index and doping level homogeneity of such materials are excellent and we achieved excellent background fiber attenuation of the active core material down to about 20 dB/km at 1200 nm. The improvement of the Yb-doped fused bulk silica has enabled the development of multi-kW fiber laser systems based on a single extra large multimode laser fiber (XLMA fiber). When a single active fiber is used in combination with the XLMA multimode fiber of 1200 μm diameter simple and robust high power fiber laser setups without complex fiber coupling and fiber combiner systems become possible. In this papper, we will discuss in detail the development of the core material based on Yb-doped bulk silica and the characterization of Yb-doped fibers with different core compositions. We will also report on the excellent performance of a 4 kW fiber laser based on a single XLMA-fiber and show the first experimental welding results of steel sheets achieved with such a laser.

Two kinds of novel tunable Thulium-doped fiber laser

NASA Astrophysics Data System (ADS)

Ma, Xiaowei; Chen, Daru; Feng, Gaofeng; Yang, Junyong

2014-11-01

Two kinds of tunable Thulium-doped fiber laser (TDFL) respectively using a Sagnac loop mirror and a novel tunable multimode interference (MMI) fiber filter are experimentally demonstrated. The TDFL with the Sagnac loop mirror made by a 145.5-cm polarization-maintaining fiber (PMF) can operate with stable dual-wavelength lasing or tunable single-wavelength lasing around 1860nm. Both stable dual-wavelength and tunable single-wavelength lasing are achieved by adjusting a polarization controller in the Sagnac loop mirror. The TDFL with a novel tunable MMI fiber filter formed by splicing a segment of a special no-core fiber that is an all silica fiber without fiber core to single mode fibers can achieve tuning range from 1813.52 nm to 1858.70 nm. The no-core fiber with a large diameter of 200 μm is gradually vertically covered by refractive index matching liquid, which leads to a wavelength tuning of the transmission peak of the MMI fiber filter. The relationship between the refractive index of the refractive index matching liquid and the peak wavelength shift of the MMI fiber filter is also discussed. Using the MMI fiber filter, a Thulium-doped fiber laser with a tuning range of 45.18 nm is demonstrated.

Fluorescence-based remote irradiation sensor in liquid-filled hollow-core photonic crystal fiber

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

Zeltner, R.; Russell, P. St.J.; Department of Physics, University of Erlangen-Nuremberg, Guenther-Scharowsky-Str. 1, 91058 Erlangen

2016-06-06

We report an irradiation sensor based on a fluorescent “flying particle” that is optically trapped and propelled inside the core of a water-filled hollow-core photonic crystal fiber. When the moving particle passes through an irradiated region, its emitted fluorescence is captured by guided modes of the fiber core and so can be monitored using a filtered photodiode placed at the fiber end. The particle speed and position can be precisely monitored using in-fiber Doppler velocimetry, allowing the irradiation profile to be measured to a spatial resolution of ∼10 μm. The spectral response can be readily adjusted by appropriate choice of particlemore » material. Using dye-doped polystyrene particles, we demonstrate detection of green (532 nm) and ultraviolet (340 nm) light.« less

Chemical composition and functional characteristics of dietary fiber-rich powder obtained from core of maize straw.

PubMed

Lv, Jin-Shun; Liu, Xiao-Yan; Zhang, Xiao-Pan; Wang, Lin-Shuang

2017-07-15

A novel dietary fiber (MsCDF) based core of maize straw (Core) was prepared by using high boiling solvent of sodium peroxide by high pressure pretreatment (HBSHP). The composition of MsCDF, and several physicochemical properties for MsCDF related to its nutritional quality were investigated. The results revealed that the MsCDF contains high contents total dietary fiber (TDF), soluble dietary fiber (SDF), insoluble dietary fiber (IDF) and two main monosaccharaides, xylose and glucose. Meanwhile, the studies of physicochemical properties of MsCDF indicated that MsCDF performed well water-holding capacity (WHC), oil-holding capacity (OHC), Swelling, solubility (SOL), Glucose dialysis retardation index (GDRI) and adsorption capacity on cholesterol. The results of this study serve as evidence that MsCDF can be used as a functional food additive, Core can be used as a crude material to produce MsCDF and the technology of HBSHP can be used to modify the physico-chemical properties of Core. Copyright © 2017 Elsevier Ltd. All rights reserved.

A theoretical investigation of soliton induced supercontinuum generation in liquid core photonic crystal fiber and dual core optical fiber

NASA Astrophysics Data System (ADS)

Porsezian, K.; Nithyanandan, K.; Vasantha Jayakantha Raja, R.; Ganapathy, R.

2013-07-01

The supercontinuum generation (SCG) in liquid core photonic crystal fiber (LCPCF) with versatile nonlinear response and the spectral broadening in dual core optical fiber is presented. The analysis is presented in two phase, phase I deals with the SCG in LCPCF with the effect of saturable nonlinearity and re-orientational nonlinearity. We identify and discuss the generic nature of the saturable nonlinearity and reorientational nonlinearity in the SCG, using suitable model. For the physical explanation, modulational instability and soliton fission techniques is implemented to investigate the impact of saturable nonlinear response and slow nonlinear response, respectively. It is observed that the saturable nonlinearity inevitably suppresses the MI and the subsequent SCG. On the other hand, the re-orientational nonlinearity contributes to the slow nonlinear response in addition to the conventional fast response due to the electronic contribution. The phase II features the exclusive investigation of the spectral broadening in the dual core optical fiber.

A Novel Inter Core-Cladding Lithium Niobate Thin Film Coated Fiber Modulator/Sensor

NASA Technical Reports Server (NTRS)

Jamison, Tracee L.; Komriech, Phillip; Yu, Chung

2004-01-01

A fiber modulator/sensor has been fabricated by depositing a lithium niobate sol-gel thin film between the core and cladding of a fiber preform. The preform is then drawn into 125 micron fiber. The proposed design of lithium niobate cylinder fibers can enhance the existing methodology for detecting sound waves under water utilizing the acoustooptic properties of lithium niobate. Upon application of a stress or strain, light propagating inside the core, according to the principle of total internal reflection, escapes, into the cladding because of the photoelastic boundary layer of lithium niobate. Test results of the lithium niobate fiber reveal a reduction in the 1550 nm, 4mW source with applied tension. The source power from an ordinary quartz fiber under the same stress condition remained invariant to applied tension.

Environmental performance of an elliptical core polarization maintaining optical fiber for fiber optic gyro applications

NASA Astrophysics Data System (ADS)

Martinelli, Vincent P.; Squires, Emily M.; Watkins, James J.

1994-03-01

Corning has introduced a new polarization-maintaining optical fiber to satisfy customer requirements for a range of commercial and military FOG applications. This fiber has an elliptical core, matched-clad design, and is intended for operation in the 780 to 850 nm wavelength region. The fiber has a beat length less than 1.5 mm, attenuation rate less than 10 dB/km, and a typical coiled h-parameter less than 1.5 X 10-4 m-1 in the designated operating wavelength range. It has a cladding diameter of 80 micrometers and a coating diameter of 185 micrometers . The coating is an acrylate system, similar to that used in telecommunications optical fibers. We report on the performance of this elliptical core fiber for a variety of environmental exposures representative of an automotive application.

Generation and confinement of microwave gas-plasma in photonic dielectric microstructure.

PubMed

Debord, B; Jamier, R; Gérôme, F; Leroy, O; Boisse-Laporte, C; Leprince, P; Alves, L L; Benabid, F

2013-10-21

We report on a self-guided microwave surface-wave induced generation of ~60 μm diameter and 6 cm-long column of argon-plasma confined in the core of a hollow-core photonic crystal fiber. At gas pressure of 1 mbar, the micro-confined plasma exhibits a stable transverse profile with a maximum gas-temperature as high as 1300 ± 200 K, and a wall-temperature as low as 500 K, and an electron density level of 10¹⁴ cm⁻³. The fiber guided fluorescence emission presents strong Ar⁺ spectral lines in the visible and near UV. Theory shows that the observed combination of relatively low wall-temperature and high ionisation rate in this strongly confined configuration is due to an unprecedentedly wide electrostatic space-charge field and the subsequent ion acceleration dominance in the plasma-to-gas power transfer.

Design and optimization of a flexible high-peak-power laser-to-fiber coupled illumination system used in digital particle image velocimetry

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

Robinson, Ronald A.; Ilev, Ilko K.

We present a study on the design and parameter optimization of a flexible high-peak-power fiber-optic laser delivery system using commercially available solid-core silica fibers and an experimental glass hollow waveguide (HW). The fiber-optic delivery system provides a flexible, safe, and easily and precisely positioned laser irradiation for many applications including uniform illumination for digital particle image velocimetry (DPIV). The delivery fibers, when coupled through a line-generating lens, produce a uniform thin laser sheet illumination for accurate and repeatable DPIV two-dimensional velocity measurements. We report experimental results on homogenizing the laser beam profile using various mode-mixing techniques. Furthermore, because a fundamentalmore » problem for fiber-optic-based high-peak-power laser delivery systems is the possible damage effects of the fiber material, we determine experimentally the peak power density damage threshold of various delivery fibers designed for the visible spectral range at a typical DPIV laser wavelength of 532 nm. In the case of solid-core silica delivery fibers using conventional lens-based laser-to-fiber coupling, the damage threshold varies from 3.7 GW/cm{sup 2} for a 100-{mu}m-core-diameter high-temperature fiber to 3.9 GW/cm{sup 2} for a 200-{mu}m-core-diameter high-power delivery fiber, with a total output laser energy delivered of at least 3-10 mJ for those respective fibers. Therefore, these fibers are marginally suitable for most macro-DPIV applications. However, to improve the high-power delivery capability for close-up micro-DPIV applications, we propose and validate an experimental fiber link with much higher laser power delivery capability than the solid-core fiber links. We use an uncoated grazing-incidence-based tapered glass funnel coupled to a glass HW with hollow air-core diameter of 700 {mu}m, a low numerical aperture of 0.05, and a thin inside cladding of cyclic olefin polymer coating for optimum transmission at 532 nm. Because of the mode homogenizing effect and lower power density, the taper-waveguide laser delivery technique ensured high damage threshold for the delivery HW, and as a result, no damage occurred at the maximum measured input laser energy of 33 mJ used in this study.« less

Femtosecond laser inscription of optical circuits in the cladding of optical fibers

NASA Astrophysics Data System (ADS)

Grenier, Jason R.

The aim of this dissertation was to address the question of whether the cladding of single-mode fibers (SMFs) could be modified to enable optical fibers to serve as a more integrated, highly functional platform for optical circuit devices that can efficiently interconnect with the pre-existing fiber core waveguide. The approach adopted in this dissertation was to employ femtosecond laser direct writing (FLDW), an inherently 3D fabrication technique that harnesses non-linear laser-material interactions to modify the fused silica fiber cladding. A fiber mounting and alignment technique was developed along with oil-immersion focusing to address the strong aberrations caused by the cylindrical fiber shape. The development of real-time device monitoring during the FLDW was instrumental to overcome the acute coupling sensitivity to laser alignment errors of +/-1 ?m positional uncertainty, and thereby opened a new practical direction for the precise fabrication of optical devices inside optical fibers. These powerful and flexible laser fabrication and characterization techniques were successfully employed to optimize optical waveguiding devices positioned within the core and cladding of optical fibers. X-, S-Bend, and directional couplers were developed to enable efficient coupling between the laser-formed cladding devices and the pre-existing core waveguide, enabling up to 62% power transfer over bandwidths up to 300 nm at telecommunication wavelengths. Precise alignment of femtosecond laser modification tracks were positioned inside or near the core waveguide of SMFs was further shown to enable a flexible reshaping of the optical properties to create multimode guiding sections arbitrarily along the fiber length. This core waveguide modification facilitated the precise formation of multimode interferometers along the core waveguide to precisely tailor the modal profiles, and control the spectral and polarization response. In-fiber multimode interference (MMI) splitters and couplers were fabricated with coupling ratios from 2% to 50% over a broad 350 nm bandwidth across the telecommunication band. Laser-induced birefringence was harnessed to generate polarization dependent MMI devices for strong polarization filtering (24 dB isolation), or polarization selective taps with up to 50% tapping efficiency over a 25 nm bandwidth. This dissertation is therefore the first demonstration of femtosecond laser direct writing as a flexible and monolithic means of embedding and integrating highly functional optical circuit devices within the cladding of optical fibers that can interconnect efficiently with the pre-existing fiber core waveguide. These developments represent a significant technological advancement for creating new 3D photonic integrated microsystems within the cladding of optical fibers and underpins a new technological platform of fiber cladding photonics.

Thulium fiber laser induced vapor bubbles using bare, tapered, ball, hollow steel, and muzzle brake fiber optic tips

NASA Astrophysics Data System (ADS)

Gonzalez, David A.; Hardy, Luke A.; Hutchens, Thomas C.; Irby, Pierce B.; Fried, Nathaniel M.

2018-02-01

This study characterizes laser-induced vapor bubbles for five distal fiber optic tip configurations, to provide insight into stone retropulsion experienced during laser ablation of kidney stones. A TFL with 1908-nm wavelength delivered 34 mJ energy per pulse at 500-μs pulse duration through five different fibers: 100-μm-core/170-μm-OD bare fiber tip, 150-μm- to 300-μm-core tapered fiber tip, 100-μm-core/300-μm-OD ball tip fiber, 100-μm-core/340- μm-OD hollow steel tip fiber, and 100-μm-core/560-μm-OD muzzle brake fiber tip. A high speed camera with 10- μm spatial and 9.5-μs temporal resolution imaged vapor bubble dynamics. A needle hydrophone measured pressure transients in forward (0°) and side (90°) directions while placed at a 6.8 +/- 0.4 mm distance from fiber tip. Maximum bubble dimensions (width/length) averaged 0.7/1.5, 1.0/1.6, 0.5/1.1, 0.8/1.9, and 0.7/1.5 mm, for bare, tapered, ball, hollow steel, and muzzle tips, respectively (n=5). The hollow steel tip exhibited the most elongated vapor bubble shape, translating into increased forward pressure in this study and consistent with higher stone retropulsion in previous reports. Relative pressures (a.u.) in (forward/side) directions averaged 1.7/1.6, 2.0/2.0, 1.4/1.2, 6.8/1.1, and 0.3/1.2, for each fiber tip (n=5). For hollow steel tip, forward pressure was 4× higher than for bare fiber. For the muzzle brake fiber tip, forward pressure was 5× lower than for bare fiber. Bubble dimensions and pressure measurements demonstrated that the muzzle tip reduced forward pressure by partially venting vapors through side holes, consistent with lower stone retropulsion observed in previous reports.

A sensitivity-enhanced refractive index sensor using a single-mode thin-core fiber incorporating an abrupt taper.

PubMed

Shi, Jie; Xiao, Shilin; Yi, Lilin; Bi, Meihua

2012-01-01

A sensitivity-enhanced fiber-optic refractive index (RI) sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF) between two sections of single-mode fibers (SMFs). The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI). An abrupt taper (tens of micrometers long) made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity.

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

Ji, Xiaoyu; Lei, Shiming; Yu, Shih -Ying

Semiconductor core optical fibers with a silica cladding are of great interest in nonlinear photonics and optoelectronics applications. Laser crystallization has been recently demonstrated for crystallizing amorphous silicon fibers into crystalline form. Here we explore the underlying mechanism by which long single-crystal silicon fibers, which are novel platforms for silicon photonics, can be achieved by this process. Using finite element modeling, we construct a laser processing diagram that reveals a parameter space within which single crystals can be grown. Utilizing this diagram, we illustrate the creation of single-crystal silicon core fibers by laser crystallizing amorphous silicon deposited inside silica capillarymore » fibers by high-pressure chemical vapor deposition. The single-crystal fibers, up to 5.1 mm long, have a very welldefined core/cladding interface and a chemically pure silicon core that leads to very low optical losses down to ~0.47-1dB/cm at the standard telecommunication wavelength (1550 nm). Furthermore, tt also exhibits a photosensitivity that is comparable to bulk silicon. Creating such laser processing diagrams can provide a general framework for developing single-crystal fibers in other materials of technological importance.« less

Phosphate-core silica-clad Er/Yb-doped optical fiber and cladding pumped laser.

PubMed

Egorova, O N; Semjonov, S L; Velmiskin, V V; Yatsenko, Yu P; Sverchkov, S E; Galagan, B I; Denker, B I; Dianov, E M

2014-04-07

We present a composite optical fiber with a Er/Yb co-doped phosphate-glass core in a silica glass cladding as well as cladding pumped laser. The fabrication process, optical properties, and lasing parameters are described. The slope efficiency under 980 nm cladding pumping reached 39% with respect to the absorbed pump power and 28% with respect to the coupled pump power. Due to high doping level of the phosphate core optimal length was several times shorter than that of silica core fibers.

Optical monitoring of thin film electro-polymerization on surface of ITO-coated lossy-mode resonance sensor

NASA Astrophysics Data System (ADS)

Sobaszek, Michał; Dominik, Magdalena; Burnat, Dariusz; Bogdanowicz, Robert; Stranak, Viteszlav; Sezemsky, Petr; Śmietana, Mateusz

2017-04-01

This work presents an optical fiber sensors based on lossy-mode resonance (LMR) phenomenon supported by indium tin oxide (ITO) thin overlay for investigation of electro-polymerization effect on ITO's surface. The ITO overlays were deposited on core of polymer-clad silica (PCS) fibers using reactive magnetron sputtering (RMS) method. Since ITO is electrically conductive and electrochemically active it can be used as a working electrode in 3-electrode cyclic voltammetry setup. For fixed potential applied to the electrode current flow decrease with time what corresponds to polymer layer formation on the ITO surface. Since LMR phenomenon depends on optical properties in proximity of the ITO surface, polymer layer formation can be monitored optically in real time. The electrodeposition process has been performed with Isatin which is a strong endogenous neurochemical regulator in humans as it is a metabolic derivative of adrenaline. It was found that optical detection of Isatin is possible in the proposed configuration.

Highly Stretchable Core-Sheath Fibers via Wet-Spinning for Wearable Strain Sensors.

PubMed

Tang, Zhenhua; Jia, Shuhai; Wang, Fei; Bian, Changsheng; Chen, Yuyu; Wang, Yonglin; Li, Bo

2018-02-21

Lightweight, stretchable, and wearable strain sensors have recently been widely studied for the development of health monitoring systems, human-machine interfaces, and wearable devices. Herein, highly stretchable polymer elastomer-wrapped carbon nanocomposite piezoresistive core-sheath fibers are successfully prepared using a facile and scalable one-step coaxial wet-spinning assembly approach. The carbon nanotube-polymeric composite core of the stretchable fiber is surrounded by an insulating sheath, similar to conventional cables, and shows excellent electrical conductivity with a low percolation threshold (0.74 vol %). The core-sheath elastic fibers are used as wearable strain sensors, exhibiting ultra-high stretchability (above 300%), excellent stability (>10 000 cycles), fast response, low hysteresis, and good washability. Furthermore, the piezoresistive core-sheath fiber possesses bending-insensitiveness and negligible torsion-sensitive properties, and the strain sensing performance of piezoresistive fibers maintains a high degree of stability under harsh conditions. On the basis of this high level of performance, the fiber-shaped strain sensor can accurately detect both subtle and large-scale human movements by embedding it in gloves and garments or by directly attaching it to the skin. The current results indicate that the proposed stretchable strain sensor has many potential applications in health monitoring, human-machine interfaces, soft robotics, and wearable electronics.

Diffusion Raman stimulée à trois ondes dans une fibre optique.

PubMed

Saissy, A; Botineau, J; Azema, A; Gires, F

1980-05-15

Three-wave stimulated Raman scattering in optical fibers has been studied theoretically in connection with the characteristics of the fiber (core diameter, core-cladding refractive-index difference) and excitation conditions. We observe experimentally this type of scattering in a silica fiber, from which we can estimate the nonlinearity of silica and the index difference of the fiber.

Guiding properties and dispersion control of kagome lattice hollow-core photonic crystal fibers.

PubMed

Im, Song-Jin; Husakou, Anton; Herrmann, Joachim

2009-07-20

Dispersion properties, loss and optimum design of kagome lattice hollow-core photonic crystal fibers filled with argon are studied for the purpose of possible applications in ultrafast nonlinear optics. As will be shown numerically and by using an approximate analytical formula these fibers exhibit anomalous dispersion for visible or UV wavelengths both for a 1-cell-core as well for a 3-ring-core which can be controlled by the gas pressure and do not suffer from high loss. It is shown that while the loss is mainly influenced by the strut thickness of the kagome lattice the group velocity dispersion is almost independently controlled by the core size. These results demonstrate that kagome lattice hollow fibers have a promising potential in ultrashort pulse delivering of high-energy pulses and in several interesting applications in ultrafast nonlinear optics.

Single-crystal silicon optical fiber by direct laser crystallization

DOE PAGES

Ji, Xiaoyu; Lei, Shiming; Yu, Shih -Ying; ...

2016-12-05

Semiconductor core optical fibers with a silica cladding are of great interest in nonlinear photonics and optoelectronics applications. Laser crystallization has been recently demonstrated for crystallizing amorphous silicon fibers into crystalline form. Here we explore the underlying mechanism by which long single-crystal silicon fibers, which are novel platforms for silicon photonics, can be achieved by this process. Using finite element modeling, we construct a laser processing diagram that reveals a parameter space within which single crystals can be grown. Utilizing this diagram, we illustrate the creation of single-crystal silicon core fibers by laser crystallizing amorphous silicon deposited inside silica capillarymore » fibers by high-pressure chemical vapor deposition. The single-crystal fibers, up to 5.1 mm long, have a very welldefined core/cladding interface and a chemically pure silicon core that leads to very low optical losses down to ~0.47-1dB/cm at the standard telecommunication wavelength (1550 nm). Furthermore, tt also exhibits a photosensitivity that is comparable to bulk silicon. Creating such laser processing diagrams can provide a general framework for developing single-crystal fibers in other materials of technological importance.« less

Guiding and amplification properties of rod-type photonic crystal fibers with sectioned core doping

NASA Astrophysics Data System (ADS)

Selleri, S.; Poli, F.; Passaro, D.; Cucinotta, A.; Lægsgaard, J.; Broeng, J.

2009-05-01

Rod-type photonic crystal fibers are large mode area double-cladding fibers with an outer diameter of few millimeters which can provide important advantages for high-power lasers and amplifiers. Numerical studies have recently demonstrated the guidance of higher-order modes in these fibers, which can worsen the output beam quality of lasers and amplifiers. In the present analysis a sectioned core doping has been proposed for Ybdoped rod-type photonic crystal fibers, with the aim to improve the higher-order mode suppression. A full-vector modal solver based on the finite element method has been applied to properly design the low refractive index ring in the fiber core, which can provide an increase of the differential overlap between the fundamental and the higher-order mode. Then, the gain competition among the guided modes along the Yb-doped rod-type fibers has been investigated with a spatial and spectral amplifier model. Simulation results have shown the effectiveness of the sectioned core doping in worsening the higher-order mode overlap on the doped area, thus providing an effective single-mode behavior of the Yb-doped rod-type photonic crystal fibers.

Rigid polyurethane foam – kenaf core composites for structural applications

USDA-ARS?s Scientific Manuscript database

Kenaf (Hibiscus cannabinus L.) is a fast growing summer annual crop with numerous commercial applications (fibers, biofuels, bioremediation, paper pulp, building materials, cover crops, and livestock forages). The stalks of the kenaf plants contain two distinct fiber types, bast and core fibers. The...

Experimental investigation on the high-order modes in supercontinuum generation from step-index As-S fibers

NASA Astrophysics Data System (ADS)

Chen, Peng; Xue, Zugang; Tian, Youmei; Zhao, Zheming; Wang, Xunsi; Liu, Zijun; Zhang, Peiqing; Dai, Shixun; Nie, Qiuhua; Wang, Rongping

2018-06-01

Two kinds of step-index As-S fibers have been fabricated by an isolated extrusion method with a numerical aperture (NA) of 0.52, but with different core size of 10 or 50 µm. With a femtosecond laser pumping, their supercontinnum (SC) generation spectra were recorded in order to testify the effect of high-order modes on SC generation. The spectra spanning from 1.0 to 6.7 µm and from 1.5 to 8.6 µm can be obtained in a 16-cm-long fiber with 10 µm-core diameter pumping by central wavelength of 2.9 and 4.0 µm, respectively. The results show that high-order modes would deplete the spectra spanning in red-shifting part. The SC generation in small-core fiber is much more efficient than that in large-core fiber. This is the first comparative investigation on the SC generation from the quasi single- and multi-mode ChG fibers under the same conditions.

Laser fiber cleaving techniques: effects on tip morphology and power output.

PubMed

Vassantachart, Janna M; Lightfoot, Michelle; Yeo, Alexander; Maldonado, Jonathan; Li, Roger; Alsyouf, Muhannad; Martin, Jacob; Lee, Michael; Olgin, Gaudencio; Baldwin, D Duane

2015-01-01

Proper cleaving of reusable laser fibers is needed to maintain optimal functionality. This study quantifies the effect of different cleaving tools on power output of the holmium laser fiber and demonstrates morphologic changes using microscopy. The uncleaved tips of new 272 μm reusable laser fibers were used to obtain baseline power transmission values at 3 W (0.6 J, 5 Hz). Power output for each of four cleaving techniques-11-blade scalpel, scribe pen cleaving tool, diamond cleaving wheel, and suture scissors-was measured in a single-blinded fashion. Dispersion of light from the fibers was compared with manufacturer specifications and rated as "ideal," "acceptable," or "unacceptable" by blinded reviewers. The fiber tips were also imaged using confocal and scanning electron microscopy. Independent samples Kruskal-Wallis test and chi square were used for statistical analysis (α<0.05). New uncleaved fiber tips transmitted 3.04 W of power and were used as a reference (100%). The scribe pen cleaving tool produced the next highest output (97.1%), followed by the scalpel (83.4%), diamond cleaving wheel (77.1%), and suture scissors (61.7%), a trend that was highly significant (P<0.001). On pairwise comparison, no difference in power output was seen between the uncleaved fiber tips and those cleaved with the scribe pen (P=1.0). The rating of the light dispersion patterns from the different cleaving methods followed the same trend as the power output results (P<0.001). Microscopy showed that the scribe pen produced small defects along the fiber cladding but maintained a smooth, flat core surface. The other cleaving techniques produced defects on both the core and cladding. Cleaving techniques produce a significant effect on the initial power transmitted by reusable laser fibers. The scribe pen cleaving tool produced the most consistent and highest average power output.

Enhanced linear photonic nanojet generated by core-shell optical microfibers

NASA Astrophysics Data System (ADS)

Liu, Cheng-Yang; Yen, Tzu-Ping; Chen, Chien-Wen

2017-05-01

The generation of linear photonic nanojet using core-shell optical microfiber is demonstrated numerically and experimentally in the visible light region. The power flow patterns for the core-shell optical microfiber are calculated by using the finite-difference time-domain method. The focusing properties of linear photonic nanojet are evaluated in terms of length and width along propagation and transversal directions. In experiment, the silica optical fiber is etched chemically down to 6 μm diameter and coated with metallic thin film by using glancing angle deposition. We show that the linear photonic nanojet is enhanced clearly by metallic shell due to surface plasmon polaritons. The large-area superresolution imaging can be performed by using a core-shell optical microfiber in the far-field system. The potential applications of this core-shell optical microfiber include micro-fluidics and nano-structure measurements.

Thulium fiber laser-induced vapor bubble dynamics using bare, tapered, ball, hollow steel, and muzzle brake fiber optic tips

NASA Astrophysics Data System (ADS)

Gonzalez, David A.; Hardy, Luke A.; Hutchens, Thomas C.; Irby, Pierce B.; Fried, Nathaniel M.

2018-03-01

This study characterizes laser-induced vapor bubble dynamics for five different distal fiber optic tip configurations, to provide insight into stone retropulsion commonly experienced during laser ablation of kidney stones. A thulium fiber laser with 1908-nm wavelength delivered 34-mJ energy per pulse at 500-μs pulse duration through five different fibers such as 100-μm-core / 170-μm-OD bare fiber tip, 150- to 300-μm-core tapered fiber tip, 100-μm-core / 300-μm-OD ball tip fiber, 100-μm-core / 340-μm-OD hollow steel tip fiber, and 100-μm-core / 560-μm-OD muzzle brake fiber tip. A high-speed camera with 10-μm-spatial and 9.5-μs-temporal resolution was used to image the vapor bubble dynamics. A needle hydrophone measured pressure transients in the forward (0 deg) and side (90 deg) directions while placed at a 6.8 ± 0.4 mm distance from the distal fiber tip. Maximum bubble dimensions (width/length) averaged 0.7/1.5, 1.0/1.6, 0.5/1.1, 0.8/1.9, and 0.7 / 1.5 mm, for bare, tapered, ball, hollow steel, and muzzle brake fiber tips, respectively (n = 5). The hollow steel tip exhibited the most elongated vapor bubble shape, translating into increased forward pressure in this study and consistent with higher stone retropulsion in previous reports. Relative pressures (a.u.) in (forward/side) directions averaged 1.7/1.6, 2.0/2.0, 1.4/1.2, 6.8/1.1, and 0.3/1.2, for each fiber tip (n = 5). For the hollow steel tip, forward pressure was 4 × higher than for the bare fiber. For the muzzle brake fiber tip, forward pressure was 5 × lower than the bare fiber. Bubble dimensions and pressure measurements demonstrated that the muzzle brake fiber tip reduced forward pressure by partially venting vapors through the portholes, which is consistent with the observation of lower stone retropulsion in previous reports.

Design of a multifiber light delivery system for photoacoustic-guided surgery.

PubMed

Eddins, Blackberrie; Bell, Muyinatu A Lediju

2017-04-01

This work explores light delivery optimization for photoacoustic-guided minimally invasive surgeries, such as the endonasal transsphenoidal approach. Monte Carlo simulations were employed to study three-dimensional light propagation in tissue, comprising one or two 4-mm diameter arteries located 3 mm below bone, an absorbing metallic drill contacting the bone surface, and a single light source placed next to the 2.4-mm diameter drill shaft with a 2.9-mm diameter spherical drill tip. The optimal fiber distance from the drill shaft was determined from the maximum normalized fluence to the underlying artery. Using this optimal fiber-to-drill shaft distance, Zemax simulations were employed to propagate Gaussian beams through one or more 600 micron-core diameter optical fibers for detection on the bone surface. When the number of equally spaced fibers surrounding the drill increased, a single merged optical profile formed with seven or more fibers, determined by thresholding the resulting light profile images at 1 / e times the maximum intensity. We used these simulations to inform design requirements, build a one to seven multifiber light delivery prototype to surround a surgical drill, and demonstrate its ability to simultaneously visualize the tool tip and blood vessel targets in the absence and presence of bone. The results and methodology are generalizable to multiple interventional photoacoustic applications.

Design of a multifiber light delivery system for photoacoustic-guided surgery

NASA Astrophysics Data System (ADS)

Eddins, Blackberrie; Bell, Muyinatu A. Lediju

2017-04-01

This work explores light delivery optimization for photoacoustic-guided minimally invasive surgeries, such as the endonasal transsphenoidal approach. Monte Carlo simulations were employed to study three-dimensional light propagation in tissue, comprising one or two 4-mm diameter arteries located 3 mm below bone, an absorbing metallic drill contacting the bone surface, and a single light source placed next to the 2.4-mm diameter drill shaft with a 2.9-mm diameter spherical drill tip. The optimal fiber distance from the drill shaft was determined from the maximum normalized fluence to the underlying artery. Using this optimal fiber-to-drill shaft distance, Zemax simulations were employed to propagate Gaussian beams through one or more 600 micron-core diameter optical fibers for detection on the bone surface. When the number of equally spaced fibers surrounding the drill increased, a single merged optical profile formed with seven or more fibers, determined by thresholding the resulting light profile images at 1/e times the maximum intensity. We used these simulations to inform design requirements, build a one to seven multifiber light delivery prototype to surround a surgical drill, and demonstrate its ability to simultaneously visualize the tool tip and blood vessel targets in the absence and presence of bone. The results and methodology are generalizable to multiple interventional photoacoustic applications.

Single-shot polarimetry imaging of multicore fiber.

PubMed

Sivankutty, Siddharth; Andresen, Esben Ravn; Bouwmans, Géraud; Brown, Thomas G; Alonso, Miguel A; Rigneault, Hervé

2016-05-01

We report an experimental test of single-shot polarimetry applied to the problem of real-time monitoring of the output polarization states in each core within a multicore fiber bundle. The technique uses a stress-engineered optical element, together with an analyzer, and provides a point spread function whose shape unambiguously reveals the polarization state of a point source. We implement this technique to monitor, simultaneously and in real time, the output polarization states of up to 180 single-mode fiber cores in both conventional and polarization-maintaining fiber bundles. We demonstrate also that the technique can be used to fully characterize the polarization properties of each individual fiber core, including eigen-polarization states, phase delay, and diattenuation.

A Numerical Study on the Effect of Facesheet-Core Disbonds on the Buckling Load of Curved Honeycomb Sandwich Panels

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Myers, David E.; Bednarcyk, Brett A.; Krivanek, Thomas M.

2015-01-01

A numerical study on the effect of facesheet-core disbonds on the post-buckling response of curved honeycomb sandwich panels is presented herein. This work was conducted as part of the development of a damage tolerance approach for the next-generation Space Launch System heavy lift vehicle payload fairing. As such, the study utilized full-scale fairing barrel segments as the structure of interest. The panels were composed of carbon fiber reinforced polymer facesheets and aluminum honeycomb core. The panels were analyzed numerically using the finite element method. Facesheet and core nodes in a predetermined circular region were detached to simulate a disbond induced via low-speed impact between the outer mold line facesheet and honeycomb core. Surface-to-surface contact in the disbonded region was invoked to prevent interpenetration of the facesheet and core elements. The diameter of this disbonded region was varied and the effect of the size of the disbond on the post-buckling response was observed. A significant change in the slope of the edge load-deflection response was used to determine the onset of global buckling and corresponding buckling load.

Morphology of the core fibrous layer of the cetacean tail fluke.

PubMed

Gough, William T; Fish, Frank E; Wainwright, Dylan K; Bart-Smith, Hilary

2018-06-01

The cetacean tail fluke blades are not supported by any vertebral elements. Instead, the majority of the blades are composed of a densely packed collagenous fiber matrix known as the core layer. Fluke blades from six species of odontocete cetaceans were examined to compare the morphology and orientation of fibers at different locations along the spanwise and chordwise fluke blade axes. The general fiber morphology was consistent with a three-dimensional structure comprised of two-dimensional sheets of fibers aligned tightly in a laminated configuration along the spanwise axis. The laminated configuration of the fluke blades helps to maintain spanwise rigidity while allowing partial flexibility during swimming. When viewing the chordwise sectional face at the leading edge and mid-chord regions, fibers displayed a crossing pattern. This configuration relates to bending and structural support of the fluke blade. The trailing edge core was found to have parallel fibers arranged more dorso-ventrally. The fiber morphology of the fluke blades was dorso-ventrally symmetrical and similar in all species except the pygmy sperm whale (Kogia breviceps), which was found to have additional core layer fiber bundles running along the span of the fluke blade. These additional fibers may increase stiffness of the structure by resisting tension along their long spanwise axis. © 2018 Wiley Periodicals, Inc.

Elliptical-core two mode fiber sensors and devices incorporating photoinduced refractive index gratings

NASA Technical Reports Server (NTRS)

Greene, Jonathan A.; Miller, Mark S.; Starr, Suzanne E.; Fogg, Brian R.; Murphy, Kent A.; Claus, Richard O.; Vengsarkar, Ashish M.

1991-01-01

Results of experiments performed using germanium-doped, elliptical core, two-mode optical fibers whose sensitivity to strain was spatially varied through the use of chirped, refractive-index gratings permanently induced into the core using Argon-ion laser light are presented. This type of distributed sensor falls into the class of eighted-fiber sensors which, through a variety of means, weight the strain sensitivity of a fiber according to a specified spatial profile. We describe results of a weighted-fiber vibration mode filter which successfully enhances the particular vibration mode whose spatial profile corresponds to the profile of the grating chirp. We report on the high temperature survivability of such grating-based sensors and discuss the possibility of multiplexing more than one sensor within a single fiber.

U-shaped micro-groove fiber based on femtosecond laser processing for humidity sensing

NASA Astrophysics Data System (ADS)

Fu, Gui; Ma, Li-li; Su, Fu-fang; Shi, Meng

2018-05-01

A novel optical fiber sensor with a U-shaped micro-groove structure ablated by femtosecond laser on single-mode fiber for measuring air relative humidity (RH) is reported in this paper. In order to improve the accuracy of sensor, a graphene oxide (GO)/polyvinyl alcohol (PVA) composite film is coated on the surface of micro-groove structure. In the U-shaped micro-groove structure, the remaining core and micro-cavity in the micro-groove make up two major optical propagation paths, forming a Mach-Zehnder interferometer (MZI). The sensor has a good linear response within the RH range of 30%—85%, and the maximum sensitivity can reach 0.638 1 nm/%RH. The effect of temperature on the overall performance of the humidity sensor is also investigated. As a new type of all-fiber device, the sensor shows excellent sensitivity and stability.

Evanescent wave absorbance based fiber optic biosensor for label-free detection of E. coli at 280 nm wavelength.

PubMed

Bharadwaj, Reshma; Sai, V V R; Thakare, Kamini; Dhawangale, Arvind; Kundu, Tapanendu; Titus, Susan; Verma, Pradeep Kumar; Mukherji, Soumyo

2011-03-15

A novel label-free technique for the detection of pathogens based on evanescent wave absorbance (EWA) changes at 280 nm from a U-bent optical fiber sensor is demonstrated. Bending a decladded fiber into a U-shaped structure enhances the penetration depth of evanescent waves and hence sensitivity of the probe. We show that the enhanced EWA response from such U-bent probes, caused by the inherent optical absorbance properties of bacterial cells or biomolecules specifically bound to the sensor surface, can be exploited for the detection of pathogens. A portable optical set-up with a UV light emitting diode, a spectrometer and U-bent fiber optic probe of 200 μm core diameter, 0.75 mm bend radius and effective probe length of 1cm demonstrated an ability to detect less than 1000 cfu/ml. Copyright © 2011. Published by Elsevier B.V.

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

Role of Hydrophobic/Aromatic Residues on the Stability of Double-Wall β-Sheet Structures Formed by a Triblock Peptide.

PubMed

Ozgur, Beytullah; Sayar, Mehmet

2017-04-27

Bioinspired self-assembling peptides serve as powerful building blocks in the manufacturing of nanomaterials with tailored features. Because of their ease of synthesis, biocompatibility, and tunable activity, this emerging branch of biomolecules has become very popular. The triblock peptide architecture designed by the Hartgerink group is a versatile system that allows control over its assembly and has been shown to demonstrate tunable bioactivity. Three main forces, Coulomb repulsion, hydrogen bonding and hydrophobicity act together to guide the triblock peptides' assembly into one-dimensional objects and hydrogels. It was shown previously that both the nanofiber morphology (e.g., intersheet spacing, formation of antiparallel/parallel β-sheets) and hydrogel rheology strictly depend on the choice of the core residue where the triblock peptide fibers with aromatic cores in general form shorter fibers and yield poor hydrogels with respect to the ones with aliphatic cores. However, an elaborate understanding of the molecular reasons behind these changes remained unclear. In this study, by using carefully designed computer based free energy calculations, we analyzed the influence of the core residue on the formation of double-wall fibers and single-wall β-sheets. Our results demonstrate that the aromatic substitution impairs the fiber cores and this impairment is mainly associated with a reduced hydrophobic character of the aromatic side chains. Such weakening is most obvious in tryptophan containing peptides where the fiber core absorbs a significant amount of water. We also show that the ability of tyrosine to form side chain hydrogen bonds plays an indispensable role in the fiber stability. As opposed to the impairment of the fiber cores, single-wall β-sheets with aromatic faces become more stable compared to the ones with aliphatic faces suggesting that the choice of the core residue can also affect the underlying assembly mechanism. We also provide an in-depth comparison of competing structures (zero-dimensional aggregates, short and long fibers) in the triblock peptides' assembly and show that by adjusting the length of the terminal blocks, the fiber growth can be turned on or off while keeping the nanofiber morphology intact.

Impact of material absorption on supercontinuum generation in liquid core photonic crystal fiber

NASA Astrophysics Data System (ADS)

Nithyanandan, K.; Raja, Vasantha Jayakantha; Uthayakumar, T.; Porsezian, K.

2013-06-01

The impact of material absorption on supercontinuum generation (SCG) in liquid core photonic crystal fiber (LCPCF) is presented. While PCFs with cores made from different glasses are well studied in previous works with saturable nonlinear response (SNL), in this paper, it is planned to investigate the dynamics of nonlinear processes of supercontinuum generation in high-index fiber with material absorption to understand the physical phenomena of pulse propagation.

High-energy and high-peak-power nanosecond pulse generation with beam quality control in 200-µm core highly multimode Yb-doped fiberamplifiers

NASA Astrophysics Data System (ADS)

Cheng, Ming-Yuan; Chang, Yu-Chung; Galvanauskas, Almantas; Mamidipudi, Pri; Changkakoti, Rupak; Gatchell, Peter

2005-02-01

We explored high-energy and high-peak-power pulse generation in large-core multimode fiber amplifiers, achieving what is to our knowledge the highest reported energies, up to 82 mJ for 500-ns pulses, 27 mJ for 50-ns pulses, and 2.4-MW peak power for 4-ns pulses at 1064 nm, using 200-µm-diameter and 0.062-N.A. core Yb-doped double-clad fiber amplifiers. The highly multimode nature of the fiber core was mitigated by use of a coiling-induced mode-filtering effect to yield a significant improvement in output-beam quality from M^2 = 25 from an uncoiled fiber to M^2 = 6.5 from a properly coiled fiber, with the corresponding reduction in number of propagating transverse modes from >or=200 to <or=20.

Efficient optical probes for fast surface velocimetry: multiple frequency issues for Fabry and VISAR methods

NASA Astrophysics Data System (ADS)

Goosman, David R.; Avara, George R.; Perry, Stephen J.

2001-04-01

We have in the past used several types of optical probe lenses for delivering and collecting laser light to an experiment for laser velocimetry. When the test surface was in focus, however, the collected light would fill mostly the laser fiber rather than the collection fiber(s). We have designed, developed and used for 8 years nested-lens probe assemblies that solve this problem. Our first version used a commercial AR-coated glass achromat, which we cored to remove the inner fourth of its area. The core was then reinserted with its optical center offset from that of annulus by an amount slightly less than the separation between the laser and collector fibers. The laser and collector fibers are placed in contact with each other behind the lens and have NA values of 0.11 and 0.22, respectively. Because most of the collected light now focused on the collection fiber, this system was far superior to the single lens systems, but was laborious. For the last five years we used injection-molded acrylic aspheric nested lenses, which are inexpensive in quantity and require little labor to install into a probe. Only an azimuthal rotation and positioning of the fiber plane are needed to incorporate the plastic lens into a probe. Special ray-trace codes were written and used to design the lens, and many iterations by the molder were required to develop the injection processing parameters to produce a good lens, since it was thick for its diameter. These probes have real light collection efficiencies of 75% of theoretical, work well over a wide range of distances, with collection depths of field matching theory. The lenses can take 100 watts of pulsed power many times without damage, since the lens is designed so that reflections from the lens surface do not focus within the lens. The collection fiber size is designed to work with our manybeam velocimeter facility reported in a previous Congress, where the collection NA times collection fiber size exceeds the acceptance of the velocimeter. The Doppler-shifted light enters the collection fiber with angles between 0.11 and 0.2, with little light in the 0 to 0.11 NA region. However, the manybeam velocimeter uses just the light in the 0 to 0.11 NA range, except when we link two analyzer tables together. A slight amount of mode scrambling of the Doppler shifted light converts the light into a uniformly filled NA equals 0.2 angular range before entering the velocimeter analyzer table. We have expended seven hundred plastic nested lenses in various experiments. The most recent version of the fiber cable assembly will be shown. Six situations will be discussed where multiple reflected frequencies were observed in experiments, illustrating an advantage of the Fabry-Perot vs. the VISAR method.

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.

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.

Laser-treated electrospun fibers loaded with nano-hydroxyapatite for bone tissue engineering.

PubMed

Aragon, Javier; Navascues, Nuria; Mendoza, Gracia; Irusta, Silvia

2017-06-15

Core-shell polycaprolactone/polycaprolactone (PCL/PCL) and polycaprolactone/polyvinyl acetate (PCL/PVAc) electrospun fibers loaded with synthesized nanohydroxyapatite (HAn) were lased treated to create microporosity. The prepared materials were characterized by XRD, FTIR, TEM and SEM. Uniform and randomly oriented beadless fibrous structures were obtained in all cases. Fibers diameters were in the 150-300nm range. Needle-like HAn nanoparticles with mean diameters of 20nm and length of approximately 150nm were mostly encase inside the fibers. Laser treated materials present micropores with diameters in the range 70-120μm for PCL-HAn/PCL fibers and in the 50-90μm range for PCL-HAn/PVAC material. Only samples containing HAn presented bioactivity after incubation during 30days in simulated body fluid. All scaffolds presented high viability, very low mortality, and human osteoblast proliferation. Biocompatibility was increased by laser treatment due to the surface and porosity modification. Copyright © 2017 Elsevier B.V. All rights reserved.

Cascaded-cladding-pumped cascaded Raman fiber amplifier.

PubMed

Jiang, Huawei; Zhang, Lei; Feng, Yan

2015-06-01

The conversion efficiency of double-clad Raman fiber laser is limited by the cladding-to-core area ratio. To get high conversion efficiency, the inner-cladding-to-core area ratio has to be less than about 8, which limits the brightness enhancement. To overcome the problem, a cascaded-cladding-pumped cascaded Raman fiber laser with multiple-clad fiber as the Raman gain medium is proposed. A theoretical model of Raman fiber amplifier with multiple-clad fiber is developed, and numerical simulation proves that the proposed scheme can improve the conversion efficiency and brightness enhancement of cladding pumped Raman fiber laser.

Orientation-Dependent Displacement Sensor Using an Inner Cladding Fiber Bragg Grating

PubMed Central

Yang, Tingting; Qiao, Xueguang; Rong, Qiangzhou; Bao, Weijia

2016-01-01

An orientation-dependent displacement sensor based on grating inscription over a fiber core and inner cladding has been demonstrated. The device comprises a short piece of multi-cladding fiber sandwiched between two standard single-mode fibers (SMFs). The grating structure is fabricated by a femtosecond laser side-illumination technique. Two well-defined resonances are achieved by the downstream both core and cladding fiber Bragg gratings (FBGs). The cladding resonance presents fiber bending dependence, together with a strong orientation dependence because of asymmetrical distribution of the “cladding” FBG along the fiber cross-section. PMID:27626427

Liquid-filled simplified hollow-core photonic crystal fiber

NASA Astrophysics Data System (ADS)

Liu, Shengnan; Gao, Wei; Li, Hongwei; Dong, Yongkang; Zhang, Hongying

2014-12-01

We report on a novel type of liquid-filled simplified hollow-core photonic crystal fibers (HC-PCFs), and investigate their transmission properties with various filling liquids, including water, ethanol and FC-40. The loss and dispersion characterizations are calculated for different fiber parameters including strut thickness and core diameter. The results show that there are still low-loss windows existing for liquid-filled simplified HC-PCFs, and the low-loss windows and dispersions can be easily tailored by filling different liquids. Such liquid-filled simplified HC-PCFs open up many possibilities for nonlinear fiber optics, optical, biochemical and medical sensing.

Modeling of Thermal Phase Noise in a Solid Core Photonic Crystal Fiber-Optic Gyroscope

PubMed Central

Song, Ningfang; Ma, Kun; Jin, Jing; Teng, Fei; Cai, Wei

2017-01-01

A theoretical model of the thermal phase noise in a square-wave modulated solid core photonic crystal fiber-optic gyroscope has been established, and then verified by measurements. The results demonstrate a good agreement between theory and experiment. The contribution of the thermal phase noise to the random walk coefficient of the gyroscope is derived. A fiber coil with 2.8 km length is used in the experimental solid core photonic crystal fiber-optic gyroscope, showing a random walk coefficient of 9.25 × 10−5 deg/h. PMID:29072605

Hollow-Core Fiber Lamp

NASA Technical Reports Server (NTRS)

Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

2016-01-01

Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

Evanescent field characteristics of eccentric core optical fiber for distributed sensing.

PubMed

Liu, Jianxia; Yuan, Libo

2014-03-01

Fundamental core-mode cutoff and evanescent field are considered for an eccentric core optical fiber (ECOF). A method has been proposed to calculate the core-mode cutoff by solving the eigenvalue equations of an ECOF. Using conformal mapping, the asymmetric geometrical structure can be transformed into a simple, easily solved axisymmetric optical fiber with three layers. The variation of the fundamental core-mode cut-off frequency (V(c)) is also calculated with different eccentric distances, wavelengths, core radii, and coating refractive indices. The fractional power of evanescent fields for ECOF is also calculated with the eccentric distances and coating refractive indices. These calculations are necessary to design the structural parameters of an ECOF for long-distance, single-mode distributed evanescent field absorption sensors.

Method and apparatus for determining peak temperature along an optical fiber

DOEpatents

Fox, R.J.

1982-07-29

The invention relates to a new method and new apparatus for determining the hottest temperature or the coldest temperature prevailing along the length of an optical-fiber light guide. The invention is conducted with an optical fiber capable of supporting multidiode propagation of light and comprising a core, a cladding, and a jacket. The core is selected to have (1) a higher refractive index than the core and the cladding and (2) a relatively high negative temperature coefficient of refractive index. A light beam capable of establishing substantially single-mode propagation in the core is launched into an end thereof at an angle to the axis. The angle is increased to effect the onset of light fraction from the core into the cladding. The value of the launch angle corresponding to the onset is determined and then used to establish the refractive index of the core corresponding to the onset angle. The maximum temperature prevailing along the fiber then is determined from the (1) refractive index so determined and (2) the temperature coefficient of refractive index for the core. The invention is based on the finding that the launch angle corresponding to the onset of refraction into the cladding is uniquely determined by the maximum value of the ratio of the core refractive index to the cladding refractive index, which maximum occurs at the hottest point along the fiber.

Method and apparatus for determining peak temperature along an optical fiber

DOEpatents

Fox, Richard J.

1985-01-01

The invention relates to a new method and new apparatus for determining the hottest temperature or the coldest temperature prevailing along the length of an optical-fiber light guide. The invention is conducted with an optical fiber capable of supporting multidiode propagation of light and comprising a core, a cladding, and a jacket. The core is selected to have (1) a higher refractive index than the core and the cladding and (2) a relatively high negative temperature coefficient of refractive index. A light beam capable of establishing substantially single-mode propagation in the core is launched into an end thereof at an angle to the axis. The angle is increased to effect the onset of light refraction from the core into the cladding. The value of the launch angle corresponding to the onset is determined and then used to establish the refractive index of the core corresponding to the onset angle. The maximum temperature prevailing along the fiber then is determined from the (1) refractive index so determined and (2) the temperature coefficient of refractive index for the core. The invention is based on the finding that the launch angle corresponding to the onset of refraction into the cladding is uniquely determined by the maximum value of the ratio of the core refractive index to the cladding refractive index, which maximum occurs at the hottest point along the fiber.

Low-loss single-mode hollow-core fiber with anisotropic anti-resonant elements.

PubMed

Habib, Md Selim; Bang, Ole; Bache, Morten

2016-04-18

A hollow-core fiber using anisotropic anti-resonant tubes in the cladding is proposed for low loss and effectively single-mode guidance. We show that the loss performance and higher-order mode suppression is significantly improved by using symmetrically distributed anisotropic anti-resonant tubes in the cladding, elongated in the radial direction, when compared to using isotropic, i.e. circular, anti-resonant tubes. The effective single-mode guidance of the proposed fiber is achieved by enhancing the coupling between the cladding modes and higher-order-core modes by suitably engineering the anisotropic anti-resonant elements. With a silica-based fiber design aimed at 1.06 µm, we show that the loss extinction ratio between the higher-order core modes and the fundamental core mode can be more than 1000 in the range 1.0-1.65 µm, while the leakage loss of the fundamental core mode is below 15 dB/km in the same range.

Solvent-based self-healing approaches for fiber-reinforced composites

NASA Astrophysics Data System (ADS)

Jones, Amanda R.

Damage in composite materials spans many length scales and is often difficult to detect or costly to repair. The incorporation of self-healing functionality in composite materials has the potential to greatly extend material lifetime and reliability. Although there has been remarkable progress in self-healing polymers over the past decade, self-repair in fiber-reinforced composite materials presents significant technical challenges due to stringent manufacturing and performance requirements. For high performance, fiber-reinforced composites, the self-healing components need to survive high temperature processing, reside in matrix interstitial regions to retain a high fiber volume fraction, and have minimal impact on the mechanical properties of the host material. This dissertation explores several microencapsulated solvent-based self-healing approaches for fiber-reinforced composites at the fiber/ matrix interface size scale as well as matrix cracking. Systems are initially developed for room temperature cured epoxies/ glass fiber interfaces and successfully transitioned to carbon fibers and high temperature-cured, thermoplastic-toughened matrices. Full recovery of interfacial bond strength after complete fiber/matrix debonding is achieved with a microencapsulated solvent-based healing chemistry. The surface of a glass fiber is functionalized with microcapsules containing varying concentrations of reactive epoxy resin and ethyl phenyl acetate (EPA) solvent. Microbond specimens consisting of a single fiber and a microdroplet of epoxy are cured at 35°C, tested, and the interfacial shear strengths (IFSS) during the initial (virgin) debonding and subsequent healing events are measured. Debonding of the fiber/matrix interface ruptures the capsules, releasing resin and solvent into the crack plane. The solvent swells the matrix, initiating transport of residual amine functionality for further curing with the epoxy resin delivered to the crack plane. Using a resin-solvent ratio of 3:97, a maximum of 100% IFSS recovery is achieved-- a significant enhancement over prior work that reported 44% average recovery of IFSS with microencapsulated dicyclopentadiene (DCPD) monomer and Grubbs' 1st Generation catalyst healing agents. The effects of capsule coverage, resin-solvent ratio, and capsule size on recovery of IFSS are also determined, providing guidelines for integration of this healing system into high fiber volume fraction structural composites. High healing efficiencies are achieved with capsules as small as 0.6 mum average diameter. The resin-solvent healing system is then extended to repair of a carbon fiber/epoxy interfacial bond. A binder is necessary to improve the retention of capsules on the carbon fiber surface. Two different methods for applying a binder to a carbon fiber surface are investigated. Healing efficiency is assessed by recovery of IFSS of a single functionalized fiber embedded in an epoxy microbond specimen. The two binder protocols produce comparable results, both yielding higher recovery of IFSS than samples prepared without a binder. A maximum of 91% recovery of IFSS is achieved. In the next study, the resin-solvent healing system is applied to both interfacial damage and matrix cracking in a model composite specimen, consisting of discrete fiber tows embedded in a room temperature cured epoxy. Glass fiber tows are precisely placed in a compact tension specimen for controlled crack growth. The progression of matrix cracking and fiber debonding is observed optically during testing. Healing potential is assessed by injection of the healing agents into reference specimens (no capsules). The area under the load-displacement curve recovered during the healing event serves as a metric for evaluation of healing performance. Though full recovery is achieved in neat epoxy specimens, healing efficiency in multi-tow specimens is limited to 50%, due to the larger crack separations and energy lost during fiber fracture. In the case of only a singular embedded fiber tow, healing efficiency increases to an average of 83% recovery with full recovery in several samples. Additionally, microcapsules are incorporated into the compact tension specimen and along the fiber tow interface to evaluate in situ healing. Several strategies to improve microcapsule thermal stability are investigated in order to transition solvent-based healing to high temperature cured material systems. A double shell wall technique is adopted for several different size scales of microcapsules. First, the effect of the inner polyurethane (PU) shell wall thickness on thermal stability is evaluated. Though high thermal stability at 180°C is achieved for large (ca. 150 mum in diameter) capsules, smaller capsules (> 2 mum in diameter) suffer from increased core loss. The addition of certain core thickeners improves thermal stability for small capsules (ca. 20% increase in core retention) when compared to capsules with solvent alone. However, an additional poly(dopamine) coating leads to the greatest improvement in thermal stability, with nearly full retention of the core solvent for all capsule size scales. Finally, a thermoplastic resin poly(bisphenol A-co-epichlorohydrin), PBAE, is blended with a high glass transition temperature (Tg) epoxy matrix to simultaneously toughen and act as a healing agent in combination with encapsulated solvents. Microcapsules are coated with poly(dopamine) to improve the thermal stability and retain the core solvent during a cure cycle at 180°C. The fracture toughness of the high Tg epoxy (EPON 828: diamino diphenyl sulfone) is doubled by the addition of 20 wt % PBAE alone and tripled by the addition of both microcapsules and the thermoplastic phase. Self-healing is achieved with up to 57% recovery of fracture toughness of the toughened epoxy. Healing performance and fracture toughness of the microcapsule containing material remain stable after aging 30 days. The relative amounts of thermoplastic phase and the presence of solvent-filled microcapsules influence the storage modulus, Tg, and healing performance of the polymer.

Diamond fiber field emitters

DOEpatents

Blanchet-Fincher, Graciela B.; Coates, Don M.; Devlin, David J.; Eaton, David F.; Silzars, Aris K.; Valone, Steven M.

1996-01-01

A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.

Micro-device for coupling, multiplexing and demultiplexing using elliptical-core two-mode fiber

NASA Technical Reports Server (NTRS)

Wang, A.; Murphy, K. A.; Wang, G. Z.; Vengsarkar, A. M.; Claus, R. O.

1990-01-01

We propose and demonstrate experimentally a fiber optic micro-device that is capable of tunably splitting, multiplexing, and demultiplexing optical signals using elliptical-core two-mode optical fiber. A crosstalk of 15 dB with an insertion loss of 1.2 dB was obtained.

Ultra low-loss hybrid core porous fiber for broadband applications.

PubMed

Islam, Md Saiful; Sultana, Jakeya; Atai, Javid; Abbott, Derek; Rana, Sohel; Islam, Mohammad Rakibul

2017-02-01

In this paper, we present the design and analysis of a novel hybrid porous core octagonal lattice photonic crystal fiber for terahertz (THz) wave guidance. The numerical analysis is performed using a full-vector finite element method (FEM) that shows that 80% of bulk absorption material loss of cyclic olefin copolymer (COC), commercially known as TOPAS can be reduced at a core diameter of 350 μm. The obtained effective material loss (EML) is as low as 0.04  cm^-1 at an operating frequency of 1 THz with a core porosity of 81%. Moreover, the proposed photonic crystal fiber also exhibits comparatively higher core power fraction, lower confinement loss, higher effective mode area, and an ultra-flattened dispersion profile with single mode propagation. This fiber can be readily fabricated using capillary stacking and sol-gel techniques, and it can be used for broadband terahertz applications.

Eigenvalue equation and core-mode cutoff of weakly guiding tapered fiber as three layer optical waveguide and used as biochemical sensor.

PubMed

Linslal, C L; Mohan, P M S; Halder, A; Gangopadhyay, T K

2012-06-01

The core-mode cutoff plays a major role in evanescent field absorption based sensors. A method has been proposed to calculate the core-mode cutoff by solving the eigenvalue equations of a weakly guiding three layer optical waveguide graphically. The variation of normalized waveguide parameter (V) is also calculated with different wavelengths at core-mode cutoff. At the first step, theoretical analysis of tapered fiber parameters has been performed for core-mode cutoff. The taper angle of an adiabatic tapered fiber is also analyzed using the length-scale criterion. Secondly, single-mode tapered fiber has been developed to make a precision sensor element suitable for chemical detection. Finally, the sensor element has been used to detect absorption peak of ethylenediamine. Results are presented in which an absorption peak at 1540 nm is observed.

Physical deterioration of preservative treated poles and pilings exposed to salt water

Treesearch

Grant T. Kirker; Jessie Glaeser; Stan T. Lebow; Frederick Green III; Carol A. Clausen

2011-01-01

This report details the results of laboratory analyses of wooden pilings sent to the USDA Forest Products Laboratory in March 2011. These samples were removed from coastal wooden posts, poles, piles, and deck boards. A total of 22 samples, consisting of either core borings or surface fiber samples, were removed from four installations along the South Carolina coast....

Pump absorption in coiled and twisted double-clad hexagonal fiber: effect of launching conditions and core location

NASA Astrophysics Data System (ADS)

Dalidet, Romain; Peterka, Pavel; Doya, Valérie; Aubrecht, Jan; Koška, Pavel

2018-02-01

Ever extending applications of fiber lasers require energy efficient, high-power, small footprint and reliable fiber lasers and laser wavelength versatility. To meet these demands, next generation of active fibers for high-power fiber lasers is coming out that will eventually offer tailored spectroscopic properties, high robustness and reduced cooling requirements and improved efficiency through tailored pump absorption. We report on numerical modelling of the efficiency of the pump absorption in double clad active fibers with hexagonal shape of the inner cladding cross section and rare-earth-doped core. We analyze both the effect of different radii of the spool on which the fiber is coiled and different fiber twisting rates. Two different launching conditions were investigated: the Gaussian input pump beam and a speckle pattern that mimics the output of the pump laser diode pigtail. We have found that by asymmetric position of the rare-earth-doped core we can significantly improve the pump absorption.

Design of a family of ring-core fibers for OAM transmission studies.

PubMed

Brunet, Charles; Ung, Bora; Wang, Lixian; Messaddeq, Younès; LaRochelle, Sophie; Rusch, Leslie A

2015-04-20

We propose a family of ring-core fibers, designed for the transmission of OAM modes, that can be fabricated by drawing five different fibers from a single preform. This novel technique allows us to experimentally sweep design parameters and speed up the fiber design optimization process. Such a family of fibers could be used to examine system performance, but also facilitate understanding of parameter impact in the transition from design to fabrication. We present design parameters characterizing our fiber, and enumerate criteria to be satisfied. We determine targeted fiber dimensions and explain our strategy for examining a design family rather than a single fiber design. We simulate modal properties of the designed fibers, and compare the results with measurements performed on fabricated fibers.

Spectral efficiency in crosstalk-impaired multi-core fiber links

NASA Astrophysics Data System (ADS)

Luís, Ruben S.; Puttnam, Benjamin J.; Rademacher, Georg; Klaus, Werner; Agrell, Erik; Awaji, Yoshinari; Wada, Naoya

2018-02-01

We review the latest advances on ultra-high throughput transmission using crosstalk-limited single-mode multicore fibers and compare these with the theoretical spectral efficiency of such systems. We relate the crosstalkimposed spectral efficiency limits with fiber parameters, such as core diameter, core pitch, and trench design. Furthermore, we investigate the potential of techniques such as direction interleaving and high-order MIMO to improve the throughput or reach of these systems when using various modulation formats.

Chemical tapering of polymer optical fiber

NASA Astrophysics Data System (ADS)

Rashid, Affa Rozana Abdul; Afiqah Nasution, Amna; Hanim Suranin, Aisyah; Athirah Taib, Nur; Maisarah Mukhtar, Wan; Dasuki, Karsono Ahmad; Annuar Ehsan, Abang

2017-11-01

Polymer optical fibers (POFs) have significant advantages over numerous sensing applications. The key element in developing sensor is by removing the cladding of the fiber. The use of organic solvent is one of the methods to create tapered POF in order to expose the core region. In this study, the etching chemicals involved is acetone, methyl isobutyl ketone (MIBK), and acetone-methanol mixture. The POF is immersed in 100%, 80%, and 50% of acetone and MIBK dilution. In addition, the mixture of acetone and methanol is also used for POF etching by the ratio 2:1 of the volume. Acetone has shown to be the most reactive solvent towards POF due to its fastest etching rate compared to MIBK and acetone-methanol mixture. The POF is immersed and lifted from the solution for a specific time, depending on the power loss properties for the purpose of producing unclad POF. In comparison to silica fiber optic, the advantages of POF in terms of its simple technique and easy handling enable it to produce unclad POF without damaging the core region. The surface roughness of the POF is investigated under the microscope after being immersed into different solvent. This method of chemical tapering of POF can be used as the fundamental technique for sensor development. Next, the unclad fiber is immersed into ethanol solutions in order to determine the reaction of unclad POF towards its surrounding. The findings show that this particular sensor is sensitive towards concentration changes ranging between 10 wt% to 50 wt%.

Ion-imprinted nanoparticles for the concurrent estimation of Pb(II) and Cu(II) ions over a two channel surface plasmon resonance-based fiber optic platform

NASA Astrophysics Data System (ADS)

Shrivastav, Anand Mohan; Gupta, Banshi D.

2018-01-01

We report the design, fabrication, and characterization of an optical fiber sensor based on the surface plasmon resonance (SPR) technique for the simultaneous determination of lead (Pb) and copper (Cu) metal ions in aqueous samples. Two cascade channels over a single optical fiber are fabricated by removing cladding from two well-separated regions of the fiber. SPR working as a transducing mechanism for the sensor is realized by coating thin films of copper and silver over unclad cores of channel I and channel II, respectively. Ion-imprinted nanoparticles for both ions are separately synthesized and coated over the metal-coated unclad cores of the fiber as the recognition layers for sensor fabrication. A first channel having layer of Pb(II) ion-imprinted nanoparticles detects Pb(II) ions and a second channel having layer of Cu(II) ion-imprinted nanoparticles are used for the detection of Cu(II) ions. Both channels are characterized using the wavelength interrogation method. The sensor operates in the range between 0 to 1000 μg/L and 0 to 1000 mg/L for Pb(II) and Cu(II) ions, respectively. These ranges cover water resources and the human body for these ions. The sensitivities of channel I and channel II are found to be 8.19×104 nm/(μg/L) and 4.07×105 nm/(mg/L) near the lowest concentration of Pb(II) and Cu(II) ions, respectively. The sensor can detect concentrations of Pb(II) and Cu(II) ions as low as 4.06 × 10-12 g/L and 8.18 × 10-10 g/L, respectively, which are the least among the reported values in the literature. Further, the probe is simple, cost effective, highly selective, and applicable for online monitoring and remote sensing.

Transmission characteristics of femtosecond optical pulses in hollow-core fibers

NASA Astrophysics Data System (ADS)

Mohebbi, Mohammad

2005-09-01

Hollow-core fibers with fused silica and metal claddings are studied for transmission of femtosecond optical pulses at a wavelength of 800 nm. The measured transmission loss of a silver-coated hollow fiber with a core diameter of 250 μm is 0.44 dB/m. A bending loss of 1.1 dB/m was measured for this waveguide with a radius of curvature of 1 m. It is shown that the fundamental hybrid mode HE 11 has negligible pulse spreading. In the presence of higher order modes modal dispersion becomes dominant and depends strongly on the core diameter.

Compact Hybrid Laser Rod and Laser System

NASA Technical Reports Server (NTRS)

Pierrottet, Diego F. (Inventor); Busch, George E. (Inventor); Amzajerdian, Farzin (Inventor)

2017-01-01

A hybrid fiber rod includes a fiber core and inner and outer cladding layers. The core is doped with an active element. The inner cladding layer surrounds the core, and has a refractive index substantially equal to that of the core. The outer cladding layer surrounds the inner cladding layer, and has a refractive index less than that of the core and inner cladding layer. The core length is about 30 to 2000 times the core diameter. A hybrid fiber rod laser system includes an oscillator laser, modulating device, the rod, and pump laser diode(s) energizing the rod from opposite ends. The rod acts as a waveguide for pump radiation but allows for free-space propagation of laser radiation. The rod may be used in a laser resonator. The core length is less than about twice the Rayleigh range. Degradation from single-mode to multi-mode beam propagation is thus avoided.

Development of As-Se tapered suspended-core fibers for ultra-broadband mid-IR wavelength conversion

NASA Astrophysics Data System (ADS)

Anashkina, E. A.; Shiryaev, V. S.; Koptev, M. Y.; Stepanov, B. S.; Muravyev, S. V.

2018-01-01

We designed and developed tapered suspended-core fibers of high-purity As39Se61 glass for supercontinuum generation in the mid-IR with a standard fiber laser pump source at 2 ${\\mu}$m. It was shown that microstructuring allows shifting a zero dispersion wavelength to the range shorter than 2 ${\\mu}$m in the fiber waist with a core diameter of about 1 ${\\mu}$m. In this case, supercontinuum generation in the 1-10 ${\\mu}$m range was obtained numerically with 150-fs 100-pJ pump pulses at 2 ${\\mu}$m. We also performed experiments on wavelength conversion of ultrashort optical pulses at 1.57 ${\\mu}$m from Er: fiber laser system in the manufactured As-Se tapered fibers. The measured broadening spectra were in a good agreement with the ones simulated numerically.

Analysis and characterization of high-resolution and high-aspect-ratio imaging fiber bundles.

PubMed

Motamedi, Nojan; Karbasi, Salman; Ford, Joseph E; Lomakin, Vitaliy

2015-11-10

High-contrast imaging fiber bundles (FBs) are characterized and modeled for wide-angle and high-resolution imaging applications. Scanning electron microscope images of FB cross sections are taken to measure physical parameters and verify the variations of irregular fibers due to the fabrication process. Modal analysis tools are developed that include irregularities in the fiber core shapes and provide results in agreement with experimental measurements. The modeling demonstrates that the irregular fibers significantly outperform a perfectly regular "ideal" array. Using this method, FBs are designed that can provide high contrast with core pitches of only a few wavelengths of the guided light. Structural modifications of the commercially available FB can reduce the core pitch by 60% for higher resolution image relay.

High power resonant pumping of Tm-doped fiber amplifiers in core- and cladding-pumped configurations.

PubMed

Creeden, Daniel; Johnson, Benjamin R; Rines, Glen A; Setzler, Scott D

2014-11-17

We have demonstrated ultra-high efficiency amplification in Tm-doped fiber with both core- and cladding-pumped configurations using a resonant tandem-pumping approach. These Tm-doped fiber amplifiers are pumped in-band with a 1908 nm Tm-doped fiber laser and operate at 1993 nm with >90% slope efficiency. In a core-pumped configuration, we have achieved 92.1% slope efficiency and 88.4% optical efficiency at 41 W output power. In a cladding-pumped configuration, we have achieved 123.1 W of output power with 90.4% optical efficiency and a 91.6% slope efficiency. We believe these are the highest optical efficiencies achieved in a Tm-doped fiber amplifier operating in the 2-micron spectral region.

In-fiber refractive index sensor based on single eccentric hole-assisted dual-core fiber.

PubMed

Yang, Jing; Guan, Chunying; Tian, Peixuan; Yuan, Tingting; Zhu, Zheng; Li, Ping; Shi, Jinhui; Yang, Jun; Yuan, Libo

2017-11-01

We propose a novel and simple in-fiber refractive index sensor based on resonant coupling, constructed by a short section of single eccentric hole-assisted dual-core fiber (SEHADCF) spliced between two single-mode fibers. The coupling characteristics of the SEHADCF are calculated numerically. The strong resonant coupling occurs when the fundamental mode of the center core phase-matches to that of the suspended core in the air hole. The effective refractive index of the fundamental mode of the suspended core can be obviously changed by injecting solution into the air hole. The responses of the proposed devices to the refractive index and temperature are experimentally measured. The refractive index sensitivity is 627.5 nm/refractive index unit in the refractive index range of 1.335-1.385. The sensor without solution filling is insensitive to temperature in the range of 30-90°C. The proposed refractive index sensor has outstanding advantages, such as simple fabrication, good mechanical strength, and excellent microfluidic channel, and will be of importance in biological detection, chemical analysis, and environment monitoring.

Fiber up-tapering and down-tapering for low-loss coupling between anti-resonant hollow-core fiber and solid-core fiber

NASA Astrophysics Data System (ADS)

Zhang, Naiqian; Wang, Zefeng; Xi, Xiaoming

2017-10-01

In this paper, we demonstrate a novel method for the low-loss coupling between solid-core multi-mode fibers (MMFs) and anti-resonant hollow-core fibers (AR-HCFs). The core/cladding diameter of the MMF is 50/125μm and the mode field diameter of the AR-HCFs are 33.3μm and 71.2μm of the ice-cream type AR-HCFs and the non-node type ARHCFs, respectively. In order to match the mode field diameters of these two specific AR-HCFs, the mode field diameter of the MMFs is increased or decreased by up-tapering or down-tapering the MMFs. Then, according to the principle of coupled fiber mode matching, the optimal diameter of tapered fiber for low-loss coupling is calculated. Based on beam propagation method, the calculated coupling losses without tapering process are 0.31dB and 0.89dB, respectively for a MMF-HCF-MMF structure of the ice-cream type AR-HCFs and the non-node type AR-HCFs. These values can be reduced to 0.096dB and 0.047dB when the outer diameters of the MMF are down-tapered to 116μm and up-tapered to 269μm, respectively. What's more, these results can also be verified by existing experiments.

Nonlinear performance of asymmetric coupler based on dual-core photonic crystal fiber: Towards sub-nanojoule solitonic ultrafast all-optical switching

NASA Astrophysics Data System (ADS)

Curilla, L.; Astrauskas, I.; Pugzlys, A.; Stajanca, P.; Pysz, D.; Uherek, F.; Baltuska, A.; Bugar, I.

2018-05-01

We demonstrate ultrafast soliton-based nonlinear balancing of dual-core asymmetry in highly nonlinear photonic crystal fiber at sub-nanojoule pulse energy level. The effect of fiber asymmetry was studied experimentally by selective excitation and monitoring of individual fiber cores at different wavelengths between 1500 nm and 1800 nm. Higher energy transfer rate to non-excited core was observed in the case of fast core excitation due to nonlinear asymmetry balancing of temporal solitons, which was confirmed by the dedicated numerical simulations based on the coupled generalized nonlinear Schrödinger equations. Moreover, the simulation results correspond qualitatively with the experimentally acquired dependences of the output dual-core extinction ratio on excitation energy and wavelength. In the case of 1800 nm fast core excitation, narrow band spectral intensity switching between the output channels was registered with contrast of 23 dB. The switching was achieved by the change of the excitation pulse energy in sub-nanojoule region. The performed detailed analysis of the nonlinear balancing of dual-core asymmetry in solitonic propagation regime opens new perspectives for the development of ultrafast nonlinear all-optical switching devices.

Low-cost integrated-optic fiber couplers

NASA Astrophysics Data System (ADS)

Sheem, Sang K.; Zhang, Feng; Choi, Jong-Ho; Lee, Yong-Woo; Low, Sarah; Lu, Shih-Yau

1997-04-01

In an effort to lower the cost of fiber optic couplers, integrated optic channel waveguide circuits are made of a UV-curable polymer using a molding technique, and then a novel fiber-to-channel connecting approach is employed in which UV light radiating from an optical fiber core cures the polymer in the channel, thus accomplishing a 'touchdown' of the core-extension waveguide onto the walls of the channel waveguide.

Breaking the glass ceiling: hollow OmniGuide fibers

NASA Astrophysics Data System (ADS)

Johnson, Steven G.; Ibanescu, Mihai; Skorobogatiy, Maksim A.; Weisberg, Ori; Engeness, Torkel D.; Soljacic, Marin; Jacobs, Steven A.; Joannopoulos, John D.; Fink, Yoel

2002-04-01

We argue that OmniGuide fibers, which guide light within a hollow core by concentric multilayer films having the property of omnidirectional reflection, have the potential to lift several physical limitations of silica fibers. We show how the strong confinement in OmniGuide fibers greatly suppresses the properties of the cladding materials: even if highly lossy and nonlinear materials are employed, both the intrinsic losses and nonlinearities of silica fibers can be surpassed by orders of magnitude. This feat, impossible to duplicate in an index-guided fiber with existing materials, would open up new regimes for long-distance propagation and dense wavelength-division multiplexing (DWDM). The OmniGuide-fiber modes bear a strong analogy to those of hollow metallic waveguides; from this analogy, we are able to derive several general scaling laws with core radius. Moreover, there is strong loss discrimination between guided modes, depending upon their degree of confinement in the hollow core: this allows large, ostensibly multi-mode cores to be used, with the lowest-loss TE01 mode propagating in an effectively single-mode fashion. Finally, because this TE01 mode is a cylindrically symmetrical ('azimuthally' polarized) singlet state, it is immune to polarization-mode dispersion (PMD), unlike the doubly-degenerate linearly-polarized modes in silica fibers that are vulnerable to birefringence.

Delivery of high intensity beams with large clad step-index fibers for engine ignition

NASA Astrophysics Data System (ADS)

Joshi, Sachin; Wilvert, Nick; Yalin, Azer P.

2012-09-01

We show, for the first time, that step-index silica fibers with a large clad (400 μm core and 720 μm clad) can be used to transmit nanosecond duration pulses in a way that allows reliable (consistent) spark formation in atmospheric pressure air by the focused output light from the fiber. The high intensity (>100 GW/cm2) of the focused output light is due to the combination of high output power (typical of fibers of this core size) with high output beam quality (better than that typical of fibers of this core size). The high output beam quality, which enables tight focusing, is due to the large clad which suppresses microbending-induced diffusion of modal power to higher order modes owing to the increased rigidity of the core-clad interface. We also show that extending the pulse duration provides a means to increase the delivered pulse energy (>20 mJ delivered for 50 ns pulses) without causing fiber damage. Based on this ability to deliver high energy sparks, we report the first reliable laser ignition of a natural gas engine including startup under typical procedures using silica fiber optics for pulse delivery.

Characteristics of a high extinction ratio comb-filter based on LP01-LP11even mode elliptical multilayer-core fibers

NASA Astrophysics Data System (ADS)

Liang, Xiao; Liu, Shuo; Li, Yang; Liu, Zhibo; Jian, Shuisheng

2015-01-01

We experimentally characterized an all-fiber microstructure Mach-Zehnder comb-filter (MZ comb-filter), which based on homemade elliptical multilayer-core fibers (EMCF) and consisted of an EMCF-SMF-EMCF (ESE) structure. To the best of our knowledge, the dual-mode elliptical multilayer-core fiber was the first time to produce and apply in MZ comb filer. The EMCF, in which only two modes could be propagated, can be easier to fabricate a filter with clean comb spectrum than many fibers, such as multimode fibers, thin-core fibers, PCFs and et al. A comb-filter with extinction ratio (˜25 dB) was successfully achieved with an EMCF-SMF-EMCF structure. The wavelengths of the lead-out light shifted with the changing of surrounding refractive indexes (SRI) and temperature. Thus, this MZ comb-filter had potential for improving the SRI and temperature measurement resolutions. A maximum sensitivity of 53.744 nm per refractive index unit (RIU) within a linear range of 1.333-1.383 and 59.875 pm/°C within temperature range of 0-80 °C were experimentally achieved, respectively.

Injection efficiency of bound modes. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira

1990-01-01

Previous work on efficiency of light injection into the core of a fiber from a thin film and a bulk distribution of sources in the cladding have used the fields of a weakly guiding fiber. This approximation simplifies the analysis of the power efficiency by introducing universal values for the eigenvalues of different fibers with the same V-number, but cannot predict accurately the behavior of the injected light into a fiber with arbitrary differences in indices of refraction. The exact field solution was used in the expressions of the power efficiency, p sub eff, and its behavior as a function of the fiber parameter was analyzed. Weakly guiding results obtained previously are confirmed. However, P sub eff does not always increase with the V-number but with the difference in the indices of refraction, eta sub core-eta sub clad. For the bulk distribution it was found that P sub eff increases with the wavelength, lambda, and decreases with the fiber core radius, a, i.e., it decreases with the V-number. However, for the thin film, the P sub eff remains almost constant with lambda and the fiber core radius.

Porcelain monolayers and porcelain/alumina bilayers reinforced by Al2O3/GdAlO3 fibers.

PubMed

Sgura, Ricardo; Medeiros, Igor Studart; Cesar, Paulo Francisco; Campos, Adeliani Almeida; Hernandes, Antonio Carlos

2012-01-01

This work tested the effect of the addition of Al(2)O(3)/GdAlO(3) longitudinal fibers in different contents to veneering porcelain of two dental all ceramic systems. Fibers (0.5 mm diameter) obtained by the Laser Heated Pedestal Growth (LHPG) method were added to bar-shaped specimens made by veneer porcelain (monolayers) or both the veneer and the core ceramic (bilayers) of two all-ceramic systems: In-Ceram Alumina-glass infiltrated alumina composite (GIA) and In-Ceram 2000 AL Cubes-alumina polycrystal (AP) (VITA Zahnfabrik). The longitudinal fibers were added to veneering porcelain (VM7) in two different proportions: 10 or 17 vol%. The bars were divided into nine experimental conditions (n=10) according to material used: VM7 porcelain monolayers, VM7/GIA, VM7/AP; and according to the amount of fibers within the porcelain layer: no fibers, 10 vol% or 17 vol%. After grinding and polishing the specimens were submitted to a three point bending test (crosshead speed = 0.5 mm/min) with porcelain positioned at tensile side. Data were analyzed by means of one-way ANOVA and a Tukey's test (α=5%). Scanning electronic microscopy (SEM) was conducted for fractographic analysis. Regarding the groups without fiber addition, VM7/AP showed the highest flexural strength (MPa), followed by VM7/GIA and VM7 monolayers. The addition of fibers led to a numerical increase in flexural strength for all groups. For VM7/GIA bilayers the addition of 17 vol% of fibers resulted in a significant 48% increase in the flexural strength compared to the control group. Fractographic analysis revealed that the crack initiation site was in porcelain at the tensile surface. Cracks also propagated between fibers before heading for the alumina core. The addition of 17 vol% of Al(2)O(3)/GdAlO(3) longitudinal fibers to porcelain/glass infiltrated alumina bilayers significantly improved its flexural strength. 10 vol% or 17 vol% of fibers inclusion increased the flexural strength for all groups. Copyright © 2011 Elsevier Ltd. All rights reserved.

Enhanced-locality fiber-optic two-photon-fluorescence live-brain interrogation

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

Fedotov, I. V.; Doronina-Amitonova, L. V.; Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 1430125

2014-02-24

Two-photon excitation is shown to substantially enhance the locality of fiber-based optical interrogation of strongly scattering biotissues. In our experiments, a high-numerical-aperture, large-core-are fiber probe is used to deliver the 200-fs output of a 100-MHz mode-locked ytterbium fiber laser to samples of live mouse brain, induce two-photon fluorescence of nitrogen–vacancy centers in diamond markers in brain sample. Fiber probes with a high numerical aperture and a large core area are shown to enable locality enhancement in fiber-laser–fiber-probe two-photon brain excitation and interrogation without sacrificing the efficiency of fluorescence response collection.

Optofluidic tuning of multimode interference fiber filters

NASA Astrophysics Data System (ADS)

Antonio-Lopez, J. E.; May-Arrioja, D. A.; LiKamWa, P.

2009-05-01

We report on the optofluidic tuning of MMI-based bandpass filters. It is well known that MMI devices exhibit their highest sensitivity when their diameter (D) is modified, since they have a D2 wavelength dependence. In order to increase the MMF diameter we use a special fiber, called No-Core fiber, which is basically a MMF with a diameter of 125 μm with air as the cover. Therefore, when this No-Core fiber is immersed in liquids with different refractive indexes, as a result of the Goes-Hänchen shift the effective width (fundamental mode width) of the No-Core fiber is increased, and thus the peak wavelength is tuned. A tunability of almost 40 nm in going from air (n=1.333) to ethylene glycol (n=1.434) was easily obtained, with a minimum change in peak transmission, contrast, and bandwidth. Moreover, since replacing the entire liquid can be difficult, the device was placed vertically and the liquid was covering the No-Core fiber in small steps. This provided similar amount of tuning as before, but a more controllable tuning mechanism.

Thermoluminescence characteristics of Ge-doped optical fibers with different dimensions for radiation dosimetry.

PubMed

Begum, Mahfuza; Rahman, A K M Mizanur; Abdul-Rashid, H A; Yusoff, Z; Begum, Mahbuba; Mat-Sharif, K A; Amin, Y M; Bradley, D A

2015-06-01

Important thermoluminescence (TL) properties of five (5) different core sizes Ge-doped optical fibers have been studied to develop new TL material with better response. These are drawn from same preform applying different speed and tension during drawing phase to produce Ge-doped optical fibers with five (5) different core sizes. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge-doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (SEM) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in Secondary Standard Dosimetry Lab (SSDL) was used for irradiation covering dose range from 1Gy to 10Gy. The essential dosimetric parameters that have been studied are TL linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5cm length are annealed at temperature of 400°C for 1h period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1h at 400°C and subsequently 2h at 100°C to yield the highest sensitivity. TL responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Zeff) is found in the range (13.25-13.69) which is higher than soft tissue (7.5) however within the range of human-bone (11.6-13.8). All the fibers can also be re-used several times as a detector after annealing. TL properties of the Ge-doped optical fibers indicate promising applications in ionizing radiation dosimetry. Copyright © 2014 Elsevier Ltd. All rights reserved.

Axial and radial nanostructures in electrospun polymer fibers

NASA Astrophysics Data System (ADS)

Greenfeld, Israel; Camposeo, Andrea; Tantussi, Francesco; Pagliara, Stefano; Fuso, Francesco; Allegrini, Maria; Pisignano, Dario; Zussman, Eyal

2013-03-01

The high tensional stresses during electrospinning of semidilute polymer solutions affect the dynamic conformation of the polymer network within the liquid jet, leaving a distinctive trace in the molecular structure after solidification. We investigated such effects in electrospun nanofibers made of conjugated polymers. Modeling the polymer network evolution during electrospinning showed that as the network stretches axially, it contracts towards the jet core. The model represents the semi-flexible conjugated polymer chains as flexible freely-jointed chains, whose joints are bonding defects. Using the conjugated polymer MEH-PPV dissolved in a mixture of THF and DMF solvents, and taking advantage of its unique photophysical characteristics, we investigated optically the variations in the density and orientation of the polymer macromolecules in electrospun nanofibers. In agreement with our model, we found higher density and axial orientation at the fiber core, while lower density and radial orientation closer to the fiber surface. The non-uniformity of the resulting molecular structure can be tuned and exploited in diverse optical and structural applications. We acknowledge: V. Fasano, G. Potente, S. Girardo and E. Caldi for assistance in measurements; United States-Israel BSF, RBNI Institute, and the Israel Science Foundation for financial support.

Thulium fiber laser lithotripsy using small spherical distal fiber tips

NASA Astrophysics Data System (ADS)

Wilson, Christopher R.; Hardy, Luke A.; Kennedy, Joshua D.; Irby, Pierce B.; Fried, Nathaniel M.

2016-02-01

This study tests a 100-μm-core fiber with 300-μm-diameter ball tip during Thulium fiber laser (TFL) lithotripsy. The TFL was operated at 1908 nm wavelength with 35-mJ pulse energy, 500-μs pulse duration, and 300-Hz pulse rate. Calcium oxalate/phosphate stone samples were weighed, laser procedure times measured, and ablation rates calculated for ball tip fibers, with comparison to bare tip fibers. Photographs of ball tips were taken before and after each procedure to observe ball tip degradation and determine number of procedures completed before need to replace fiber. Saline irrigation rates and ureteroscope deflection were measured with and without TFL fiber present. There was no statistical difference (P > 0.05) between stone ablation rates for single-use ball tip fiber (1.3 +/- 0.4 mg/s) (n=10), multiple-use ball tip fiber (1.3 +/- 0.5 mg/s) (n=44), and conventional single-use bare tip fibers (1.3 +/- 0.2 mg/s) (n=10). Ball tip durability varied widely, but fibers averaged > 4 stone procedures before decline in stone ablation rates due to mechanical damage at front surface of ball tip. The small fiber diameter did not impact ureteroscope deflection or saline flow rates. The miniature ball tip fiber may provide a cost-effective design for safe fiber insertion through the ureteroscope working channel and the ureter without risk of scope damage or tissue perforation, and without compromising stone ablation efficiency during TFL ablation of kidney stones.

Nanomechanical Optical Fiber with Embedded Electrodes Actuated by Joule Heating.

PubMed

Lian, Zhenggang; Segura, Martha; Podoliak, Nina; Feng, Xian; White, Nicholas; Horak, Peter

2014-07-31

Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure.

A hetero-core fiber optic smart mat sensor for discrimination between a moving human and object on temporal loss peaks

NASA Astrophysics Data System (ADS)

Hosoki, Ai; Nishiyama, Michiko; Choi, Yongwoon; Watanabe, Kazuhiro

2011-05-01

In this paper, we propose discrimination method between a moving human and object by means of a hetero-core fiber smart mat sensor which induces the optical loss change in time. In addition to several advantages such as flexibility, thin size and resistance to electro-magnetic interference for a fiber optic sensor, a hetero-core fiber optic sensor is sensitive to bending action of the sensor portion and independent of temperature fluctuations. Therefore, the hetero-core fiber thin mat sensor can have a fewer sensing portions than the conventional floor pressure sensors, furthermore, can detect the wide area covering the length of strides. The experimental results for human walking tests showed that the mat sensors were reproducibly working in real-time under limiting locations the foot passed in the mat sensor. Focusing on the temporal peak numbers in the optical loss, human walking and wheeled platform moving action induced the peak numbers in the range of 1 - 3 and 5 - 7, respectively, for the 10 persons including 9 male and 1 female. As a result, we conclude that the hetero-core fiber mat sensor is capable of discriminating between the moving human and object such as a wheeled platform focusing on the peak numbers in the temporal optical loss.

In Situ Observation of Modulated Light Emission of Fiber Fuse Synchronized with Void Train over Hetero-Core Splice Point

PubMed Central

Todoroki, Shin-ichi

2008-01-01

Background Fiber fuse is a process of optical fiber destruction under the action of laser radiation, found 20 years ago. Once initiated, opical discharge runs along the fiber core region to the light source and leaves periodic voids whose shape looks like a bullet pointing the direction of laser beam. The relation between damage pattern and propagation mode of optical discharge is still unclear even after the first in situ observation three years ago. Methodology/Principal Findings Fiber fuse propagation over hetero-core splice point (Corning SMF-28e and HI 1060) was observed in situ. Sequential photographs obtained at intervals of 2.78 µs recorded a periodic emission at the tail of an optical discharge pumped by 1070 nm and 9 W light. The signal stopped when the discharge ran over the splice point. The corresponding damage pattern left in the fiber core region included a segment free of periodicity. Conclusions The spatial modulation pattern of the light emission agreed with the void train formed over the hetero-core splice point. Some segments included a bullet-shaped void pointing in the opposite direction to the laser beam propagation although the sequential photographs did not reveal any directional change in the optical discharge propagation. PMID:18815621

Tuning the field distribution and fabrication of an Al@ZnO core-shell nanostructure for a SPR-based fiber optic phenyl hydrazine sensor.

PubMed

Tabassum, Rana; Kaur, Parvinder; Gupta, Banshi D

2016-05-27

We report the fabrication and characterization of a surface plasmon resonance (SPR)-based fiber optic sensor that uses coatings of silver and aluminum (Al)-zinc oxide (ZnO) core-shell nanostructure (Al@ZnO) for the detection of phenyl hydrazine (Ph-Hyd). To optimize the volume fraction (f) of Al in ZnO and the thickness of the core-shell nanostructure layer (d), the electric field intensity along the normal to the multilayer system is simulated using the two-dimensional multilayer matrix method. The Al@ZnO core-shell nanostructure is prepared using the laser ablation technique. Various probes are fabricated with different values of f and an optimized thickness of core-shell nanostructure for the characterization of the Ph-Hyd sensor. The performance of the Ph-Hyd sensor is evaluated in terms of sensitivity. It is found that the Ag/Al@ZnO nanostructure core-shell-coated SPR probe with f = 0.25 and d = 0.040 μm possesses the maximum sensitivity towards Ph-Hyd. These results are in agreement with the simulated ones obtained using electric field intensity. In addition, the performance of the proposed probe is compared with that of probes coated with (i) Al@ZnO nanocomposite, (ii) Al nanoparticles and (iii) ZnO nanoparticles. It is found that the probe coated with an Al@ZnO core-shell nanostructure shows the largest resonance wavelength shift. The detailed mechanism of the sensing (involving chemical reactions) is presented. The sensor also manifests optimum performance at pH 7.

A Multi-D-Shaped Optical Fiber for Refractive Index Sensing

PubMed Central

Chen, Chien-Hsing; Tsao, Tzu-Chein; Tang, Jaw-Luen; Wu, Wei-Te

2010-01-01

A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated could range from three to seven. Each D-shaped zone covered a sensor volume of 100 μm depth, 250 μm width, and 1 mm length. The mean roughness of the core surface obtained by the AFM images was 231.7 nm, which is relatively smooth. Results of the tensile test indicated that the fibers have sufficient mechanical strength to resist damage from further processing. The multi-D-shaped optical fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 1.27 × 10−3–3.13 × 10−4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the multi-D-shaped fibers are attractive for chemical, biological, and biochemical sensing with aqueous solutions. PMID:22399908

Graphene-clad tapered fiber: effective nonlinearity and propagation losses.

PubMed

Gorbach, A V; Marini, A; Skryabin, D V

2013-12-15

We derive a pulse propagation equation for a graphene-clad optical fiber, treating the optical response of the graphene and nonlinearity of the dielectric fiber core as perturbations in asymptotic expansion of Maxwell equations. We analyze the effective nonlinear and attenuation coefficients due to the graphene layer. Based on the recent experimental measurements of the nonlinear graphene conductivity, we predict considerable enhancement of the effective nonlinearity for subwavelength fiber core diameters.

LP01 to LP11 mode convertor based on side-polished small-core single-mode fiber

NASA Astrophysics Data System (ADS)

Liu, Yan; Li, Yang; Li, Wei-dong

2018-03-01

An all-fiber LP01-LP11 mode convertor based on side-polished small-core single-mode fibers (SMFs) is numerically demonstrated. The linearly polarized incident beam in one arm experiences π shift through a fiber half waveplate, and the side-polished parts merge into an equivalent twin-core fiber (TCF) which spatially shapes the incident LP01 modes to the LP11 mode supported by the step-index few-mode fiber (FMF). Optimum conditions for the highest conversion efficiency are investigated using the beam propagation method (BPM) with an approximate efficiency as high as 96.7%. The proposed scheme can operate within a wide wavelength range from 1.3 μm to1.7 μm with overall conversion efficiency greater than 95%. The effective mode area and coupling loss are also characterized in detail by finite element method (FEM).

Temperature and strain characterization of long period gratings in air guiding fiber

NASA Astrophysics Data System (ADS)

Iadicicco, Agostino; Cutolo, Antonello; Cusano, Andrea; Campopiano, Stefania

2013-05-01

This paper reports on the fabrication of Long Period Gratings (LPGs) in hollow-core air-silica photonic bandgap fibers by using pressure assisted Electrode Arc Discharge (EAD) technique. In particular, the fabrication procedure relies on the combined use of EAD step, to locally heat the HC fiber, and of a static pressure (slightly higher than the external one) inside the fiber holes, to modify the holes. This procedure permits to preserve the holey structure of the host fiber avoiding any hole collapsing and it enables a local effective refractive index change due to the size and shape modifications of core and cladding holes. Periodically repeated EAD treatments permit the fabrication of LPGs based devices in hollow core optical fibers enabling new functionalities hitherto not possible. Here, the experimental fabrication of LPG prototypes with different periods and lengths are discussed. And, the HC-LPGs sensitivity to environmental parameters such as strain and temperature are investigated.

Hollow steel tips for reducing distal fiber burn-back during thulium fiber laser lithotripsy.

PubMed

Hutchens, Thomas C; Blackmon, Richard L; Irby, Pierce B; Fried, Nathaniel M

2013-07-01

The use of thulium fiber laser (TFL) as a potential alternative laser lithotripter to the clinical holmium:YAG laser is being studied. The TFL's Gaussian spatial beam profile provides efficient coupling of higher laser power into smaller core fibers without proximal fiber tip degradation. Smaller fiber diameters are more desirable, because they free up space in the single working channel of the ureteroscope for increased saline irrigation rates and allow maximum ureteroscope deflection. However, distal fiber tip degradation and "burn-back" increase as fiber diameter decreases due to both excessive temperatures and mechanical stress experienced during stone ablation. To eliminate fiber tip burn-back, the distal tip of a 150-μm core silica fiber was glued inside 1-cm-long steel tubing with fiber tip recessed 100, 250, 500, 1000, or 2000 μm inside the steel tubing to create the hollow-tip fiber. TFL pulse energy of 34 mJ with 500-μs pulse duration and 150-Hz pulse rate was delivered through the hollow-tip fibers in contact with human calcium oxalate monohydrate urinary stones during ex vivo studies. Significant fiber tip burn-back and degradation was observed for bare 150-μm core-diameter fibers. However, hollow steel tip fibers experienced minimal fiber burn-back without compromising stone ablation rates. A simple, robust, compact, and inexpensive hollow fiber tip design was characterized for minimizing distal fiber burn-back during the TFL lithotripsy. Although an increase in stone retropulsion was observed, potential integration of the hollow fiber tip into a stone basket may provide rapid stone vaporization, while minimizing retropulsion.

Ultrabroadband polarization splitter based on three-core photonic crystal fiber with a modulation core.

PubMed

Zhao, Tongtong; Lou, Shuqin; Wang, Xin; Zhou, Min; Lian, Zhenggang

2016-08-10

We design an ultrabroadband polarization splitter based on three-core photonic crystal fiber (PCF). A modulation core and two fluorine-doped cores are introduced to achieve an ultrawide bandwidth. The properties of three-core PCF are modeled by using the full-vector finite element method along with the full-vector beam propagation method. Numerical results demonstrate that an ultrabroadband splitter with 320 nm bandwidth with an extinction ratio as low as -20  dB can be achieved by using 52.8 mm long three-core PCF. This splitter also has high compatibility with standard single-mode fibers as the input and output ports due to low splicing loss of 0.02 dB. All the air holes in the proposed structure are circular holes and arranged in a triangular lattice that makes it easy to fabricate.

Efficient 1.5-μm Raman generation in ethane-filled hollow-core fiber

NASA Astrophysics Data System (ADS)

Chen, Yubin; Gu, Bo; Wang, Zefeng; Lu, Qisheng

2016-11-01

We demonstrated for the first time a novel and effective method for obtaining both high peak-power and narrow linewidth 1.5 μm fiber sources through gas Raman effect in hollow core fibers. An Ethane-filled ice-cream antiresonance hollow-core fiber is pumped with a high peak-power pulse 1064 nm microchip laser, generating 1552.7 nm Stokes wave by pure vibrational stimulated Raman scattering of ethane molecules. A maximum peak-power of about 400 kW is achieved with 6 meter fiber length at 2 bar pressure, and the linewidth is about 6.3 GHz. The maximum Raman conversion efficiency of 1064 nm to 1552.7 nm is about 38%, and the corresponding laser slope efficiency is about 61.5%.

Light-weight sandwich panel honeycomb core with hybrid carbon-glass fiber composite skin for electric vehicle application

NASA Astrophysics Data System (ADS)

Cahyono, Sukmaji Indro; Widodo, Angit; Anwar, Miftahul; Diharjo, Kuncoro; Triyono, Teguh; Hapid, A.; Kaleg, S.

2016-03-01

The carbon fiber reinforced plastic (CFRP) composite is relative high cost material in current manufacturing process of electric vehicle body structure. Sandwich panels consisting polypropylene (PP) honeycomb core with hybrid carbon-glass fiber composite skin were investigated. The aim of present paper was evaluate the flexural properties and bending rigidity of various volume fraction carbon-glass fiber composite skins with the honeycomb core. The flexural properties and cost of panels were compared to the reported values of solid hybrid Carbon/Glass FRP used for the frame body structure of electric vehicle. The finite element model of represented sandwich panel was established to characterize the flexural properties of material using homogenization technique. Finally, simplified model was employed to crashworthiness analysis for engine hood of the body electric vehicle structure. The good cost-electiveness of honeycomb core with hybrid carbon-glass fiber skin has the potential to be used as a light-weight alternative material in body electric vehicle fabricated.

Twin-Core Fiber-Based Mach Zehnder Interferometer for Simultaneous Measurement of Strain and Temperature

PubMed Central

Kowal, Dominik; Urbanczyk, Waclaw; Mergo, Pawel

2018-01-01

In this paper we present an all-fiber interferometric sensor for the simultaneous measurement of strain and temperature. It is composed of a specially fabricated twin-core fiber spliced between two pieces of a single-mode fiber. Due to the refractive index difference between the two cores in a twin-core fiber, a differential interference pattern is produced at the sensor output. The phase response of the interferometer to strain and temperature is measured in the 850–1250 nm spectral range, showing zero sensitivity to strain at 1000 nm. Due to the significant difference in sensitivities to both parameters, our interferometer is suitable for two-parameter sensing. The simultaneous response of the interferometer to strain and temperature was studied using the two-wavelength interrogation method and a novel approach based on the spectral fitting of the differential phase response. As the latter technique uses all the gathered spectral information, it is more reliable and yields the results with better accuracy. PMID:29558386

Mid-infrared 1  W hollow-core fiber gas laser source.

PubMed

Xu, Mengrong; Yu, Fei; Knight, Jonathan

2017-10-15

We report the characteristics of a 1 W hollow-core fiber gas laser emitting CW in the mid-IR. Our system is based on an acetylene-filled hollow-core optical fiber guiding with low losses at both the pump and laser wavelengths and operating in the single-pass amplified spontaneous emission regime. Through systematic characterization of the pump absorption and output power dependence on gas pressure, fiber length, and pump intensity, we determine that the reduction of pump absorption at high pump flux and the degradation of gain performance at high gas pressure necessitate the use of increased gain fiber length for efficient lasing at higher powers. Low fiber attenuation is therefore key to efficient high-power laser operation. We demonstrate 1.1 W output power at a 3.1 μm wavelength by using a high-power erbium-doped fiber amplifier pump in a single-pass configuration, approximately 400 times higher CW output power than in the ring cavity previously reported.

All-fiber gas sensor with intracavity photothermal spectroscopy.

PubMed

Zhao, Yan; Jin, Wei; Lin, Yuechuan; Yang, Fan; Ho, Hoi Lut

2018-04-01

We present an all-fiber intracavity photothermal (IC-PT) spectroscopic gas sensor with a hollow-core photonic bandgap fiber (HC-PBF) gas cell. The gas cell is placed inside a fiber-ring laser cavity to achieve higher laser light intensity in the hollow core and hence higher PT modulation signal. An experiment with a 0.62-m-long HC-PBF gas cell demonstrated a noise equivalent concentration of 176 ppb acetylene. Theoretical modeling shows that the IC-PT sensor has the potential of achieving sub-ppb (parts-per-billion) acetylene detection sensitivity.

Polarization characteristics of double-clad elliptical fibers.

PubMed

Zhang, F; Lit, J W

1990-12-20

A scalar variational analysis based on a Gaussian approximation of the fundamental mode of a double-clad elliptical fiber with a depressed inner cladding is studied. The polarization properties and graphic results are presented; they are given in terms of three parameters: the ratio of the major axis to the minor axis of the core, the ratio of the inner cladding major axis to the core major axis, and the difference between the core index and the inner cladding index. The variations of both the spot size and the field intensity with core ellipticity are examined. It is shown that high birefringence and dispersion-free orthogonal polarization modes can be obtained within the single-mode region and that the field intensity distribution may be more confined to the fiber center than in a single-clad elliptical fiber.

Fiber optic refractive index monitor

DOEpatents

Weiss, Jonathan David

2002-01-01

A sensor for measuring the change in refractive index of a liquid uses the lowest critical angle of a normal fiber optic to achieve sensitivity when the index of the liquid is significantly less than the index of the fiber core. Another embodiment uses a liquid filled core to ensure that its index is approximately the same as the liquid being measured.

Photonic bandgap narrowing in conical hollow core Bragg fibers

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

Ozturk, Fahri Emre; Yildirim, Adem; Kanik, Mehmet

2014-08-18

We report the photonic bandgap engineering of Bragg fibers by controlling the thickness profile of the fiber during the thermal drawing. Conical hollow core Bragg fibers were produced by thermal drawing under a rapidly alternating load, which was applied by introducing steep changes to the fiber drawing speed. In conventional cylindrical Bragg fibers, light is guided by omnidirectional reflections from interior dielectric mirrors with a single quarter wave stack period. In conical fibers, the diameter reduction introduced a gradient of the quarter wave stack period along the length of the fiber. Therefore, the light guided within the fiber encountered slightlymore » smaller dielectric layer thicknesses at each reflection, resulting in a progressive blueshift of the reflectance spectrum. As the reflectance spectrum shifts, longer wavelengths of the initial bandgap cease to be omnidirectionally reflected and exit through the cladding, which narrows the photonic bandgap. A narrow transmission bandwidth is particularly desirable in hollow waveguide mid-infrared sensing schemes, where broadband light is coupled to the fiber and the analyte vapor is introduced into the hollow core to measure infrared absorption. We carried out sensing simulations using the absorption spectrum of isopropyl alcohol vapor to demonstrate the importance of narrow bandgap fibers in chemical sensing applications.« less

Infrared light sensor applied to early detection of tooth decay

NASA Astrophysics Data System (ADS)

Benjumea, Eberto; Espitia, José; Díaz, Leonardo; Torres, Cesar

2017-08-01

The approach dentistry to dental care is gradually shifting to a model focused on early detection and oral-disease prevention; one of the most important methods of prevention of tooth decay is opportune diagnosis of decay and reconstruction. The present study aimed to introduce a procedure for early diagnosis of tooth decay and to compare result of experiment of this method with other common treatments. In this setup, a laser emitting infrared light is injected in core of one bifurcated fiber-optic and conduced to tooth surface and with the same bifurcated fiber the radiation reflected for the same tooth is collected and them conduced to surface of sensor that measures thermal and light frequencies to detect early signs of decay below a tooth surface, where demineralization is difficult to spot with x-ray technology. This device will can be used to diagnose tooth decay without any chemicals and rays such as high power lasers or X-rays.

The solvation structures of cellulose microfibrils in ionic liquids.

PubMed

Mostofian, Barmak; Smith, Jeremy C; Cheng, Xiaolin

2011-12-01

The use of ionic liquids for non-derivatized cellulose dissolution promises an alternative method for the thermochemical pretreatment of biomass that may be more efficient and environmentally acceptable than more conventional techniques in aqueous solution. Here, we performed equilibrium MD simulations of a cellulose microfibril in the ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) and compared the solute structure and the solute-solvent interactions at the interface with those from corresponding simulations in water. The results indicate a higher occurrence of solvent-exposed orientations of cellulose surface hydroxymethyl groups in BmimCl than in water. Moreover, spatial and radial distribution functions indicate that hydrophilic surfaces are a preferred site of interaction between cellulose and the ionic liquid. In particular, hydroxymethyl groups on the hydrophilic fiber surface adopt a different conformation from their counterparts oriented towards the fiber's core. Furthermore, the glucose units with these solvent-oriented hydroxymethyls are surrounded by the heterocyclic organic cation in a preferred parallel orientation, suggesting a direct and distinct interaction scheme between cellulose and BmimCl.

Thin metal bilayer for surface plasmon resonance sensors in a multimode plastic optical fiber: the case of palladium and gold metal films

NASA Astrophysics Data System (ADS)

Cennamo, Nunzio; Zuppella, Paola; Bacco, Davide; Corso, Alain J.; Pelizzo, Maria G.; Pesavento, Maria; Zeni, Luigi

2016-05-01

A novel sensing platform based on thin metal bilayer for surface plasmon resonance (SPR) in a D-shaped plastic optical fiber (POF) has been designed, implemented and tested. The experimental results are congruent with the numerical studies. This platform has been properly optimized to work in the 1.38 -1.42 refractive index range and it exhibits excellent sensitivity. This refractive index range is very interesting for bio-chemical applications, where the polymer layer are used as receptors (e.g. molecularly imprinted polymer) or to immobilize the bio-receptor on the metal surface. The proposed metallic bilayer is based on palladium and gold films and replaces the traditional gold by exhibiting higher performances. Furthermore, the deposition of the thin bilayer is a single process and no further manufacturing step is required. In fact, in this case the photoresist buffer layer between the POF core and the metal layer, usually required to increase the refractive index range, is no longer necessary.

Fiber-based three-dimensional multi-mode interference device as efficient power divider and vector curvature sensor

NASA Astrophysics Data System (ADS)

Zhang, Ziyang; Fiebrandt, Julia; Haynes, Dionne; Sun, Kai; Madhav, Kalaga; Stoll, Andreas; Makan, Kirill; Makan, Vadim; Roth, Martin

2018-03-01

Three-dimensional multi-mode interference devices are demonstrated using a single-mode fiber (SMF) center-spliced to a section of polygon-shaped core multimode fiber (MMF). This simple structure can effectively generate well-localized self-focusing spots that match to the layout of a chosen multi-core fiber (MCF) as a launcher device. An optimized hexagon-core MMF can provide efficient coupling from a SMF to a 7-core MCF with an insertion loss of 0.6 dB and a power imbalance of 0.5 dB, while a square-core MMF can form a self-imaging pattern with symmetrically distributed 2 × 2, 3 × 3 or 4 × 4 spots. These spots can be directly received by a two-dimensional detector array. The device can work as a vector curvature sensor by comparing the relative power among the spots with a resolution of ∼0.1° over a 1.8 mm-long MMF.

Star-pseudopolyrotaxane organized in nanoplatelets for poly(ε-caprolactone)-based nanofibrous scaffolds with enhanced surface reactivity.

PubMed

Oster, Murielle; Hébraud, Anne; Gallet, Sébastien; Lapp, Alain; Pollet, Eric; Avérous, Luc; Schlatter, Guy

2015-02-01

Herein, it is demonstrated that star pseudopolyrotaxanes (star-pPRs) obtained from the inclusion complexation of α-cyclodextrin (CD) and four-branched star poly(ε-caprolactone) (star-PCL) organize into nanoplatelets in dimethyl sulfoxide at 35 °C. This peculiar property, not observed for linear pseudopolyrotaxanes, allows the processing of star-pPRs while preserving their supramolecular assembly. Thus, original PCL:star-pPR core:shell nanofibers are elaborated by coaxial electrospinning. The star-pPR shell ensures the presence of available CD hydroxyl functions on the fiber surface allowing its postfunctionalization. As proof of concept, fluorescein isothiocyanate is grafted. Moreover, the morphology of the fibers is maintained due to the star-pPR shell that acts as a shield, preventing the fiber dissolution during chemical modification. The proposed strategy is simple and avoids the synthesis of polyrotaxanes, i.e., pPR end-capping to prevent the CD dethreading. As PCL is widely used for biomedical applications, this strategy paves the way for simple functionalization with any bioactive molecules. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Post-Buckling Analysis of Curved Honeycomb Sandwich Panels Containing Interfacial Disbonds

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Bednarcyk, Brett A.; Krivanek, Thomas K.

2016-01-01

A numerical study on the effect of facesheet-core disbonds on the post-buckling response of curved honeycomb sandwich panels is presented herein. This work was conducted as part of the development of a damage tolerance plan for the next-generation Space Launch System heavy lift launch vehicle payload fairing. As such, the study utilized full-scale fairing barrel segments as the structure of interest. The panels were composed of carbon fiber reinforced polymer facesheets and aluminum honeycomb core. The panels were analyzed numerically using the finite element method incorporating geometric nonlinearity. In a predetermined circular region, facesheet and core nodes were detached to simulate a disbond, between the outer mold line facesheet and honeycomb core, induced via low-speed impact. Surface-to-surface contact in the disbonded region was invoked to prevent interpenetration of the facesheet and core elements and obtain realistic stresses in the core. The diameter of this disbonded region was varied and the effect of the size of the disbond on the post-buckling response was observed. Significant changes in the slope of the edge load-deflection response were used to determine the onset of global buckling and corresponding buckling load. Finally, several studies were conducted to determine the sensitivity of the numerical predictions to refinement in the finite element mesh.

Characteristics of 1.9-μm laser emission from hydrogen-filled hollow-core fiber by vibrational stimulated Raman scattering

NASA Astrophysics Data System (ADS)

Gu, Bo; Chen, Yubin; Wang, Zefeng

2016-12-01

We report here the characteristics of 1.9-μm laser emission from a gas-filled hollow-core fiber by stimulated Raman scattering (SRS). A 6.5-m hydrogen-filled ice-cream negative curvature hollow-core fiber is pumped with a high peak-power, narrow linewidth, linearly polarized subnanosecond pulsed 1064-nm microchip laser, generating a pulsed vibrational Stokes wave at 1908.5 nm. The maximum quantum efficiency of about 48% is obtained, which is mainly limited by the mode mismatch between the pump laser beam and the Stokes wave in the hollow-core fiber. The linewidths of the pump laser and the first-order vibrational Stokes wave are measured to be about 1 and 2 GHz, respectively, by a scanning Fabry-Perot interferometer. The pressure selection phenomenon of the vibrational anti-Stokes waves is also investigated. The pulse duration of the vibrational Stokes wave is recorded to be narrower than that of the pump laser. The polarization properties of the hollow-core fiber and the polarization dependence of the vibrational and the rotational SRS are also studied. The beam profile of the vibrational Stokes wave shows good quality.

Design and analysis of large-core single-mode windmill single crystal sapphire optical fiber

DOE PAGES

Cheng, Yujie; Hill, Cary; Liu, Bo; ...

2016-06-01

We present a large-core single-mode “windmill” single crystal sapphire optical fiber (SCSF) design, which exhibits single-mode operation by stripping off the higher-order modes (HOMs) while maintaining the fundamental mode. The “windmill” SCSF design was analyzed using the finite element analysis method, in which all the HOMs are leaky. The numerical simulation results show single-mode operation in the spectral range from 0.4 to 2 μm in the windmill SCSF, with an effective core diameter as large as 14 μm. Such fiber is expected to improve the performance of many of the current sapphire fiber optic sensor structures.

Tunable arbitrary unitary transformer based on multiple sections of multicore fibers with phase control.

PubMed

Zhou, Junhe; Wu, Jianjie; Hu, Qinsong

2018-02-05

In this paper, we propose a novel tunable unitary transformer, which can achieve arbitrary discrete unitary transforms. The unitary transformer is composed of multiple sections of multi-core fibers with closely aligned coupled cores. Phase shifters are inserted before and after the sections to control the phases of the waves in the cores. A simple algorithm is proposed to find the optimal phase setup for the phase shifters to realize the desired unitary transforms. The proposed device is fiber based and is particularly suitable for the mode division multiplexing systems. A tunable mode MUX/DEMUX for a three-mode fiber is designed based on the proposed structure.

Polarization splitter in three-core photonic crystal fibers.

PubMed

Saitoh, Kunimasa; Sato, Y; Koshiba, M

2004-08-23

A novel design of polarization splitter in three-core photonic crystal fibers (PCFs) has been proposed. The three-core PCF consists of two given identical cores with two-fold symmetry separated by a core with high birefringence. The polarization splitter is based on the phenomenon of resonant tunneling. Numerical simulations with a full vectorial beam propagation method demonstrate that it is possible to obtain a 1.9-mm-long splitter with the extinction ratio better than -20 dB and a bandwidth of 37nm.

Vector mode conversion based on tilted fiber Bragg grating in ring-core fibers

NASA Astrophysics Data System (ADS)

Mi, Yuean; Ren, Guobin; Gao, Yixiao; Li, Haisu; Zhu, Bofeng; Liu, Yu

2018-03-01

We propose a vector mode conversion approach based on tilted fiber Bragg grating (TFBG) written in ring-core fiber with effective separation of eigenmodes. The mode coupling properties of TFBG are numerically investigated. It is shown that under the constraint of phase matching, the conversion of high-order vector modes could be achieved at specific wavelengths. Moreover, the polarization of incident light and tilt angle of TFBG play critical roles in mode coupling process. The proposed TFBG provides an efficient method to realize high-order vector mode conversion, and it shows great potential for fibers based OAM beam generation and fiber lasers with vortex beams output.

2013 R&D 100 Award: New tech could mean more power for fiber lasers

ScienceCinema

Dawson, Jay

2018-01-16

An LLNL team of six physicists has developed a new technology that is a stepping stone to enable some of the limitations on high-power fiber lasers to be overcome. Their technology, dubbed "Efficient Mode-Converters for High-Power Fiber Amplifiers," allows the power of fiber lasers to be increased while maintaining high beam quality. Currently, fiber lasers are used in machining, on factory floors and in a number of defense applications and can produce tens of kilowatts of power.The conventional fiber laser design features a circular core and has fundamental limitations that make it impractical to allow higher laser power unless the core area is increased. LLNL researchers have pioneered a design to increase the laser's core area along the axis of the ribbon fiber. Their design makes it difficult to use a conventional laser beam, so the LLNL team converted the beam into a profile that propagates into the ribbon fiber and is converted back once it is amplified. The use of this LLNL technology will permit the construction of higher power lasers for lower costs and increase the power of fiber lasers from tens of kilowatts of power to about 100 kilowatts and potentially even higher.

Soliton propagation in tapered silicon core fibers.

PubMed

Peacock, Anna C

2010-11-01

Numerical simulations are used to investigate soliton-like propagation in tapered silicon core optical fibers. The simulations are based on a realistic tapered structure with nanoscale core dimensions and a decreasing anomalous dispersion profile to compensate for the effects of linear and nonlinear loss. An intensity misfit parameter is used to establish the optimum taper dimensions that preserve the pulse shape while reducing temporal broadening. Soliton formation from Gaussian input pulses is also observed--further evidence of the potential for tapered silicon fibers to find use in a range of signal processing applications.

Piezoelectric Micro- and Nanostructured Fibers Fabricated from Thermoplastic Nanocomposites Using a Fiber Drawing Technique: Comparative Study and Potential Applications.

PubMed

Lu, Xin; Qu, Hang; Skorobogatiy, Maksim

2017-02-28

We report an all-polymer flexible piezoelectric fiber that uses both judiciously chosen geometry and advanced materials in order to enhance fiber piezoelectric response. The microstructured/nanostructured fiber features a soft hollow polycarbonate core surrounded by a spiral multilayer cladding consisting of alternating layers of piezoelectric nanocomposites (polyvinylidene enhanced with BaTiO 3 , PZT, or CNT) and conductive polymer (carbon-filled polyethylene). The conductive polymer layers serve as two electrodes, and they also form two spatially offset electric connectors on the fiber surface designed for the ease of connectorization. Kilometer-long piezoelectric fibers of sub-millimeter diameters are thermally drawn from a macroscopic preform. The fibers exhibit high output voltage of up to 6 V under moderate bending, and they show excellent mechanical and electrical durability in a cyclic bend-release test. The micron/nanosize multilayer structure enhances in-fiber poling efficiency due to the small distance between the conducting electrodes sandwiching the piezoelectric composite layers. Additionally, the spiral structure greatly increases the active area of the piezoelectric composite, thus promoting higher voltage generation and resulting in 10-100 higher power generation efficiency over the existing piezoelectric cables. Finally, we weave the fabricated piezoelectric fibers into technical textiles and demonstrate their potential applications in power generation when used as a sound detector, smart car seat upholstery, or wearable materials.

Muscle spindles exhibit core lesions and extensive degeneration of intrafusal fibers in the Ryr1{sup I4895T/wt} mouse model of core myopathy

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

Zvaritch, Elena; MacLennan, David H., E-mail: david.maclennan@utoronto.ca

Muscle spindles from the hind limb muscles of adult Ryr1{sup I4895T/wt} (IT/+) mice exhibit severe structural abnormalities. Up to 85% of the spindles are separated from skeletal muscle fascicles by a thick layer of connective tissue. Many intrafusal fibers exhibit degeneration, with Z-line streaming, compaction and collapse of myofibrillar bundles, mitochondrial clumping, nuclear shrinkage and pyknosis. The lesions resemble cores observed in the extrafusal myofibers of this animal model and of core myopathy patients. Spindle abnormalities precede those in extrafusal fibers, indicating that they are a primary pathological feature in this murine Ryr1-related core myopathy. Muscle spindle involvement, if confirmedmore » for human core myopathy patients, would provide an explanation for an array of devastating clinical features characteristic of these diseases and provide novel insights into the pathology of RYR1-related myopathies. - Highlights: • Muscle spindles exhibit structural abnormalities in a mouse model of core myopathy. • Myofibrillar collapse and mitochondrial clumping is observed in intrafusal fibers. • Myofibrillar degeneration follows a pattern similar to core formation in extrafusal myofibers. • Muscle spindle abnormalities are a part of the pathological phenotype in the mouse model of core myopathy. • Direct involvement of muscle spindles in the pathology of human RYR1-related myopathies is proposed.« less

Nanofiber Based Optical Sensors for Oxygen Determination

NASA Astrophysics Data System (ADS)

Xue, Ruipeng

Oxygen sensors based on luminescent quenching of nanofibers were developed for measurement of both gaseous and dissolved oxygen concentrations. Electrospinning was used to fabricate "core-shell" fiber configurations in which oxygen-sensitive transition metal complexes are embedded into a polymer 'core' while a synthetic biocompatible polymer provides a protective 'shell.' Various matrix polymers and luminescent probes were studied in terms of their sensitivity, linear calibration, reversibility, response time, stability and probe-matrix interactions. Due to the small size and high surface area of these nanofibers, all samples showed rapid response and a highly linear response to oxygen. The sensitivity and photostability of the sensors were controlled by the identity of both the probe molecule and the polymer matrix. Such nanofiber sensor forms are particularly suitable in biological applications due to the fact that they do not consume oxygen, are biocompatible and biomimetic and can be easily incorporated into cell culture. Applications of these fibers in cancer cell research, wound healing, breath analysis and waste water treatment were explored.

Lightweight bipolar storage battery

NASA Technical Reports Server (NTRS)

Rowlette, John J. (Inventor)

1992-01-01

An apparatus [10] is disclosed for a lightweight bipolar battery of the end-plate cell stack design. Current flow through a bipolar cell stack [12] is collected by a pair of copper end-plates [16a,16b] and transferred edgewise out of the battery by a pair of lightweight, low resistance copper terminals [28a,28b]. The copper terminals parallel the surface of a corresponding copper end-plate [16a,16b] to maximize battery throughput. The bipolar cell stack [12], copper end-plates [16a,16b] and copper terminals [28a,28b] are rigidly sandwiched between a pair of nonconductive rigid end-plates [20] having a lightweight fiber honeycomb core which eliminates distortion of individual plates within the bipolar cell stack due to internal pressures. Insulating foam [30] is injected into the fiber honeycomb core to reduce heat transfer into and out of the bipolar cell stack and to maintain uniform cell performance. A sealed battery enclosure [ 22] exposes a pair of terminal ends [26a,26b] for connection with an external circuit.

Determining the minimum conditions for soda-anthraquinone pulping of kenaf bast, core, and whole stalk fibers

Treesearch

James S. Han; Thomas A. Rymsza

1999-01-01

Chemical pulping of kenaf fiber is comparatively new. In this study, bast, core, and whole stalk kenaf fibers were pulped using a soda-AQ pulping process and various pulping conditions. Handsheets were evaluated for density, Canadian standard freeness, brightness, opacity, smoothness, and tensile, burst, and tear indexes and strength. The results indicate that...

Development of self-sensing BFRP bars with distributed optic fiber sensors

NASA Astrophysics Data System (ADS)

Tang, Yongsheng; Wu, Zhishen; Yang, Caiqian; Shen, Sheng; Wu, Gang; Hong, Wan

2009-03-01

In this paper, a new type of self-sensing basalt fiber reinforced polymer (BFRP) bars is developed with using the Brillouin scattering-based distributed optic fiber sensing technique. During the fabrication, optic fiber without buffer and sheath as a core is firstly reinforced through braiding around mechanically dry continuous basalt fiber sheath in order to survive the pulling-shoving process of manufacturing the BFRP bars. The optic fiber with dry basalt fiber sheath as a core embedded further in the BFRP bars will be impregnated well with epoxy resin during the pulling-shoving process. The bond between the optic fiber and the basalt fiber sheath as well as between the basalt fiber sheath and the FRP bar can be controlled and ensured. Therefore, the measuring error due to the slippage between the optic fiber core and the coating can be improved. Moreover, epoxy resin of the segments, where the connection of optic fibers will be performed, is uncured by isolating heat from these parts of the bar during the manufacture. Consequently, the optic fiber in these segments of the bar can be easily taken out, and the connection between optic fibers can be smoothly carried out. Finally, a series of experiments are performed to study the sensing and mechanical properties of the propose BFRP bars. The experimental results show that the self-sensing BFRP bar is characterized by not only excellent accuracy, repeatability and linearity for strain measuring but also good mechanical property.

[Comparison of clinical effects of Co-Cr alloy cast post-core and everStick fiber post in restoration of labially or lingually inclined maxillary central incisor].

PubMed

Qian, Yu-Mei; Zhong, Qun; Chen, Shuang

2017-02-01

To compare the clinical effect of Co-Cr alloy cast post-core and everStick fiber post in restoration of maxillary central incisor with labial or lingual inclination, and provide theoretical basis for clinical application. Ninety-seven labially or lingually inclined maxillary central incisors were treated in our hospital from March 2012 to March 2014. The patients were randomly divided into group A (n=49) and group B (n=48), and received post -core and crown restoration. Patients in group A underwent Co-Cr alloy cast post and core restoration and patients in group B underwent everStick fiber post and core restoration. After two-year of follow-up, root fracture, post break, crown or post dislodgment and gingival marginal discoloration were recorded and analyzed using SPSS 19.0 software package. Chi-square test showed that the success rate of restoration was significantly different between 2 groups (P<0.05). The incidence of root fracture and gingival marginal discoloration of Co-Cr alloy cast post-core was higher than that of everStick fiber post, but there was no significant difference in the incidence of post break, crown or post dislodgment. EverStick fiber post is better than Co-Cr alloy cast post and core to prevent root fracture and gingival marginal discoloration. Its fracture pattern is repairable and favorable for preserving tooth.

Hemodynamic monitoring in different cortical layers with a single fiber optical system

NASA Astrophysics Data System (ADS)

Yu, Linhui; Noor, M. Sohail; Kiss, Zelma H. T.; Murari, Kartikeya

2018-02-01

Functional monitoring of highly-localized deep brain structures is of great interest. However, due to light scattering, optical methods have limited depth penetration or can only measure from a large volume. In this research, we demonstrate continuous measurement of hemodynamics in different cortical layers in response to thalamic deep brain stimulation (DBS) using a single fiber optical system. A 200-μm-core-diameter multimode fiber is used to deliver and collect light from tissue. The fiber probe can be stereotaxically implanted into the brain region of interest at any depth to measure the di use reflectance spectra from a tissue volume of 0.02-0.03 mm3 near the fiber tip. Oxygenation is then extracted from the reflectance spectra using an algorithm based on Monte Carlo simulations. Measurements were performed on the surface (cortical layer I) and at 1.5 mm depth (cortical layer VI) of the motor cortex in anesthetized rats with thalamic DBS. Preliminary results revealed the oxygenation changes in response to DBS. Moreover, the baseline as well as the stimulus-evoked change in oxygenation were different at the two depths of cortex.

Chalcogenide fiber-optic SPR chemical sensor with MoS2 monolayer, polymer clad, and polythiophene layer in NIR using selective ray launching

NASA Astrophysics Data System (ADS)

Sharma, Anuj K.; Kaur, Baljinder

2018-07-01

Surface plasmon resonance (SPR) based chalcogenide fiber-optic sensor with polymer clad and MoS2 monolayer is simulated and analyzed in near infrared (NIR) for detection of mixture of alcohols (ethanol and methanol) dissolved in water solution. The proposed fiber optic sensor is analyzed under angular interrogation method, which is based on selective ray (on-axis) launching of monochromatic light into the fiber core at varying angle followed by measuring the loss of power (in dB) after passing through the SPR probe region. The performance of the sensor is analyzed in terms of its figure of merit (FOM). The sensor's specificity towards alcohols along with considerably larger FOM is achieved by utilizing a polythiophene (PT) layer. The results indicate that longer NIR wavelength (λ) provides superior sensing performance. The sensor's performance is better for larger volume fraction of methanol in the water solution. The proposed fiber optic SPR sensor has the capability of providing much greater FOM compared with the previously-reported SPR sensors.

Studies in fiber guided excimer laser surgery for cutting and drilling bone and meniscus.

PubMed

Dressel, M; Jahn, R; Neu, W; Jungbluth, K H

1991-01-01

Our experiments on transmitting high-power excimer laser pulses through optical fibers and our investigations on excimer laser ablation of hard tissue show the feasibility of using the excimer laser as an additional instrument in general and accident surgery involving minimal invasive surgery. By combining XeCl-excimer lasers and tapered fused silica fibers we obtained output fluences up to 32 J/cm2 and ablation rates of 3 microns/pulse of hard tissue. This enables us to cut bone and cartilage in a period of time which is suitable for clinical operations. Various experiments were carried out on cadavers in order to optimize the parameters of the excimer laser and fibers: e.g., wavelength, pulse duration, energy, repetition rate, fiber core diameter. The surfaces of the cut tissue are comparable to cuts with conventional instruments. No carbonisation was observed. The temperature increase is below 40 degrees C in the tissue surrounding the laser spot. The healing rate of an excimer laser cut is not slower than mechanical treatments; the quality is comparable.

Immunosensing with Near-Infrared Plasmonic Optical Fiber Gratings.

PubMed

Caucheteur, Christophe; Ribaut, Clotilde; Malachovska, Viera; Wattiez, Ruddy

2017-01-01

Surface Plasmon resonance (SPR) optical fiber biosensors constitute a miniaturized counterpart to the bulky prism configuration and offer remote operation in very small volumes of analyte. They are a cost-effective and relatively straightforward technique to yield in situ (or even possibly in vivo) molecular detection. They are usually obtained from a gold-coated fiber segment for which the core-guided light is brought into contact with the surrounding medium, either by etching (or side-polishing) or by using grating coupling. Recently, SPR generation was achieved in gold-coated tilted fiber Bragg gratings (TFBGs). These sensors probe the surrounding medium with near-infrared narrowband resonances, which enhances both the penetration depth of the evanescent field in the external medium and the wavelength resolution of the interrogation. They constitute the unique configuration able to probe all the fiber cladding modes individually, with high Q-factors. We use these unique spectral features in our work to sense proteins and extra-cellular membrane receptors that are both overexpressed in cancerous tissues. Impressive limit of detection (LOD) and sensitivity are reported, which paves the way for the further use of such immunosensors for cancer diagnosis.

Optical fiber tip with point light source of SPPs driven by three-dimensional nanostructured asymmetric metal-insulator-metal layer cap

NASA Astrophysics Data System (ADS)

Oshikane, Yasushi; Murai, Kensuke; Nakano, Motohiro

2015-09-01

Numerical analysis of three dimensional optical electro-magnetic field in a circular-truncated conical optical fiber covered by asymmetric MIM structure has been performed by a commercial finite element method package, COMSOL Multiphysics coupled with Wave Optics Module. The outermost thick metallic layer has twin nano-hole, and the waveguiding twin-hole could draw surface plasmon polaritions (SPPs) excited in the MIM structure to the surface. Finally the guided two SPPs could unite each other and may create a single bright spot. The systematic simulation is continuing, and the results will give us valuable counsel for control of surface plasmon polaritons (SPPs) appearing around the MIM structure and twin nano-hole. (1) Optimal design of the 3D FEM model for 8-core Xeon server and rational approach for the FEM analysis, (2) behavior of SPPs affected by wavelength and polarization of light travel through fiber, (3) change in excitation condition of SPPs caused by shape of the MIM structure and twin-hole, (4) effectiveness of additional nanostructures that are aimed at focusing control of two SPPs come out from the corners of twin-hole, (5) scanning ability of the MIM/twin-hole probe at nanostructured sample surface (i.e. amount of forward and backward scattering of SPPs) will be presented and discussed. Several FIBed prototypes and their characteristic of light emission will also reported.

[Fiber reinforced composite posts: literature review].

PubMed

Frydman, G; Levatovsky, S; Pilo, R

2013-07-01

FRC (Fiber-reinforced composite) posts have been used since the beginning of the 90s with the introduction of carbon fiber posts. Fiber posts are widely used to restore endodontically treated teeth that have insufficient coronal tooth structure. Many in vitro and in vivo studies have shown the advantage of using FRC over prefabricated and cast metal post especially indicated in narrow root canals which are prone to vertically root fracture. The most frequent failure of FRC is debonding of a post at the resin cement/dentin interface. Bonding to dentin may be achieved by using etch-and-rinse and self-etch adhesives. The bond strength formed by self-adhesive cements is noticeably lower in comparison to the bond strength formed with resin cements applied in combination with etch-and-rinse adhesives. In an attempt to maximize resin bonding to fiber posts, several surface treatments have been suggested. Sandblasting with alumina particles results in an increased surface roughness and surface area without affecting the integrity of the post as long as it is applied by 50 microm alumina particles at 2.5 bars for maximally 5 seconds at a distance of 30 mm. The efficiency of post salinization is controversial and its contribution to the retention is of minor importance. Hydrofluoric acid has recently been proposed for etching glass fiber posts but this technique produced substantial damage to the glass fibers and affected the integrity of the post. Delayed cementation of fiber post (at least 24h post endodontic treatment) resulted in higher retentive strengths in comparison to immediate cementation and the best results were obtained when the luting agent was brought into the post space with lentulo spirals or specific syringes. The resin cement film thickness also influences the pullout strengths of fiber-reinforced posts .The highest bond strength values were obtained when the cement layer oversized the post spaces but not larger than 0.3 mm. The use of core build-up materials as post luting cements is not recommended. The use of FRC post, combined with proper adhesive cementation technique can give an excellent solution when restoring endodontically treated teeth that are prone to fracture.

DNA recognition by peptide nucleic acid-modified PCFs: from models to real samples

NASA Astrophysics Data System (ADS)

Selleri, S.; Coscelli, E.; Poli, F.; Passaro, D.; Cucinotta, A.; Lantano, C.; Corradini, R.; Marchelli, R.

2010-04-01

The increased concern, emerged in the last few years, on food products safety has stimulated the research on new techniques for traceability of raw food materials. DNA analysis is one of the most powerful tools for the certification of food quality, and it is presently performed through the polymerase chain reaction technique. Photonic crystal fibers, due to the presence of an array of air holes running along their length, can be exploited for performing DNA recognition by derivatizing hole surfaces and checking hybridization of complementary nucledotide chains in the sample. In this paper the application of a suspended core photonic crystal fiber in the recognition of DNA sequences is discussed. The fiber is characterized in terms of electromagnetic properties by means of a full-vector modal solver based on the finite element method. Then, the performances of the fiber in the recognition of mall synthetic oligonucleotides are discussed, together with a test of the possibility to extend this recognition to samples of DNA of applicative interest, such as olive leaves.

Quantitative analysis and temperature-induced variations of moiré pattern in fiber-coupled imaging sensors.

PubMed

Karbasi, Salman; Arianpour, Ashkan; Motamedi, Nojan; Mellette, William M; Ford, Joseph E

2015-06-10

Imaging fiber bundles can map the curved image surface formed by some high-performance lenses onto flat focal plane detectors. The relative alignment between the focal plane array pixels and the quasi-periodic fiber-bundle cores can impose an undesirable space variant moiré pattern, but this effect may be greatly reduced by flat-field calibration, provided that the local responsivity is known. Here we demonstrate a stable metric for spatial analysis of the moiré pattern strength, and use it to quantify the effect of relative sensor and fiber-bundle pitch, and that of the Bayer color filter. We measure the thermal dependence of the moiré pattern, and the achievable improvement by flat-field calibration at different operating temperatures. We show that a flat-field calibration image at a desired operating temperature can be generated using linear interpolation between white images at several fixed temperatures, comparing the final image quality with an experimentally acquired image at the same temperature.

Coupled-mode propagation in multicore fibers characterized by optical low-coherence reflectometry.

PubMed

Salathé, R P; Gilgen, H; Bodmer, G

1996-07-01

A fiber-optical low-coherence ref lectometer has been used to probe a multicore fiber locally at a wavelength of 1.3 microm. This technique allows one to determine the group index of refraction of the modes in the multicore fiber with high accuracy. Light propagation that is due to noncoherent coupling of energy from one fiber core to adjacent cores through cladding modes can be distinguished quantitatively from light propagating in coherently coupled modes. Intercore coupling constants in the range of 0.6-2 mm(-1) have been evaluated for the coupled modes.

Controllable photoinduced optical attenuation in a single-mode optical fiber by irradiation of a femtosecond pulse laser.

PubMed

Himei, Yusuke; Qiu, Jianrong; Nakajima, Sotohiro; Sakamoto, Akihiko; Hirao, Kazuyuki

2004-12-01

Novel optical attenuation fibers were fabricated by the irradiation of a focused infrared femtosecond pulsed laser onto the core of a silica glass single-mode optical fiber. Optical attenuation at a wavelength of 1.55 microm proportionally increased with increasing numbers of irradiation points and was controllable under laser irradiation conditions. The single-mode property of the waveguide and the mode-field diameter of the optical fiber were maintained after irradiation of the femtosecond laser. It is suggested that the attenuation results from optical scattering at photoinduced spots formed inside the fiber core.

Spinnability and Characteristics of Polyvinylidene Fluoride (PVDF)-based Bicomponent Fibers with a Carbon Nanotube (CNT) Modified Polypropylene Core for Piezoelectric Applications

PubMed Central

Glauß, Benjamin; Steinmann, Wilhelm; Walter, Stephan; Beckers, Markus; Seide, Gunnar; Gries, Thomas; Roth, Georg

2013-01-01

This research explains the melt spinning of bicomponent fibers, consisting of a conductive polypropylene (PP) core and a piezoelectric sheath (polyvinylidene fluoride). Previously analyzed piezoelectric capabilities of polyvinylidene fluoride (PVDF) are to be exploited in sensor filaments. The PP compound contains a 10 wt % carbon nanotubes (CNTs) and 2 wt % sodium stearate (NaSt). The sodium stearate is added to lower the viscosity of the melt. The compound constitutes the fiber core that is conductive due to a percolation CNT network. The PVDF sheath’s piezoelectric effect is based on the formation of an all-trans conformation β phase, caused by draw-winding of the fibers. The core and sheath materials, as well as the bicomponent fibers, are characterized through different analytical methods. These include wide-angle X-ray diffraction (WAXD) to analyze crucial parameters for the development of a crystalline β phase. The distribution of CNTs in the polymer matrix, which affects the conductivity of the core, was investigated by transmission electron microscopy (TEM). Thermal characterization is carried out by conventional differential scanning calorimetry (DSC). Optical microscopy is used to determine the fibers’ diameter regularity (core and sheath). The materials’ viscosity is determined by rheometry. Eventually, an LCR tester is used to determine the core’s specific resistance. PMID:28811400

Highly flexible binder-free core-shell nanofibrous electrode for lightweight electrochemical energy storage using recycled water bottles

NASA Astrophysics Data System (ADS)

Shi, HaoTian H.; Naguib, Hani E.

2016-08-01

The creation of a novel flexible nanocomposite fiber with conductive polymer polyaniline (PAni) coating on a polyethylene terephthalate (PET) substrate allowed for increased electrochemical performance while retaining ideal mechanical properties such as very high flexibility. Binder-free PAni-wrapped PET (PAni@PET) fiber with a core-shell structure was successfully fabricated through a novel technique. The PET nanofiber substrate was fabricated through an optimized electrospinning method, while the PAni shell was chemically polymerized onto the surface of the nanofibers. The PET substrate can be made directly from recycled PETE1 grade plastic water bottles. The resulting nanofiber with an average diameter of 121 nm ± 39 nm, with a specific surface area of 83.72 m2 g-1, led to better ionic interactions at the electrode/electrolyte interface. The PAni active layer coating was found to be 69 nm in average thickness. The specific capacitance was found to have increased dramatically from pure PAni with carbon binders. The specific capacitance was found to be 347 F g-1 at a relatively high scan rate of 10 mV s-1. The PAni/PET fiber also experienced very little degradation (4.4%) in capacitance after 1500 galvanostatic charge/discharge cycles at a specific current of 1.2 A g-1. The mesoporous structure of the PAni@PET fibrous mat also allowed for tunable capacitance by controlling the pore sizes. This novel fabrication method offers insights for the utilization of recycled PETE1 based bottles as a high performance, low cost, highly flexible supercapacitor device.

Designing optical-fiber modulators by using magnetic fluids.

PubMed

Horng, H E; Chieh, J J; Chao, Y H; Yang, S Y; Hong, Chin-Yih; Yang, H C

2005-03-01

To reduce interface loss between optical fibers and devices in telecommunication systems, the development of an optical-fiber-based device that can be fused directly with fibers is important. A novel optical modulator consisting of a bare fiber core surrounded by magnetic fluids instead of by a SiO2 cladding layer is proposed. Applying a magnetic field raises the refractive index of the magnetic fluid. Thus we can control the occurrence of total reflection at the interface between the fiber core and the magnetic fluid when light propagates along the fiber. As a result, the intensity of the outgoing light is modulated by variation in field strength. Details of the design, fabrication, and working properties of such a modulator are presented.

Design of vibration sensor based on fiber Bragg grating

NASA Astrophysics Data System (ADS)

Zhang, Zhengyi; Liu, Chuntong

2017-12-01

Fiber grating is a kind of new type of fiber optic light source device which has been rapidly changing in the refractive index of the core in recent years. Especially, it can realize the high precision of the external parameters by means of the special structure design and the encapsulation technology [1, 2]. In this paper, a fiber grating vibration sensor which is suitable for vibration monitoring in key areas is designed based on the technical background of vibration monitoring system. The sensor uses a single beam structure and pastes the fiber Bragg grating (FBG) to measure the vibration wavelength on the surface. When the vibration is simply harmonic vibration, the Bragg reflection wavelength will change periodically, and the periodic variation of the wavelength curve can be measured by the fiber grating demodulator, then the correctness of the experimental results is verified. In this paper, through the analysis of the data measured by the demodulator, the MATLAB software is used to verify the data, and the different frequency domains, the modes, and the phase frequency curves are obtained. The measurement range is 0 Hz-100 Hz, and the natural frequency is 90.6 Hz.

Molecular imprinted polymer-coated optical fiber sensor for the identification of low molecular weight molecules.

PubMed

Lépinay, Sandrine; Ianoul, Anatoli; Albert, Jacques

2014-10-01

A biomimetic optical probe for detecting low molecular weight molecules (maltol, 3-hydroxy-2-methyl-4H-pyran-4-one, molecular weight of 126.11 g/mol), was designed, fabricated, and characterized. The sensor couples a molecular imprinted polymer (MIP) and the Bragg grating refractometry technology into an optical fiber. The probe is fabricated first by inscribing tilted grating planes in the core of the fiber, and then by photopolymerization to immobilize a maltol imprinted MIP on the fiber cladding surface over the Bragg grating. The sensor response to the presence of maltol in different media is obtained by spectral interrogation of the fiber transmission signal. The results showed that the limit of detection of the sensor reached 1 ng/mL in pure water with a sensitivity of 6.3 × 10(8)pm/M. The selectivity of the sensor against other compounds and its reusability were also studied experimentally. Finally, the unambiguous detection of concentrations as little as 10nM of maltol in complex media (real food samples) by the MIP-coated tilted fiber Bragg grating sensor was demonstrated. Copyright © 2014 Elsevier B.V. All rights reserved.

A Simple Small Size and Low Cost Sensor Based on Surface Plasmon Resonance for Selective Detection of Fe(III)

PubMed Central

Cennamo, Nunzio; Alberti, Giancarla; Pesavento, Maria; D'Agostino, Girolamo; Quattrini, Federico; Biesuz, Raffaela; Zeni, Luigi

2014-01-01

A simple, small size, and low cost sensor based on a Deferoxamine Self Assembled Monolayer (DFO-SAM) and Surface Plasmon Resonance (SPR) transduction, in connection with a Plastic Optical Fiber (POF), has been developed for the selective detection of Fe(III). DFO-SAM sensors based on appropriate electrochemical techniques can be frequently found in the scientific literature. In this work, we present the first example of a DFO-SAM sensor based on SPR in an optical fiber. The SPR sensing platform was realized by removing the cladding of a plastic optical fiber along half the circumference, spin coating a buffer of Microposit S1813 photoresist on the exposed core, and finally sputtering a thin gold film. The hydroxamate siderophore deferoxamine (DFO), having high binding affinity for Fe(III), is then used in its immobilized form, as self-assembled monolayer on the gold layer surface of the POF sensor. The results showed that the DFO-SAM-POF-sensor was able to sense the formation of the Fe(III)/DFO complex in the range of concentrations between 1 μm and 50 μm with a linearity range from 0 to 30 μm of Fe(III). The selectivity of the sensor was also proved by interference tests. PMID:24608007

A simple small size and low cost sensor based on surface plasmon resonance for selective detection of Fe(III).

PubMed

Cennamo, Nunzio; Alberti, Giancarla; Pesavento, Maria; D'Agostino, Girolamo; Quattrini, Federico; Biesuz, Raffaela; Zeni, Luigi

2014-03-07

A simple, small size, and low cost sensor based on a Deferoxamine Self Assembled Monolayer (DFO-SAM) and Surface Plasmon Resonance (SPR) transduction, in connection with a Plastic Optical Fiber (POF), has been developed for the selective detection of Fe(III). DFO-SAM sensors based on appropriate electrochemical techniques can be frequently found in the scientific literature. In this work, we present the first example of a DFO-SAM sensor based on SPR in an optical fiber. The SPR sensing platform was realized by removing the cladding of a plastic optical fiber along half the circumference, spin coating a buffer of Microposit S1813 photoresist on the exposed core, and finally sputtering a thin gold film. The hydroxamate siderophore deferoxamine (DFO), having high binding affinity for Fe(III), is then used in its immobilized form, as self-assembled monolayer on the gold layer surface of the POF sensor. The results showed that the DFO-SAM-POF-sensor was able to sense the formation of the Fe(III)/DFO complex in the range of concentrations between 1 μm and 50 μm with a linearity range from 0 to 30 μm of Fe(III). The selectivity of the sensor was also proved by interference tests.

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.

Hollow-core photonic-crystal-fiber-based optical frequency references

NASA Astrophysics Data System (ADS)

Holá, Miroslava; Hrabina, Jan; Mikel, Břetislav; Lazar, Josef; Číp, Ondřej

2016-12-01

This research deals with preparation of an optical frequency references based on hollow-core photonic crystal fibers (HC-PCF). This fiber-based type of absorption cells represents a effiecient way how to replace classic bulky and fragile glass made tubes references with low-weight and low-volume optical fibers. This approach allows not only to increase possible interaction length between incident light and absorption media but it also carries a possibility of manufacturing of easy-operable reference which is set up just by plugging-in of optical connectors into the optical setup. We present the results of preparation, manufacturing and filling of a set of fiber-based cells intended for lasers frequency stabilization. The work deals with setting and optimalization of HC-PCF splicing processes, minimalization of optical losses between HC-PCF and SMF fiber transitions and finishing of HC-PCF spliced ends with special care for optimal closing of hollow-core structure needed for avoiding of absorption media leakage.

Simultaneous monitoring the real and imaginary parts of the analyte refractive index using liquid-core photonic bandgap Bragg fibers.

PubMed

Li, Jingwen; Qu, Hang; Skorobogatiy, Maksim

2015-09-07

We demonstrate simultaneous monitoring of the real and imaginary parts of the liquid analyte refractive index by using a hollow-core Bragg fiber. We apply this two-channel fiber sensor to monitor concentrations of various commercial cooling oils. The sensor operates using spectral monitoring of the fiber bandgap center wavelength, as well as monitoring of the fiber transmission amplitude at mid-bandgap position. The sensitivity of the fiber sensor to changes in the real part of the core refractive index is found to be 1460nm/Refractive index unit (RIU). By using spectral modality and effective medium theory, we determine the concentrations of the two commercial fluids from the measured refractive indices with an accuracy of ~0.57% for both low- and high-loss oils. Moreover, using an amplitude-based detection modality allows determination of the oil concentration with accuracy of ~1.64% for low-loss oils and ~2.81% for the high-loss oils.

Structural characterization of cup-stacked-type nanofibers with an entirely hollow core

NASA Astrophysics Data System (ADS)

Endo, M.; Kim, Y. A.; Hayashi, T.; Fukai, Y.; Oshida, K.; Terrones, M.; Yanagisawa, T.; Higaki, S.; Dresselhaus, M. S.

2002-02-01

Straight long carbon nanofibers with a large hollow core obtained by a floating reactant method show a stacking morphology of truncated conical graphene layers, which in turn exhibit a large portion of open edges on the outer surface and also in the inner channels. Through a judicious choice of oxidation conditions, nanofibers with increased active edge sites are obtained without disrupting the fiber's morphology. A graphitization process induces a morphological change from a tubular type to a reversing saw-toothed type and the formation of loops along the inner channel of the nanofibers, accompanied by a decrease in interlayer spacing.

Combined optical coherence tomography and hyper-spectral imaging

NASA Astrophysics Data System (ADS)

Attendu, Xavier; Guay-Lord, Robin; Strupler, Mathias; Godbout, Nicolas; Boudoux, Caroline

2017-02-01

In this proceeding we demonstrate a system combining optical coherence tomography (OCT) and hyper-spectral imaging (HSI) into a single dual-clad fiber (DCF). Combining these modalities gives access to the sample morphology through OCT and to its molecular content through HSI. Both modalities have their illumination through the fiber core. The OCT is then collected through the core while the HSI is collected through the inner cladding of the DCF. A double-clad fiber coupler (DCFC) is used to address both channels separately. A scanning spectral filter was developed to successively inject narrow spectral bands of visible light into the fiber core and sweep across the entire visible spectrum. This allows for rapid HSI acquisition and high miniaturization potential.

Simple and reliable light launch from a conventional single-mode fiber into a helical-core fiber through an adiabatically tapered splice.

PubMed

Kim, Hyuntai; Kim, Jongki; Jung, Yongmin; Vazquez-Zuniga, Luis Alonso; Lee, Seung Jong; Choi, Geunchang; Oh, Kyunghwan; Wang, Pu; Clarkson, W A; Jeong, Yoonchan

2012-11-05

We propose a simple and efficient light launch scheme for a helical-core fiber (HCF) by using an adiabatically tapered splice technique, through which we overcome its inherent difficulty with light launch owing to the large lateral offset and angular tilt of its core. We experimentally demonstrate single-mode excitation in the HCF in this configuration, which yields the coupling efficiency of around -5.9 dB (26%) for a ~1.1-μm light input when the splice joint is tapered down to 30 μm in diameter. To our knowledge, this is the first proof-of-principle report on the fusion-splice coupling between an HCF and a conventional single-mode fiber.

Amplification and noise properties of an erbium-doped multicore fiber amplifier.

PubMed

Abedin, K S; Taunay, T F; Fishteyn, M; Yan, M F; Zhu, B; Fini, J M; Monberg, E M; Dimarcello, F V; Wisk, P W

2011-08-15

A multicore erbium-doped fiber (MC-EDF) amplifier for simultaneous amplification in the 7-cores has been developed, and the gain and noise properties of individual cores have been studied. The pump and signal radiation were coupled to individual cores of MC-EDF using two tapered fiber bundled (TFB) couplers with low insertion loss. For a pump power of 146 mW, the average gain achieved in the MC-EDF fiber was 30 dB, and noise figure was less than 4 dB. The net useful gain from the multicore-amplifier, after taking into consideration of all the passive losses, was about 23-27 dB. Pump induced ASE noise transfer between the neighboring channel was negligible. © 2011 Optical Society of America

Temperature- and phase-independent lateral force sensor based on a core-offset multi-mode fiber interferometer.

PubMed

Dong, Bo; Zhou, Da-Peng; Wei, Li; Liu, Wing-Ki; Lit, John W Y

2008-11-10

A novel lateral force sensor based on a core-offset multi-mode fiber (MMF) interferometer is reported. High extinction ratio can be obtained by misaligning a fused cross section between the single-mode fiber (SMF) and MMF. With the variation of the lateral force applied to a short section of the MMF, the extinction ratio changes while the interference phase remains almost constant. The change of the extinction ratio is independent of temperature variations. The proposed force sensor has the advantages of temperature- and phase-independency, high extinction ratio sensitivity, good repeatability, low cost, and simple structure. Moreover, the core-offset MMF interferometer is expected to have applications in fiber filters and tunable phase-independent attenuators.

2 × 2 MIMO OFDM/OQAM radio signals over an elliptical core few-mode fiber.

PubMed

Mo, Qi; He, Jiale; Yu, Dawei; Deng, Lei; Fu, Songnian; Tang, Ming; Liu, Deming

2016-10-01

We experimentally demonstrate a 4.46  Gb/s2×2 multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM)/OQAM radio signal over a 2 km elliptical core 3-mode fiber, together with 0.4 m wireless transmission. Meanwhile, to cope with differential channel delay (DCD) among involved MIMO channels, we propose a time-offset crosstalk cancellation algorithm to extend the DCD tolerance from 10 to 60 ns without using a circle prefix (CP), leading to an 18.7% improvement of spectral efficiency. For the purpose of comparison, we also examine the transmission performance of CP-OFDM signals with different lengths of CPs, under the same system configuration. The proposed algorithm is also effective for the DCD compensation of a radio signal over a 2 km 7-core fiber. These results not only demonstrate the feasibility of space division multiplexing for RoF application but also validate that the elliptical core few-mode fiber can provide the same independent channels as the multicore fiber.

Fugitive methane leak detection using mid-infrared hollow-core photonic crystal fiber containing ultrafast laser drilled side-holes

NASA Astrophysics Data System (ADS)

Karp, Jason; Challener, William; Kasten, Matthias; Choudhury, Niloy; Palit, Sabarni; Pickrell, Gary; Homa, Daniel; Floyd, Adam; Cheng, Yujie; Yu, Fei; Knight, Jonathan

2016-05-01

The increase in domestic natural gas production has brought attention to the environmental impacts of persistent gas leakages. The desire to identify fugitive gas emission, specifically for methane, presents new sensing challenges within the production and distribution supply chain. A spectroscopic gas sensing solution would ideally combine a long optical path length for high sensitivity and distributed detection over large areas. Specialty micro-structured fiber with a hollow core can exhibit a relatively low attenuation at mid-infrared wavelengths where methane has strong absorption lines. Methane diffusion into the hollow core is enabled by machining side-holes along the fiber length through ultrafast laser drilling methods. The complete system provides hundreds of meters of optical path for routing along well pads and pipelines while being interrogated by a single laser and detector. This work will present transmission and methane detection capabilities of mid-infrared photonic crystal fibers. Side-hole drilling techniques for methane diffusion will be highlighted as a means to convert hollow-core fibers into applicable gas sensors.

Photoelastic stress analysis of different prefabricated post-and-core materials.

PubMed

Asvanund, Pattapon; Morgano, Steven M

2011-01-01

The purpose of this study was to investigate stress developed by a combination of a stainless steel post or a fiber-reinforced resin post with a silver amalgam core or a composite resin core. Two-dimensional photoelastic models were used to simulate root dentin. Posts (ParaPost XT and ParaPost-FiberWhite) were cemented with a luting agent (RelyX Unicem). Silver amalgam cores and composite resin cores were fabricated on the posts. Complete crowns were fabricated and cemented on the cores. Each model was analyzed with 2 force magnitudes and in 2 directions. Fringe orders were recorded and compared using ANOVA (p=0.05) and the Scheffe's test. With vertical force, no stress differences occurred among the 4 groups (p=0.159). With a 30-degree force, there was stress differences among the 4 groups (p<0.001). The combination of a fiber-reinforced post and composite resin core could potentially reduce stresses within the radicular dentin when angled loads are applied.

Highly conductive thermoplastic composites for rapid production of fuel cell bipolar plates

DOEpatents

Huang, Jianhua [Blacksburg, VA; Baird, Donald G [Blacksburg, VA; McGrath, James E [Blacksburg, VA

2008-04-29

A low cost method of fabricating bipolar plates for use in fuel cells utilizes a wet lay process for combining graphite particles, thermoplastic fibers, and reinforcing fibers to produce a plurality of formable sheets. The formable sheets are then molded into a bipolar plates with features impressed therein via the molding process. The bipolar plates formed by the process have conductivity in excess of 150 S/cm and have sufficient mechanical strength to be used in fuel cells. The bipolar plates can be formed as a skin/core laminate where a second polymer material is used on the skin surface which provides for enhanced conductivity, chemical resistance, and resistance to gas permeation.

Comparison of different photoresist buffer layers in SPR sensors based on D-shaped POF and gold film

NASA Astrophysics Data System (ADS)

Cennamo, Nunzio; Pesavento, Maria; De Maria, Letizia; Galatus, Ramona; Mattiello, Francesco; Zeni, Luigi

2017-04-01

A comparative analysis of two optical fiber sensing platforms is presented. The sensors are based on surface plasmon resonance (SPR) in a D-shaped plastic optical fiber (POF) with a photoresist buffer layer between the exposed POF core and the thin gold film. We show how the sensor's performances change when the photoresist layer changes. The photoresist layers proposed in this analysis are SU-8 3005 and S1813. The experimental results are congruent with the numerical studies and it is instrumental for chemical and bio-chemical applications. Usually, the photoresist layer is required in order to increase the performance of the SPR-POF sensor.

Fabrication of bundle-structured tube-leaky optical fibers for infrared thermal imaging

NASA Astrophysics Data System (ADS)

Kobayashi, T.; Katagiri, T.; Matsuura, Y.

2017-02-01

Bundled glass tubular fibers were fabricated by glass drawing technique for endoscopic infrared-thermal imaging. The bundle fibers were made of borosilicate glass and have a structure like a photonic crystal fiber having multiple hollow cores. Fabricated fibers have a length of 90 cm and each pixel sizes are less than 80 μm. By setting the thickness of glass wall to a quarter-wavelength optical thickness, light is confined in the air core as a leaky mode with a low loss owing to the interference effect of the thin glass wall and this type of hollow-core fibers is known as tube leaky fibers. The transmission losses of bundled fibers were firstly measured and it was found that bundled tube-leaky fibers have reasonably low transmission losses in spite of the small pixel size. Then thermal images were delivered by the bundled fibers combining with an InSb infrared camera. Considering applications with rigid endoscopes, an imaging system composed of a 30-cm long fiber bundle and a half-ball lens with a diameter of 2 mm was fabricated. By using this imaging system, a metal wire with a thickness of 200 μm was successfully observed and another test showed that the minimum detected temperature was 32.0 °C and the temperature resolution of the system was around 0.7 °C.

Optical fiber design and the trapping of Cerenkov radiation.

PubMed

Law, S H; Fleming, S C; Suchowerska, N; McKenzie, D R

2006-12-20

Cerenkov radiation is generated in optical fibers immersed in radiation fields and can interfere with signal transmission. We develop a theory for predicting the intensity of Cerenkov radiation generated within the core of a multimode optical fiber by using a ray optic approach and use it to make predictions of the intensity of radiation transmitted down the fiber in propagating modes. The intensity transmitted down the fiber is found to be dominated by bound rays with a contribution from tunneling rays. It is confirmed that for relativistic particles the intensity of the radiation that is transmitted along the fiber is a function of the angle between the particle beam and the fiber axis. The angle of peak intensity is found to be a function of the fiber refractive index difference as well as the core refractive index, with larger refractive index differences shifting the peak significantly toward lower angles. The angular range of the distribution is also significantly increased in both directions by increasing the fiber refractive index difference. The intensity of the radiation is found to be proportional to the cube of the fiber core radius in addition to its dependence on refractive index difference. As the particle energy is reduced into the nonrelativistic range the entire distribution is shifted toward lower angles. Recommendations on minimizing the quantity of Cerenkov light transmitted in the fiber optic system in a radiation field are given.

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.

Modified rod-in-tube for high-NA tellurite glass fiber fabrication: materials and technologies.

PubMed

Chen, Qiuling; Wang, Hui; Wang, Qingwei; Chen, Qiuping; Hao, Yinlei

2015-02-01

In this paper, we report the whole fabrication process for high-numerical aperture (NA) tellurite glass fibers from material preparation to preform fabrication, and eventually, fiber drawing. A tellurite-based high-NA (0.9) magneto-optical glass fiber was drawn successfully and characterized. First, matchable core and cladding glasses were fabricated and matched in terms of physical properties. Second, a uniform bubble-free preform was fabricated by means of a modified rod-in-tube technique. Finally, the fiber drawing process was studied and optimized. The high-NA fibers (∅(core), 40-50 μm and ∅(cladding), 120-130 μm) so obtained were characterized for their geometrical and optical properties.

Electrospun core-shell fibers for robust silicon nanoparticle-based lithium ion battery anodes.

PubMed

Hwang, Tae Hoon; Lee, Yong Min; Kong, Byung-Seon; Seo, Jin-Seok; Choi, Jang Wook

2012-02-08

Because of its unprecedented theoretical capacity near 4000 mAh/g, which is approximately 10-fold larger compared to those of the current commercial graphite anodes, silicon has been the most promising anode for lithium ion batteries, particularly targeting large-scale energy storage applications including electrical vehicles and utility grids. Nevertheless, Si suffers from its short cycle life as well as the limitation for scalable electrode fabrication. Herein, we develop an electrospinning process to produce core-shell fiber electrodes using a dual nozzle in a scalable manner. In the core-shell fibers, commercially available nanoparticles in the core are wrapped by the carbon shell. The unique core-shell structure resolves various issues of Si anode operations, such as pulverization, vulnerable contacts between Si and carbon conductors, and an unstable sold-electrolyte interphase, thereby exhibiting outstanding cell performance: a gravimetric capacity as high as 1384 mAh/g, a 5 min discharging rate capability while retaining 721 mAh/g, and cycle life of 300 cycles with almost no capacity loss. The electrospun core-shell one-dimensional fibers suggest a new design principle for robust and scalable lithium battery electrodes suffering from volume expansion. © 2011 American Chemical Society

The multifunctional wound dressing with core-shell structured fibers prepared by coaxial electrospinning

NASA Astrophysics Data System (ADS)

Wei, Qilin; Xu, Feiyang; Xu, Xingjian; Geng, Xue; Ye, Lin; Zhang, Aiying; Feng, Zengguo

2016-06-01

The non-woven wound dressing with core-shell structured fibers was prepared by coaxial electrospinning. The polycaprolactone (PCL) was electrospun as the fiber's core to provide mechanical strength whereas collagen was fabricated into the shell in order to utilize its good biocompatibility. Simultaneously, the silver nanoparticles (Ag-NPs) as anti-bacterial agent were loaded in the shell whereas the vitamin A palmitate (VA) as healing-promoting drug was encapsulated in the core. Resulting from the fiber's core-shell structure, the VA released from the core and Ag-NPs present in the shell can endow the dressing both heal-promoting and anti-bacteria ability simultaneously, which can greatly enhance the dressing's clinical therapeutic effect. The dressing can maintain high swelling ratio of 190% for 3 d indicating its potential application as wet dressing. Furthermore, the dressing's anti-bacteria ability against Staphylococcus aureus was proved by in vitro anti-bacteria test. The in vitro drug release test showed the sustainable release of VA within 72 h, while the cell attachment showed L929 cells can well attach on the dressing indicating its good biocompatibility. In conclusion, the fabricated nanofibrous dressing possesses multiple functions to benefit wound healing and shows promising potential for clinical application.

Method Of Bonding A Metal Connection To An Electrode Including A Core Having A Fiber Or Foam Type Structure For An Electrochemical Cell, An

DOEpatents

Loustau, Marie-Therese; Verhoog, Roelof; Precigout, Claude

1996-09-24

A method of bonding a metal connection to an electrode including a core having a fiber or foam-type structure for an electrochemical cell, in which method at least one metal strip is pressed against one edge of the core and is welded thereto under compression, wherein, at least in line with the region in which said strip is welded to the core, which is referred to as the "main core", a retaining core of a type analogous to that of the main core is disposed prior to the welding.

Optimized coupling of cold atoms into a fiber using a blue-detuned hollow-beam funnel

NASA Astrophysics Data System (ADS)

Poulin, Jerome; Light, Philip S.; Kashyap, Raman; Luiten, Andre N.

2011-11-01

We theoretically investigate the process of coupling cold atoms into the core of a hollow-core photonic-crystal optical fiber using a blue-detuned Laguerre-Gaussian beam. In contrast to the use of a red-detuned Gaussian beam to couple the atoms, the blue-detuned hollow beam can confine cold atoms to the darkest regions of the beam, thereby minimizing shifts in the internal states and making the guide highly robust to heating effects. This single optical beam is used as both a funnel and a guide to maximize the number of atoms into the fiber. In the proposed experiment, Rb atoms are loaded into a magneto-optical trap (MOT) above a vertically oriented optical fiber. We observe a gravito-optical trapping effect for atoms with high orbital momentum around the trap axis, which prevents atoms from coupling to the fiber: these atoms lack the kinetic energy to escape the potential and are thus trapped in the laser funnel indefinitely. We find that by reducing the dipolar force to the point at which the trapping effect just vanishes, it is possible to optimize the coupling of atoms into the fiber. Our simulations predict that by using a low-power (2.5 mW) and far-detuned (300 GHz) Laguerre-Gaussian beam with a 20-μm-radius core hollow fiber, it is possible to couple 11% of the atoms from a MOT 9 mm away from the fiber. When the MOT is positioned farther away, coupling efficiencies over 50% can be achieved with larger core fibers.

Crack Propagation Calculations for Optical Fibers under Static Bending and Tensile Loads Using Continuum Damage Mechanics

PubMed Central

Chen, Yunxia; Cui, Yuxuan; Gong, Wenjun

2017-01-01

Static fatigue behavior is the main failure mode of optical fibers applied in sensors. In this paper, a computational framework based on continuum damage mechanics (CDM) is presented to calculate the crack propagation process and failure time of optical fibers subjected to static bending and tensile loads. For this purpose, the static fatigue crack propagation in the glass core of the optical fiber is studied. Combining a finite element method (FEM), we use the continuum damage mechanics for the glass core to calculate the crack propagation path and corresponding failure time. In addition, three factors including bending radius, tensile force and optical fiber diameter are investigated to find their impacts on the crack propagation process and failure time of the optical fiber under concerned situations. Finally, experiments are conducted and the results verify the correctness of the simulation calculation. It is believed that the proposed method could give a straightforward description of the crack propagation path in the inner glass core. Additionally, the predicted crack propagation time of the optical fiber with different factors can provide effective suggestions for improving the long-term usage of optical fibers. PMID:29140284

An evanescent wave biosensor--Part I: Fluorescent signal acquisition from step-etched fiber optic probes.

PubMed

Anderson, G P; Golden, J P; Ligler, F S

1994-06-01

A fiber-optic biosensor capable of remote continuous monitoring has recently been designed. To permit sensing at locations separate from the optoelectronic instrumentation, long optical fibers are utilized. An evanescent wave immuno-probe is prepared by removing the cladding near the distal end of the fiber and covalently attaching antibodies to the core. Probes with a radius unaltered from that of the original core inefficiently returned the signal produced upon binding the fluorescent-labelled antigen. To elucidate the limiting factors in signal acquisition, a series of fibers with increasingly reduced probe core radius was examined. The results were consistent with the V-number mismatch, the difference in mode carrying capacity between the clad and unclad fiber, being a critical factor in limiting signal coupling from the fiber probe. However, it was also delineated that conditions which conserve excitation power, such that power in the evanescent wave is optimized, must also be met to obtain a maximal signal. The threshold sensitivity for the optimal step-etched fiber probe was improved by over 20-fold in an immunoassay, although, it was demonstrated that signal acquisition decreased along the probe length, suggesting that a sensor region of uniform radius is not ideal.

Crack Propagation Calculations for Optical Fibers under Static Bending and Tensile Loads Using Continuum Damage Mechanics.

PubMed

Chen, Yunxia; Cui, Yuxuan; Gong, Wenjun

2017-11-15

Static fatigue behavior is the main failure mode of optical fibers applied in sensors. In this paper, a computational framework based on continuum damage mechanics (CDM) is presented to calculate the crack propagation process and failure time of optical fibers subjected to static bending and tensile loads. For this purpose, the static fatigue crack propagation in the glass core of the optical fiber is studied. Combining a finite element method (FEM), we use the continuum damage mechanics for the glass core to calculate the crack propagation path and corresponding failure time. In addition, three factors including bending radius, tensile force and optical fiber diameter are investigated to find their impacts on the crack propagation process and failure time of the optical fiber under concerned situations. Finally, experiments are conducted and the results verify the correctness of the simulation calculation. It is believed that the proposed method could give a straightforward description of the crack propagation path in the inner glass core. Additionally, the predicted crack propagation time of the optical fiber with different factors can provide effective suggestions for improving the long-term usage of optical fibers.

Impact of the Curve Diameter and Laser Settings on Laser Fiber Fracture.

PubMed

Haddad, Mattieu; Emiliani, Esteban; Rouchausse, Yann; Coste, Frederic; Doizi, Steeve; Berthe, Laurent; Butticé, Salvatore; Somani, Bhaskar; Traxer, Olivier

2017-09-01

To analyze the risk factors for laser fiber fractures when deflected to form a curve, including laser settings, size of the laser fiber, and the fiber bending diameter. Single-use 272 and 365 μm fibers (Rocamed ® , Monaco) were employed along with a holmium laser (Rocamed). Five different fiber curve diameters were tested: 9, 12, 15, 18, and 20 mm. Fragmentation and dusting settings were used at a theoretical power of 7.5 W. The laser was activated for 5 minutes and the principal judgment criterion was fiber fracture. Every test for each parameter, bending diameter, and fiber size combinations was repeated 10 times. With dusting settings, fibers broke more frequently at a curved diameter of 9 mm for both 272 and 365 μm fibers (p = 0.037 and 0.006, respectively). Using fragmentation settings, fibers broke more frequently at 12 mm for 272 μm and 15 mm for 365 μm (p = 0.007 and 0.033, respectively). Short pulse and high energy were significant risk factors for fiber fracture using the 365 μm fibers (p = 0.02), but not for the 272 μm fibers (p = 0.35). Frequency was not a risk factor for fiber rupture. Fiber diameters also seemed to be involved in the failure with a higher number of broken fibers for the 365 μm fibers, but this was not statistically significant when compared with the 272 μm fibers (p > 0.05). Small-core fibers are more resistant than large-core fibers as lower bending diameters (<9 mm) are required to break smaller fibers. In acute angles, the use of small-core fibers, at a low energy and long-pulse (dusting) setting, will reduce the risk of fiber rupture.

STRETCHY ELECTRONICS. Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles.

PubMed

Liu, Z F; Fang, S; Moura, F A; Ding, J N; Jiang, N; Di, J; Zhang, M; Lepró, X; Galvão, D S; Haines, C S; Yuan, N Y; Yin, S G; Lee, D W; Wang, R; Wang, H Y; Lv, W; Dong, C; Zhang, R C; Chen, M J; Yin, Q; Chong, Y T; Zhang, R; Wang, X; Lima, M D; Ovalle-Robles, R; Qian, D; Lu, H; Baughman, R H

2015-07-24

Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties. Copyright © 2015, American Association for the Advancement of Science.

Stability of Ince-Gaussian beams in elliptical core few-mode fibers.

PubMed

Sakpal, Sahil; Milione, Giovanni; Li, Min-Jun; Nouri, Mehdi; Shahoei, Hiva; LaFave, Tim; Ashrafi, Solyman; MacFarlane, Duncan

2018-06-01

A comparative stability analysis of Ince-Gaussian and Hermite-Gaussian modes in elliptical core few-mode fibers is provided to inform the design of spatial division multiplexing systems. The correlation method is used to construct crosstalk matrices that characterize the spatial modes of the fiber. Up to six low-order modes are shown to exhibit about -20  dB crosstalk. The crosstalk performance of each mode set is found to be similar. However, a direct comparison between modes of equal Gouy phase shift, a parameter that ensures identical beam quality, and phase at the detector, demonstrates better relative power transmission for Ince-Gaussian beams. This result is consistent with the natural modes supported by a 100 m elliptical core fiber for which a mode ellipticity of ϵ=2 was found to be optimal. The relative power difference is expected to be magnified over longer fiber lengths in favor of Ince-Gaussian modes.

Theoretical model for a thin cylindrical film optical fiber fluorosensor

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1992-01-01

The analytical treatment of power efficiency (P(eff) is undertaken for the case of a positively guiding optical fiber with a thin-film source distributed in the core-cladding interface. The approach adopts the exact solution of the cylindrical optical fiber with an infinite cladding to account for differences between the indices of refraction of the core and the cladding. The excitation of low-loss leaky modes by the cladding is ignored, and only the injection by the evanescent field is considered. The formulas permit the analysis of the power-injection efficiency of fibers with arbitrary differences in indices of refraction. P(eff) does not always increase with V number, but rather varies slightly with wavelength and fiber-core radius and varies significantly with the difference in the indices of refraction. The theoretical results of the work are of interest for designing an atomic-O chemical sensor based on evanescent-wave coupling.

Nanosphere Lithography on Fiber: Towards Engineered Lab-On-Fiber SERS Optrodes

PubMed Central

Quero, Giuseppe; Zito, Gianluigi; Cusano, Andrea

2018-01-01

In this paper we report on the engineering of repeatable surface enhanced Raman scattering (SERS) optical fiber sensor devices (optrodes), as realized through nanosphere lithography. The Lab-on-Fiber SERS optrode consists of polystyrene nanospheres in a close-packed arrays configuration covered by a thin film of gold on the optical fiber tip. The SERS surfaces were fabricated by using a nanosphere lithography approach that is already demonstrated as able to produce highly repeatable patterns on the fiber tip. In order to engineer and optimize the SERS probes, we first evaluated and compared the SERS performances in terms of Enhancement Factor (EF) pertaining to different patterns with different nanosphere diameters and gold thicknesses. To this aim, the EF of SERS surfaces with a pitch of 500, 750 and 1000 nm, and gold films of 20, 30 and 40 nm have been retrieved, adopting the SERS signal of a monolayer of biphenyl-4-thiol (BPT) as a reliable benchmark. The analysis allowed us to identify of the most promising SERS platform: for the samples with nanospheres diameter of 500 nm and gold thickness of 30 nm, we measured values of EF of 4 × 105, which is comparable with state-of-the-art SERS EF achievable with highly performing colloidal gold nanoparticles. The reproducibility of the SERS enhancement was thoroughly evaluated. In particular, the SERS intensity revealed intra-sample (i.e., between different spatial regions of a selected substrate) and inter-sample (i.e., between regions of different substrates) repeatability, with a relative standard deviation lower than 9 and 15%, respectively. Finally, in order to determine the most suitable optical fiber probe, in terms of excitation/collection efficiency and Raman background, we selected several commercially available optical fibers and tested them with a BPT solution used as benchmark. A fiber probe with a pure silica core of 200 µm diameter and high numerical aperture (i.e., 0.5) was found to be the most promising fiber platform, providing the best trade-off between high excitation/collection efficiency and low background. This work, thus, poses the basis for realizing reproducible and engineered Lab-on-Fiber SERS optrodes for in-situ trace detection directed toward highly advanced in vivo sensing. PMID:29495322

Effect of components and surface treatments of fiber-reinforced composite posts on bond strength to composite resin.

PubMed

Asakawa, Yuya; Takahashi, Hidekazu; Kobayashi, Masahiro; Iwasaki, Naohiko

2013-10-01

The aim of this study was to clarify the effect of the components and surface treatments of fiber-reinforced composite (FRC) posts on the durable bonding to core build-up resin evaluated using the pull-out and microtensile tests. Four types of experimental FRC posts, combinations of two types of matrix resins (polymethyl methacrylate and urethane dimethacrylate) and two types of fiberglass (E-glass and zirconia-containing glass) were examined. The FRC posts were subjected to one of three surface treatments (cleaned with ethanol, dichloromethane, or sandblasting). The bond strength between the FRC posts and core build-up resin were measured using the pull-out and microtensile tests before and after thermal cycling. The bond strengths obtained by each test before and after thermal cycling were statistically analyzed by three-way ANOVA and Tukey's multiple comparisons test (p<0.05). The bond strengths except for UDMA by the pull-out test decreased after thermal cycling. Regardless the test method and thermal cycling, matrix resins, the surface treatment and their interaction were statistically significant, but fiberglass did not. Dichloromethane treatment was effective for the PMMA-based FRC posts by the pull-out test, but not by the microtensile test. Sandblasting was effective for both PMMA- and UDMA-based FRC posts, regardless of the test method. The bond strengths were influenced by the matrix resin of the FRC post and the surface treatment. The bond strengths of the pull-out test showed a similar tendency of those of the microtensile test, but the value obtained by these test were different. Copyright © 2013 Elsevier Ltd. All rights reserved.

Extremely low-loss, dispersion flattened porous-core photonic crystal fiber for terahertz regime

NASA Astrophysics Data System (ADS)

Islam, Saiful; Islam, Mohammad Rakibul; Faisal, Mohammad; Arefin, Abu Sayeed Muhammad Shamsul; Rahman, Hasan; Sultana, Jakeya; Rana, Sohel

2016-07-01

A porous-core octagonal photonic crystal fiber (PC-OPCF) with ultralow effective material loss (EML), high core power fraction, and ultra flattened dispersion is proposed for terahertz (THz) wave propagation. At an operating frequency of 1 THz and core diameter of 345 μm, simulation results display an extremely low EML of 0.047 cm-1, 49.1% power transmission through core air holes, decreased confinement loss with the increase of frequency, and dispersion variation of 0.15 ps/THz/cm. In addition, the proposed PCF can successfully operate in single-mode condition. All the simulations are performed with finite-element modeling package, COMSOL v4.2. The design can be fabricated using a stacking and drilling method. Thus, the proposed fiber has the potential of being an effective transmission medium of broadband THz waves.

Experimental observation of spontaneous depolarized guided acoustic-wave Brillouin scattering in side cores of a multicore fiber

NASA Astrophysics Data System (ADS)

Hayashi, Neisei; Mizuno, Yosuke; Nakamura, Kentaro; Set, Sze Yun; Yamashita, Shinji

2018-06-01

Spontaneous depolarized guided acoustic-wave Brillouin scattering (GAWBS) was experimentally observed in one of the side cores of an uncoated multicore fiber (MCF). The frequency bandwidth in the side core was up to ∼400 MHz, which is 0.5 times that in the central core. The GAWBS spectrum of the side core of the MCF included intrinsic peaks, which had different acoustic resonance frequencies from those of the central core. In addition, the spontaneous depolarized GAWBS in the central/side core was unaffected by that in the other core. These results will lead to the development of polarization/phase modulators using an MCF.

Modeling the permeability of multiaxial electrospun poly(ε-caprolactone)-gelatin hybrid fibers for controlled doxycycline release.

PubMed

Khalf, Abdurizzagh; Madihally, Sundararajan V

2017-07-01

Recent advances in electrospinning allow the formation of multiple layers of micro and nanosize fibers to regulate drug/therapeutic agent release. Although there has been significant progress in fiber formation techniques and drug loading, fundamental models providing insights into controlling individual permeabilities is lacking. In this regard, we first explored forming coaxial hybrid fibers from hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic gelatin (GT) in three different configurations, and the release of hydrophilic doxycycline (Dox) at 37°C over five days. Triaxial fibers were also formed with a GT layer between PCL/GT layers. Fibers were analyzed for fiber thickness, matrix porosity and thickness, surface morphologies, internal structures, stability in hydrated condition, viability and attachment of human adipocyte stem cells (hASC). Formed fibers were 10-30μm in diameter. hASC were viable, and showed attachment. Various release profiles were obtained from these fibers based on the combination of the core and shell polymers over five days. Using fiber characteristics and release profiles from each configuration, we obtained the overall permeability using Fick's first law and then individual layer permeability using resistance in series model. Calculated overall permeability showed dependency on fiber thickness and partition coefficient of the drug in the region where it was loaded. Our modeling approach helps in optimizing the electrospinning process, drug loading, and polymer solution configuration in regulating controlled release of a drug. Copyright © 2017 Elsevier B.V. All rights reserved.

Switchable and responsive liquid crystal-functionalized microfibers produced via coaxial electrospinning

NASA Astrophysics Data System (ADS)

Lagerwall, Jan P. F.

2012-03-01

"Wearable technology" or "smart textiles" are concepts that are very rapidly gaining in attention around the world, as industry as well as academia are making major advances in integrating advanced devices with various textiles around our household. The technological challenges involved in this development are however considerable, calling for new solutions, new materials and truly original thinking. An attractive approach to realize certain classes of wearable devices may be to use textile fibers functionalized by responsive materials such as liquid crystals, normally not connected to textiles. We can produce non-woven textiles with such fibers by means of electrospinning, a technique for producing very thin polymer fibers that can be uniform or with core-sheath geometries. Since the core can be made out of traditionally non-spinnable materials we can use coaxial electrospinning (one fluid spun inside another) to produce composite fibers with a core of liquid crystal inside a polymer sheath. The resulting fibers constitute an entirely new configuration for applying liquid crystals, giving the fibers functionality and responsiveness. For instance, with a cholesteric core we can produce non-woven mats with iridescent color that can be tuned (or removed) e.g. by heating or cooling. In this paper I describe our method of producing these novel functionalized fibers and their characterization, and I will discuss the directions for future research and application possibilities, e.g. in clothing-integrated sensors and indicators.

Guest-host polymer fibers for nonlinear optics

NASA Astrophysics Data System (ADS)

Kuzyk, M. G.; Paek, U. C.; Dirk, C. W.

1991-08-01

We report on the fabrication of poly(methyl methacrylate) (PMMA) nonlinear optical fibers with dye-doped cores. The dye-doped cores have an elevated refractive index that defines a waveguiding region with a large third-order susceptibility and with single-mode dimensions. The measured third-order susceptibility of a squarylium-doped PMMA film material and the measured optical loss of the dye-doped fiber core results in a figure of merit that is suitable for all-optical device applications at λ=1.3 μm. The impact of further improvements in PMMA loss and chromophore nonlinearity are also discussed.

Toward single-mode active crystal fibers for next-generation high-power fiber devices.

PubMed

Lai, Chien-Chih; Gao, Wan-Ting; Nguyen, Duc Huy; Ma, Yuan-Ron; Cheng, Nai-Chia; Wang, Shih-Chang; Tjiu, Jeng-Wei; Huang, Chun-Ming

2014-08-27

We report what we believe to be the first demonstration of a facile approach with controlled geometry for the production of crystal-core ceramic-clad hybrid fibers for scaling fiber devices to high average powers. The process consists of dip coating a solution of polycrystalline alumina onto a high-crystallinity 40-μm-diameter Ti:sapphire single-crystalline core followed by thermal treatments. Comparison of the measured refractive index with high-resolution transmission electron microscopy reveals that a Ca/Si-rich intragranular layer is precipitated at grain boundaries by impurity segregation and liquid-phase formation due to the relief of misfit strain energy in the Al2O3 matrix, slightly perturbing the refractive index and hence the optical properties. Additionally, electron backscatter diffractions supply further evidence that the Ti:sapphire single-crystalline core provides the template for growth into a sacrificial polycrystalline cladding, bringing the core and cladding into a direct bond. The thus-prepared doped crystal core with the undoped crystal cladding was achieved through the abnormal grain-growth process. The presented results provide a general guideline both for controlling crystal growth and for the performance of hybrid materials and provides insights into how one might design single-mode high-power crystal fiber devices.

2013 R&D 100 Award: New tech could mean more power for fiber lasers

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

Dawson, Jay

2014-04-03

An LLNL team of six physicists has developed a new technology that is a stepping stone to enable some of the limitations on high-power fiber lasers to be overcome. Their technology, dubbed "Efficient Mode-Converters for High-Power Fiber Amplifiers," allows the power of fiber lasers to be increased while maintaining high beam quality. Currently, fiber lasers are used in machining, on factory floors and in a number of defense applications and can produce tens of kilowatts of power.The conventional fiber laser design features a circular core and has fundamental limitations that make it impractical to allow higher laser power unless themore » core area is increased. LLNL researchers have pioneered a design to increase the laser's core area along the axis of the ribbon fiber. Their design makes it difficult to use a conventional laser beam, so the LLNL team converted the beam into a profile that propagates into the ribbon fiber and is converted back once it is amplified. The use of this LLNL technology will permit the construction of higher power lasers for lower costs and increase the power of fiber lasers from tens of kilowatts of power to about 100 kilowatts and potentially even higher.« less

Optical and electrical characterizations of multifunctional silver phosphate glass and polymer-based optical fibers.

PubMed

Rioux, Maxime; Ledemi, Yannick; Morency, Steeve; de Lima Filho, Elton Soares; Messaddeq, Younès

2017-03-03

In recent years, the fabrication of multifunctional fibers has expanded for multiple applications that require the transmission of both light and electricity. Fibers featuring these two properties are usually composed either of a single material that supports the different characteristics or of a combination of different materials. In this work, we fabricated (i) novel single-core step-index optical fibers made of electrically conductive AgI-AgPO 3 -WO 3 glass and (ii) novel multimaterial fibers with different designs made of AgI-AgPO 3 -WO 3 glass and optically transparent polycarbonate and poly (methyl methacrylate) polymers. The multifunctional fibers produced show light transmission over a wide range of wavelengths from 500 to 1000 nm for the single-core fibers and from 400 to 1000 nm for the multimaterial fibers. Furthermore, these fibers showed excellent electrical conductivity with values ranging between 10 -3 and 10 -1  S·cm -1 at room temperature within the range of AC frequencies from 1 Hz to 1 MHz. Multimodal taper-tipped fibre microprobes were then fabricated and were characterized. This advanced design could provide promising tools for in vivo electrophysiological experiments that require light delivery through an optical core in addition to neuronal activity recording.

Optical and electrical characterizations of multifunctional silver phosphate glass and polymer-based optical fibers

PubMed Central

Rioux, Maxime; Ledemi, Yannick; Morency, Steeve; de Lima Filho, Elton Soares; Messaddeq, Younès

2017-01-01

In recent years, the fabrication of multifunctional fibers has expanded for multiple applications that require the transmission of both light and electricity. Fibers featuring these two properties are usually composed either of a single material that supports the different characteristics or of a combination of different materials. In this work, we fabricated (i) novel single-core step-index optical fibers made of electrically conductive AgI-AgPO3-WO3 glass and (ii) novel multimaterial fibers with different designs made of AgI-AgPO3-WO3 glass and optically transparent polycarbonate and poly (methyl methacrylate) polymers. The multifunctional fibers produced show light transmission over a wide range of wavelengths from 500 to 1000 nm for the single-core fibers and from 400 to 1000 nm for the multimaterial fibers. Furthermore, these fibers showed excellent electrical conductivity with values ranging between 10−3 and 10−1 S·cm−1 at room temperature within the range of AC frequencies from 1 Hz to 1 MHz. Multimodal taper-tipped fibre microprobes were then fabricated and were characterized. This advanced design could provide promising tools for in vivo electrophysiological experiments that require light delivery through an optical core in addition to neuronal activity recording. PMID:28256608

A novel computer-aided method to fabricate a custom one-piece glass fiber dowel-and-core based on digitized impression and crown preparation data.

PubMed

Chen, Zhiyu; Li, Ya; Deng, Xuliang; Wang, Xinzhi

2014-06-01

Fiber-reinforced composite dowels have been widely used for their superior biomechanical properties; however, their preformed shape cannot fit irregularly shaped root canals. This study aimed to describe a novel computer-aided method to create a custom-made one-piece dowel-and-core based on the digitization of impressions and clinical standard crown preparations. A standard maxillary die stone model containing three prepared teeth each (maxillary lateral incisor, canine, premolar) requiring dowel restorations was made. It was then mounted on an average value articulator with the mandibular stone model to simulate natural occlusion. Impressions for each tooth were obtained using vinylpolysiloxane with a sectional dual-arch tray and digitized with an optical scanner. The dowel-and-core virtual model was created by slicing 3D dowel data from impression digitization with core data selected from a standard crown preparation database of 107 records collected from clinics and digitized. The position of the chosen digital core was manually regulated to coordinate with the adjacent teeth to fulfill the crown restorative requirements. Based on virtual models, one-piece custom dowel-and-cores for three experimental teeth were milled from a glass fiber block with computer-aided manufacturing techniques. Furthermore, two patients were treated to evaluate the practicality of this new method. The one-piece glass fiber dowel-and-core made for experimental teeth fulfilled the clinical requirements for dowel restorations. Moreover, two patients were treated to validate the technique. This novel computer-aided method to create a custom one-piece glass fiber dowel-and-core proved to be practical and efficient. © 2013 by the American College of Prosthodontists.

The MaNGA integral field unit fiber feed system for the Sloan 2.5 m telescope

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

Drory, N.; MacDonald, N.; Byler, N.

2015-02-01

We describe the design, manufacture, and performance of bare-fiber integral field units (IFUs) for the SDSS-IV survey Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) on the the Sloan 2.5 m telescope at Apache Point Observatory. MaNGA is a luminosity-selected integral-field spectroscopic survey of 10{sup 4} local galaxies covering 360–1030 nm at R∼2200. The IFUs have hexagonal dense packing of fibers with packing regularity of 3 μm (rms), and throughput of 96 ± 0.5% from 350 nm to 1 μm in the lab. Their sizes range from 19 to 127 fibers (3–7 hexagonal layers) using Polymicro FBP 120:132:150 μm core:clad:buffermore » fibers to reach a fill fraction of 56%. High throughput (and low focal-ratio degradation (FRD)) is achieved by maintaining the fiber cladding and buffer intact, ensuring excellent surface polish, and applying a multi-layer anti-reflection (AR) coating of the input and output surfaces. In operations on-sky, the IFUs show only an additional 2.3% FRD-related variability in throughput despite repeated mechanical stressing during plate plugging (however other losses are present). The IFUs achieve on-sky throughput 5% above the single-fiber feeds used in SDSS-III/BOSS, attributable to equivalent performance compared to single fibers and additional gains from the AR coating. The manufacturing process is geared toward mass-production of high-multiplex systems. The low-stress process involves a precision ferrule with a hexagonal inner shape designed to lead inserted fibers to settle in a dense hexagonal pattern. The ferrule ID is tapered at progressively shallower angles toward its tip and the final 2 mm are straight and only a few microns larger than necessary to hold the desired number of fibers. Our IFU manufacturing process scales easily to accommodate other fiber sizes and can produce IFUs with substantially larger fiber counts. To assure quality, automated testing in a simple and inexpensive system enables complete characterization of throughput and fiber metrology. Future applications include larger IFUs, higher fill factors with stripped buffer, de-cladding, and lenslet coupling.« less

The MaNGA Integral Field Unit Fiber Feed System for the Sloan 2.5 m Telescope

NASA Astrophysics Data System (ADS)

Drory, N.; MacDonald, N.; Bershady, M. A.; Bundy, K.; Gunn, J.; Law, D. R.; Smith, M.; Stoll, R.; Tremonti, C. A.; Wake, D. A.; Yan, R.; Weijmans, A. M.; Byler, N.; Cherinka, B.; Cope, F.; Eigenbrot, A.; Harding, P.; Holder, D.; Huehnerhoff, J.; Jaehnig, K.; Jansen, T. C.; Klaene, M.; Paat, A. M.; Percival, J.; Sayres, C.

2015-02-01

We describe the design, manufacture, and performance of bare-fiber integral field units (IFUs) for the SDSS-IV survey Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) on the the Sloan 2.5 m telescope at Apache Point Observatory. MaNGA is a luminosity-selected integral-field spectroscopic survey of 104 local galaxies covering 360-1030 nm at R˜ 2200. The IFUs have hexagonal dense packing of fibers with packing regularity of 3 μm (rms), and throughput of 96 ± 0.5% from 350 nm to 1 μm in the lab. Their sizes range from 19 to 127 fibers (3-7 hexagonal layers) using Polymicro FBP 120:132:150 μm core:clad:buffer fibers to reach a fill fraction of 56%. High throughput (and low focal-ratio degradation (FRD)) is achieved by maintaining the fiber cladding and buffer intact, ensuring excellent surface polish, and applying a multi-layer anti-reflection (AR) coating of the input and output surfaces. In operations on-sky, the IFUs show only an additional 2.3% FRD-related variability in throughput despite repeated mechanical stressing during plate plugging (however other losses are present). The IFUs achieve on-sky throughput 5% above the single-fiber feeds used in SDSS-III/BOSS, attributable to equivalent performance compared to single fibers and additional gains from the AR coating. The manufacturing process is geared toward mass-production of high-multiplex systems. The low-stress process involves a precision ferrule with a hexagonal inner shape designed to lead inserted fibers to settle in a dense hexagonal pattern. The ferrule ID is tapered at progressively shallower angles toward its tip and the final 2 mm are straight and only a few microns larger than necessary to hold the desired number of fibers. Our IFU manufacturing process scales easily to accommodate other fiber sizes and can produce IFUs with substantially larger fiber counts. To assure quality, automated testing in a simple and inexpensive system enables complete characterization of throughput and fiber metrology. Future applications include larger IFUs, higher fill factors with stripped buffer, de-cladding, and lenslet coupling.

Magneto-Optic Field Coupling in Optical Fiber Bragg Gratings

NASA Technical Reports Server (NTRS)

Carman, Gregory P. (Inventor); Mohanchandra, Panduranga K. (Inventor); Emmons, Michael C. (Inventor); Richards, William Lance (Inventor)

2016-01-01

The invention is a magneto-optic coupled magnetic sensor that comprises a standard optical fiber Bragg grating system. The system includes an optical fiber with at least one Bragg grating therein. The optical fiber has at least an inner core and a cladding that surrounds the inner core. The optical fiber is part of an optical system that includes an interrogation device that provides a light wave through the optical fiber and a system to determine the change in the index of refraction of the optical fiber. The cladding of the optical fiber comprises at least a portion of which is made up of ferromagnetic particles so that the ferromagnetic particles are subject to the light wave provided by the interrogation system. When a magnetic field is present, the ferromagnetic particles change the optical properties of the sensor directly.

Monolithic diffraction-limited 976-nm laser based on saddle-shaped photo darkening-free Yb-doped fiber

NASA Astrophysics Data System (ADS)

Aleshkina, Svetlana S.; Lipatov, Denis S.; Levchenko, Andrei E.; Medvedkov, Oleg I.; Bobkov, Konstantin K.; Bubnov, Mikhail M.; Guryanov, Alexei N.; Likhachev, Mikhail E.

2018-02-01

Monolithic 976 nm laser design based on a newly developed saddle-shaped Yb-doped fiber has been proposed. The fiber has central single-mode part with core diameter of about 12 μm and ultra-thin square-shaped clad with side of about 42x42 μm. At the both ends of the saddle-shaped fiber the core and the clad sizes were adiabatically increased up to 20/(70x70) μm and the fiber could be spliced with standard (80..125 μm clad) passive fibers using commercially available equipment. Single-mode laser at 976 nm based on the developed fiber has been fabricated and photodarkening-free operation with output power of 10.6 W, which is the record high for all-fiber laser schemes, has been demonstrated.

PCS optical fibers for an automobile data bus

NASA Astrophysics Data System (ADS)

Clarkin, James P.; Timmerman, Richard J.; Stolte, Gary W.; Klein, Karl-Friedrich

2005-02-01

Optical fibers have been used for data communications in automobiles for several years. The fiber of choice thus far has been a plastic core/plastic clad optical fiber (POF) consisting of the plastic polymethylmethacrylate (PMMA). The POF fiber provides a low cost fiber with relatively easy termination. However, increasing demands regarding temperature performance, transmission losses and bandwidth have pushed the current limits of the POF fiber, and the automotive industry is now moving towards an optical fiber with a silica glass core/plastic clad (PCS). PCS optical fibers have been used successfully in industrial, medical, sensor, military and data communications systems for over two decades. The PCS fiber is now being adapted specifically for automotive use. In the following, the design criteria and design alternatives for the PCS as well as optical, thermal, and mechanical testing results for key automotive parameters are described. The fiber design tested was 200&mum synthetic silica core/230&mum fluoropolymer cladding/1510&mum nylon buffer. Key attributes such as 700 - 900 nm spectral attenuation, 125°C thermal soak, -40 to 125°C thermal cycling, bending losses, mechanical strength, termination capability, and cost are discussed and compared. Overall, a specifically designed PCS fiber is expected to be acceptable for the use in an automotive data bus, and will show improvement in optical transmission, temperature range and bandwidth. However, the final selection of buffer and jacket materials and properties will be most dependent on the selection of a reliable and economical termination method.

Nano-cone optical fiber array sensors for MiRNA profiling

NASA Astrophysics Data System (ADS)

Wang, Yunshan; Senapati, Satyajyoti; Stoddart, Paul; Howard, Scott; Chang, Hsueh-Chia

2013-09-01

Up/down regulation of microRNA panels has been correlated to cardiovascular diseases and cancer. Frequent miRNA profiling at home can hence allow early cancer diagnosis and home-use chronic disease monitoring, thus reducing both mortality rate and healthcare cost. However, lifetime of miRNAs is less than 1 hour without preservation and their concentrations range from pM to mM. Despite rapid progress in the last decade, modern nucleic acid analysis methods still do not allow personalized miRNA profiling---Real-time PCR and DNA micro-array both require elaborate miRNA preservation steps and expensive equipment and nano pore sensors cannot selectively quantify a large panel with a large dynamic range. We report a novel and low-cost optical fiber sensing platform, which has the potential to profile a panel of miRNA with simple LED light sources and detectors. The individual tips of an optical imaging fiber bundle (mm in diameter with 7000 fiber cores) were etched into cones with 10 nm radius of curvature and coated with Au. FRET (Forster Resonant Energy Transfer) hairpin oligo probes, with the loop complementary to a specific miRNA that can release the hairpin, were functionalized onto the conic tips. Exciting light in the optical fiber waveguide is optimally coupled to surface plasmonics on the gold surface, which then converges to the conic tips with two orders of magnitude enhancement in intensity. Unlike nanoparticle plasmonics, tip plasmonics can be excited over a large band width and hence the plasmonic enhanced fluorescence signal of the FRET reporter is also focused towards the tip--- and is further enhanced with the periodic resonant grid of the fiber array which gives rise to pronounced standing wave interference patterns. Multiplexing is realized by functionalizing different probes onto one fiber bundle using a photoactivation process.

A tactile sensing element based on a hetero-core optical fiber for force measurement and texture detection

NASA Astrophysics Data System (ADS)

Yamazaki, Hiroshi; Koyama, Yuya; Watanabe, Kazuhiro

2014-05-01

Tactile sensing technology can measure a given property of an object through physical contact between a sensing element and the object. Various tactile sensing techniques have been developed for several applications such as intelligent robots, tactile interface, medical support and nursing care support. A desirable tactile sensing element for supporting human daily life can be embedded in the soft material with high sensitivity and accuracy in order to prevent from damaging to human or object physically. This report describes a new tactile sensing element. Hetero-core optical fibers have high sensitivity of macro-bending at local sensor portion and temperature independency, including advantages of optical fiber itself; thin size, light weight, flexible transmission line, and immunity to electro-magnetic interference. The proposed tactile sensing element could detect textures of touched objects through the optical loss caused by the force applied to the sensing element. The characteristics of the sensing element have been evaluated, in which the sensing element has the monotonic and non-linear sensitivity against the normal force ranged from 0 to 5 N with lower accuracy than 0.25 dB. Additionally, texture detection have been successfully demonstrated in which small surface figures of 0.1 mm in height were detected with spatial resolution of 0.4 mm.

Microstructured optical fiber interferometric breathing sensor

NASA Astrophysics Data System (ADS)

Favero, Fernando C.; Villatoro, Joel; Pruneri, Valerio

2012-03-01

In this paper a simple photonic crystal fiber (PCF) interferometric breathing sensor is introduced. The interferometer consists of a section of PCF fusion spliced at the distal end of a standard telecommunications optical fiber. Two collapsed regions in the PCF caused by the splicing process allow the excitation and recombination of a core and a cladding PCF mode. As a result, the reflection spectrum of the device exhibits a sinusoidal interference pattern that instantly shifts when water molecules, present in exhaled air, are adsorbed on or desorbed from the PCF surface. The device can be used to monitor a person's breathing whatever the respiration rate. The device here proposed could be particularly important in applications where electronic sensors fail or are not recommended. It may also be useful in the evaluation of a person's health and even in the diagnosis and study of the progression of serious illnesses such as sleep apnea syndrome.

Effect Of Fluorine Doping On Radiation Hardness Of Graded Index Optical Fibers

NASA Astrophysics Data System (ADS)

Wei, T.; Singh, M. P.; Miniscalco, W. J.; Onorato, P. I. K.; Wall, J. A.

1987-01-01

We report an experimental and theoretical investigation of the effects of doping and processing on precursor defects in graded index multimode fibers. Fabrication parameters that significantly influence radiation sensitivity have been identified. In particular, we examined the role of fluorine doping in defect formation and its relationship to radiation sensitivity. The experimental effort included fiber fabrication and radiation-induced loss measurements on graded index, Ge-doped core fibers. Fluorine was added to the core and/or the cladding of test fibers. Two critical parameters, barrier layer thickness and core dopants, have been identified and correlate with induced loss. In addition, the reproducibility of both fiber fabrication and measurement with respect to induced loss has been tested and found to be excellent. Induced loss was found to be proportional to Ge concentration in the core; however, the trend with fluorine doping was less clear. The experimental results are consistent with molecular dynamics simulations which indicate the types and numbers of structural defects in the glasses. The simulations revealed significant differences in defect types and concentrations among glass corn-positions that included pure silica, Ge-doped silica, and Ge/F-codoped silica. Fluorine codoping decreases the number of germanium-related defects but increases the number of defects associated with silicon.

Coatings influencing thermal stress in photonic crystal fiber laser

NASA Astrophysics Data System (ADS)

Pang, Dongqing; Li, Yan; Li, Yao; Hu, Minglie

2018-06-01

We studied how coating materials influence the thermal stress in the fiber core for three holding methods by simulating the temperature distribution and the thermal stress distribution in the photonic-crystal fiber laser. The results show that coating materials strongly influence both the thermal stress in the fiber core and the stress differences caused by holding methods. On the basis of the results, a two-coating PCF was designed. This design reduces the stress differences caused by variant holding conditions to zero, then the stability of laser operations can be improved.

Mid-infrared supercontinuum generation spanning from 1.9 to 5.7 μm in a chalcogenide fiber taper with ultra-high NA

NASA Astrophysics Data System (ADS)

Wang, Yingying; Dai, Shixun; Peng, Xuefeng; Zhang, Peiqing; Wang, Xunsi; You, Chenyang

2018-01-01

We report a broadband supercontinuum generation in a chalcogenide fiber taper with an ultra-high numerical aperture. The chalcogenide step-index fiber consisting of As2Se3 core and As2S3 cladding was fabricated by using the isolated stacked extrusion method. The fiber taper with a core diameter of 1.75 μm was prepared by employing a homemade tapering setup. By pumping the fiber taper with a femtosecond laser pulses at 3.3 μm, a broadband supercontinuum generation spanning from 1.9 to 5.7 μm was achieved.

High pulse energy sub-nanosecond Tm-doped fiber laser

NASA Astrophysics Data System (ADS)

Cserteg, Andras; Guillemet, Sebastien; Hernandez, Yves; Giannone, Domenico

2012-02-01

We report a core pumped thulium-doped fiber amplifier that generates 1.4 μJ pulses at 1980 nm with a repetition rate of 3.6 MHz preserving the original spectral bandwidth of the oscillator. The amplifier chain is seeded by a passively modelocked fiber laser with 5 mW output power and the pulses are stretched to 800 picoseconds. The amplifier is core pumped by a single mode erbium fiber laser. The slope efficiency is 35%. To the best of our knowledge, this is the first demonstration of sub nanosecond pulses with energies higher than 1 μJ coming out of a thulium-doped fiber amplifier.

A tunable optofluidic circular liquid fiber

NASA Astrophysics Data System (ADS)

Li, Lei; Wu, Wei; Shi, Yang; Gong, Enze; Yang, Yi

2016-01-01

This paper presents a tunable optofluidic circular liquid fiber through the numerical simulation. Fiber is a significant optical device and has been widely applied on optical fiber communication. But the fiber based solid has limited tunability. Compared to solid fiber, the fiber based liquid material is relatively infrequent. Cause for the liquid optical device has more freedom tunable properties than solid counterpart, it has attracted more interest. The traditional optofluidic waveguide is designed like a sandwich in planar channel. This two-dimensional (2D) structure liquid waveguide will face huge transmission loss in the perpendicular direction of the flow streams. In this paper, a curving microchannel is designed inside the microchip to produce centrifugal effect. Two different liquids are injected into the chip by external pumps. In a particular situation, the core flow will be totally surrounded by the cladding flow. So the liquid can form an optical waveguide. Its structure is similar to an optical fiber which high refractive index (RI) liquid is core of the waveguide and the low RI liquid is cladding of the waveguide. Profit from the reconfigurability of liquid material, this liquid fiber has excellent tunability. The diameter of the core flow can be tuned in a wider range by changing the volume ratio of the flows through the finite element analysis. It is predictable that such a tunable liquid fiber may find wider applications in lab-on-a-chip systems and integrated optical devices.

Air core detectors for Cerenkov-free scintillation dosimetry of brachytherapy β-sources.

PubMed

Eichmann, Marion; Thomann, Benedikt

2017-09-01

Plastic scintillation detectors are used for dosimetry in small radiation fields with high dose gradients, e.g., provided by β-emitting sources like 106 Ru/ 106 Rh eye plaques. A drawback is a background signal caused by Cerenkov radiation generated by electrons passing the optical fibers (light guides) of this dosimetry system. Common approaches to correct for the Cerenkov signal are influenced by uncertainties resulting from detector positioning and calibration procedures. A different approach to avoid any correction procedure is to suppress the Cerenkov signal by replacing the solid core optical fiber with an air core light guide, previously shown for external beam therapy. In this study, the air core concept is modified and applied to the requirements of dosimetry in brachytherapy, proving its usability for measuring water energy doses in small radiation fields. Three air core detectors with different air core lengths are constructed and their performance in dosimetry for brachytherapy β-sources is compared with a standard two-fiber system, which uses a second fiber for Cerenkov correction. The detector systems are calibrated with a 90 Sr/ 90 Y secondary standard and tested for their angular dependence as well as their performance in depth dose measurements of 106 Ru/ 106 Rh sources. The signal loss relative to the standard detector increases with increasing air core length to a maximum value of 58.3%. At the same time, however, the percentage amount of Cerenkov light in the total signal is reduced from at least 12.1% to a value below 1.1%. There is a linear correlation between induced dose and measured signal current. The air core detectors determine the dose rates for 106 Ru/ 106 Rh sources without any form of correction for the Cerenkov signal. The air core detectors show advantages over the standard two-fiber system especially when measuring in radiation fields with high dose gradients. They can be used as simple one-fiber systems and allow for an almost Cerenkov-free scintillation dosimetry of brachytherapy β-sources. © 2017 American Association of Physicists in Medicine.

Single mode tapered fiber-optic interferometer based refractive index sensor and its application to protein sensing.

PubMed

Yadav, T K; Narayanaswamy, R; Abu Bakar, M H; Kamil, Y Mustapha; Mahdi, M A

2014-09-22

We demonstrate refractive index sensors based on single mode tapered fiber and its application as a biosensor. We utilize this tapered fiber optic biosensor, operating at 1550 nm, for the detection of protein (gelatin) concentration in water. The sensor is based on the spectroscopy of mode coupling based on core modes-fiber cladding modes excited by the fundamental core mode of an optical fiber when it transitions into tapered regions from untapered regions. The changes are determined from the wavelength shift of the transmission spectrum. The proposed fiber sensor has sensitivity of refractive index around 1500 nm/RIU and for protein concentration detection, its highest sensitivity is 2.42141 nm/%W/V.

Multi-material optoelectronic fiber devices

NASA Astrophysics Data System (ADS)

Sorin, F.; Yan, Wei; Volpi, Marco; Page, Alexis G.; Nguyen Dang, Tung; Qu, Y.

2017-05-01

The recent ability to integrate materials with different optical and optoelectronic properties in prescribed architectures within flexible fibers is enabling novel opportunities for advanced optical probes, functional surfaces and smart textiles. In particular, the thermal drawing process has known a series of breakthroughs in recent years that have expanded the range of materials and architectures that can be engineered within uniform fibers. Of particular interest in this presentation will be optoelectronic fibers that integrate semiconductors electrically addressed by conducting materials. These long, thin and flexible fibers can intercept optical radiation, localize and inform on a beam direction, detect its wavelength and even harness its energy. They hence constitute ideal candidates for applications such as remote and distributed sensing, large-area optical-detection arrays, energy harvesting and storage, innovative health care solutions, and functional fabrics. To improve performance and device complexity, tremendous progresses have been made in terms of the integrated semiconductor architectures, evolving from large fiber solid-core, to sub-hundred nanometer thin-films, nano-filaments and even nanospheres. To bridge the gap between the optoelectronic fiber concept and practical applications however, we still need to improve device performance and integration. In this presentation we will describe the materials and processing approaches to realize optoelectronic fibers, as well as give a few examples of demonstrated systems for imaging as well as light and chemical sensing. We will then discuss paths towards practical applications focusing on two main points: fiber connectivity, and improving the semiconductor microstructure by developing scalable approaches to make fiber-integrated single-crystal nanowire based devices.

Temperature insensitive all-fiber accelerometer using a photonic crystal fiber long-period grating interferometer

NASA Astrophysics Data System (ADS)

Zheng, Shijie; Zhu, Yinian; Krishnaswamy, Sridhar

2012-04-01

Fiber-optic accelerometers have attracted great attention in recent years due to the fact that they have many advantages over electrical counterparts because all-fiber accelerometers have the capabilities for multiplexing to reduce cabling and to transmit signals over a long distance. They are also immune to electromagnetic interference. We propose and develop a compact and robust photonic crystal fiber (PCF) Mach-Zehnder interferometer (MZI) that can be implemented as an accelerometer for measurements of vibration and displacement. To excite core mode to couple out with cladding modes, two long-period gratings (LPGs) with identical transmission spectra are needed to be written in an endless single-mode PCF using a CO2 laser. The first LPG can couple a part of core mode to several cladding modes. After the light beams travel at different speeds over a certain length of the core and cladding, the cladding modes will be recoupled back to the core when they meet the second LPG, resulting in interference between the core mode and cladding modes. Dynamic strain is introduced to the PCF-MZI fiber segment that is bonded onto a spring-mass system. The shift of interference fringe can be measured by a photodetector, and the transformed analog voltage signal is proportional to the acceleration of the sensor head. Based on simulations of the PCF-MZI accelerometer, we can get a sensitivity of ~ 0.08 nm/g which is comparable with fiber Bragg grating (FBG) accelerometers. The proposed accelerometer has a capability of temperature insensitivity; therefore, no thermal-compensation scheme is required. Experimental results indicate that the PCF-MZI accelerometer may be a good candidate sensor for applications in civil engineering infrastructure and aeronautical platforms.

Research on high-temperature sensing characteristics based on modular interference of single-mode multimode single-mode fiber

NASA Astrophysics Data System (ADS)

Peng, Zhaozhuang; Wang, Li; Yan, Huanhuan

2016-11-01

Application of high temperature fiber sensing system is very extensive. It can be mainly used in high temperature test aerospace, such as, materials, chemicals, and energy. In recent years, various on-line optical fiber interferometric sensors based on modular interference of single-mode-multimode-single-mode(SMS) fiber have been largely explored in high temperature fiber sensor. In this paper we use the special fiber of a polyimide coating, its sensor head is composed of a section of multimode fiber spliced in the middle of Single-mode fiber. When the light is launched into the multimode fiber(MMF) through the lead-in single-mode fiber(SMF), the core mode and cladding modes are excited and propagate in the MMF respectively. Then, at the MMF-SMF spliced point, the excited cladding modes coupled back into the core of lead-out SMF interfere with SMF core mode. And the wavelength of the interference dip would shift differently with the variation of the temperature. By this mean, we can achieve the measurement of temperature. The experimental results also show that the fiber sensor based on SMS structure has a highly temperature sensitivity. From 30° to 300°, with the temperature increasing, the interference dip slightly shifts toward longer wavelength and the temperature sensitivity coefficient is 0.0115nm/°. With high sensitivity, simple structure, immunity to electromagnetic interferences and a good linearity of the experimental results, the structure has an excellent application prospect in engineering field.

Advancing flexible volatile compound sensors using liquid crystals encapsulated in polymer fibers

NASA Astrophysics Data System (ADS)

Reyes, Catherine G.; Lagerwall, Jan P. F.

2018-02-01

Until recently, organic vapor sensors using liquid crystals (LCs) have employed rigid glass substrates for confining the LC, and bulky equipment for vapor detection. Previously, we demonstrated that coaxially electrospinning nematic LC within the core of polymer fibers provides an alternative and improved form factor for confinement. This enables ppm level sensitivity to harmful industrial organics, such as toluene, while giving the flexibility of textile-like sheets (imparted by polymer encapsulation). Moreover, toluene vapor responses of the LC-core fiber mats were visible macroscopically with the naked eye depending on the morphology of the fibers produced, and whether they were oriented in specific geometries (aligned, or random). We identified two types of responses: one corresponds to the LC transition from nematic to isotropic, and the other we suggest is due to an anchoring change at the LC-polymer interface that influences the alignment. While we need to study the presence that defects can have in more detail, we noted that fiber mat thickness is crucial in attempting to understand how and why we are able to visualize two responses in aligned LC-fiber mats. Ultimately, we noted that the response of the polymer sheath itself (softening) to organic vapor exposure affects the liquid crystal confinement in the core. From the microscopic point of view, this will influence the threshold concentration that fibers in a mat will overall respond to. In this paper we will discuss three findings the morphologies enabling LC-core fiber mat response to vapor seen both micro- and macroscopically, how thickness of the fiber mat can play a role in the visualization of the responses, and the effect that the polymer structure has in the mat's sensitivity threshold.

Optimization of the contents of hollow glass microsphere and sodium hexametaphosphate for glass fiber vacuum insulation panel

NASA Astrophysics Data System (ADS)

Li, C. D.; Chen, Z. F.; Zhou, J. M.

2016-07-01

In this paper, various additive amounts of hollow glass microspheres (HGMs) and sodium hexametaphosphate (SHMP) powders were blended with flame attenuated glass wool (FAGW) to form hybrid core materials (HCMs) through the wet method. Among them, the SHMP was dissolved in the glass fiber suspension and coated on the surface of glass fibers while the HGMs were insoluble in the glass fiber suspension and filled in the fiber-fiber pores. The average pore diameter of the FAGW/HGM HCMs was 8-11 μm which was near the same as that of flame attenuated glass fiber mats (FAGMs, i.e., 10.5 µm). The tensile strength of the SHMP coated FAGMs was enhanced from 160 N/m to 370 N/m when SHMP content increased from 0 wt.% to 0.2 wt.%. By contrast, the tensile strength of the FAGW/HGM HCMs decreased from 160 N/m to 40 N/m when HGM content increased from 0 wt.% to 50 wt.%. Both the FAGW/HGM HCMs and SHMP coated FAGMs were vacuumed completely to form vacuum insulation panels (VIPs). The results showed that both the addition of SHMP and HGM led a slight increase in the thermal conductivity of the corresponding VIPs. To obtain a high-quality VIP, the optimal SHMP content and HGM content in glass fiber suspension was 0.12-0.2 wt.% and 0 wt.%.

Rapid constructions of microstructures for optical fiber sensors using a commercial CO2 laser system.

PubMed

Irawan, Rudi; Chuan, Tjin Swee; Meng, Tay Chia; Ming, Tan Khay

2008-06-27

Exposing an optical fiber core to the measurand surrounding the fiber is often used to enhance the sensitivity of an optical fiber sensor. This paper reports on the rapid fabrication of microstructures in an optical fiber using a CO₂ laser system which help exposing the optical fiber core to the measurand. The direct-write CO₂ laser system used is originally designed for engraving the polymeric material. Fabrications of microstructures such as in-fiber microhole, D-shaped fiber, in-fiber microchannel, side-sliced fiber and tapered fiber were attempted. The microstructures in the fibers were examined using a SEM and an optical microscope. Quality of microstructures shown by the SEM images and promising results from fluorescence sensor tests using in-fiber microchannels of 100μm width, 210μm depth and 10mm length show the prospect of this method for use in optical fiber sensor development. The direct-write CO₂ laser system is a flexible and fast machining tool for fabricating microstructures in an optical fiber, and can possibly be a replacement of the time consuming chemical etching and polishing methods used for microstructure fabrications of optical the fiber sensors reported in other literatures.

Rapid Constructions of Microstructures for Optical Fiber Sensors Using a Commercial CO2 Laser System

PubMed Central

Irawan, Rudi; Chuan, Tjin Swee; Meng, Tay Chia; Ming, Tan Khay

2008-01-01

Exposing an optical fiber core to the measurand surrounding the fiber is often used to enhance the sensitivity of an optical fiber sensor. This paper reports on the rapid fabrication of microstructures in an optical fiber using a CO2 laser system which help exposing the optical fiber core to the measurand. The direct-write CO2 laser system used is originally designed for engraving the polymeric material. Fabrications of microstructures such as in-fiber microhole, D-shaped fiber, in-fiber microchannel, side-sliced fiber and tapered fiber were attempted. The microstructures in the fibers were examined using a SEM and an optical microscope. Quality of microstructures shown by the SEM images and promising results from fluorescence sensor tests using in-fiber microchannels of 100μm width, 210μm depth and 10mm length show the prospect of this method for use in optical fiber sensor development. The direct-write CO2 laser system is a flexible and fast machining tool for fabricating microstructures in an optical fiber, and can possibly be a replacement of the time consuming chemical etching and polishing methods used for microstructure fabrications of optical the fiber sensors reported in other literatures. PMID:19662114

Hollow fiber apparatus and use thereof for fluids separations and heat and mass transfers

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

Bikson, Benjamin; Etter, Stephen; Ching, Nathaniel

A hollow fiber fluid separation device includes a hollow fiber cartridge, comprising a plurality of hollow fiber membranes arranged around a central tubular core, a first tubesheet and a second tubesheet encapsulating respective distal ends of the hollow fiber bundle. The tubesheets have boreholes in fluid communication with bores of the hollow fiber membrane. In at least one of the tubesheets, the boreholes are formed radially and are in communication with the central tubular core. The hollow fiber fluid separation device can be utilized in liquid separation applications such as ultrafiltration and in gas separation processes such as air separation.more » The design disclosed herein is light weight and compact and is particularly advantageous at high operating temperatures when the pressure of the feed fluid introduced into the bores of hollow fibers is higher than the pressure on the shell side of the device.« less

High-efficiency, 154  W CW, diode-pumped Raman fiber laser with brightness enhancement.

PubMed

Glick, Yaakov; Fromzel, Viktor; Zhang, Jun; Ter-Gabrielyan, Nikolay; Dubinskii, Mark

2017-01-20

We demonstrate a high-power, high-efficiency Raman fiber laser pumped directly by laser diode modules at 978 nm. 154 W of CW power were obtained at a wavelength of 1023 nm with an optical to optical efficiency of 65%. A commercial graded-index (GRIN) core fiber acts as the Raman fiber in a power oscillator configuration, which includes spectral selection to prevent generation of the second Stokes. In addition, brightness enhancement of the pump beam by a factor of 8.4 is attained due to the Raman gain distribution profile in the GRIN fiber. To the best of our knowledge this is the highest power and highest efficiency Raman fiber laser demonstrated in any configuration allowing brightness enhancement (i.e., in either cladding-pumped configuration or with GRIN fibers, excluding step-index core pumped), regardless of pumping scheme (i.e., either diode pumped or fiber laser pumped).

Geometrical analysis of an optical fiber bundle displacement sensor

NASA Astrophysics Data System (ADS)

Shimamoto, Atsushi; Tanaka, Kohichi

1996-12-01

The performance of a multifiber optical lever was geometrically analyzed by extending the Cook and Hamm model [Appl. Opt. 34, 5854-5860 (1995)] for a basic seven-fiber optical lever. The generalized relationships between sensitivity and the displacement detection limit to the fiber core radius, illumination irradiance, and coupling angle were obtained by analyses of three various types of light source, i.e., a parallel beam light source, an infinite plane light source, and a point light source. The analysis of the point light source was confirmed by a measurement that used the light source of a light-emitting diode. The sensitivity of the fiber-optic lever is inversely proportional to the fiber core radius, whereas the receiving light power is proportional to the number of illuminating and receiving fibers. Thus, the bundling of the finer fiber with the larger number of illuminating and receiving fibers is more effective for improving sensitivity and the displacement detection limit.

Self-phase modulation of submicrojoule femtosecond pulses in a hollow-core photonic-crystal fiber

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

Konorov, S.O.; Sidorov-Biryukov, D.A.; Zheltikov, A.M.

Hollow-core photonic-crystal fibers (PCFs) capable of transporting sub-100-fs pulses of Ti:sapphire laser radiation in one of their transmission peaks centered around 800 nm have been designed and demonstrated. These fibers are shown to enhance self-phase modulation of submicrojoule 100-fs Ti:sapphire laser pulses, allowing a spectral bandwidth of 35 nm to be achieved with an 8-cm PCF sample.

High-sensitivity four-layer polymer fiber-optic evanescent wave sensor.

PubMed

Xin, Xin; Zhong, Nianbing; Liao, Qiang; Cen, Yanyan; Wu, Ruohua; Wang, Zhengkun

2017-05-15

We present a novel four-layer structure consisting of bottom, second, third, and surface layers in the sensing region, for a D-shaped step-index fiber-optic evanescent wave (FOEW) sensor. To reduce the background noise, the surface of the longitudinal section in the D-shaped region is coated with a light-absorbing film. We check the morphologies of the second and surface layers, examine the refractive indices (RIs) of the third and surface layers, and analyze the composition of the surface layer. We also investigate the effects of the thicknesses and RIs of the third and surface layers and the LA film on the light transmission and sensitivity of the FOEW sensors. The results highlight the very good sensitivity of the proposed FOEW sensor with a four-layer structure, which reached -0.077 (μg/l) -1 in the detection of the target antibody; the sensitivity of the novel FOEW sensor was 7.60 and 1.52 times better than that of a conventional sensor with a core-cladding structure and an FOEW sensor with a three-layer structure doped with GeO 2 . The applications of this high-sensitivity FOEW sensor can be extended to biodefense, disease diagnosis, and biomedical and biochemical analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Transvaginal photoacoustic imaging probe and system based on a multiport fiber-optic beamsplitter and a real time imager for ovarian cancer detection

NASA Astrophysics Data System (ADS)

Kumavor, Patrick D.; Alqasemi, Umar; Tavakoli, Behnoosh; Li, Hai; Yang, Yi; Zhu, Quing

2013-03-01

This paper presents a real-time transvaginal photoacoustic imaging probe for imaging human ovaries in vivo. The probe consists of a high-throughput (up to 80%) fiber-optic 1 x 19 beamsplitters, a commercial array ultrasound transducer, and a fiber protective sheath. The beamsplitter has a 940-micron core diameter input fiber and 240-micron core diameter output fibers numbering 36. The 36 small-core output fibers surround the ultrasound transducer and delivers light to the tissue during imaging. A protective sheath, modeled in the form of the transducer using a 3-D printer, encloses the transducer with array of fibers. A real-time image acquisition system collects and processes the photoacoustic RF signals from the transducer, and displays the images formed on a monitor in real time. Additionally, the system is capable of coregistered pulse-echo ultrasound imaging. In this way, we obtain both morphological and functional information from the ovarian tissue. Photoacousitc images of malignant human ovaries taken ex vivo with the probe revealed blood vascular and networks that was distinguishable from normal ovaries, making the probe potential useful for characterizing ovarian tissue.

5  W output power from a double-clad hybrid fiber with Yb-doped phosphate core and silicate cladding.

PubMed

Wang, Longfei; He, Dongbing; Zhang, Lei; Yu, Chunlei; Feng, Suya; Wang, Meng; Chen, Danping; Hu, Lili

2017-08-01

For the first time, to the best of our knowledge, we report on the realization of a laser from a Yb-doped phosphate core/silicate cladding double-clad hybrid fiber. 5 W output power was extracted with 14.6% slope efficiency and a laser spectrum of a 1027 nm central wavelength from a 20 cm long single-mode fiber with a ∼10  μm core diameter in a 20%-4% laser cavity. The laser efficiency can be significantly enhanced by correspondingly adjusting and optimizing the laser oscillator.

All-fiber magnetic field sensor based on tapered thin-core fiber and magnetic fluid.

PubMed

Zhang, Junying; Qiao, Xueguang; Yang, Hangzhou; Wang, Ruohui; Rong, Qiangzhou; Lim, Kok-Sing; Ahmad, Harith

2017-01-10

A method for the measurement of a magnetic field by combining a tapered thin-core fiber (TTCF) and magnetic fluid is proposed and experimentally demonstrated. The modal interference effect is caused by the core mode and excited eigenmodes in the TTCF cladding. The transmission spectra of the proposed sensor are measured and theoretically analyzed at different magnetic field strengths. The results field show that the magnetic sensitivity reaches up to -0.1039  dB/Oe in the range of 40-1600 e. The proposed method possesses high sensitivity and low cost compared with other expensive methods.