Hollow cathode lamp based Faraday anomalous dispersion optical filter.

PubMed

Pan, Duo; Xue, Xiaobo; Shang, Haosen; Luo, Bin; Chen, Jingbiao; Guo, Hong

2016-07-15

The Faraday anomalous dispersion optical filter (FADOF), which has acquired wide applications, is mainly limited to some gaseous elements and low melting-point metals before, for the restriction of the attainable atomic density. In conventional FADOF systems a high atomic density is usually achieved by thermal equilibrium at the saturated vapor pressure, hence for elements with high melting-points a high temperature is required. To avoid this restriction, we propose a scheme of FADOF based on the hollow cathode lamp (HCL), instead of atomic vapor cells. Experimental results in strontium atoms verified this scheme, where a transmission peak corresponding to the (88)Sr (5s(2))(1)S0 - (5s5p)(1)P1 transition (461 nm) is obtained, with a maximum transmittance of 62.5% and a bandwith of 1.19 GHz. The dependence of transmission on magnetic field and HCL discharge current is also studied. Since the state-of-art commercial HCLs cover about 70 elements, this scheme can greatly expand the applications of FADOFs, and the abundant atomic transitions they provide bring the HCL based FADOFs potential applications for frequency stabilization.

Hollow cathode lamp based Faraday anomalous dispersion optical filter

NASA Astrophysics Data System (ADS)

Pan, Duo; Xue, Xiaobo; Shang, Haosen; Luo, Bin; Chen, Jingbiao; Guo, Hong

2016-07-01

The Faraday anomalous dispersion optical filter (FADOF), which has acquired wide applications, is mainly limited to some gaseous elements and low melting-point metals before, for the restriction of the attainable atomic density. In conventional FADOF systems a high atomic density is usually achieved by thermal equilibrium at the saturated vapor pressure, hence for elements with high melting-points a high temperature is required. To avoid this restriction, we propose a scheme of FADOF based on the hollow cathode lamp (HCL), instead of atomic vapor cells. Experimental results in strontium atoms verified this scheme, where a transmission peak corresponding to the 88Sr (5s2)1S0 - (5s5p)1P1 transition (461 nm) is obtained, with a maximum transmittance of 62.5% and a bandwith of 1.19 GHz. The dependence of transmission on magnetic field and HCL discharge current is also studied. Since the state-of-art commercial HCLs cover about 70 elements, this scheme can greatly expand the applications of FADOFs, and the abundant atomic transitions they provide bring the HCL based FADOFs potential applications for frequency stabilization.

Simultaneous Faraday filtering of the Mollow triplet sidebands with the Cs-D1 clock transition.

PubMed

Portalupi, Simone Luca; Widmann, Matthias; Nawrath, Cornelius; Jetter, Michael; Michler, Peter; Wrachtrup, Jörg; Gerhardt, Ilja

2016-11-25

Hybrid quantum systems integrating semiconductor quantum dots (QDs) and atomic vapours become important building blocks for scalable quantum networks due to the complementary strengths of individual parts. QDs provide on-demand single-photon emission with near-unity indistinguishability comprising unprecedented brightness-while atomic vapour systems provide ultra-precise frequency standards and promise long coherence times for the storage of qubits. Spectral filtering is one of the key components for the successful link between QD photons and atoms. Here we present a tailored Faraday anomalous dispersion optical filter based on the caesium-D 1 transition for interfacing it with a resonantly pumped QD. The presented Faraday filter enables a narrow-bandwidth (Δω=2π × 1 GHz) simultaneous filtering of both Mollow triplet sidebands. This result opens the way to use QDs as sources of single as well as cascaded photons in photonic quantum networks aligned to the primary frequency standard of the caesium clock transition.

Optical vector network analysis of ultranarrow transitions in 166Er3+ : 7LiYF4 crystal.

PubMed

Kukharchyk, N; Sholokhov, D; Morozov, O; Korableva, S L; Cole, J H; Kalachev, A A; Bushev, P A

2018-02-15

We present optical vector network analysis (OVNA) of an isotopically purified Er166 3+ :LiYF 4 7 crystal. The OVNA method is based on generation and detection of a modulated optical sideband by using a radio-frequency vector network analyzer. This technique is widely used in the field of microwave photonics for the characterization of optical responses of optical devices such as filters and high-Q resonators. However, dense solid-state atomic ensembles induce a large phase shift on one of the optical sidebands that results in the appearance of extra features on the measured transmission response. We present a simple theoretical model that accurately describes the observed spectra and helps to reconstruct the absorption profile of a solid-state atomic ensemble as well as corresponding change of the refractive index in the vicinity of atomic resonances.

Techniques for optically compressing light intensity ranges

DOEpatents

Rushford, Michael C.

1989-01-01

A pin hole camera assembly for use in viewing an object having a relatively large light intensity range, for example a crucible containing molten uranium in an atomic vapor laser isotope separator (AVLIS) system is disclosed herein. The assembly includes means for optically compressing the light intensity range appearing at its input sufficient to make it receivable and decipherable by a standard video camera. A number of different means for compressing the intensity range are disclosed. These include the use of photogray glass, the use of a pair of interference filters, and the utilization of a new liquid crystal notch filter in combination with an interference filter.

Techniques for optically compressing light intensity ranges

DOEpatents

Rushford, M.C.

1989-03-28

A pin hole camera assembly for use in viewing an object having a relatively large light intensity range, for example a crucible containing molten uranium in an atomic vapor laser isotope separator (AVLIS) system is disclosed herein. The assembly includes means for optically compressing the light intensity range appearing at its input sufficient to make it receivable and decipherable by a standard video camera. A number of different means for compressing the intensity range are disclosed. These include the use of photogray glass, the use of a pair of interference filters, and the utilization of a new liquid crystal notch filter in combination with an interference filter. 18 figs.

Fibre Optic Mechanical Sensors For Aerospace Applications

NASA Astrophysics Data System (ADS)

Batchellor, C. R.; Dakin, J. P.; Pearce, D. A. J.

1989-04-01

A fiber optic multisensor methane detection system matched to topology and environment of a coal mine is reported. The system involves time domain multiplexed (TDM) methane sensors based on selective absorption of source radiation by atomic or molecular species in the gas sensing heads. A two-wavelength ratiometric approach allows simple self referencing, cancels out errors arising from other contaminants, and improves the measurement contrast. The laboratory system consists of a high radiance LED source, multimode fiber, optical sensing head, optical bandpass filters, and involves synchronous detection with low noise photodiodes and a lock-in amplifier. Detection sensitivity upon spectral resolution of the optical filters has also been investigated and described. The system performance was evaluated and the results are presented.

Self-Referenced Fiber Optic System For Remote Methane Detection

NASA Astrophysics Data System (ADS)

Zientkiewicz, Jacek K.

1989-10-01

The paper discusses a fiber optic multisensor methane detection system matched to topology and environment of the underground mine. The system involves time domain multiplexed (TDM) methane sensors based on selective absorption of source radiation by atomic/molecular species in the gas sensing heads. A two-wavelength ratiometric approach allows simple self-referencing, cancels out errors arising from other contaminants, and improves the measurement contrast. The laboratory system consists of a high radiance LED source, multimode fiber, optical sensing head, optical bandpass filters, and involves synchronous detection with low noise photodiodes and a lock-in amplifier. Detection sensitivity versus spectral resolution of the optical filters has also been investigated and described. The system performance was evaluated and the results are presented.

Hollow cathode lamp based Faraday anomalous dispersion optical filter

PubMed Central

Pan, Duo; Xue, Xiaobo; Shang, Haosen; Luo, Bin; Chen, Jingbiao; Guo, Hong

2016-01-01

The Faraday anomalous dispersion optical filter (FADOF), which has acquired wide applications, is mainly limited to some gaseous elements and low melting-point metals before, for the restriction of the attainable atomic density. In conventional FADOF systems a high atomic density is usually achieved by thermal equilibrium at the saturated vapor pressure, hence for elements with high melting-points a high temperature is required. To avoid this restriction, we propose a scheme of FADOF based on the hollow cathode lamp (HCL), instead of atomic vapor cells. Experimental results in strontium atoms verified this scheme, where a transmission peak corresponding to the 88Sr (5s2)1S0 − (5s5p)1P1 transition (461 nm) is obtained, with a maximum transmittance of 62.5% and a bandwith of 1.19 GHz. The dependence of transmission on magnetic field and HCL discharge current is also studied. Since the state-of-art commercial HCLs cover about 70 elements, this scheme can greatly expand the applications of FADOFs, and the abundant atomic transitions they provide bring the HCL based FADOFs potential applications for frequency stabilization. PMID:27418112

Fluoride coatings for vacuum ultraviolet reflection filters.

PubMed

Guo, Chun; Kong, Mingdong; Lin, Dawei; Li, Bincheng

2015-12-10

LaF3/MgF2 reflection filters with a high spectral-discrimination capacity of the atomic-oxygen lines at 130.4 and 135.6 nm, which were employed in vacuum ultraviolet imagers, were prepared by molybdenum-boat thermal evaporation. The optical properties of reflection filters were characterized by a high-precision vacuum ultraviolet spectrophotometer. The vulnerability of the filter's microstructures to environmental contamination and the recovery of the optical properties of the stored filter samples with ultraviolet ozone cleaning were experimentally demonstrated. For reflection filters with the optimized nonquarter-wave multilayer structures, the reflectance ratios R135.6 nm/R130.4 nm of 92.7 and 20.6 were achieved for 7° and 45° angles of incidence, respectively. On the contrary, R135.6 nm/R130.4 nm ratio of 12.4 was obtained for a reflection filter with a standard π-stack multilayer structure with H/L=1/4 at 7° AOI.

Quantum Optics with Atom-like Systems in Diamond

DTIC Science & Technology

2013-11-19

emission from the NV is separated by dichroic filters from the 532 nm excitation path ( Semrock LPD01-532RS-25) and ZPL path ( Semrock Di01- R635-25x35...before being filtered to remove any leakage or dominant raman lines (2x Semrock NF01-633U-25, Semrock LP01-633RS-25). It is then coupled into a...filtered by two narrow frequency filters (custom Andover 1 nm bandpass around 638 nm, Semrock FF01-640/14-25) and detected by a low-dark count APD (Micro

Single and pair-wise manipulation of atoms in a 3D optical lattice

NASA Astrophysics Data System (ADS)

Corcovilos, Theodore; Wang, Yang; Weiss, David

2013-05-01

We describe the hardware used in a quantum computing experiment using individual Cs atoms in a 5 μm -spaced 3D optical lattice as qubits. Far-off-resonance addressing beams can be steered to any site in the array using MEMS mirrors within 10 μs , allowing the translation of individual atoms between lattice sites, for example to remove vacancies in the atom array, and the manipulation of single atoms for single qubit gates in < 100 μs . Two-qubit gates on adjacent atoms can be performed via the Rydberg blockade mechanism using a second MEMS system and high-NA imaging objective. The lasers for the Rydberg excitation are built using a new extended cavity diode laser design utilizing an interference filter as the frequency selecting element following Baillard, et al. (Opt. Comm. 266: 609 (2009)), but using commercially available components. We gratefully acknowledge funding from ARO and DARPA.

Crystalline Colloidal Arrays in Polymer Matrices

NASA Technical Reports Server (NTRS)

Sunkara, Hari B.; Penn, B. G.; Frazier, D. O.; Ramachandran, N.

1997-01-01

Crystalline Colloidal Arrays (CCA, also known as colloidal crystals), composed of aqueous or nonaqueous dispersions of self-assembled nanosized polymer colloidal spheres, are emerging toward the development of advanced optical devices for technological applications. The spontaneous self assembly of polymer spheres in a dielectric medium results from the electrostatic repulsive interaction between particles of uniform size and charge distribution. In a way similar to atomic crystals that diffract X-rays, CCA dispersions in thin quartz cells selectively and efficiently Bragg diffract the incident visible light. The reason for this diffraction is because the lattice (body or face centered cubic) spacing is on the order of the wavelength of visible light. Unlike the atomic crystals that diffract a fixed wavelength, colloidal crystals in principle, depending on the particle size, particle number and charge density, can diffract W, Vis or IR light. Therefore, the CCA dispersions can be used as laser filters. Besides, the diffraction intensity depends on the refractive index mismatch between polymer spheres and dielectric medium; therefore, it is possible to modulate incident light intensities by manipulating the index of either the spheres or the medium. Our interest in CCA is in the fabrication of all-optical devices such as optical switches, limiters, and spatial light modulators for optical signal processing. The two major requirements from a materials standpoint are the incorporation of suitable nonlinear optical materials (NLO) into polymer spheres which will allow us to alter the refractive index of the spheres by intense laser radiation, and preparation of solid CCA filters which can resist laser damage. The fabrication of solid composite filters not only has the advantage that the films are easier to handle, but also the arrays in solid films are more robust than in liquid media. In this paper, we report the photopolymerization process used to trap CCA in polymer matrices, the factors which affect the optical diffraction qualities of resulting polymer films, and methods to improve the efficiencies of solid optical filters. Before this, we also present the experimental demonstration, of controlling the optical diffraction intensities from aqueous CCA dispersions by varying the temperature, which establishes the feasibility of fabricating all-optical switching devices with nonlinear periodic array structures.

An open source digital servo for atomic, molecular, and optical physics experiments

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

Leibrandt, D. R., E-mail: david.leibrandt@nist.gov; Heidecker, J.

2015-12-15

We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of themore » laser used to probe the narrow clock transition of {sup 27}Al{sup +} in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser.« less

An open source digital servo for atomic, molecular, and optical physics experiments.

PubMed

Leibrandt, D R; Heidecker, J

2015-12-01

We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of the laser used to probe the narrow clock transition of (27)Al(+) in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser.

An open source digital servo for atomic, molecular, and optical physics experiments

NASA Astrophysics Data System (ADS)

Leibrandt, D. R.; Heidecker, J.

2015-12-01

We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of the laser used to probe the narrow clock transition of 27Al+ in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser.

An open source digital servo for atomic, molecular, and optical physics experiments

PubMed Central

Leibrandt, D. R.; Heidecker, J.

2016-01-01

We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of the laser used to probe the narrow clock transition of 27Al+ in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser. PMID:26724014

Faraday imaging at high temperatures

DOEpatents

Hackel, L.A.; Reichert, P.

1997-03-18

A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid. 3 figs.

Faraday imaging at high temperatures

DOEpatents

Hackel, Lloyd A.; Reichert, Patrick

1997-01-01

A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid.

Short-term stability improvements of an optical frequency standard based on free Ca atoms

NASA Astrophysics Data System (ADS)

Sherman, Jeff; Oates, Chris

2010-03-01

Compared to optical frequency standards featuring trapped ions or atoms in optical lattices, the strength of a standard using freely expanding neutral calcium atoms is not ultimate accuracy but rather short-term stability and experimental simplicity. Recently, a fractional frequency instability of 4 x10-15 at 1 second was demonstrated for the Ca standard at 657 nm [1]. The short cycle time (˜2 ms) combined with only a moderate interrogation duty cycle (˜15 %) is thought to introduce excess, and potentially critically limiting technical noise due to the Dick effect---high-frequency noise on the laser oscillator is not averaged away but is instead down-sampled by aliasing. We will present results of two strategies employed to minimize this effect: the reduction of clock laser noise by filtering the master clock oscillator through a high-finesse optical cavity [2], and an optimization of the interrogation cycle to match our laser's noise spectrum.[4pt] [1] Oates et al., Optics Letters, 25(21), 1603--5 (2000)[0pt] [2] Nazarova et al., J. Opt. Soc. Am. B, 5(10), 1632--8 (2008)

Diode laser operating on an atomic transition limited by an isotope ⁸⁷Rb Faraday filter at 780 nm.

PubMed

Tao, Zhiming; Hong, Yelong; Luo, Bin; Chen, Jingbiao; Guo, Hong

2015-09-15

We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope (87)Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope (87)Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15°C to 35°C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications.

Interlaced spin grating for optical wave filtering

NASA Astrophysics Data System (ADS)

Linget, H.; Chanelière, T.; Le Gouët, J.-L.; Berger, P.; Morvan, L.; Louchet-Chauvet, A.

2015-02-01

Interlaced spin grating is a scheme for the preparation of spectrospatial periodic absorption gratings in an inhomogeneously broadened absorption profile. It relies on the optical pumping of atoms in a nearby long-lived ground state sublevel. The scheme takes advantage of the sublevel proximity to build large contrast gratings with unlimited bandwidth and preserved average optical depth. It is particularly suited to Tm-doped crystals in the context of classical and quantum signal processing. In this paper, we study the optical pumping dynamics at play in an interlaced spin grating and describe the corresponding absorption profile shape in an optically thick atomic ensemble. We show that, in Tm:YAG, the diffraction efficiency of such a grating can reach 18.3 % in the small-angle and 11.6 % in the large-angle configuration when the excitation is made of simple pulse pairs, considerably outperforming conventional gratings.

Cavity Self-Stabilization and Enhancement of Laser Gyroscopes by (Coupled) Optical Resonators

NASA Technical Reports Server (NTRS)

Smith, David D.

2006-01-01

We analyze the effect of a highly dispersive element placed inside a modulated optical cavity on the frequency and amplitude of the modulation to determine the conditions for cavity self-stabilization and enhanced gyroscopic sensitivity. Hence, we model cavity rotation or instability by an arbitrary AM/FM modulation, and the dispersive element as a phase and amplitude filter. We find that anomalous dispersion may be used to self-stabilize a laser cavity, provided the magnitude of the group index of refraction is smaller than the phase index of refraction in the cavity. The optimal stabilization is found to occur when the group index is zero. Group indices with magnitudes larger than the phase index (both normal and anomalous dispersion) are found to enhance the sensitivity of a laser gyroscope to rotation. Furthermore, our results indicate that atomic media, even coherent superpositions in multilevel atoms, are not useful for these applications, because the amplitude and phase filters work against one another, i.e., decreasing the modulation frequency increases its amplitude and vice versa, with one exception: negative group indices whose magnitudes are larger than the phase index result in negative, but enhanced, beat frequencies. On the other hand, for optical resonators the dispersion reversal associated with critical coupling enables the amplitude and phase filters to work together under a greater variety of circumstances than for atomic media. We find that for single over-coupled resonators, or in the case of under-coupled coupled-resonator-induced absorption, the absorption and normal dispersion on-resonance increase the contrast and frequency of the beat-note, respectively, resulting in a substantial enhancement of the gyroscopic response. Moreover, for cavity self-stabilization, we propose the use of a variety of coupled-resonator induced transparency that is accompanied by anomalous dispersion.

Atomic magnetometer

DOEpatents

Schwindt, Peter [Albuquerque, NM; Johnson, Cort N [Albuquerque, NM

2012-07-03

An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.

Bandwidth-induced reversal of asymmetry in optical-double-resonance amplitudes

NASA Astrophysics Data System (ADS)

Nitz, D. E.; Smith, A. V.; Levenson, M. D.; Smith, S. J.

1981-07-01

Optical-double-resonance measurements using ionization detection have been carried out in the 3S12-3P12-4D atomic-sodium system. Asymmetries observed in production of 4D atoms from the two components of the Stark-split 3P12 state are found to be controlled by the far, very weak wings of the 17-MHz full-width-at-half-maximum laser line which is used to drive the 3S12-3P12 transition at detunings in the range 0-70 GHz. Suppression of the wings with a Fabry-Perot filter causes a pronounced reversal of the asymmetry.

The performance and limitations of FPGA-based digital servos for atomic, molecular, and optical physics experiments

NASA Astrophysics Data System (ADS)

Yu, Shi Jing; Fajeau, Emma; Liu, Lin Qiao; Jones, David J.; Madison, Kirk W.

2018-02-01

In this work, we address the advantages, limitations, and technical subtleties of employing field programmable gate array (FPGA)-based digital servos for high-bandwidth feedback control of lasers in atomic, molecular, and optical physics experiments. Specifically, we provide the results of benchmark performance tests in experimental setups including noise, bandwidth, and dynamic range for two digital servos built with low and mid-range priced FPGA development platforms. The digital servo results are compared to results obtained from a commercially available state-of-the-art analog servo using the same plant for control (intensity stabilization). The digital servos have feedback bandwidths of 2.5 MHz, limited by the total signal latency, and we demonstrate improvements beyond the transfer function offered by the analog servo including a three-pole filter and a two-pole filter with phase compensation to suppress resonances. We also discuss limitations of our FPGA-servo implementation and general considerations when designing and using digital servos.

The performance and limitations of FPGA-based digital servos for atomic, molecular, and optical physics experiments.

PubMed

Yu, Shi Jing; Fajeau, Emma; Liu, Lin Qiao; Jones, David J; Madison, Kirk W

2018-02-01

In this work, we address the advantages, limitations, and technical subtleties of employing field programmable gate array (FPGA)-based digital servos for high-bandwidth feedback control of lasers in atomic, molecular, and optical physics experiments. Specifically, we provide the results of benchmark performance tests in experimental setups including noise, bandwidth, and dynamic range for two digital servos built with low and mid-range priced FPGA development platforms. The digital servo results are compared to results obtained from a commercially available state-of-the-art analog servo using the same plant for control (intensity stabilization). The digital servos have feedback bandwidths of 2.5 MHz, limited by the total signal latency, and we demonstrate improvements beyond the transfer function offered by the analog servo including a three-pole filter and a two-pole filter with phase compensation to suppress resonances. We also discuss limitations of our FPGA-servo implementation and general considerations when designing and using digital servos.

Fast wavelength calibration method for spectrometers based on waveguide comb optical filter

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

Yu, Zhengang; Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240; Huang, Meizhen, E-mail: mzhuang@sjtu.edu.cn

2015-04-15

A novel fast wavelength calibration method for spectrometers based on a standard spectrometer and a double metal-cladding waveguide comb optical filter (WCOF) is proposed and demonstrated. By using the WCOF device, a wide-spectrum beam is comb-filtered, which is very suitable for spectrometer wavelength calibration. The influence of waveguide filter’s structural parameters and the beam incident angle on the comb absorption peaks’ wavelength and its bandwidth are also discussed. The verification experiments were carried out in the wavelength range of 200–1100 nm with satisfactory results. Comparing with the traditional wavelength calibration method based on discrete sparse atomic emission or absorption lines,more » the new method has some advantages: sufficient calibration data, high accuracy, short calibration time, fit for produce process, stability, etc.« less

Light-Shifts of an Integrated Filter-Cell Rubidium Atomic Clock

DTIC Science & Technology

2015-05-25

the light-shift coefficient for two different rf- discharge lamps (i.e., a pure 87Rb lamp and a lamp filled with the natural Rb isotope abundance...for the Galileo Rb clock under the assumption of a natural (or 85Rb isotopically enriched) rf- discharge lamp for the Galileo clock. I...satellites [14]. 6.8347… GHz 85Rb Filter Cell Cell Resonance Photodiode Microwave Cavity 87Rb Discharge Lamp 87Rb & N2 Rb & Xe, Kr Optical Pumping 87Rb

Stabilizing Microwave Frequency of a Photonic Oscillator

NASA Technical Reports Server (NTRS)

Maleki, Lute; Yu, Nan; Tu, Meirong

2006-01-01

A scheme for stabilizing the frequency of a microwave signal is proposed that exploits the operational characteristics of a coupled optoelectronic oscillator (COEO) and related optoelectronic equipment. An essential element in the scheme is a fiber mode-locked laser (MLL), the optical frequency of which is locked to an atomic transition. In this scheme, the optical frequency stability of the mode-locked laser is transferred to that of the microwave in the same device. Relative to prior schemes for using wideband optical frequency comb to stabilize microwave signals, this scheme is simpler and lends itself more readily to implementation in relatively compact, rugged equipment. The anticipated development of small, low-power, lightweight, highly stable microwave oscillators based on this scheme would afford great benefits in communication, navigation, metrology, and fundamental sciences. COEOs of various designs, at various stages of development, in some cases called by different names, have been described in a number of prior NASA Tech Briefs articles. A COEO is an optoelectronic apparatus that generates both short (picosecond) optical pulses and a steady microwave signal having an ultrahigh degree of spectral purity. The term "coupled optoelectronic" in the full name of such an apparatus signifies that its optical and electronic oscillations are coupled to each other in a single device. The present frequency-stabilization scheme is best described indirectly by describing the laboratory apparatus used to demonstrate it. The apparatus (see figure) includes a COEO that generates a comb-like optical spectrum, the various frequency components of which interfere, producing short optical pulses. This spectrum is centered at a nominal wavelength of 1,560 nm. The spectrum separation of this comb is about 10 GHz, as determined primarily by the length of an optical loop and the bandpass filter in the microwave feedback loop. The optical loop serves as microwave resonator having a very high value of the resonance quality factor (Q). The optical frequency of MLL is then stabilized by locking it to an atomic transition as described below. The COEO contains a tunable 1-nm band-pass optical filter and a piezoelectric-transducer (PZT) drum over which a stretch of fiber is wound. The 1-nm-wide pass band of the filter provides coarse tuning to overlap the frequency comb with the atomic transition frequency. Controlled stretching of the fiber by means of the PZT drum can be used in conjunction with temperature control for locking the laser frequency. To reference to an atomic resonance at 780 nm in this demonstration setup, the optical output of the COEO at 1,560 nm is fed through an erbium-doped-fiber amplifier (EDFA) to a frequency doubler in the form of a periodically poled lithium niobate (PPLN) crystal. The frequency-doubled output is combined with the output of a separate frequency-stabilized diode laser at a photodetector. As described thus far, the two 780-nm laser subsystems are nominally independent of each other and can, therefore, operate at different frequencies. Hence, at the photodetector, the two laser beams interfere, so that the output of the photodetector includes a beat note (a component at the difference between the two laser frequencies).

Simple and Efficient Single Photon Filter for a Rb-based Quantum Memory

NASA Astrophysics Data System (ADS)

Stack, Daniel; Li, Xiao; Quraishi, Qudsia

2015-05-01

Distribution of entangled quantum states over significant distances is important to the development of future quantum technologies such as long-distance cryptography, networks of atomic clocks, distributed quantum computing, etc. Long-lived quantum memories and single photons are building blocks for systems capable of realizing such applications. The ability to store and retrieve quantum information while filtering unwanted light signals is critical to the operation of quantum memories based on neutral-atom ensembles. We report on an efficient frequency filter which uses a glass cell filled with 85Rb vapor to attenuate noise photons by an order of magnitude with little loss to the single photons associated with the operation of our cold 87Rb quantum memory. An Ar buffer gas is required to differentiate between signal and noise photons or similar statement. Our simple, passive filter requires no optical pumping or external frequency references and provides an additional 18 dB attenuation of our pump laser for every 1 dB loss of the single photon signal. We observe improved non-classical correlations and our data shows that the addition of a frequency filter increases the non-classical correlations and readout efficiency of our quantum memory by ~ 35%.

Atom Skimmers and Atom Lasers Utilizing Them

NASA Technical Reports Server (NTRS)

Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

2005-01-01

Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

Speckle reduction in optical coherence tomography images based on wave atoms

PubMed Central

Du, Yongzhao; Liu, Gangjun; Feng, Guoying; Chen, Zhongping

2014-01-01

Abstract. Optical coherence tomography (OCT) is an emerging noninvasive imaging technique, which is based on low-coherence interferometry. OCT images suffer from speckle noise, which reduces image contrast. A shrinkage filter based on wave atoms transform is proposed for speckle reduction in OCT images. Wave atoms transform is a new multiscale geometric analysis tool that offers sparser expansion and better representation for images containing oscillatory patterns and textures than other traditional transforms, such as wavelet and curvelet transforms. Cycle spinning-based technology is introduced to avoid visual artifacts, such as Gibbs-like phenomenon, and to develop a translation invariant wave atoms denoising scheme. The speckle suppression degree in the denoised images is controlled by an adjustable parameter that determines the threshold in the wave atoms domain. The experimental results show that the proposed method can effectively remove the speckle noise and improve the OCT image quality. The signal-to-noise ratio, contrast-to-noise ratio, average equivalent number of looks, and cross-correlation (XCOR) values are obtained, and the results are also compared with the wavelet and curvelet thresholding techniques. PMID:24825507

Three-dimensional photonic crystals as intermediate filter for thin-film tandem solar cells

NASA Astrophysics Data System (ADS)

Bielawny, Andreas; Miclea, Paul T.; Wehrspohn, Ralf B.; Lee, Seung-Mo; Knez, Mato; Rockstuhl, Carsten; Lisca, Marian; Lederer, Falk L.; Carius, Reinhard

2008-04-01

The concept of a 3D photonic crystal structure as diffractive and spectrally selective intermediate filter within 'micromorphous' (a-Si/μc-Si) tandem solar cells has been investigated numerically and experimentally. Our device aims for the enhancement of the optical pathway of incident light within the amorphous silicon top cell in its spectral region of low absorption. From our previous simulations, we expect a significant improvement of the tandem cell efficiency of about absolutely 1.3%. This increases the efficiency for a typical a-Si / μc-Si tandem cell from 11.1% to 12.4%, as a result of the optical current-matching of the two junctions. We suggest as wavelength-selective optical element a 3D-structured optical thin-film, prepared by self-organized artificial opal templates and replicated with atomic layer deposition. The resulting samples are highly periodic thin-film inverted opals made of conducting and transparent zinc-oxide. We describe the fabrication processes and compare experimental data on the optical properties in reflection and transmission with our simulations and photonic band structure calculations.

Magneto-optical rotation in cavity QED with Zeeman coherence

NASA Astrophysics Data System (ADS)

Sun, Hui; Jia, Xiaohua; Fan, Shuangli; Zhang, Hongjun; Guo, Hong

2018-06-01

We investigate theoretically the magneto-optical rotation in cavity QED system with atomic Zeeman coherence, which is established via coherent population trapping. Owing to Zeeman coherence, the ultranarrow transmission spectrum less than 1 MHz with gain can be achieved with a flat-top Faraday rotation angle. By controlling the parameters appropriately, the input probe components within the flat-top regime rotate with almost the same angle, and transmit through the cavity perpendicularly to the other components outside the flat-top regime. The concepts discussed here provide an important tool for perfect ultranarrow Faraday optical filter and quantum information processing.

Atomic Clock Based on Opto-Electronic Oscillator

NASA Technical Reports Server (NTRS)

Maleki, Lute; Yu, Nan

2005-01-01

A proposed highly accurate clock or oscillator would be based on the concept of an opto-electronic oscillator (OEO) stabilized to an atomic transition. Opto-electronic oscillators, which have been described in a number of prior NASA Tech Briefs articles, generate signals at frequencies in the gigahertz range characterized by high spectral purity but not by longterm stability or accuracy. On the other hand, the signals generated by previously developed atomic clocks are characterized by long-term stability and accuracy but not by spectral purity. The proposed atomic clock would provide high spectral purity plus long-term stability and accuracy a combination of characteristics needed to realize advanced developments in communications and navigation. In addition, it should be possible to miniaturize the proposed atomic clock. When a laser beam is modulated by a microwave signal and applied to a photodetector, the electrical output of the photodetector includes a component at the microwave frequency. In atomic clocks of a type known as Raman clocks or coherent-population-trapping (CPT) clocks, microwave outputs are obtained from laser beams modulated, in each case, to create two sidebands that differ in frequency by the amount of a hyperfine transition in the ground state of atoms of an element in vapor form in a cell. The combination of these sidebands produces a transparency in the population of a higher electronic level that can be reached from either of the two ground-state hyperfine levels by absorption of a photon. The beam is transmitted through the vapor to a photodetector. The components of light scattered or transmitted by the atoms in the two hyperfine levels mix in the photodetector and thereby give rise to a signal at the hyperfine- transition frequency. The proposed atomic clock would include an OEO and a rubidium- or cesium- vapor cell operating in the CPT/Raman regime (see figure). In the OEO portion of this atomic clock, as in a typical prior OEO, a laser beam would pass through an electro-optical modulator, the modulated beam would be fed into a fiber-optic delay line, and the delayed beam would be fed to a photodetector. The electrical output of the photodetector would be detected, amplified, filtered, and fed back to the microwave input port of the modulator. The laser would be chosen to have the same wavelength as that of the pertinent ground-state/higher-state transition of the atoms in the vapor. The modulator/ filter combination would be designed to operate at the microwave frequency of the hyperfine transition. Part of the laser beam would be tapped from the fiberoptic loop of the OEO and introduced into the vapor cell. After passing through the cell, this portion of the beam would be detected differentially with a tapped portion of the fiber-optically-delayed beam. The electrical output of the photodetector would be amplified and filtered in a loop that would control a DC bias applied to the modulator. In this manner, the long-term stability and accuracy of the atomic transition would be transferred to the OEO.

Chaotic quantum ratchets and filters with cold atoms in optical lattices: Properties of Floquet states

NASA Astrophysics Data System (ADS)

Hur, Gwang-Ok

The -kicked rotor is a paradigm of quantum chaos. Its realisation with clouds of cold atoms in pulsed optical lattices demonstrated the well-known quantum chaos phenomenon of 'dynamical localisation'. In those experi ments by several groups world-wide, the £-kicks were applied at equal time intervals. However, recent theoretical and experimental work by the cold atom group at UCL Monteiro et al 2002, Jonckheere et al 2003, Jones et al 2004 showed that novel quantum and classical dynamics arises if the atomic cloud is pulsed with repeating sequences of unequally spaced kicks. In Mon teiro et al 2002 it was found that the energy absorption rates depend on the momentum of the atoms relative to the optical lattice hence a type of chaotic ratchet was proposed. In Jonckheere et al and Jones et al, a possible mechanism for selecting atoms according to their momenta (velocity filter) was investigated. The aim of this thesis was to study the properties of the underlying eigen values and eigenstates. Despite the unequally-spaced kicks, these systems are still time-periodic, so we in fact investigated the Floquet states, which are eigenstates of U(T), the one-period time evolution operator. The Floquet states and corresponding eigenvalues were obtained by diagonalising a ma trix representation of the operator U(T). It was found that the form of the eigenstates enables us to analyse qual itatively the atomic momentum probability distributions, N(p) measured experimentally. In particular, the momentum width of the individual eigen states varies strongly with < p > as expected from the theoretical and ex- perimental results obtained previously. In addition, at specific < p > close to values which in the experiment yield directed motion (ratchet transport), the probability distribution of the individual Floquet states is asymmetric, mirroring the asymmetric N(p) measured in clouds of cesium atoms. In the penultimate chapter, the spectral fluctuations (eigenvalue statis tics) are investigated for one particular system, the double-delta kicked rotor. We computed Nearest Neighbour Spacing (NNS) distributions as well as the number variances (E2 statistics). We find that even in regimes where the corresponding classical dynamics are fully chaotic, the statistics are, unex pectedly, intermediate between fully chaotic (GOE) and fully regular (Pois- son). It is argued that they are analogous to the critical statistics seen in the Anderson metal-insulator transition.

Coherent optical transients observed in rubidium atomic line filtered Doppler velocimetry experiments

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

Fajardo, Mario E., E-mail: mario.fajardo@eglin.af.mil; Molek, Christopher D.; Vesely, Annamaria L.

2015-10-14

We report the first successful results from our novel Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus, along with unanticipated oscillatory signals due to coherent optical transients generated within pure Rb vapor cells. RALF is a high-velocity and high-acceleration extension of the well-known Doppler Global Velocimetry (DGV) technique for constructing multi-dimensional flow velocity vector maps in aerodynamics experiments [H. Komine, U.S. Patent No. 4,919,536 (24 April 1990)]. RALF exploits the frequency dependence of pressure-broadened Rb atom optical absorptions in a heated Rb/N{sub 2} gas cell to encode the Doppler shift of reflected near-resonant (λ{sub 0} ≈ 780.24 nm) laser light onto the intensitymore » transmitted by the cell. The present RALF apparatus combines fiber optic and free-space components and was built to determine suitable operating conditions and performance parameters for the Rb/N{sub 2} gas cells. It yields single-spot velocities of thin laser-driven-flyer test surfaces and incorporates a simultaneous Photonic Doppler Velocimetry (PDV) channel [Strand et al., Rev. Sci. Instrum. 77, 083108 (2006)] for validation of the RALF results, which we demonstrate here over the v = 0 to 1 km/s range. Both RALF and DGV presume the vapor cells to be simple Beer's Law optical absorbers, so we were quite surprised to observe oscillatory signals in experiments employing low pressure pure Rb vapor cells. We interpret these oscillations as interference between the Doppler shifted reflected light and the Free Induction Decay (FID) coherent optical transient produced within the pure Rb cells at the original laser frequency; this is confirmed by direct comparison of the PDV and FID signals. We attribute the different behaviors of the Rb/N{sub 2} vs. Rb gas cells to efficient dephasing of the atomic/optical coherences by Rb-N{sub 2} collisions. The minimum necessary N{sub 2} buffer gas density ≈0.3 amagat translates into a smallest useful velocity range of 0 to 2 km/s, which can readily be extended to cover the 0 to 10 km/s range, and beyond. The recognition that coherent optical transients can be produced within low pressure vapor cells during velocimetry experiments may offer new insights into some quantitative discrepancies reported in earlier DGV studies. Future plans include “line-RALF” experiments with streak camera detection, and two-dimensional surface velocity mapping using pulsed laser illumination and/or gated intensified CCD camera detection.« less

Signal intensity influences on the atomic Faraday filter.

PubMed

Luo, Bin; Yin, Longfei; Xiong, Junyu; Chen, Jingbiao; Guo, Hong

2018-06-01

Previous studies of the Faraday anomalous dispersion optical filter (FADOF) mainly focus on the weak signal light filtering, without regard for the influences of the signal light intensity on the filter itself. However, in some applications the signal light is strong enough to change the filter's performance. In this work, the influences of the signal light intensity on the transmittance spectrum is experimentally investigated in a 780 nm Rb85 FADOF in both the line-center and wings operation modes. The results show that the transmittance spectrum varies significantly with the signal light intensity. As the signal light increases, some existing transmittance peaks decline, some new transmittance peaks appear, and the maximum transmittance peak frequency may change. The spectrum in strong signal lights can be quite different from those calculated by programs in the condition of weak signal lights. These results are important for applications of the FADOF in the condition of strong signal lights.

On-Chip Photonic Circuits for Atom-Light Interaction in Quantum Information and Integrated Optical Spectrometer for Astrophotonics

NASA Astrophysics Data System (ADS)

Meng, Yang

Photonic circuits are becoming very promising in many different applications, such as optical amplification, optical switching and wavelength division multiplexing optical networks, lab-on-chip in bioengineering, atom-light interaction in quantum information processing, wavelength selecting and filtering in astronomy, etc. Thanks to major developments in the nanofabrication technology, smaller but more powerful photonic circuits can be made to realize more complex applications. Here we propose two on-chip photonic circuits: one is for atom-light interaction in quantum information, and the other is for an optical spectrometer in astronomy. Part I. The atom-light interaction can be used for a number of quantum based application, such as quantum information processing and atomic sensing. These significant applications make atom-light interaction a strong candidate for next-generation quantum computers and ultraprecise magnetic or navigation sensors. People have proposed various types of atom-photon interaction, and enhancing the interaction by using a small mode area has also been demonstrated in several platforms such as a hollow-core fiber, a hollow-core waveguide, a tapered fiber, and a nanowaveguide. In our work, we propose a nanowaveguide platform for collective atom-light interaction through the evanescent optical field coupling. We have demonstrated a centimeter-long silicon nitride nanowaveguide that has a sub-micrometer mode area and high fiber-to-waveguide coupling efficiencies for near-infrared wavelengths, working as evanescent field atom trapping/probing of an ensemble of 87Rb atoms. Inverse tapers are made at both ends of the waveguide that adiabatically transfer the weakly guided fiber-coupled mode to a strongly guided mode with an evanescent field for a better fiber-waveguide coupling efficiency. The coupling efficiency improves from around 2% to around 80% for both wavelengths. Trapping atoms by nanowaveguide modes is challenging because the small mode area generates high heat flux at the waveguide in an ultra-high vacuum. This platform has good thermal conductance and could transfer high enough optical powers to trap atoms in an ultra-high vacuum compared to a standalone photonic crystal waveguide with no substrate or an evanescent field coupled with a nanofiber. We have experimentally measured the optical absorption of thermal 87Rb atoms through the guided waveguide mode. We have also demonstrated an atom-chip mirror MOT with the same dimension of the platform that can be transferred to the proximity of the surface by magnetic field controls. Part II. In astronomical applications, wavelength analysis is very important especially for the wavelength selecting and filtering. Here we focus on the wavelength range from 1microm to 1.7microm. There are many valuable applications that make this near infrared wavelength range so important. For example, the Lyman-alpha line of hydrogen is one of the very important emission lines of hydrogen for understanding the origin and creation of the universe. Since the universe has expanded for more than 10 billion years after the big bang, the Lyman-alpha line of hydrogen has redshifted from 121.5nm to the 1microm-to-1.7microm wavelength range according to Hubble's Law. In addition, analysis of this wavelength range can also help us understand many other cosmic phenomena such as quasars, Gamma-ray bursts, etc. Therefore, a good spectrometer is needed to achieve this. Here we present an echelle grating which is based on an on-chip spectrometer that covers the near infrared wavelength range from 1.45um to 1.7um. To begin with, we use optical waveguides as the input and output channels. We have successfully achieved a reliable fabrication process to make the on-chip echelle-grating spectrometer. We have also achieved high fiber-waveguide coupling efficiency (94% per facet at 1550nm) and low propagation loss (-0.975dB/cm at 1550nm) for the input and output waveguides. In addition, we have characterized the bending loss of the waveguide. Finally, we have successfully measured the output spectrum of the echelle grating we designed and found it to be in good agreement with our simulation.

Spatial shaping for generating arbitrary optical dipole traps for ultracold degenerate gases

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

Lee, Jeffrey G., E-mail: jglee@umd.edu; Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742; Hill, W. T., E-mail: wth@umd.edu

2014-10-15

We present two spatial-shaping approaches – phase and amplitude – for creating two-dimensional optical dipole potentials for ultracold neutral atoms. When combined with an attractive or repulsive Gaussian sheet formed by an astigmatically focused beam, atoms are trapped in three dimensions resulting in planar confinement with an arbitrary network of potentials – a free-space atom chip. The first approach utilizes an adaptation of the generalized phase-contrast technique to convert a phase structure embedded in a beam after traversing a phase mask, to an identical intensity profile in the image plane. Phase masks, and a requisite phase-contrast filter, can be chemicallymore » etched into optical material (e.g., fused silica) or implemented with spatial light modulators; etching provides the highest quality while spatial light modulators enable prototyping and realtime structure modification. This approach was demonstrated on an ensemble of thermal atoms. Amplitude shaping is possible when the potential structure is made as an opaque mask in the path of a dipole trap beam, followed by imaging the shadow onto the plane of the atoms. While much more lossy, this very simple and inexpensive approach can produce dipole potentials suitable for containing degenerate gases. High-quality amplitude masks can be produced with standard photolithography techniques. Amplitude shaping was demonstrated on a Bose-Einstein condensate.« less

Optoelectronic Properties of X-Doped (X = O, S, Te) Photovoltaic CSe with Puckered Structure.

PubMed

Zhang, Qiang; Xin, Tianyuan; Lu, Xiaoke; Wang, Yuexia

2018-03-16

We exploited novel two-dimensional (2D) carbon selenide (CSe) with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT) method indicated that 2D CSe possesses dynamic stability, which made it possible to tune and equip CSe with outstanding properties by way of X-doping (X = O, S, Te), i.e., X substituting Se atoms. Then systematic investigation on the structural, electronic, and optical properties of pristine and X-doped monolayer CSe was carried out using the density functional theory (DFT) method. It was found that the bonding feature of C-X is intimately associated with the electronegativity and radius of the doping atoms, which leads to diverse electronic and optical properties for doping different group VI elements. All the systems possess direct gaps, except for O-doping. Substituting O for Se atoms in monolayer CSe brings about a transition from a direct Γ-Γ band gap to an indirect Γ-Y band gap. Moreover, the value of the band gap decreases with increased doping concentration and radius of doping atoms. A red shift in absorption spectra occurs toward the visible range of radiation after doping, and the red-shift phenomenon becomes more obvious with increased radius and concentration of doping atoms. The results can be useful for filtering doping atoms according to their radius or electronegativity in order to tailor optical spectra efficiently.

Optoelectronic Properties of X-Doped (X = O, S, Te) Photovoltaic CSe with Puckered Structure

PubMed Central

Zhang, Qiang; Xin, Tianyuan; Lu, Xiaoke; Wang, Yuexia

2018-01-01

We exploited novel two-dimensional (2D) carbon selenide (CSe) with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT) method indicated that 2D CSe possesses dynamic stability, which made it possible to tune and equip CSe with outstanding properties by way of X-doping (X = O, S, Te), i.e., X substituting Se atoms. Then systematic investigation on the structural, electronic, and optical properties of pristine and X-doped monolayer CSe was carried out using the density functional theory (DFT) method. It was found that the bonding feature of C-X is intimately associated with the electronegativity and radius of the doping atoms, which leads to diverse electronic and optical properties for doping different group VI elements. All the systems possess direct gaps, except for O-doping. Substituting O for Se atoms in monolayer CSe brings about a transition from a direct Γ-Γ band gap to an indirect Γ-Y band gap. Moreover, the value of the band gap decreases with increased doping concentration and radius of doping atoms. A red shift in absorption spectra occurs toward the visible range of radiation after doping, and the red-shift phenomenon becomes more obvious with increased radius and concentration of doping atoms. The results can be useful for filtering doping atoms according to their radius or electronegativity in order to tailor optical spectra efficiently. PMID:29547504

Theoretical model for frequency locking a diode laser with a Faraday cell

NASA Technical Reports Server (NTRS)

Wanninger, P.; Shay, T. M.

1992-01-01

A new method was developed for frequency locking a diode lasers, called 'the Faraday anomalous dispersion optical transmitter (FADOT) laser locking', which is much simpler than other known locking schemes. The FADOT laser locking method uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. The FADOT method is vibration insensitive and exhibits minimal thermal expansion effects. The system has a frequency pull in the range of 443.2 GHz (9 A). The method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters.

Quantum state engineering with ultra-short-period (AlN)m/(GaN)n superlattices for narrowband deep-ultraviolet detection.

PubMed

Gao, Na; Lin, Wei; Chen, Xue; Huang, Kai; Li, Shuping; Li, Jinchai; Chen, Hangyang; Yang, Xu; Ji, Li; Yu, Edward T; Kang, Junyong

2014-12-21

Ultra-short-period (AlN)m/(GaN)n superlattices with tunable well and barrier atomic layer numbers were grown by metal-organic vapour phase epitaxy, and employed to demonstrate narrowband deep ultraviolet photodetection. High-resolution transmission electron microscopy and X-ray reciprocal space mapping confirm that superlattices containing well-defined, coherently strained GaN and AlN layers as thin as two atomic layers (∼ 0.5 nm) were grown. Theoretical and experimental results demonstrate that an optical absorption band as narrow as 9 nm (210 meV) at deep-ultraviolet wavelengths can be produced, and is attributable to interband transitions between quantum states along the [0001] direction in ultrathin GaN atomic layers isolated by AlN barriers. The absorption wavelength can be precisely engineered by adjusting the thickness of the GaN atomic layers because of the quantum confinement effect. These results represent a major advance towards the realization of wavelength selectable and narrowband photodetectors in the deep-ultraviolet region without any additional optical filters.

Technique for compressing light intensity ranges utilizing a specifically designed liquid crystal notch filter

DOEpatents

Rushford, Michael C.

1988-01-01

A pin hole camera assembly for use in viewing an object having a relatively large light intensity range, for example a crucible containing molten metal in an atomic vapor laser isotope separation (AVLIS) system is disclosed herein. The assembly includes means for optically compressing the light intensity range appearing at its input sufficient to make it receivable and decipherable by a standard video camera. To accomplish this, the assembly utilizes the combination of interference filter and a liquid crystal notch filter. The latter which preferably includes a cholesteric liquid crystal arrangement is configured to pass light at all wavelengths, except a relatively narrow wavelength band which defines the filter's notch, and includes means for causing the notch to vary to at least a limited extent with the intensity of light at its light incidence surface.

A digital optical phase-locked loop for diode lasers based on field programmable gate array.

PubMed

Xu, Zhouxiang; Zhang, Xian; Huang, Kaikai; Lu, Xuanhui

2012-09-01

We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382∕MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad(2) and transition time of 100 μs under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

A digital optical phase-locked loop for diode lasers based on field programmable gate array

NASA Astrophysics Data System (ADS)

Xu, Zhouxiang; Zhang, Xian; Huang, Kaikai; Lu, Xuanhui

2012-09-01

We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382/MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat note line width below 1 Hz, residual mean-square phase error of 0.14 rad2 and transition time of 100 μs under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.

Plasmonic computing of spatial differentiation

NASA Astrophysics Data System (ADS)

Zhu, Tengfeng; Zhou, Yihan; Lou, Yijie; Ye, Hui; Qiu, Min; Ruan, Zhichao; Fan, Shanhui

2017-05-01

Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.

Fabrication and characterization of optical super-smooth surfaces

NASA Astrophysics Data System (ADS)

Schmitt, Dirk-Roger; Kratz, Frank; Ringel, Gabriele A.; Mangelsdorf, Juergen; Creuzet, Francois; Garratt, John D.

1995-08-01

Intercomparison roughness measurements have been carried out at supersmooth artefacts fabricated from BK7, fused silica, and Zerodur. The surface parameters were determined using a special prototype of the mechanical profiler Nanostep (Rank Taylor Hobson), the Optical Heterodyne Profiler Z5500 (Zygo), and an Atomic Force Microscope (Park Scientific) with an improved acquisition technique. The intercomparison was performed after the range of collected spatial wavelength for each instrument was adjusted using digital filtering techniques. It is demonstrated for different roughness ranges that are applied superpolishing techniques yield supersmooth artefacts which can be used for more intercomparisons.

A direct temporal domain approach for ultrafast optical signal processing and its implementation using planar lightwave circuits

NASA Astrophysics Data System (ADS)

Xia, Bing

Ultrafast optical signal processing, which shares the same fundamental principles of electrical signal processing, can realize numerous important functionalities required in both academic research and industry. Due to the extremely fast processing speed, all-optical signal processing and pulse shaping have been widely used in ultrafast telecommunication networks, photonically-assisted RFlmicro-meter waveform generation, microscopy, biophotonics, and studies on transient and nonlinear properties of atoms and molecules. In this thesis, we investigate two types of optical spectrally-periodic (SP) filters that can be fabricated on planar lightwave circuits (PLC) to perform pulse repetition rate multiplication (PRRM) and arbitrary optical waveform generation (AOWG). First, we present a direct temporal domain approach for PRRM using SP filters. We show that the repetition rate of an input pulse train can be multiplied by a factor N using an optical filter with a free spectral range that does not need to be constrained to an integer multiple of N. Furthermore, the amplitude of each individual output pulse can be manipulated separately to form an arbitrary envelope at the output by optimizing the impulse response of the filter. Next, we use lattice-form Mach-Zehnder interferometers (LF-MZI) to implement the temporal domain approach for PRRM. The simulation results show that PRRM with uniform profiles, binary-code profiles and triangular profiles can be achieved. Three silica based LF-MZIs are designed and fabricated, which incorporate multi-mode interference (MMI) couplers and phase shifters. The experimental results show that 40 GHz pulse trains with a uniform envelope pattern, a binary code pattern "1011" and a binary code pattern "1101" are generated from a 10 GHz input pulse train. Finally, we investigate 2D ring resonator arrays (RRA) for ultraf ast optical signal processing. We design 2D RRAs to generate a pair of pulse trains with different binary-code patterns simultaneously from a single pulse train at a low repetition rate. We also design 2D RRAs for AOWG using the modified direct temporal domain approach. To demonstrate the approach, we provide numerical examples to illustrate the generation of two very different waveforms (square waveform and triangular waveform) from the same hyperbolic secant input pulse train. This powerful technique based on SP filters can be very useful for ultrafast optical signal processing and pulse shaping.

Theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency

NASA Astrophysics Data System (ADS)

Liu, Yang; Li, Shu-qing; Feng, Zhong-ying; Liu, Xiao-fei; Gao, Jin-yue

2016-12-01

To obtain the weak signal light detection from the high background noise, we present a theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency. In a three-level Λ -type atomic system in the rubidium D1 line, the bandwidth of the EIT atomic filter is narrowed to ~6.5 \\text{MHz} . And the single peak transmission of the filter can be up to 86% . Moreover, the transmission wavelength can be tuned by changing the coupling light frequency. This theoretical scheme can also be applied to other alkali atomic systems.

Optical filter including a sub-wavelength periodic structure and method of making

DOEpatents

Kaushik, Sumanth; Stallard, Brian R.

1998-01-01

An optical filter includes a dielectric layer formed within a resonant optical cavity, with the dielectric layer having formed therein a sub-wavelength periodic structure to define, at least in part, a wavelength for transmission of light through the resonant optical cavity. The sub-wavelength periodic structure can be formed either by removing material from the dielectric layer (e.g. by etching through an electron-beam defined mask), or by altering the composition of the layer (e.g. by ion implantation). Different portions of the dielectric layer can be patterned to form one or more optical interference filter elements having different light transmission wavelengths so that the optical filter can filter incident light according to wavelength and/or polarization. For some embodiments, the optical filter can include a detector element in optical alignment with each optical interference filter element to quantify or measure the filtered light for analysis thereof. The optical filter has applications to spectrometry, colorimetry, and chemical sensing.

Optical filter including a sub-wavelength periodic structure and method of making

DOEpatents

Kaushik, S.; Stallard, B.R.

1998-03-10

An optical filter includes a dielectric layer formed within a resonant optical cavity, with the dielectric layer having formed therein a sub-wavelength periodic structure to define, at least in part, a wavelength for transmission of light through the resonant optical cavity. The sub-wavelength periodic structure can be formed either by removing material from the dielectric layer (e.g. by etching through an electron-beam defined mask), or by altering the composition of the layer (e.g. by ion implantation). Different portions of the dielectric layer can be patterned to form one or more optical interference filter elements having different light transmission wavelengths so that the optical filter can filter incident light according to wavelength and/or polarization. For some embodiments, the optical filter can include a detector element in optical alignment with each optical interference filter element to quantify or measure the filtered light for analysis thereof. The optical filter has applications to spectrometry, colorimetry, and chemical sensing. 17 figs.

Optical identification using imperfections in 2D materials

NASA Astrophysics Data System (ADS)

Cao, Yameng; Robson, Alexander J.; Alharbi, Abdullah; Roberts, Jonathan; Woodhead, Christopher S.; Noori, Yasir J.; Bernardo-Gavito, Ramón; Shahrjerdi, Davood; Roedig, Utz; Fal'ko, Vladimir I.; Young, Robert J.

2017-12-01

The ability to uniquely identify an object or device is important for authentication. Imperfections, locked into structures during fabrication, can be used to provide a fingerprint that is challenging to reproduce. In this paper, we propose a simple optical technique to read unique information from nanometer-scale defects in 2D materials. Imperfections created during crystal growth or fabrication lead to spatial variations in the bandgap of 2D materials that can be characterized through photoluminescence measurements. We show a simple setup involving an angle-adjustable transmission filter, simple optics and a CCD camera can capture spatially-dependent photoluminescence to produce complex maps of unique information from 2D monolayers. Atomic force microscopy is used to verify the origin of the optical signature measured, demonstrating that it results from nanometer-scale imperfections. This solution to optical identification with 2D materials could be employed as a robust security measure to prevent counterfeiting.

A digital optical phase-locked loop for diode lasers based on field programmable gate array

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

Xu Zhouxiang; Zhang Xian; Huang Kaikai

2012-09-15

We have designed and implemented a highly digital optical phase-locked loop (OPLL) for diode lasers in atom interferometry. The three parts of controlling circuit in this OPLL, including phase and frequency detector (PFD), loop filter and proportional integral derivative (PID) controller, are implemented in a single field programmable gate array chip. A structure type compatible with the model MAX9382/MCH12140 is chosen for PFD and pipeline and parallelism technology have been adapted in PID controller. Especially, high speed clock and twisted ring counter have been integrated in the most crucial part, the loop filter. This OPLL has the narrow beat notemore » line width below 1 Hz, residual mean-square phase error of 0.14 rad{sup 2} and transition time of 100 {mu}s under 10 MHz frequency step. A main innovation of this design is the completely digitalization of the whole controlling circuit in OPLL for diode lasers.« less

Self-aligned spatial filtering using laser optical tweezers.

PubMed

Birkbeck, Aaron L; Zlatanovic, Sanja; Esener, Sadik C

2006-09-01

We present an optical spatial filtering device that has been integrated into a microfluidic system and whose motion and alignment is controlled using a laser optical tweezer. The lithographically patterned micro-optical spatial filter device filters out higher frequency additive noise components by automatically aligning itself in three dimensions to the focus of the laser beam. This self-alignment capability is achieved through the attachment of a refractive optical element directly over the circular aperture or pinhole of the spatial filter. A discussion of two different spatial filter designs is presented along with experimental results that demonstrate the effectiveness of the self-aligned micro-optic spatial filter.

Matrix-Assisted Plasma Atomization Emission Spectrometry for Surface Sampling Elemental Analysis

PubMed Central

Yuan, Xin; Zhan, Xuefang; Li, Xuemei; Zhao, Zhongjun; Duan, Yixiang

2016-01-01

An innovative technology has been developed involving a simple and sensitive optical spectrometric method termed matrix-assisted plasma atomization emission spectrometry (MAPAES) for surface sampling elemental analysis using a piece of filter paper (FP) for sample introduction. MAPAES was carried out by direct interaction of the plasma tail plume with the matrix surface. The FP absorbs energy from the plasma source and releases combustion heating to the analytes originally present on its surface, thus to promote the atomization and excitation process. The matrix-assisted plasma atomization excitation phenomenon was observed for multiple elements. The FP matrix served as the partial energy producer and also the sample substrate to adsorb sample solution. Qualitative and quantitative determinations of metal ions were achieved by atomic emission measurements for elements Ba, Cu, Eu, In, Mn, Ni, Rh and Y. The detection limits were down to pg level with linear correlation coefficients better than 0.99. The proposed MAPAES provides a new way for atomic spectrometry which offers advantages of fast analysis speed, little sample consumption, less sample pretreatment, small size, and cost-effective. PMID:26762972

Tunable Optical Filters Having Electro-optic Whispering-gallery-mode Resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy (Inventor); Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Maleki, Lutfollah (Inventor)

2006-01-01

Tunable optical filters using whispering-gallery-mode (WGM) optical resonators are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.

The multisensor payload 'Structura' for the observation of atmospheric night glows from the ISS board

NASA Astrophysics Data System (ADS)

Krot, Yury; Beliaev, Boris; Katkovsky, Leonid

2016-10-01

Aerospace Research Department of the Institute of Applied Physical Problems at Belarusian State University has developed a prototype of the optical payload intended for a space experiment on the ISS board. The prototype includes four optical modules for the night glows observation, in particular spatial-brightness and spectral characteristics in the altitude range of 80-320 km. Objects of the interest are emitting top layers of the atmosphere including exited OH radicals, atomic and molecular oxygen and sodium layers. The goal of the space experiment is a research of night glows over different regions of the Earth and a connection with natural disasters like earthquakes, cyclones, etc. Two optical modules for spatial distribution of atomic oxygen layers along the altitude consist of input lenses, spectral interferential filters and line CCD detectors. The optical module for registration of exited OH radical emissions is formed from CCD array spectrometer. The payload includes also a panchromatic (400-900 nm) high sensitive imaging camera for observing of the glows general picture. The optical modules of the prototype have been tested and general optical characteristics were determined in laboratory conditions. A solution of an astigmatism reducing of a concave diffraction grating and a method of the second diffraction order correction were applied and improved spectrometer's optical characteristics. Laboratory equipment and software were developed to imitate a dynamic scene of the night glows in laboratory conditions including an imitation of linear spectra and the spatial distribution of emissions.

Quick-Change Optical-Filter Holder

NASA Technical Reports Server (NTRS)

Leone, Peter

1988-01-01

Dark slide and interlock protect against ambient light. Quick-change filter holder contains interlocking mechanism preventing simultaneous removal of both dark slide and filter drawer. Designed for use with Band pass optical filters in 10 channels leading to photomultiplier tubes in water-vapor lidar/ozone instrument, mechanism can be modified to operate in other optical systems requiring optical change in filters.

Large-aperture MOEMS Fabry-Perot interferometer for miniaturized spectral imagers

NASA Astrophysics Data System (ADS)

Rissanen, Anna; Langner, Andreas; Viherkanto, Kai; Mannila, Rami

2015-02-01

VTT's optical MEMS Fabry-Perot interferometers (FPIs) are tunable optical filters, which enable miniaturization of spectral imagers into small, mass producible hand-held sensors with versatile optical measurement capabilities. FPI technology has also created a basis for various hyperspectral imaging instruments, ranging from nanosatellites, environmental sensing and precision agriculture with UAVs to instruments for skin cancer detection. Until now, these application demonstrations have been mostly realized with piezo-actuated FPIs fabricated by non-monolithical assembly method, suitable for achieving very large optical apertures and with capacity to small-to-medium volumes; however large-volume production of MEMS manufacturing supports the potential for emerging spectral imaging applications also in large-volume applications, such as in consumer/mobile products. Previously reported optical apertures of MEMS FPIs in the visible range have been up to 2 mm in size; this paper presents the design, successful fabrication and characterization of MEMS FPIs for central wavelengths of λ = 500 nm and λ = 650 nm with optical apertures up to 4 mm in diameter. The mirror membranes of the FPI structures consist of ALD (atomic layer deposited) TiO2-Al2O3 λ/4- thin film Bragg reflectors, with the air gap formed by sacrificial polymer etching in O2 plasma. The entire fabrication process is conducted below 150 °C, which makes it possible to monolithically integrate the filter structures on other ICdevices such as detectors. The realized MEMS devices are aimed for nanosatellite space application as breadboard hyperspectral imager demonstrators.

Multi-tap complex-coefficient incoherent microwave photonic filters based on optical single-sideband modulation and narrow band optical filtering.

PubMed

Sagues, Mikel; García Olcina, Raimundo; Loayssa, Alayn; Sales, Salvador; Capmany, José

2008-01-07

We propose a novel scheme to implement tunable multi-tap complex coefficient filters based on optical single sideband modulation and narrow band optical filtering. A four tap filter is experimentally demonstrated to highlight the enhanced tuning performance provided by complex coefficients. Optical processing is performed by the use of a cascade of four phase-shifted fiber Bragg gratings specifically fabricated for this purpose.

Manufacture and calibration of optical supersmooth roughness artifacts for intercomparisons

NASA Astrophysics Data System (ADS)

Ringel, Gabriele A.; Kratz, Frank; Schmitt, Dirk-Roger; Mangelsdorf, Juergen; Creuzet, Francois; Garratt, John D.

1995-09-01

Intercomparison roughness measurements have been carried out on supersmooth artifacts fabricated from BK7, fused silica, and Zerodur. The surface parameters were determined using the optical heterodyne profiler Z5500 (Zygo), a special prototype of the mechanical profiler Nanostep (Rank Taylor Hobson), and an Atomic Force Microscope (Park Scientific Instruments) with an improved acquisition technique. The intercomparison was performed after the range of collected spatial wavelengths for each instrument was adjusted using digital filtering techniques. It is demonstrated for different roughness ranges that the applied superpolishing techniques yield supersmooth artifacts which can be used for more intercomparisons. More than 100 samples were investigated. Criteria were developed to select artifacts from the sample stock.

Enabling High Performance Instruments for UV Astronomy and Space Exploration with ALD

NASA Technical Reports Server (NTRS)

Greer, F.; Hoenk, M. E.; Jones, T. J.; Jacquot, B. C.; Monacos, S.; Nikzad, S.; Hamden, E.; Schiminovich, D.

2011-01-01

Benefits of Atomic Layer Deposition (ALD) for UV instruments and application are: (1) Ultrathin, highly conformal, and uniform films over arbitrarily large surface area (2) High quality films (density, roughness, conductivity, etc.) (3) Angstrom level control of stoichiometry, interfaces, and surface properties (3a) Multilayer nanolaminates/nanocomposites (3b) Low temperature surface engineering UV flight applications enabled by ALD. (1) Anti -reflective coatings/Mirrors/Filters/Optics for UV/Vis/NIR Detectors (2) Surface Passivation for III -N detectors

Optical filter having coupled whispering-gallery-mode resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy (Inventor); Ilchenko, Vladimir (Inventor); Maleki, Lutfollah (Inventor); Handley, Timothy A. (Inventor)

2006-01-01

Optical filters having at least two coupled whispering-gallery-mode (WGM) optical resonators to produce a second order or higher order filter function with a desired spectral profile. At least one of the coupled WGM optical resonators may be tunable by a control signal to adjust the filtering function.

Rydberg-atom based radio-frequency electrometry using frequency modulation spectroscopy in room temperature vapor cells.

PubMed

Kumar, Santosh; Fan, Haoquan; Kübler, Harald; Jahangiri, Akbar J; Shaffer, James P

2017-04-17

Rydberg atom-based electrometry enables traceable electric field measurements with high sensitivity over a large frequency range, from gigahertz to terahertz. Such measurements are particularly useful for the calibration of radio frequency and terahertz devices, as well as other applications like near field imaging of electric fields. We utilize frequency modulated spectroscopy with active control of residual amplitude modulation to improve the signal to noise ratio of the optical readout of Rydberg atom-based radio frequency electrometry. Matched filtering of the signal is also implemented. Although we have reached similarly, high sensitivity with other read-out methods, frequency modulated spectroscopy is advantageous because it is well-suited for building a compact, portable sensor. In the current experiment, ∼3 µV cm^-1 Hz^-1/2 sensitivity is achieved and is found to be photon shot noise limited.

Design of tunable thermo-optic C-band filter based on coated silicon slab

NASA Astrophysics Data System (ADS)

Pinhas, Hadar; Malka, Dror; Danan, Yossef; Sinvani, Moshe; Zalevsky, Zeev

2018-03-01

Optical filters are required to have narrow band-pass filtering in the spectral C-band for applications such as signal tracking, sub-band filtering or noise suppression. These requirements lead to a variety of filters such as Mach-Zehnder interferometer inter-leaver in silica, which offer thermo-optic effect for optical switching, however, without proper thermal and optical efficiency. In this paper we propose tunable thermo-optic filtering device based on coated silicon slab resonator with increased Q-factor for the C-band optical switching. The device can be designed either for long range wavelength tuning of for short range with increased wavelength resolution. Theoretical examination of the thermal parameters affecting the filtering process is shown together with experimental results. Proper channel isolation with an extinction ratio of 20dBs is achieved with spectral bandpass width of 0.07nm.

Optical Sensing Device Containing Fiber Bragg Gratings

DTIC Science & Technology

2000-08-01

Fabry - Perot (SFP) filter-based interrogation (Kersey et al. Opt. Lett.. 18, 1370-2. 1993), tunable acousto-optic filter inteiTOgation (Geiger et al...a tunable Fabry - Perot filter, and a tunable acousto-optical filter. Alternatively, scanning filter 28 can be omitted in device 10 of the present...invention when broadband light source 20 is a tunable broadband light source. More preferably, scanning filter 28 is a tunable Fabry - Perot filter

Fiber-Optic Linear Displacement Sensor Based On Matched Interference Filters

NASA Astrophysics Data System (ADS)

Fuhr, Peter L.; Feener, Heidi C.; Spillman, William B.

1990-02-01

A fiber optic linear displacement sensor has been developed in which a pair of matched interference filters are used to encode linear position on a broadband optical signal as relative intensity variations. As the filters are displaced, the optical beam illuminates varying amounts of each filter. Determination of the relative intensities at each filter pairs' passband is based on measurements acquired with matching filters and photodetectors. Source power variation induced errors are minimized by basing determination of linear position on signal Visibility. A theoretical prediction of the sensor's performance is developed and compared with experiments performed in the near IR spectral region using large core multimode optical fiber.

Tunable thin-film optical filters for hyperspectral microscopy

NASA Astrophysics Data System (ADS)

Favreau, Peter F.; Rich, Thomas C.; Prabhat, Prashant; Leavesley, Silas J.

2013-02-01

Hyperspectral imaging was originally developed for use in remote sensing applications. More recently, it has been applied to biological imaging systems, such as fluorescence microscopes. The ability to distinguish molecules based on spectral differences has been especially advantageous for identifying fluorophores in highly autofluorescent tissues. A key component of hyperspectral imaging systems is wavelength filtering. Each filtering technology used for hyperspectral imaging has corresponding advantages and disadvantages. Recently, a new optical filtering technology has been developed that uses multi-layered thin-film optical filters that can be rotated, with respect to incident light, to control the center wavelength of the pass-band. Compared to the majority of tunable filter technologies, these filters have superior optical performance including greater than 90% transmission, steep spectral edges and high out-of-band blocking. Hence, tunable thin-film optical filters present optical characteristics that may make them well-suited for many biological spectral imaging applications. An array of tunable thin-film filters was implemented on an inverted fluorescence microscope (TE 2000, Nikon Instruments) to cover the full visible wavelength range. Images of a previously published model, GFP-expressing endothelial cells in the lung, were acquired using a charge-coupled device camera (Rolera EM-C2, Q-Imaging). This model sample presents fluorescently-labeled cells in a highly autofluorescent environment. Linear unmixing of hyperspectral images indicates that thin-film tunable filters provide equivalent spectral discrimination to our previous acousto-optic tunable filter-based approach, with increased signal-to-noise characteristics. Hence, tunable multi-layered thin film optical filters may provide greatly improved spectral filtering characteristics and therefore enable wider acceptance of hyperspectral widefield microscopy.

A Faraday laser lasing on Rb 1529 nm transition.

PubMed

Chang, Pengyuan; Peng, Huanfa; Zhang, Shengnan; Chen, Zhangyuan; Luo, Bin; Chen, Jingbiao; Guo, Hong

2017-08-21

We present the design and performance characterization of a Faraday laser directly lasing on the Rb 1529 nm transition (Rb, 5P 3/2  - 4D 5/2 ) with high stability, narrow spectral linewidth and low cost. This system does not need an additional frequency-stabilized pump laser as a prerequisite to preparing Rb atom from 5S to 5P excited state. Just by using a performance-improved electrodeless discharge lamp-based excited-state Faraday anomalous dispersion optical filter (LESFADOF), we realized a heterogeneously Faraday laser with the frequency corresponding to atomic transition, working stably over a range of laser diode (LD) current from 85 mA to 171 mA and the LD temperature from 11 °C to 32 °C, as well as the 24-hour long-term frequency fluctuation range of no more than 600 MHz. Both the laser linewidth and relative intensity noisy (RIN) are measured. The Faraday laser lasing on Rb 1529 nm transition (telecom C-band) can be applied to further research on metrology, microwave photonics and optical communication systems. Besides, since the transitions correspongding to the populated excited-states of alkali atoms within lamp are extraordinarily rich, this scheme can increase the flexibility for choosing proper wavelengths for Faraday laser and greatly expand the coverage of wavelength corresponding to atomic transmission for laser frequency stabilization.

Optical ranked-order filtering using threshold decomposition

DOEpatents

Allebach, Jan P.; Ochoa, Ellen; Sweeney, Donald W.

1990-01-01

A hybrid optical/electronic system performs median filtering and related ranked-order operations using threshold decomposition to encode the image. Threshold decomposition transforms the nonlinear neighborhood ranking operation into a linear space-invariant filtering step followed by a point-to-point threshold comparison step. Spatial multiplexing allows parallel processing of all the threshold components as well as recombination by a second linear, space-invariant filtering step. An incoherent optical correlation system performs the linear filtering, using a magneto-optic spatial light modulator as the input device and a computer-generated hologram in the filter plane. Thresholding is done electronically. By adjusting the value of the threshold, the same architecture is used to perform median, minimum, and maximum filtering of images. A totally optical system is also disclosed.

Polarization-Insensitive Tunable Optical Filters based on Liquid Crystal Polarization Gratings

NASA Astrophysics Data System (ADS)

Nicolescu, Elena

Tunable optical filters are widely used for a variety of applications including spectroscopy, optical communication networks, remote sensing, and biomedical imaging and diagnostics. All of these application areas can greatly benefit from improvements in the key characteristics of the tunable optical filters embedded in them. Some of these key parameters include peak transmittance, bandwidth, tuning range, and transition width. In recent years research efforts have also focused on miniaturizing tunable optical filters into physically small packages for compact portable spectroscopy and hyperspectral imaging applications such as real-time medical diagnostics and defense applications. However, it is important that miniaturization not have a detrimental effect on filter performance. The overarching theme of this dissertation is to explore novel configurations of Polarization Gratings (PGs) as simple, low-cost, polarization-insensitive alternatives to conventional optical filtering technologies for applications including hyperspectral imaging and telecommunications. We approach this goal from several directions with a combination of theory and experimental demonstration leading to, in our opinion, a significant contribution to the field. We present three classes of tunable optical filters, the first of which is an angle-filtering scheme where the stop-band wavelengths are redirected off axis and the passband is transmitted on-axis. This is achieved using a stacked configuration of polarization gratings of various thicknesses. To improve this class of filter, we also introduce a novel optical element, the Bilayer Polarization Grating, exhibiting unique optical properties and demonstrating complex anchoring conditions with high quality. The second class of optical filter is analogous to a Lyot filter, utilizing stacks of static or tunable waveplates sandwiched with polarizing elements. However, we introduce a new configuration using PGs and static waveplates to replace the polarizers in the system, thereby greatly increasing the filter throughput. We then turn our attention to a Fourier filtering technique. This is a fundamentally different filtering approach involving a single PG where the filtering functionality involves selecting a spectral band with a movable aperture or slit and a diffractive element (PG in our case). Finally, we study the integration of a PG in a multi-channel wavelength blocker system focusing on the practical and fundamental limitations of using a PG as a variable optical attenuator/wavelength blocker in a commercial optical telecommunications network.

Analysis of the selected optical parameters of filters protecting against hazardous infrared radiation.

PubMed

Gralewicz, Grzegorz; Owczarek, Grzegorz

2016-09-01

The paper analyses the selected optical parameters of protective optic filters used for protection of the eyes against hazardous radiation within the visible (VIS) and near infrared (NIR) spectrum range. The indexes characterizing transmission and reflection of optic radiation incident on the filter are compared. As it follows from the completed analysis, the newly developed interference filters provide more effective blocking of infrared radiation in comparison with the currently used protective filters.

Optical path switching based differential absorption radiometry for substance detection

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor)

2005-01-01

An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

Optical path switching based differential absorption radiometry for substance detection

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor)

2003-01-01

An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

Optically tunable optical filter

NASA Astrophysics Data System (ADS)

James, Robert T. B.; Wah, Christopher; Iizuka, Keigo; Shimotahira, Hiroshi

1995-12-01

We experimentally demonstrate an optically tunable optical filter that uses photorefractive barium titanate. With our filter we implement a spectrum analyzer at 632.8 nm with a resolution of 1.2 nm. We simulate a wavelength-division multiplexing system by separating two semiconductor laser diodes, at 1560 nm and 1578 nm, with the same filter. The filter has a bandwidth of 6.9 nm. We also use the same filter to take 2.5-nm-wide slices out of a 20-nm-wide superluminescent diode centered at 840 nm. As a result, we experimentally demonstrate a phenomenal tuning range from 632.8 to 1578 nm with a single filtering device.

Polarization-independent optical wavelength filter for channel dropping applications

DOEpatents

Deri, R.J.; Patterson, F.

1996-05-07

The polarization dependence of optical wavelength filters is eliminated by using waveguide directional couplers. Material birefringence is used to compensate for the waveguide (electromagnetic) birefringence which is the original cause of the polarization dependence. Material birefringence is introduced in a controllable fashion by replacing bulk waveguide layers by finely layered composites, such as multiple quantum wells using III-V semiconductor materials. The filter has use in wavelength-division multiplexed fiber optic communication systems. This filter has broad application for wavelength-tunable receivers in fiber optic communication links, which may be used for telecommunications, optical computer interconnect links, or fiber optic sensor systems. Since multiple-wavelength systems are increasingly being used for all of these applications, the filter is useable whenever a rapidly tunable, wavelength-filtering receiver is required. 14 figs.

Polarization-independent optical wavelength filter for channel dropping applications

DOEpatents

Deri, Robert J.; Patterson, Frank

1996-01-01

The polarization dependence of optical wavelength filters is eliminated by using waveguide directional couplers. Material birefringence is used to compensate for the waveguide (electromagnetic) birefringence which is the original cause of the polarization dependence. Material birefringence is introduced in a controllable fashion by replacing bulk waveguide layers by finely layered composites, such as multiple quantum wells using III-V semiconductor materials. The filter has use in wavelength-division-multiplexed fiber optic communication systems. This filter has broad application for wavelength-tunable receivers in fiber optic communication links, which may be used for telecommunications, optical computer interconnect links, or fiber optic sensor systems. Since multiple-wavelength systems are increasingly being used for all of these applications, the filter is useable whenever a rapidly tunable, wavelength-filtering receiver is required.

Optical ranked-order filtering using threshold decomposition

DOEpatents

Allebach, J.P.; Ochoa, E.; Sweeney, D.W.

1987-10-09

A hybrid optical/electronic system performs median filtering and related ranked-order operations using threshold decomposition to encode the image. Threshold decomposition transforms the nonlinear neighborhood ranking operation into a linear space-invariant filtering step followed by a point-to-point threshold comparison step. Spatial multiplexing allows parallel processing of all the threshold components as well as recombination by a second linear, space-invariant filtering step. An incoherent optical correlation system performs the linear filtering, using a magneto-optic spatial light modulator as the input device and a computer-generated hologram in the filter plane. Thresholding is done electronically. By adjusting the value of the threshold, the same architecture is used to perform median, minimum, and maximum filtering of images. A totally optical system is also disclosed. 3 figs.

Comparison of the Frequency Response and Voltage Tuning Characteristics of a FFP and a MEMS Fiber Optic Tunable Filter

DTIC Science & Technology

2004-05-12

Structural Engineering, La Jolla, CA 92093 14. ABSTRACT Tunable optical filters based on a Fabry - Perot element are a critical component in many...wavelength based fiber optic sensor systems. This report compares the performance of two fiber-pigtailed tunable optical filters, the fiber Fabry - Perot (FFP...both filters suggests that they can operate at frequencies up to 20 kHz and possibly as high as 100 kHz. 15. SUBJECT TERMS Tunable Fabry - Perot filters

An adaptive spatio-temporal Gaussian filter for processing cardiac optical mapping data.

PubMed

Pollnow, S; Pilia, N; Schwaderlapp, G; Loewe, A; Dössel, O; Lenis, G

2018-06-04

Optical mapping is widely used as a tool to investigate cardiac electrophysiology in ex vivo preparations. Digital filtering of fluorescence-optical data is an important requirement for robust subsequent data analysis and still a challenge when processing data acquired from thin mammalian myocardium. Therefore, we propose and investigate the use of an adaptive spatio-temporal Gaussian filter for processing optical mapping signals from these kinds of tissue usually having low signal-to-noise ratio (SNR). We demonstrate how filtering parameters can be chosen automatically without additional user input. For systematic comparison of this filter with standard filtering methods from the literature, we generated synthetic signals representing optical recordings from atrial myocardium of a rat heart with varying SNR. Furthermore, all filter methods were applied to experimental data from an ex vivo setup. Our developed filter outperformed the other filter methods regarding local activation time detection at SNRs smaller than 3 dB which are typical noise ratios expected in these signals. At higher SNRs, the proposed filter performed slightly worse than the methods from literature. In conclusion, the proposed adaptive spatio-temporal Gaussian filter is an appropriate tool for investigating fluorescence-optical data with low SNR. The spatio-temporal filter parameters were automatically adapted in contrast to the other investigated filters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Optical add/drop filter for wavelength division multiplexed systems

DOEpatents

Deri, Robert J.; Strand, Oliver T.; Garrett, Henry E.

2002-01-01

An optical add/drop filter for wavelength division multiplexed systems and construction methods are disclosed. The add/drop filter includes a first ferrule having a first pre-formed opening for receiving a first optical fiber; an interference filter oriented to pass a first set of wavelengths along the first optical fiber and reflect a second set of wavelengths; and, a second ferrule having a second pre-formed opening for receiving the second optical fiber, and the reflected second set of wavelengths. A method for constructing the optical add/drop filter consists of the steps of forming a first set of openings in a first ferrule; inserting a first set of optical fibers into the first set of openings; forming a first set of guide pin openings in the first ferrule; dividing the first ferrule into a first ferrule portion and a second ferrule portion; forming an interference filter on the first ferrule portion; inserting guide pins through the first set of guide pin openings in the first ferrule portion and second ferrule portion to passively align the first set of optical fibers; removing material such that light reflected from the interference filter from the first set of optical fibers is accessible; forming a second set of openings in a second ferrule; inserting a second set of optical fibers into the second set of openings; and positioning the second ferrule with respect to the first ferrule such that the second set of optical fibers receive the light reflected from the interference filter.

Optical filter finesses enhancement based on nested coupled cavities and active medium

NASA Astrophysics Data System (ADS)

Adib, George A.; Sabry, Yasser M.; Khalil, Diaa

2016-04-01

Optical filters with relatively large FSR and narrow linewidth are simultaneously needed for different applications. The ratio between the FSR and the 3-dB linewidth is given by finesse of the filter, which is solely determined by the different energy loss mechanisms limited by the technology advancement. In this work, we present a novel coupled-cavity configuration embedding an optical filter and a gain medium; allowing an overall finesse enhancement and simultaneous FSR and 3-dB linewidth engineering beyond the technological limits of the filter fabrication method. The configuration consists of two resonators. An active ring resonator comprises an optical gain medium and a passive resonator. In one configuration, the optical filter is the passive resonator itself. In a second configuration, the passive resonator is another ring resonator that embeds the optical filter. The presented configurations using a semiconductor optical amplifier are applied one time to a mechanically Fabry-Perot filter in the first presented configuration; and a second time to a fiber ring filter in the second presented configuration. The mechanical filter has an original 3-dB linewidth of 1nm and an FSR that is larger than 100nm while the enhanced linewidth is about 0.3nm. The fiber ring filter length is 4 m and directional coupler ratios of 90/10corresponding to a 3-dBlinewidth of about 4MHz and an FSR of 47 MHz. The enhanced 3- dBlinewidth of the overall filter configuration is 200kHz, demonstrating finesse enhancement up to20 times the original finesse of the filter.

Optical filter selection for high confidence discrimination of strongly overlapping infrared chemical spectra.

PubMed

Major, Kevin J; Poutous, Menelaos K; Ewing, Kenneth J; Dunnill, Kevin F; Sanghera, Jasbinder S; Aggarwal, Ishwar D

2015-09-01

Optical filter-based chemical sensing techniques provide a new avenue to develop low-cost infrared sensors. These methods utilize multiple infrared optical filters to selectively measure different response functions for various chemicals, dependent on each chemical's infrared absorption. Rather than identifying distinct spectral features, which can then be used to determine the identity of a target chemical, optical filter-based approaches rely on measuring differences in the ensemble response between a given filter set and specific chemicals of interest. Therefore, the results of such methods are highly dependent on the original optical filter choice, which will dictate the selectivity, sensitivity, and stability of any filter-based sensing method. Recently, a method has been developed that utilizes unique detection vector operations defined by optical multifilter responses, to discriminate between volatile chemical vapors. This method, comparative-discrimination spectral detection (CDSD), is a technique which employs broadband optical filters to selectively discriminate between chemicals with highly overlapping infrared absorption spectra. CDSD has been shown to correctly distinguish between similar chemicals in the carbon-hydrogen stretch region of the infrared absorption spectra from 2800-3100 cm(-1). A key challenge to this approach is how to determine which optical filter sets should be utilized to achieve the greatest discrimination between target chemicals. Previous studies used empirical approaches to select the optical filter set; however this is insufficient to determine the optimum selectivity between strongly overlapping chemical spectra. Here we present a numerical approach to systematically study the effects of filter positioning and bandwidth on a number of three-chemical systems. We describe how both the filter properties, as well as the chemicals in each set, affect the CDSD results and subsequent discrimination. These results demonstrate the importance of choosing the proper filter set and chemicals for comparative discrimination, in order to identify the target chemical of interest in the presence of closely matched chemical interferents. These findings are an integral step in the development of experimental prototype sensors, which will utilize CDSD.

Few-Photon Nonlinearity with an Atomic Ensemble in an Optical Cavity

NASA Astrophysics Data System (ADS)

Tanji, Haruka

2011-12-01

This thesis investigates the effect of the cavity vacuum field on the dispersive properties of an atomic ensemble in a strongly coupled high-finesse cavity. In particular, we demonstrate vacuum-induced transparency (VIT). The light absorption by the ensemble is suppressed by up to 40% in the presence of a cavity vacuum field. The sharp transparency peak is accompanied by the reduction in the group velocity of a light pulse, measured to be as low as 1800 m/s. This observation is a large step towards the realization of photon number-state filters, recently proposed by Nikoghosyan et al. Furthermore, we demonstrate few-photon optical nonlinearity, where the transparency is increased from 40% to 80% with ˜12 photons in the cavity mode. The result may be viewed as all-optical switching, where the transmission of photons in one mode may be controlled by 12 photons in another. These studies point to the possibility of nonlinear interaction between photons in different free-space modes, a scheme that circumvents cavity-coupling losses that plague cavity-based quantum information processing. Potential applications include advanced quantum devices such as photonic quantum gates, photon-number resolving detectors, and single-photon transistors. In the efforts leading up to these results, we investigate the collective enhancement of atomic coupling to a single mode of a low-finesse cavity. With the strong collective coupling, we obtain exquisite control of quantum states in the atom-photon coupled system. In this system, we demonstrate a heralded single-photon source with 84% conditional efficiency, a quantum bus for deterministic entanglement of two remote ensembles, and heralded polarization-state quantum memory with fidelity above 90%.

Passive thermo-optic feedback for robust athermal photonic systems

DOEpatents

Rakich, Peter T.; Watts, Michael R.; Nielson, Gregory N.

2015-06-23

Thermal control devices, photonic systems and methods of stabilizing a temperature of a photonic system are provided. A thermal control device thermally coupled to a substrate includes a waveguide for receiving light, an absorption element optically coupled to the waveguide for converting the received light to heat and an optical filter. The optical filter is optically coupled to the waveguide and thermally coupled to the absorption element. An operating point of the optical filter is tuned responsive to the heat from the absorption element. When the operating point is less than a predetermined temperature, the received light is passed to the absorption element via the optical filter. When the operating point is greater than or equal to the predetermined temperature, the received light is transmitted out of the thermal control device via the optical filter, without being passed to the absorption element.

Achromatic elemental mapping beyond the nanoscale in the transmission electron microscope.

PubMed

Urban, K W; Mayer, J; Jinschek, J R; Neish, M J; Lugg, N R; Allen, L J

2013-05-03

Newly developed achromatic electron optics allows the use of wide energy windows and makes feasible energy-filtered transmission electron microscopy (EFTEM) at atomic resolution. In this Letter we present EFTEM images formed using electrons that have undergone a silicon L(2,3) core-shell energy loss, exhibiting a resolution in EFTEM of 1.35 Å. This permits elemental mapping beyond the nanoscale provided that quantum mechanical calculations from first principles are done in tandem with the experiment to understand the physical information encoded in the images.

Coronal and chromospheric physics

NASA Technical Reports Server (NTRS)

Jefferies, J. T.; Landman, D. A.; Orrall, F. Q.

1983-01-01

Achievements and completed results are discussed for investigations covering solar activity during the solar maximum mission and the solar maximum year; other studies of solar activity and variability; infrared and submillimeter photometry; solar-related atomic physics; coronal and transition region studies; prominence research; chromospheric research in quiet and active regions; solar dynamics; eclipse studies; and polarimetry and magnetic field measurements. Contributions were also made in defining the photometric filterograph instrument for the solar optical telescope, designing the combined filter spectrograph, and in expressing the scientific aims and implementation of the solar corona diagnostic mission.

Optical imaging module for astigmatic detection system

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

Wang, Wei-Min; Cheng, Chung-Hsiang; Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan

2016-05-15

In this paper, an optical imaging module design for an astigmatic detection system (ADS) is presented. The module is based on a commercial optical pickup unit (OPU) and it contains a coaxial illuminant for illuminating a specimen. Furthermore, the imaging module facilitates viewing the specimen and the detection laser spot of the ADS with a lateral resolution of approximately 1 μm without requiring the removal of an element of the OPU. Two polarizers and one infrared filter are used to eliminate stray laser light in the OPU and stray light produced by the illuminant. Imaging modules designed for digital versatilemore » disks (DVDs) and Blu-ray DVDs were demonstrated. Furthermore, the module can be used for imaging a small cantilever with approximate dimensions of 2 μm (width) × 5 μm (length), and therefore, it has the potential to be used in high-speed atomic force microscopy.« less

Multiple Optical Filter Design Simulation Results

NASA Astrophysics Data System (ADS)

Mendelsohn, J.; Englund, D. C.

1986-10-01

In this paper we continue our investigation of the application of matched filters to robotic vision problems. Specifically, we are concerned with the tray-picking problem. Our principal interest in this paper is the examination of summation affects which arise from attempting to reduce the matched filter memory size by averaging of matched filters. While the implementation of matched filtering theory to applications in pattern recognition or machine vision is ideally through the use of optics and optical correlators, in this paper the results were obtained through a digital simulation of the optical process.

Acousto-Optic Tunable Filter for Time-Domain Processing of Ultra-Short Optical Pulses,

DTIC Science & Technology

The application of acousto - optic tunable filters for shaping of ultra-fast pulses in the time domain is analyzed and demonstrated. With the rapid...advance of acousto - optic tunable filter (AOTF) technology, the opportunity for sophisticated signal processing capabilities arises. AOTFs offer unique

An Experimental Study of the Fluorescence Spectrum of Cesium Atoms in the Presence of a Buffer Gas

NASA Astrophysics Data System (ADS)

Davydov, V. G.; Kulyasov, V. N.

2018-01-01

A direct experiment is performed to determine the quantum efficiency of a cesium fluorescence filter. The fluorescence spectra of cesium atoms are recorded under excitation of the upper states of the second resonance doublet with a Bell-Bloom cesium lamp. Introduction of different noble gases into the cell with cesium leads to the appearance of additional fluorescence photons. It is found that a fluorescence filter based on atomic cesium vapor with addition of helium in the working cell has the highest efficiency and response rate of all known fluorescence filters based on alkali-metal atomic vapors.

Optimal Filter Estimation for Lucas-Kanade Optical Flow

PubMed Central

Sharmin, Nusrat; Brad, Remus

2012-01-01

Optical flow algorithms offer a way to estimate motion from a sequence of images. The computation of optical flow plays a key-role in several computer vision applications, including motion detection and segmentation, frame interpolation, three-dimensional scene reconstruction, robot navigation and video compression. In the case of gradient based optical flow implementation, the pre-filtering step plays a vital role, not only for accurate computation of optical flow, but also for the improvement of performance. Generally, in optical flow computation, filtering is used at the initial level on original input images and afterwards, the images are resized. In this paper, we propose an image filtering approach as a pre-processing step for the Lucas-Kanade pyramidal optical flow algorithm. Based on a study of different types of filtering methods and applied on the Iterative Refined Lucas-Kanade, we have concluded on the best filtering practice. As the Gaussian smoothing filter was selected, an empirical approach for the Gaussian variance estimation was introduced. Tested on the Middlebury image sequences, a correlation between the image intensity value and the standard deviation value of the Gaussian function was established. Finally, we have found that our selection method offers a better performance for the Lucas-Kanade optical flow algorithm.

Concept for Inclusion of Analytical and Computational Capability in Optical Plume Anomaly Detection (OPAD) for Measurement of Neutron Flux

NASA Technical Reports Server (NTRS)

Patrick, Marshall Clint; Cooper, Anita E.; Powers, W. T.

2004-01-01

Researchers are working on many fronts to make possible high-speed, automated classification and quantification of constituent materials in numerous environments. NASA's Marshall Space Flight Center has implemented a system for rocket engine flowfields/plumes. The Optical Plume Anomaly Detector (OPAD) system was designed to utilize emission and absorption spectroscopy for monitoring molecular and atomic particulates in gas plasma. An accompanying suite of tools and analytical package designed to utilize information collected by OPAD is known as the Engine Diagnostic Filtering System (EDiFiS). The current combination of these systems identifies atomic and molecular species and quantifies mass loss rates in H2/O2 rocket plumes. Capabilities for real-time processing are being advanced on several fronts, including an effort to hardware encode components of the EDiFiS for health monitoring and management. This paper addresses the OPAD with its tool suites, and discusses what is considered a natural progression: a concept for taking OPAD to the next logical level of high energy physics, incorporating fermion and boson particle analyses in measurement of neutron flux.

Optical filters for wavelength selection in fluorescence instrumentation.

PubMed

Erdogan, Turan

2011-04-01

Fluorescence imaging and analysis techniques have become ubiquitous in life science research, and they are poised to play an equally vital role in in vitro diagnostics (IVD) in the future. Optical filters are crucial for nearly all fluorescence microscopes and instruments, not only to provide the obvious function of spectral control, but also to ensure the highest possible detection sensitivity and imaging resolution. Filters make it possible for the sample to "see" light within only the absorption band, and the detector to "see" light within only the emission band. Without filters, the detector would not be able to distinguish the desired fluorescence from scattered excitation light and autofluorescence from the sample, substrate, and other optics in the system. Today the vast majority of fluorescence instruments, including the widely popular fluorescence microscope, use thin-film interference filters to control the spectra of the excitation and emission light. Hence, this unit emphasizes thin-film filters. After briefly introducing different types of thin-film filters and how they are made, the unit describes in detail different optical filter configurations in fluorescence instruments, including both single-color and multicolor imaging systems. Several key properties of thin-film filters, which can significantly affect optical system performance, are then described. In the final section, tunable optical filters are also addressed in a relative comparison.

Optical correlation based pose estimation using bipolar phase grayscale amplitude spatial light modulators

NASA Astrophysics Data System (ADS)

Outerbridge, Gregory John, II

Pose estimation techniques have been developed on both optical and digital correlator platforms to aid in the autonomous rendezvous and docking of spacecraft. This research has focused on the optical architecture, which utilizes high-speed bipolar-phase grayscale-amplitude spatial light modulators as the image and correlation filter devices. The optical approach has the primary advantage of optical parallel processing: an extremely fast and efficient way of performing complex correlation calculations. However, the constraints imposed on optically implementable filters makes optical correlator based posed estimation technically incompatible with the popular weighted composite filter designs successfully used on the digital platform. This research employs a much simpler "bank of filters" approach to optical pose estimation that exploits the inherent efficiency of optical correlation devices. A novel logarithmically mapped optically implementable matched filter combined with a pose search algorithm resulted in sub-degree standard deviations in angular pose estimation error. These filters were extremely simple to generate, requiring no complicated training sets and resulted in excellent performance even in the presence of significant background noise. Common edge detection and scaling of the input image was the only image pre-processing necessary for accurate pose detection at all alignment distances of interest.

Real-time optical signal processors employing optical feedback: amplitude and phase control.

PubMed

Gallagher, N C

1976-04-01

The development of real-time coherent optical signal processors has increased the appeal of optical computing techniques in signal processing applications. A major limitation of these real-time systems is the. fact that the optical processing material is generally of a phase-only type. The result is that the spatial filters synthesized with these systems must be either phase-only filters or amplitude-only filters. The main concern of this paper is the application of optical feedback techniques to obtain simultaneous and independent amplitude and phase control of the light passing through the system. It is shown that optical feedback techniques may be employed with phase-only spatial filters to obtain this amplitude and phase control. The feedback system with phase-only filters is compared with other feedback systems that employ combinations of phase-only and amplitude-only filters; it is found that the phase-only system is substantially more flexible than the other two systems investigated.

(3) He Spin Filter for Neutrons.

PubMed

Batz, M; Baeßler, S; Heil, W; Otten, E W; Rudersdorf, D; Schmiedeskamp, J; Sobolev, Y; Wolf, M

2005-01-01

The strongly spin-dependent absorption of neutrons in nuclear spin-polarized (3)He opens up the possibility of polarizing neutrons from reactors and spallation sources over the full kinematical range of cold, thermal and hot neutrons. This paper gives a report on the neutron spin filter (NSF) development program at Mainz. The polarization technique is based on direct optical pumping of metastable (3)He atoms combined with a polarization preserving mechanical compression of the gas up to a pressure of several bar, necessary to run a NSF. The concept of a remote type of operation using detachable NSF cells is presented which requires long nuclear spin relaxation times of order 100 hours. A short survey of their use under experimental conditions, e.g. large solid-angle polarization analysis, is given. In neutron particle physics NSFs are used in precision measurements to test fundamental symmetry concepts.

Modified-hybrid optical neural network filter for multiple object recognition within cluttered scenes

NASA Astrophysics Data System (ADS)

Kypraios, Ioannis; Young, Rupert C. D.; Chatwin, Chris R.

2009-08-01

Motivated by the non-linear interpolation and generalization abilities of the hybrid optical neural network filter between the reference and non-reference images of the true-class object we designed the modifiedhybrid optical neural network filter. We applied an optical mask to the hybrid optical neural network's filter input. The mask was built with the constant weight connections of a randomly chosen image included in the training set. The resulted design of the modified-hybrid optical neural network filter is optimized for performing best in cluttered scenes of the true-class object. Due to the shift invariance properties inherited by its correlator unit the filter can accommodate multiple objects of the same class to be detected within an input cluttered image. Additionally, the architecture of the neural network unit of the general hybrid optical neural network filter allows the recognition of multiple objects of different classes within the input cluttered image by modifying the output layer of the unit. We test the modified-hybrid optical neural network filter for multiple objects of the same and of different classes' recognition within cluttered input images and video sequences of cluttered scenes. The filter is shown to exhibit with a single pass over the input data simultaneously out-of-plane rotation, shift invariance and good clutter tolerance. It is able to successfully detect and classify correctly the true-class objects within background clutter for which there has been no previous training.

Magnetometer Based on Optoelectronic Microwave Oscillator

NASA Technical Reports Server (NTRS)

Maleki, Lute; Strekalov, Dmitry; Matsko, Andrey

2005-01-01

proposed instrument, intended mainly for use as a magnetometer, would include an optoelectronic oscillator (OEO) stabilized by an atomic cell that could play the role of a magnetically tunable microwave filter. The microwave frequency would vary with the magnetic field in the cell, thereby providing an indication of the magnetic field. The proposed magnetometer would offer a combination of high accuracy and high sensitivity, characterized by flux densities of less than a picotesla. In comparison with prior magnetometers, the proposed magnetometer could, in principle, be constructed as a compact, lightweight instrument: It could fit into a package of about 10 by 10 by 10 cm and would have a mass <0.5 kg. As described in several prior NASA Tech Briefs articles, an OEO is a hybrid of photonic and electronic components that generates highly spectrally pure microwave radiation, and optical radiation modulated by the microwave radiation, through direct conversion between laser light and microwave radiation in an optoelectronic feedback loop. As used here, "atomic cell" signifies a cell containing a vapor, the constituent atoms of which can be made to undergo transitions between quantum states, denoted hyperfine levels, when excited by light in a suitable wavelength range. The laser light must be in this range. The energy difference between the hyperfine levels defines the microwave frequency. In the proposed instrument (see figure), light from a laser would be introduced into an electro-optical modulator (EOM). Amplitude-modulated light from the exit port of the EOM would pass through a fiber-optic splitter having two output branches. The light in one branch would be sent through an atomic cell to a photodiode. The light in the other branch would constitute the microwave-modulated optical output. Part of the light leaving the atomic cell could also be used to stabilize the laser at a frequency in the vicinity of the desired hyperfine or other quantum transition. The microwave signal from the output of the photodiode would be amplified (if necessary, as explained below) and fed back into the EOM. This system would oscillate if the amplification in the closed loop exceeded the linear absorption of the loop. The microwave amplifier may be unnecessary to sustain stable oscillations, depending on the power of the laser radiation at the photodetector and on particular features of the modulator and optical delay line.

All-fiber optical filter with an ultranarrow and rectangular spectral response.

PubMed

Zou, Xihua; Li, Ming; Pan, Wei; Yan, Lianshan; Azaña, José; Yao, Jianping

2013-08-15

Optical filters with an ultranarrow and rectangular spectral response are highly desired for high-resolution optical/electrical signal processing. An all-fiber optical filter based on a fiber Bragg grating with a large number of phase shifts is designed and fabricated. The measured spectral response shows a 3 dB bandwidth of 650 MHz and a rectangular shape factor of 0.513 at the 25 dB bandwidth. This is the narrowest rectangular bandpass response ever reported for an all-fiber filter, to the best of our knowledge. The filter has also the intrinsic advantages of an all-fiber implementation.

Photonic filtering of microwave signals in the frequency range of 0.01-20 GHz using a Fabry-Perot filter

NASA Astrophysics Data System (ADS)

Aguayo-Rodríguez, G.; Zaldívar-Huerta, I. E.; García-Juárez, A.; Rodríguez-Asomoza, J.; Larger, L.; Courjal, N.

2011-01-01

We demonstrate experimentally the efficiency of tuning of a photonic filter in the frequency range of 0.01 to 20 GHz. The presented work combines the use of a multimode optical source associated with a dispersive optical fiber to obtain the filtering effect. Tunability effect is achieved by the use of a Fabry-Perot filter that allows altering the spectral characteristics of the optical source. Experimental results are validated by means of numerical simulations. The scheme here proposed has a potential application in the field of optical telecommunications.

Optical Imagers | CTIO

Science.gov Websites

DECam SAM 0.9-m CCD Goodman SOI Optical Spectrographs CHIRON COSMOS Goodman Filters Telescopes Blanco 4 magnitudes, astrometric, and spectral properties Filters Filter Overview Filter list (all filters up to and including 4x4-inch, sorted by wavelength) Filters - 3 & 4 inch (for SOAR, Schmidt, 0.9-m imaging

Hemispherical-field-of-view, nonimaging narrow-band spectral filter

NASA Technical Reports Server (NTRS)

Miles, R. B.; Webb, S. G.; Griffith, E. L.

1981-01-01

Two compound parabolic concentrators are used to create a 180-deg-field-of-view spectral filter. The collection optics are reflective and are designed to collimate the light through a multilayer interference filter and then to refocus it onto an optical detector. Assuming unit reflectance and no loss through the optical filter, this device operates at the thermodynamic collection limit.

Hemispherical-field-of-view, nonimaging narrow-band spectral filter.

PubMed

Miles, R B; Webb, S G; Griffith, E L

1981-12-01

Two compound parabolic concentrators are used to create a 180 degrees -field-of-view spectral filter. The collection optics are reflective and are designed to collimate the light through a multilayer interference filter and then to refocus it onto an optical detector. Assuming unit reflectance and no loss through the optical filter, this device operates at the thermodynamic collection limit.

Characteristics of tuneable optical filters using optical ring resonator with PCF resonance loop

NASA Astrophysics Data System (ADS)

Shalmashi, K.; Seraji, F. E.; Mersagh, M. R.

2012-05-01

A theoretical analysis of a tuneable optical filter is presented by proposing an optical ring resonator (ORR) using photonic crystal fiber (PCF) as the resonance loop. The influences of the characteristic parameters of the PCF on the filter response have been analyzed under steady-state condition of the ORR. It is shown that the tuneability of the filter is mainly achieved by changing the modulation frequency of the light signal applied to the resonator. The analyses have shown that the sharpness and the depth of the filter response are controlled by parameters such as amplitude modulation index of applied field, the coupling coefficient of the ORR, and hole-spacing and air-filling ratio of the PCF, respectively. When transmission coefficient of the loop approaches the coupling coefficient, the filter response enhances sharply with PCF parameters. The depth and the full-width at half-maximum (FWHM) of the response strongly depend on the number of field circulations in the resonator loop. With the proposed tuneability scheme for optical filter, we achieved an FWHM of ~1.55 nm. The obtained results may be utilized in designing optical add/drop filters used in WDM communication systems.

Spectral multiplexing for scalable quantum photonics using an atomic frequency comb quantum memory and feed-forward control.

PubMed

Sinclair, Neil; Saglamyurek, Erhan; Mallahzadeh, Hassan; Slater, Joshua A; George, Mathew; Ricken, Raimund; Hedges, Morgan P; Oblak, Daniel; Simon, Christoph; Sohler, Wolfgang; Tittel, Wolfgang

2014-08-01

Future multiphoton applications of quantum optics and quantum information science require quantum memories that simultaneously store many photon states, each encoded into a different optical mode, and enable one to select the mapping between any input and a specific retrieved mode during storage. Here we show, with the example of a quantum repeater, how to employ spectrally multiplexed states and memories with fixed storage times that allow such mapping between spectral modes. Furthermore, using a Ti:Tm:LiNbO_{3} waveguide cooled to 3 K, a phase modulator, and a spectral filter, we demonstrate storage followed by the required feed-forward-controlled frequency manipulation with time-bin qubits encoded into up to 26 multiplexed spectral modes and 97% fidelity.

Optical Filter Assembly for Interplanetary Optical Communications

NASA Technical Reports Server (NTRS)

Chen, Yijiang; Hemmati, Hamid

2013-01-01

Ground-based, narrow-band, high throughput optical filters are required for optical links from deep space. We report on the development of a tunable filter assembly that operates at telecommunication window of 1550 nanometers. Low insertion loss of 0.5 decibels and bandwidth of 90 picometers over a 2000 nanometers operational range of detectors has been achieved.

Electro-optical tunable birefringent filter

DOEpatents

Levinton, Fred M [Princeton, NJ

2012-01-31

An electrically tunable Lyot type filter is a Lyot that include one or more filter elements. Each filter element may have a planar, solid crystal comprised of a material that exhibits birefringence and is electro-optically active. Transparent electrodes may be coated on each face of the crystal. An input linear light polarizer may be located on one side of the crystal and oriented at 45 degrees to the optical axis of the birefringent crystal. An output linear light polarizer may be located on the other side of the crystal and oriented at -45 degrees with respect to the optical axis of the birefringent crystal. When an electric voltage is applied between the electrodes, the retardation of the crystal changes and so does the spectral transmission of the optical filter.

Sidelobe suppression in all-fiber acousto-optic tunable filter using torsional acoustic wave.

PubMed

Lee, Kwang Jo; Hwang, In-Kag; Park, Hyun Chul; Kim, Byoung Yoon

2010-06-07

We propose two techniques to suppress intrinsic sidelobe spectra in all-fiber acousto-optic tunable filter using torsional acoustic wave. The techniques are based on either double-pass filter configuration or axial tailoring of mode coupling strength along an acousto-optic interaction region in a highly birefringent optical fiber. The sidelobe peak in the filter spectrum is experimentally suppressed from -8.3 dB to -16.4 dB by employing double-pass configuration. Axial modulation of acousto-optic coupling strength is proposed using axial variation of the fiber diameter, and the simulation results show that the maximum side peak of -9.3 dB can be reduced to -22.2dB. We also discuss the possibility of further spectral shaping of the filter based on the axial tailoring of acousto-optic coupling strength.

Tunable optical filter based on Sagnac phase-shift using single optical ring resonator

NASA Astrophysics Data System (ADS)

Seraji, Faramarz E.; Asghari, Fatemeh

2010-02-01

In this paper, a single optical ring resonator connected to a Sagnac loop is used to demonstrate theoretically a novel narrow band optical filter response that is based on Sagnac phase-shift Δ φ. The given filter structure permits the Sagnac rotation to control the filter response. It is shown that by changing the Sagnac rotation rate, we can tune the filter response for desired bandwidths. To increase the wavelength selectivity of the filter, the Sagnac phase-shift should be as small as possible that is limited by the loop length. For Δ φ=0.1 rad, the obtained FWHM is 2.63 MHz for tuning loop length of 2 m. The simulation response agrees fairly with the recently reported experimental result.

Bandwidth-variable tunable optical filter unit for illumination and spectral imaging systems using thin-film optical band-pass filters.

PubMed

Hennig, Georg; Brittenham, Gary M; Sroka, Ronald; Kniebühler, Gesa; Vogeser, Michael; Stepp, Herbert

2013-04-01

An optical filter unit is demonstrated, which uses two successively arranged tunable thin-film optical band-pass filters and allows for simultaneous adjustment of the central wavelength in the spectral range 522-555 nm and of the spectral bandwidth in the range 3-16 nm with a wavelength switching time of 8 ms∕nm. Different spectral filter combinations can cover the complete visible spectral range. The transmitted intensity was found to decrease only linearly with the spectral bandwidth for bandwidths >6 nm, allowing a high maximum transmission efficiency of >75%. The image of a fiber bundle was spectrally filtered and analyzed in terms of position-dependency of the transmitted bandwidth and central wavelength.

Spectral filters for laser communications

NASA Technical Reports Server (NTRS)

Shaik, K.

1991-01-01

Optical communication systems must perform reliabily under strong background light interference. Since the transmitting lasers operate within a narrow spectral band, high signal to noise ratios can be achieved when narrowband spectral optical filters can be used to reject out of band light. Here, a set of general requirements for such filters are developed, and an overview is given of suitable spectral filter technologies for optical communication systems.

Spatial mode filters realized with multimode interference couplers

NASA Astrophysics Data System (ADS)

Leuthold, J.; Hess, R.; Eckner, J.; Besse, P. A.; Melchior, H.

1996-06-01

Spatial mode filters based on multimode interference couplers (MMI's) that offer the possibility of splitting off antisymmetric from symmetric modes are presented, and realizations of these filters in InGaAsP / InP are demonstrated. Measured suppression of the antisymmetric first-order modes at the output for the symmetric mode is better than 18 dB. Such MMI's are useful for monolithically integrating mode filters with all-optical devices, which are controlled through an antisymmetric first-order mode. The filtering out of optical control signals is necessary for cascading all-optical devices. Another application is the improvement of on-off ratios in optical switches.

A potassium Faraday anomalous dispersion optical filter

NASA Technical Reports Server (NTRS)

Yin, B.; Shay, T. M.

1992-01-01

The characteristics of a potassium Faraday anomalous dispersion optical filter operating on the blue and near infrared transitions are calculated. The results show that the filter can be designed to provide high transmission, very narrow pass bandwidth, and low equivalent noise bandwidth. The Faraday anomalous dispersion optical filter (FADOF) provides a narrow pass bandwidth (about GHz) optical filter for laser communications, remote sensing, and lidar. The general theoretical model for the FADOF has been established in our previous paper. In this paper, we have identified the optimum operational conditions for a potassium FADOF operating on the blue and infrared transitions. The signal transmission, bandwidth, and equivalent noise bandwidth (ENBW) are also calculated.

Nonlinear filter based decision feedback equalizer for optical communication systems.

PubMed

Han, Xiaoqi; Cheng, Chi-Hao

2014-04-07

Nonlinear impairments in optical communication system have become a major concern of optical engineers. In this paper, we demonstrate that utilizing a nonlinear filter based Decision Feedback Equalizer (DFE) with error detection capability can deliver a better performance compared with the conventional linear filter based DFE. The proposed algorithms are tested in simulation using a coherent 100 Gb/sec 16-QAM optical communication system in a legacy optical network setting.

One-dimensional photonic crystals for eliminating cross-talk in mid-IR photonics-based respiratory gas sensing

NASA Astrophysics Data System (ADS)

Fleming, L.; Gibson, D.; Song, S.; Hutson, D.; Reid, S.; MacGregor, C.; Clark, C.

2017-02-01

Mid-IR carbon dioxide (CO2) gas sensing is critical for monitoring in respiratory care, and is finding increasing importance in surgical anaesthetics where nitrous oxide (N2O) induced cross-talk is a major obstacle to accurate CO2 monitoring. In this work, a novel, solid state mid-IR photonics based CO2 gas sensor is described, and the role that 1- dimensional photonic crystals, often referred to as multilayer thin film optical coatings [1], play in boosting the sensor's capability of gas discrimination is discussed. Filter performance in isolating CO2 IR absorption is tested on an optical filter test bed and a theoretical gas sensor model is developed, with the inclusion of a modelled multilayer optical filter to analyse the efficacy of optical filtering on eliminating N2O induced cross-talk for this particular gas sensor architecture. Future possible in-house optical filter fabrication techniques are discussed. As the actual gas sensor configuration is small, it would be challenging to manufacture a filter of the correct size; dismantling the sensor and mounting a new filter for different optical coating designs each time would prove to be laborious. For this reason, an optical filter testbed set-up is described and, using a commercial optical filter, it is demonstrated that cross-talk can be considerably reduced; cross-talk is minimal even for very high concentrations of N2O, which are unlikely to be encountered in exhaled surgical anaesthetic patient breath profiles. A completely new and versatile system for breath emulation is described and the capability it has for producing realistic human exhaled CO2 vs. time waveforms is shown. The cross-talk inducing effect that N2O has on realistic emulated CO2 vs. time waveforms as measured using the NDIR gas sensing technique is demonstrated and the effect that optical filtering will have on said cross-talk is discussed.

Optical calculation of correlation filters for a robotic vision system

NASA Technical Reports Server (NTRS)

Knopp, Jerome

1989-01-01

A method is presented for designing optical correlation filters based on measuring three intensity patterns: the Fourier transform of a filter object, a reference wave and the interference pattern produced by the sum of the object transform and the reference. The method can produce a filter that is well matched to both the object, its transforming optical system and the spatial light modulator used in the correlator input plane. A computer simulation was presented to demonstrate the approach for the special case of a conventional binary phase-only filter. The simulation produced a workable filter with a sharp correlation peak.

Characterisation of optical filters for broadband UVA radiometer

NASA Astrophysics Data System (ADS)

Alves, Luciana C.; Coelho, Carla T.; Corrêa, Jaqueline S. P. M.; Menegotto, Thiago; Ferreira da Silva, Thiago; Aparecida de Souza, Muriel; Melo da Silva, Elisama; Simões de Lima, Maurício; Dornelles de Alvarenga, Ana Paula

2016-07-01

Optical filters were characterized in order to know its suitability for use in broadband UVA radiometer head for spectral irradiance measurements. The spectral transmittance, the angular dependence and the spatial uniformity of the spectral transmittance of the UVA optical filters were investigated. The temperature dependence of the transmittance was also studied.

A lithium niobate electro-optic tunable Bragg filter fabricated by electron beam lithography

NASA Astrophysics Data System (ADS)

Pierno, L.; Dispenza, M.; Secchi, A.; Fiorello, A.; Foglietti, V.

2008-06-01

We have designed and fabricated a lithium niobate tunable Bragg filter patterned by electron beam lithography and etched by reactive ion etching. Devices with 1 mm, 2 mm and 4 mm length and 360 and 1080 nm Bragg period, with 5 pm V-1 tuning efficiency, have been characterized. Some applications were identified. Optical simulation based on finite element model (FEM) software showing the optical filtering curve and the coupling factor dependence on the manufacturing parameter is reported. The tuning of the filter window position is electro-optically controlled.

3He Spin Filter for Neutrons

PubMed Central

Batz, M.; Baeßler, S.; Heil, W.; Otten, E. W.; Rudersdorf, D.; Schmiedeskamp, J.; Sobolev, Y.; Wolf, M.

2005-01-01

The strongly spin-dependent absorption of neutrons in nuclear spin-polarized 3He opens up the possibility of polarizing neutrons from reactors and spallation sources over the full kinematical range of cold, thermal and hot neutrons. This paper gives a report on the neutron spin filter (NSF) development program at Mainz. The polarization technique is based on direct optical pumping of metastable 3He atoms combined with a polarization preserving mechanical compression of the gas up to a pressure of several bar, necessary to run a NSF. The concept of a remote type of operation using detachable NSF cells is presented which requires long nuclear spin relaxation times of order 100 hours. A short survey of their use under experimental conditions, e.g. large solid-angle polarization analysis, is given. In neutron particle physics NSFs are used in precision measurements to test fundamental symmetry concepts. PMID:27308139

Low-loss interference filter arrays made by plasma-assisted reactive magnetron sputtering (PARMS) for high-performance multispectral imaging

NASA Astrophysics Data System (ADS)

Broßmann, Jan; Best, Thorsten; Bauer, Thomas; Jakobs, Stefan; Eisenhammer, Thomas

2016-10-01

Optical remote sensing of the earth from air and space typically utilizes several channels in the visible and near infrared spectrum. Thin-film optical interference filters, mostly of narrow bandpass type, are applied to select these channels. The filters are arranged in filter wheels, arrays of discrete stripe filters mounted in frames, or patterned arrays on a monolithic substrate. Such multi-channel filter assemblies can be mounted close to the detector, which allows a compact and lightweight camera design. Recent progress in image resolution and sensor sensitivity requires improvements of the optical filter performance. Higher demands placed on blocking in the UV and NIR and in between the spectral channels, in-band transmission and filter edge steepness as well as scattering lead to more complex filter coatings with thicknesses in the range of 10 - 25μm. Technological limits of the conventionally used ion-assisted evaporation process (IAD) can be overcome only by more precise and higher-energetic coating technologies like plasma-assisted reactive magnetron sputtering (PARMS) in combination with optical broadband monitoring. Optics Balzers has developed a photolithographic patterning process for coating thicknesses up to 15μm that is fully compatible with the advanced PARMS coating technology. This provides the possibility of depositing multiple complex high-performance filters on a monolithic substrate. We present an overview of the performance of recently developed filters with improved spectral performance designed for both monolithic filter-arrays and stripe filters mounted in frames. The pros and cons as well as the resulting limits of the filter designs for both configurations are discussed.

Optical Path Switching Based Differential Absorption Radiometry for Substance Detection

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor)

2000-01-01

A system and method are provided for detecting one or more substances. An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. The first wavelength band and second wavelength band are unique. Further, spectral absorption of a substance of interest is different at the first wavelength band as compared to the second wavelength band. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

Effect of metal coating in all-fiber acousto-optic tunable filter using torsional wave.

PubMed

Song, Du-Ri; Jun, Chang Su; Do Lim, Sun; Kim, Byoung Yoon

2014-12-15

Torsional mode acousto-optic tunable filter (AOTF) is demonstrated using a metal-coated birefringent optical fiber for an improved robustness. The changes in acoustic and optical properties of a metal-coated birefringent optical fiber induced by the thin metal coating were analyzed experimentally and theoretically. The filter wavelength shift is successfully explained as a result of combined effect of acoustic wavelength change and optical birefringence change. We also demonstrated a small form-factor configuration by coiling the fiber with 6 cm diameter without performance degradation. The center wavelength of the filter can be tuned >35 nm by changing the applied frequency, and the coupling efficiency is higher than 92% with <5 nm 3-dB bandwidth.

Properties of multilayer filters

NASA Technical Reports Server (NTRS)

Baumeister, P. W.

1973-01-01

New methods were investigated of using optical interference coatings to produce bandpass filters for the spectral region 110 nm to 200 nm. The types of filter are: triple cavity metal dielectric filters; all dielectric reflection filters; and all dielectric Fabry Perot type filters. The latter two types use thorium fluoride and either cryolite films or magnesium fluoride films in the stacks. The optical properties of the thorium fluoride were also measured.

Real-valued composite filters for correlation-based optical pattern recognition

NASA Technical Reports Server (NTRS)

Rajan, P. K.; Balendra, Anushia

1992-01-01

Advances in the technology of optical devices such as spatial light modulators (SLMs) have influenced the research and growth of optical pattern recognition. In the research leading to this report, the design of real-valued composite filters that can be implemented using currently available SLMs for optical pattern recognition and classification was investigated. The design of real-valued minimum average correlation energy (RMACE) filter was investigated. Proper selection of the phase of the output response was shown to reduce the correlation energy. The performance of the filter was evaluated using computer simulations and compared with the complex filters. It was found that the performance degraded only slightly. Continuing the above investigation, the design of a real filter that minimizes the output correlation energy and the output variance due to noise was developed. Simulation studies showed that this filter had better tolerance to distortion and noise compared to that of the RMACE filter. Finally, the space domain design of RMACE filter was developed and implemented on the computer. It was found that the sharpness of the correlation peak was slightly reduced but the filter design was more computationally efficient than the complex filter.

The Rb 780-nanometer Faraday anomalous dispersion optical filter: Theory and experiment

NASA Technical Reports Server (NTRS)

Yin, B.; Alvarez, L. S.; Shay, T. M.

1994-01-01

The Faraday anomalous dispersion optical filter may provide ultra-high background noise rejection for free-space laser communications systems. The theoretical model for the filter is reported. The experimental measurements and their comparison with theoretical results are discussed. The results show that the filter can provide a 56-dB solar background noise rejection with about a 2-GHz transmission bandwidth and no image degradation. To further increase the background noise rejection, a composite Zeeman and Faraday anomalous dispersion optical filter is designed and experimentally demonstrated.

Spectroscopic imaging using acousto-optic tunable filters

NASA Astrophysics Data System (ADS)

Bouhifd, Mounir; Whelan, Maurice

2007-07-01

We report on novel hyper-spectral imaging filter-modules based on acousto-optic tuneable filters (AOTF). The AOTF functions as a full-field tuneable bandpass filter which offers fast continuous or random access tuning with high filtering efficiency. Due to the diffractive nature of the device, the unfiltered zero-order and the filtered first-order images are geometrically separated. The modules developed exploit this feature to simultaneously route both the transmitted white-light image and the filtered fluorescence image to two separate cameras. Incorporation of prisms in the optical paths and careful design of the relay optics in the filter module have overcome a number of aberrations inherent to imaging through AOTFs, leading to excellent spatial resolution. A number of practical uses of this technique, both for in vivo auto-fluorescence endoscopy and in vitro fluorescence microscopy were demonstrated. We describe the operational principle and design of recently improved prototype instruments for fluorescence-based diagnostics and demonstrate their performance by presenting challenging hyper-spectral fluorescence imaging applications.

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

DTIC Science & Technology

1995-06-30

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

Combination of highly nonlinear fiber, an optical bandpass filter, and a Fabry-Perot filter to improve the signal-to-noise ratio of a supercontinuum continuous-wave optical source.

PubMed

Nan, Yinbo; Huo, Li; Lou, Caiyun

2005-05-20

We present a theoretical study of a supercontinuum (SC) continuous-wave (cw) optical source generation in highly nonlinear fiber and its noise properties through numerical simulations based on the nonlinear Schrödinger equation. Fluctuations of pump pulses generate substructures between the longitudinal modes that result in the generation of white noise and then in degradation of coherence and in a decrease of the modulation depths and the signal-to-noise ratio (SNR). A scheme for improvement of the SNR of a multiwavelength cw optical source based on a SC by use of the combination of a highly nonlinear fiber (HNLF), an optical bandpass filter, and a Fabry-Perot (FP) filter is presented. Numerical simulations show that the improvement in modulation depth is relative to the HNLF's length, the 3-dB bandwidth of the optical bandpass filter, and the reflection ratio of the FP filter and that the average improvement in modulation depth is 13.7 dB under specified conditions.

Acousto-optical tunable filter for combined wideband, spectral, and optical coherence microscopy.

PubMed

Machikhin, Alexander S; Pozhar, Vitold E; Viskovatykh, Alexander V; Burmak, Ludmila I

2015-09-01

A multimodal technique for inspection of microscopic objects by means of wideband optical microscopy, spectral microscopy, and optical coherence microscopy is described, implemented, and tested. The key feature is the spectral selection of light in the output arm of an interferometer with use of the specialized imaging acousto-optical tunable filter. In this filter, two interfering optical beams are diffracted via the same ultrasound wave without destruction of interference image structure. The basic requirements for the acousto-optical tunable filter are defined, and mathematical formulas for calculation of its parameters are derived. Theoretical estimation of the achievable accuracy of the 3D image reconstruction is presented and experimental proofs are given. It is demonstrated that spectral imaging can also be accompanied by measurement of the quantitative reflectance spectra. Examples of inspection of optically transparent and nontransparent samples demonstrate the applicability of the technique.

Investigation on filter method for smoothing spiral phase plate

NASA Astrophysics Data System (ADS)

Zhang, Yuanhang; Wen, Shenglin; Luo, Zijian; Tang, Caixue; Yan, Hao; Yang, Chunlin; Liu, Mincai; Zhang, Qinghua; Wang, Jian

2018-03-01

Spiral phase plate (SPP) for generating vortex hollow beams has high efficiency in various applications. However, it is difficult to obtain an ideal spiral phase plate because of its continuous-varying helical phase and discontinued phase step. This paper describes the demonstration of continuous spiral phase plate using filter methods. The numerical simulations indicate that different filter method including spatial domain filter, frequency domain filter has unique impact on surface topography of SPP and optical vortex characteristics. The experimental results reveal that the spatial Gaussian filter method for smoothing SPP is suitable for Computer Controlled Optical Surfacing (CCOS) technique and obtains good optical properties.

Highly efficient all-fiber tunable polarization filter using torsional acoustic wave.

PubMed

Lee, Kwang Jo; Park, Hyun Chul; Kim, Byoung Yoon

2007-09-17

We demonstrate an all-fiber tunable polarization filter with high coupling efficiency based on acousto-optic coupling between two optical polarization modes of the LP(01) mode propagating in a highly birefringent single mode optical fiber. An over-coupling between the two polarization modes is realized over the wavelength range from 1530 nm to 1610 nm using traveling torsional acoustic wave. The measured 3-dB optical bandwidth of the filter was 4.8 nm at the wavelength around 1550 nm. The details of the filter transmission and the coupling characteristics are discussed.

Signal-to-noise ratio of arbitrarily filtered spontaneous emission

NASA Astrophysics Data System (ADS)

Šprem, Marko; Bosiljevac, Marko; Babić, Dubravko

2018-02-01

The signal-to-noise ratio (SNR) of filtered incoherent light can be approximated from the product of the coherence time of the light and the equivalent (electrical) noise bandwidth of the detector. This approximation holds only for the light with very short coherence time, that is in the case where the optical bandwidth of the light is much larger than the electrical bandwidth. We present here an expression for accurate evaluation of the SNR of the filtered incoherent light, which computes SNR from arbitrary shapes of optical and electrical filter power spectral densities (PSD). The PSDs of the filters can be measured using optical and electrical spectrum analyzers. Using our expression, we show that the SNR reaches unity when the electrical filter bandwidth is becoming larger than the optical filter bandwidth. To prove the theory, we evaluate and directly measure SNR of an incoherent light source filtered with several optical filters with bandwidths larger and commensurate with the bandwidth of the detector. For later we used optical and electrical filters with 3-dB bandwidths of 15 GHz and 10 GHz, respectively. Using our expression to evaluate SNR we obtained results in a good agreement with directly measured SNR. The results also prove that the approximation for evaluating SNR does not provide accurate results. The PSD of the detector with large noise bandwidth is difficult to measure using spectrum analyzer. There- fore, we report here a method for measuring the electrical noise bandwidth of the detector using the heterodyne linewidth measurement technique with tunable laser.

Polarization-independent fiber filter with an all-polarization-maintaining fiber loop for tunable fiber lasers

NASA Astrophysics Data System (ADS)

Zhang, Jun; Wu, Weiran; Rao, Qi; Zhou, Kejiang

2018-05-01

Tunable fiber lasers are a promising light source in all-optical wavelength conversion, fiber grating sensing and optical add-drop multiplexing. In order to achieve a tunable wavelength in the output, optical filters are indispensable for the construction of tunable fiber lasers. Recently, much attention has been given to developing high-performance filters. This paper proposes an environment-insensitive filter based on a Sagnac interferometer which was designed by an all-polarization-maintaining fiber with linear birefringence. According to the Sagnac interferometer, we derived the transfer function of an environment-insensitive filter. Based on this principle, it is shown that the device is able to implement a precision filtering function that can be used in a fiber laser’s optical resonant cavity. The experiment results demonstrated the effectiveness of this structure.

Active cleaning technique for removing contamination from optical surfaces in space

NASA Technical Reports Server (NTRS)

Shannon, R. L.; Gillette, R. B.; Cruz, G. A.

1973-01-01

An active cleaning technique for removing contaminants from optical surfaces in space was investigated with emphasis on the feasibility of using plasma exposure as a means of in-situ cleaning. The major work accomplished includes: (1) development of an in-situ reflectometer for use in conjunction with the contaminant film deposition/cleaning facility; (2) completion of Apollo Telescope Mount (ATM) filter treatment experiments to assess the effects of plasma exposure on the UV transmittance; (3) attempts to correlate the atomic oxygen flux with cleaning rate; (4) completion of in-situ butadien contamination/plasma cleaning/UV reflectance measurement experiments; (5) carbon cleaning experiments using various gases; (6) completion of silicone contamination/cleaning experiments; and (7) experiments conducted at low chamber pressures to determine cleaning rate distribution and contamination of surfaces adjacent to those being cleaned.

A single-mode external cavity diode laser using an intra-cavity atomic Faraday filter with short-term linewidth <400 kHz and long-term stability of <1 MHz.

PubMed

Keaveney, James; Hamlyn, William J; Adams, Charles S; Hughes, Ifan G

2016-09-01

We report on the development of a diode laser system - the "Faraday laser" - using an atomic Faraday filter as the frequency-selective element. In contrast to typical external-cavity diode laser systems which offer tunable output frequency but require additional control systems in order to achieve a stable output frequency, our system only lases at a single frequency, set by the peak transmission frequency of the internal atomic Faraday filter. Our system has both short-term and long-term stability of less than 1 MHz, which is less than the natural linewidth of alkali-atomic D-lines, making similar systems suitable for use as a "turn-key" solution for laser-cooling experiments.

Characterization on Smart Optics Using Ellipsometry

NASA Technical Reports Server (NTRS)

Song, Kyo D.

2002-01-01

Recently, NASA Langley Research Center developed a smart active optical concept to filter narrow band pass or to control optical intensity. To characterize developed smart optics materials, we have measured thickness and reflection properties of the materials using a WVASE32 ellipsometry. This project allowed us to: (1) prepare the smart optical materials for measurement of thickness and optical properties at NASA Langley Research Center; (2) measure thickness and optical properties of the smart optical materials; (3) evaluate the measured properties in terms of applications for narrow band-pass filters. The outcomes of this research provide optical properties and physical properties of the smart optics on a selected spectral range. The applications of this development were used for field-controlled spectral smart filters.

Tunable-optical-filter-based white-light interferometry for sensing.

PubMed

Yu, Bing; Wang, Anbo; Pickrell, Gary; Xu, Juncheng

2005-06-15

We describe tunable-optical-filter-based white-light interferometry for sensor interrogation. By introducing a tunable optical filter into a white-light interferometry system, one can interrogate an interferometer with either quadrature demodulation or spectral-domain detection at low cost. To demonstrate the feasibility of effectively demodulating various types of interferometric sensor, experiments have been performed using an extrinsic Fabry-Perot tunable filter to interrogate two extrinsic Fabry-Perot interferometric temperature sensors and a diaphragm-based pressure sensor.

Concept for Inclusion of Analytical and Computational Capability in Optical Plume Anomaly Detection (OPAD) for Measurement of Neutron Flux

NASA Technical Reports Server (NTRS)

Patrick, M. Clinton; Cooper, Anita E.; Powers, W. T.

2004-01-01

Researchers are working on many konts to make possible high speed, automated classification and quantification of constituent materials in numerous environments. NASA's Marshall Space Flight Center has implemented a system for rocket engine flow fields/plumes; the Optical Plume Anomaly Detection (OPAD) system was designed to utilize emission and absorption spectroscopy for monitoring molecular and atomic particulates in gas plasma. An accompanying suite of tools and analytical package designed to utilize information collected by OPAD is known as the Engine Diagnostic Filtering System (EDIFIS). The current combination of these systems identifies atomic and molecular species and quantifies mass loss rates in H2/O2 rocket plumes. Additionally, efforts are being advanced to hardware encode components of the EDIFIS in order to address real-time operational requirements for health monitoring and management. This paper addresses the OPAD with its tool suite, and discusses what is considered a natural progression: a concept for migrating OPAD towards detection of high energy particles, including neutrons and gamma rays. The integration of these tools and capabilities will provide NASA with a systematic approach to monitor space vehicle internal and external environment.

Solid state electro-optic color filter and iris

NASA Technical Reports Server (NTRS)

1974-01-01

Test results obtained have confirmed the practicality of the solid state electro-optic filters as an optical control element in a television system. Neutral-density control range in excess of 1000:1 has been obtained on sample filters. Test results, measurements in a complete camera system, discussions of problem areas, analytical comparisons, and recommendations for future investigations are included.

An Optoelectronic Equivalent Narrowband Filter for High Resolution Optical Spectrum Analysis

PubMed Central

Feng, Kunpeng; Cui, Jiwen; Dang, Hong; Wu, Weidong; Sun, Xun; Jiang, Xuelin; Tan, Jiubin

2017-01-01

To achieve a narrow bandwidth optical filter with a wide swept range for new generation optical spectrum analysis (OSA) of high performance optical sensors, an optoelectronic equivalent narrowband filter (OENF) was investigated and a swept optical filter with bandwidth of several MHz and sweep range of several tens of nanometers was built using electric filters and a sweep laser as local oscillator (LO). The principle of OENF is introduced and analysis of the OENF system is presented. Two electric filters are optimized to be RBW filters for high and medium spectral resolution applications. Both simulations and experiments are conducted to verify the OENF principle and the results show that the power uncertainty is less than 1.2% and the spectral resolution can reach 6 MHz. Then, a real-time wavelength calibration system consisting of a HCN gas cell and Fabry–Pérot etalon is proposed to guarantee a wavelength accuracy of ±0.4 pm in the C-band and to reduce the influence of phase noise and nonlinear velocity of the LO sweep. Finally, OSA experiments on actual spectra of various optical sensors are conducted using the OENF system. These experimental results indicate that OENF system has an excellent capacity for the analysis of fine spectrum structures. PMID:28208624

An Optoelectronic Equivalent Narrowband Filter for High Resolution Optical Spectrum Analysis.

PubMed

Feng, Kunpeng; Cui, Jiwen; Dang, Hong; Wu, Weidong; Sun, Xun; Jiang, Xuelin; Tan, Jiubin

2017-02-10

To achieve a narrow bandwidth optical filter with a wide swept range for new generation optical spectrum analysis (OSA) of high performance optical sensors, an optoelectronic equivalent narrowband filter (OENF) was investigated and a swept optical filter with bandwidth of several MHz and sweep range of several tens of nanometers was built using electric filters and a sweep laser as local oscillator (LO). The principle of OENF is introduced and analysis of the OENF system is presented. Two electric filters are optimized to be RBW filters for high and medium spectral resolution applications. Both simulations and experiments are conducted to verify the OENF principle and the results show that the power uncertainty is less than 1.2% and the spectral resolution can reach 6 MHz. Then, a real-time wavelength calibration system consisting of a HCN gas cell and Fabry-Pérot etalon is proposed to guarantee a wavelength accuracy of ±0.4 pm in the C-band and to reduce the influence of phase noise and nonlinear velocity of the LO sweep. Finally, OSA experiments on actual spectra of various optical sensors are conducted using the OENF system. These experimental results indicate that OENF system has an excellent capacity for the analysis of fine spectrum structures.

Pulse Propagation Effects in Optical 2D Fourier-Transform Spectroscopy: Theory.

PubMed

Spencer, Austin P; Li, Hebin; Cundiff, Steven T; Jonas, David M

2015-04-30

A solution to Maxwell's equations in the three-dimensional frequency domain is used to calculate rephasing two-dimensional Fourier transform (2DFT) spectra of the D2 line of atomic rubidium vapor in argon buffer gas. Experimental distortions from the spatial propagation of pulses through the sample are simulated in 2DFT spectra calculated for the homogeneous Bloch line shape model. Spectral features that appear at optical densities of up to 3 are investigated. As optical density increases, absorptive and dispersive distortions start with peak shape broadening, progress to peak splitting, and ultimately result in a previously unexplored coherent transient twisting of the split peaks. In contrast to the low optical density limit, where the 2D peak shape for the Bloch model depends only on the total dephasing time, these distortions of the 2D peak shape at finite optical density vary with the waiting time and the excited state lifetime through coherent transient effects. Experiment-specific conditions are explored, demonstrating the effects of varying beam overlap within the sample and of pseudo-time domain filtering. For beam overlap starting at the sample entrance, decreasing the length of beam overlap reduces the line width along the ωτ axis but also reduces signal intensity. A pseudo-time domain filter, where signal prior to the center of the last excitation pulse is excluded from the FID-referenced 2D signal, reduces propagation distortions along the ωt axis. It is demonstrated that 2DFT rephasing spectra cannot take advantage of an excitation-detection transformation that can eliminate propagation distortions in 2DFT relaxation spectra. Finally, the high optical density experimental 2DFT spectrum of rubidium vapor in argon buffer gas [J. Phys. Chem. A 2013, 117, 6279-6287] is quantitatively compared, in line width, in depth of peak splitting, and in coherent transient peak twisting, to a simulation with optical density higher than that reported.

Narrowband diode laser pump module for pumping alkali vapors.

PubMed

Rotondaro, M D; Zhdanov, B V; Shaffer, M K; Knize, R J

2018-04-16

We describe a method of line narrowing and frequency-locking a diode laser stack to an alkali atomic line for use as a pump module for Diode Pumped Alkali Lasers. The pump module consists of a 600 W antireflection coated diode laser stack configured to lase using an external cavity. The line narrowing and frequency locking is accomplished by introducing a narrowband polarization filter based on magneto-optical Faraday effect into the external cavity, which selectively transmits only the frequencies that are in resonance with the 6 2 S 1/2 → 6 2 P 3/2 transition of Cs atoms. The resulting pump module has demonstrated that a diode laser stack, which lases with a line width of 3 THz without narrowbanding, can be narrowed to 10 GHz. The line narrowed pump module produced 518 Watts that is 80% of the power generated by the original broadband diode laser stack.

Analysis of silicon on insulator (SOI) optical microring add-drop filter based on waveguide intersections

NASA Astrophysics Data System (ADS)

Kaźmierczak, Andrzej; Bogaerts, Wim; Van Thourhout, Dries; Drouard, Emmanuel; Rojo-Romeo, Pedro; Giannone, Domenico; Gaffiot, Frederic

2008-04-01

We present a compact passive optical add-drop filter which incorporates two microring resonators and a waveguide intersection in silicon-on-insulator (SOI) technology. Such a filter is a key element for designing simple layouts of highly integrated complex optical networks-on-chip. The filter occupies an area smaller than 10μm×10μm and exhibits relatively high quality factors (up to 4000) and efficient signal dropping capabilities. In the present work, the influence of filter parameters such as the microring-resonators radii and the coupling section shape are analyzed theoretically and experimentally

Virtual experiment of optical spatial filtering in Matlab environment

NASA Astrophysics Data System (ADS)

Ji, Yunjing; Wang, Chunyong; Song, Yang; Lai, Jiancheng; Wang, Qinghua; Qi, Jing; Shen, Zhonghua

2017-08-01

The principle of spatial filtering experiment has been introduced, and the computer simulation platform with graphical user interface (GUI) has been made out in Matlab environment. Using it various filtering processes for different input image or different filtering purpose will be completed accurately, and filtering effect can be observed clearly with adjusting experimental parameters. The physical nature of the optical spatial filtering can be showed vividly, and so experimental teaching effect will be promoted.

Enhancing optical nonreciprocity by an atomic ensemble in two coupled cavities

NASA Astrophysics Data System (ADS)

Song, L. N.; Wang, Z. H.; Li, Yong

2018-05-01

We study the optical nonreciprocal propagation in an optical molecule of two coupled cavities with one of them interacting with a two-level atomic ensemble. The effect of increasing the number of atoms on the optical isolation ratio of the system is studied. We demonstrate that the significant nonlinearity supplied by the coupling of the atomic ensemble with the cavity leads to the realization of greatly-enhanced optical nonreciprocity compared with the case of single atom.

High-speed tunable microwave photonic notch filter based on phase modulator incorporated Lyot filter.

PubMed

Ge, Jia; Feng, Hanlin; Scott, Guy; Fok, Mable P

2015-01-01

A high-speed tunable microwave photonic notch filter with ultrahigh rejection ratio is presented, which is achieved by semiconductor optical amplifier (SOA)-based single-sideband modulation and optical spectral filtering with a phase modulator-incorporated Lyot (PM-Lyot) filter. By varying the birefringence of the phase modulator through electro-optic effect, electrically tuning of the microwave photonic notch filter is experimentally achieved at tens of gigahertz speed. The use of SOA-polarizer based single-sideband modulation scheme provides good sideband suppression over a wide frequency range, resulting in an ultrahigh rejection ratio of the microwave photonic notch filter. Stable filter spectrum with bandstop rejection ratio over 60 dB is observed over a frequency tuning range from 1.8 to 10 GHz. Compare with standard interferometric notch filter, narrower bandwidth and sharper notch profile are achieved with the unique PM-Lyot filter, resulting in better filter selectivity. Moreover, bandwidth tuning is also achieved through polarization adjustment inside the PM-Lyot filter, that the 10-dB filter bandwidth is tuned from 0.81 to 1.85 GHz.

Spatial optical crosstalk in CMOS image sensors integrated with plasmonic color filters.

PubMed

Yu, Yan; Chen, Qin; Wen, Long; Hu, Xin; Zhang, Hui-Fang

2015-08-24

Imaging resolution of complementary metal oxide semiconductor (CMOS) image sensor (CIS) keeps increasing to approximately 7k × 4k. As a result, the pixel size shrinks down to sub-2μm, which greatly increases the spatial optical crosstalk. Recently, plasmonic color filter was proposed as an alternative to conventional colorant pigmented ones. However, there is little work on its size effect and the spatial optical crosstalk in a model of CIS. By numerical simulation, we investigate the size effect of nanocross array plasmonic color filters and analyze the spatial optical crosstalk of each pixel in a Bayer array of a CIS with a pixel size of 1μm. It is found that the small pixel size deteriorates the filtering performance of nanocross color filters and induces substantial spatial color crosstalk. By integrating the plasmonic filters in the low Metal layer in standard CMOS process, the crosstalk reduces significantly, which is compatible to pigmented filters in a state-of-the-art backside illumination CIS.

Phase-shifted Solc-type filter based on thin periodically poled lithium niobate in a reflective geometry.

PubMed

Ding, Tingting; Zheng, Yuanlin; Chen, Xianfeng

2018-04-30

Configurable narrow bandwidth filters are indispensable components in optical communication networks. Here, we present an easily-integrated compact tunable filtering based on polarization-coupling process in a thin periodically poled lithium niobate (PPLN) in a reflective geometry via the transverse electro-optic (EO) effect. The structure, composed of an in-line polarizer and a thinned PPLN chip, forms a phase-shift Solc-type filter with similar mechanism to defected Bragg gratings. The filtering effect can be dynamically switched on and off by a transverse electric filed. Analogy of electromagnetically induced transparency (EIT) transmission spectrum and electrically controllable group delay is experimentally observed. The mechanism features tunable center wavelength in a wide range with respect to temperature and tunable optical delay to the applied voltage, which may offer another way for optical tunable filters or delay lines.

Resonator memories and optical novelty filters

NASA Astrophysics Data System (ADS)

Anderson, Dana Z.; Erle, Marie C.

Optical resonators having holographic elements are potential candidates for storing information that can be accessed through content addressable or associative recall. Closely related to the resonator memory is the optical novelty filter, which can detect the differences between a test object and a set of reference objects. We discuss implementations of these devices using continuous optical media such as photorefractive materials. The discussion is framed in the context of neural network models. There are both formal and qualitative similarities between the resonator memory and optical novelty filter and network models. Mode competition arises in the theory of the resonator memory, much as it does in some network models. We show that the role of the phenomena of "daydreaming" in the real-time programmable optical resonator is very much akin to the role of "unlearning" in neural network memories. The theory of programming the real-time memory for a single mode is given in detail. This leads to a discussion of the optical novelty filter. Experimental results for the resonator memory, the real-time programmable memory, and the optical tracking novelty filter are reviewed. We also point to several issues that need to be addressed in order to implement more formal models of neural networks.

Resonator Memories And Optical Novelty Filters

NASA Astrophysics Data System (ADS)

Anderson, Dana Z.; Erie, Marie C.

1987-05-01

Optical resonators having holographic elements are potential candidates for storing information that can be accessed through content-addressable or associative recall. Closely related to the resonator memory is the optical novelty filter, which can detect the differences between a test object and a set of reference objects. We discuss implementations of these devices using continuous optical media such as photorefractive ma-terials. The discussion is framed in the context of neural network models. There are both formal and qualitative similarities between the resonator memory and optical novelty filter and network models. Mode competition arises in the theory of the resonator memory, much as it does in some network models. We show that the role of the phenomena of "daydream-ing" in the real-time programmable optical resonator is very much akin to the role of "unlearning" in neural network memories. The theory of programming the real-time memory for a single mode is given in detail. This leads to a discussion of the optical novelty filter. Experimental results for the resonator memory, the real-time programmable memory, and the optical tracking novelty filter are reviewed. We also point to several issues that need to be addressed in order to implement more formal models of neural networks.

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

Brock, Billy C.; Allen, Steven E.

The monopulse response of radar systems utilizing a short-focal-length offset-fed parabolic reflector can be compromised by depolarization of the signal by the target and by multipath scattering from nearby objects. The polarimetric behavior of this type of antenna is examined. The use of a shroud to reduce multipath interaction with nearby objects is also described. The mechanism through which man-made targets can introduce cross-polarization components into the scattered field is explained. Two kinds of polarization filters, suitable for linear polarization, are described for mitigating the effects of depolarization due to cross-polarization scattering. The benefit of the application of a polarizationmore » filter is demonstrated by modeling a monopulse radar system viewing a dihedral corner reflector. The model demonstrates dramatic performance improvement when the filter is used, showing that usable performance can be achieved even when the target depolarization is so severe that the cross-polarized signal is more than an order of magnitude stronger than the desired co-polarized signal. Relevant and useful reference material is also included in the form of appendices describing the relationship between different polarization representations and demonstrating the conditions under which Maxwell's equations can be considered to be scale-invariant. Acknowledgements This report is the result of a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories and General Atomics Aeronautical Systems, Inc. -- CRADA No. SC08/01749. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. General Atomics Aeronautical Systems, Inc. (GA-ASI), an affiliate of privately-held General Atomics, is a leading manufacturer of Remotely Piloted Aircraft (RPA) systems, radars, and electro-optic and related mission systems, including the Predator (r) /Gray Eagle-series and Lynx (r) Multi-mode Radar. - 4 -« less

Control, Filtering and Prediction for Phased Arrays in Directed Energy Systems

DTIC Science & Technology

2016-04-30

adaptive optics. 15. SUBJECT TERMS control, filtering, prediction, system identification, adaptive optics, laser beam pointing, target tracking, phase... laser beam control; furthermore, wavefront sensors are plagued by the difficulty of maintaining the required alignment and focusing in dynamic mission...developed new methods for filtering, prediction and system identification in adaptive optics for high energy laser systems including phased arrays. The

System and Method for Generating a Frequency Modulated Linear Laser Waveform

NASA Technical Reports Server (NTRS)

Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)

2017-01-01

A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

System and Method for Generating a Frequency Modulated Linear Laser Waveform

NASA Technical Reports Server (NTRS)

Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)

2014-01-01

A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

Sub-GHz-resolution C-band Nyquist-filtering interleaver on a high-index-contrast photonic integrated circuit.

PubMed

Zhuang, Leimeng; Zhu, Chen; Corcoran, Bill; Burla, Maurizio; Roeloffzen, Chris G H; Leinse, Arne; Schröder, Jochen; Lowery, Arthur J

2016-03-21

Modern optical communications rely on high-resolution, high-bandwidth filtering to maximize the data-carrying capacity of fiber-optic networks. Such filtering typically requires high-speed, power-hungry digital processes in the electrical domain. Passive optical filters currently provide high bandwidths with low power consumption, but at the expense of resolution. Here, we present a passive filter chip that functions as an optical Nyquist-filtering interleaver featuring sub-GHz resolution and a near-rectangular passband with 8% roll-off. This performance is highly promising for high-spectral-efficiency Nyquist wavelength division multiplexed (N-WDM) optical super-channels. The chip provides a simple two-ring-resonator-assisted Mach-Zehnder interferometer, which has a sub-cm² footprint owing to the high-index-contrast Si₃N₄/SiO₂ waveguide, while manifests low wavelength-dependency enabling C-band (> 4 THz) coverage with more than 160 effective free spectral ranges of 25 GHz. This device is anticipated to be a critical building block for spectrally-efficient, chip-scale transceivers and ROADMs for N-WDM super-channels in next-generation optical communication networks.

Design and Specification of Optical Bandpass Filters for Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)

NASA Technical Reports Server (NTRS)

Leviton, Douglas B.; Tsevetanov, Zlatan; Woodruff, Bob; Mooney, Thomas A.

1998-01-01

Advanced optical bandpass filters for the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) have been developed on a filter-by-filter basis through detailed studies which take into account the instrument's science goals, available optical filter fabrication technology, and developments in ACS's charge-coupled-device (CCD) detector technology. These filters include a subset of filters for the Sloan Digital Sky Survey (SDSS) which are optimized for astronomical photometry using today's charge-coupled-devices (CCD's). In order for ACS to be truly advanced, these filters must push the state-of-the-art in performance in a number of key areas at the same time. Important requirements for these filters include outstanding transmitted wavefront, high transmittance, uniform transmittance across each filter, spectrally structure-free bandpasses, exceptionally high out of band rejection, a high degree of parfocality, and immunity to environmental degradation. These constitute a very stringent set of requirements indeed, especially for filters which are up to 90 mm in diameter. The highly successful paradigm in which final specifications for flight filters were derived through interaction amongst the ACS Science Team, the instrument designer, the lead optical engineer, and the filter designer and vendor is described. Examples of iterative design trade studies carried out in the context of science needs and budgetary and schedule constraints are presented. An overview of the final design specifications for the ACS bandpass and ramp filters is also presented.

Design considerations for near-infrared filter photometry: effects of noise sources and selectivity.

PubMed

Tarumi, Toshiyasu; Amerov, Airat K; Arnold, Mark A; Small, Gary W

2009-06-01

Optimal filter design of two-channel near-infrared filter photometers is investigated for simulated two-component systems consisting of an analyte and a spectrally overlapping interferent. The degree of overlap between the analyte and interferent bands is varied over three levels. The optimal design is obtained for three cases: a source or background flicker noise limited case, a shot noise limited case, and a detector noise limited case. Conventional photometers consist of narrow-band optical filters with their bands located at discrete wavelengths. However, the use of broadband optical filters with overlapping responses has been proposed to obtain as much signal as possible from a weak and broad analyte band typical of near-infrared absorptions. One question regarding the use of broadband optical filters with overlapping responses is the selectivity achieved by such filters. The selectivity of two-channel photometers is evaluated on the basis of the angle between the analyte and interferent vectors in the space spanned by the relative change recorded for each of the two detector channels. This study shows that for the shot noise limited or detector noise limited cases, the slight decrease in selectivity with the use of broadband optical filters can be compensated by the higher signal-to-noise ratio afforded by the use of such filters. For the source noise limited case, the best quantitative results are obtained with the use of narrow-band non-overlapping optical filters.

Geometric calibration of lens and filter distortions for multispectral filter-wheel cameras.

PubMed

Brauers, Johannes; Aach, Til

2011-02-01

High-fidelity color image acquisition with a multispectral camera utilizes optical filters to separate the visible electromagnetic spectrum into several passbands. This is often realized with a computer-controlled filter wheel, where each position is equipped with an optical bandpass filter. For each filter wheel position, a grayscale image is acquired and the passbands are finally combined to a multispectral image. However, the different optical properties and non-coplanar alignment of the filters cause image aberrations since the optical path is slightly different for each filter wheel position. As in a normal camera system, the lens causes additional wavelength-dependent image distortions called chromatic aberrations. When transforming the multispectral image with these aberrations into an RGB image, color fringes appear, and the image exhibits a pincushion or barrel distortion. In this paper, we address both the distortions caused by the lens and by the filters. Based on a physical model of the bandpass filters, we show that the aberrations caused by the filters can be modeled by displaced image planes. The lens distortions are modeled by an extended pinhole camera model, which results in a remaining mean calibration error of only 0.07 pixels. Using an absolute calibration target, we then geometrically calibrate each passband and compensate for both lens and filter distortions simultaneously. We show that both types of aberrations can be compensated and present detailed results on the remaining calibration errors.

Optical micro-cavities on silicon

NASA Astrophysics Data System (ADS)

Dai, Daoxin; Liu, Erhu; Tan, Ying

2018-01-01

Silicon-based optical microcavities are very popular for many applications because of the ultra-compact footprint, easy scalability, and functional versatility. In this paper we give a discussion about the challenges of the optical microcavities on silicon and also give a review of our recent work, including the following parts. First, a near-"perfect" high-order MRR optical filter with a box-like filtering response is realized by introducing bent directional couplers to have sufficient coupling between the access waveguide and the microrings. Second, an efficient thermally-tunable MRR-based optical filter with graphene transparent nano-heater is realized by introducing transparent graphene nanoheaters. Thirdly, a polarization-selective microring-based optical filter is realized to work with resonances for only one of TE and TM polarizations for the first time. Finally, a on-chip reconfigurable optical add-drop multiplexer for hybrid mode- /wavelength-division-multiplexing systems is realized for the first time by monolithically integrating a mode demultiplexer, four MRR optical switches, and a mode multiplexer.

Fully reconfigurable photonic microwave transversal filter based on digital micromirror device and continuous-wave, incoherent supercontinuum source.

PubMed

Lee, Ju Han; Chang, You Min; Han, Young-Geun; Lee, Sang Bae; Chung, Hae Yang

2007-08-01

The combined use of a programmable, digital micromirror device (DMD) and an ultrabroadband, cw, incoherent supercontinuum (SC) source is experimentally demonstrated to fully explore various aspects on the reconfiguration of a microwave filter transfer function by creating a range of multiwavelength optical filter shapes. Owing to both the unique characteristic of the DMD that an arbitrary optical filter shape can be readily produced and the ultrabroad bandwidth of the cw SC source that is 3 times larger than that of Er-amplified spontaneous emission, a multiwavelength optical beam pattern can be generated with a large number of wavelength filter taps apodized by an arbitrary amplitude window. Therefore various types of high-quality microwave filter can be readily achieved through the spectrum slicing-based photonic microwave transversal filter scheme. The experimental demonstration is performed in three aspects: the tuning of a filter resonance bandwidth at a fixed resonance frequency, filter resonance frequency tuning at a fixed resonance frequency, and flexible microwave filter shape reconstruction.

Nonlinear multilayers as optical limiters

NASA Astrophysics Data System (ADS)

Turner-Valle, Jennifer Anne

1998-10-01

In this work we present a non-iterative technique for computing the steady-state optical properties of nonlinear multilayers and we examine nonlinear multilayer designs for optical limiters. Optical limiters are filters with intensity-dependent transmission designed to curtail the transmission of incident light above a threshold irradiance value in order to protect optical sensors from damage due to intense light. Thin film multilayers composed of nonlinear materials exhibiting an intensity-dependent refractive index are used as the basis for optical limiter designs in order to enhance the nonlinear filter response by magnifying the electric field in the nonlinear materials through interference effects. The nonlinear multilayer designs considered in this work are based on linear optical interference filter designs which are selected for their spectral properties and electric field distributions. Quarter wave stacks and cavity filters are examined for their suitability as sensor protectors and their manufacturability. The underlying non-iterative technique used to calculate the optical response of these filters derives from recognizing that the multi-valued calculation of output irradiance as a function of incident irradiance may be turned into a single-valued calculation of incident irradiance as a function of output irradiance. Finally, the benefits and drawbacks of using nonlinear multilayer for optical limiting are examined and future research directions are proposed.

Transmission system for distribution of video over long-haul optical point-to-point links using a microwave photonic filter in the frequency range of 0.01-10 GHz

NASA Astrophysics Data System (ADS)

Zaldívar Huerta, Ignacio E.; Pérez Montaña, Diego F.; Nava, Pablo Hernández; Juárez, Alejandro García; Asomoza, Jorge Rodríguez; Leal Cruz, Ana L.

2013-12-01

We experimentally demonstrate the use of an electro-optical transmission system for distribution of video over long-haul optical point-to-point links using a microwave photonic filter in the frequency range of 0.01-10 GHz. The frequency response of the microwave photonic filter consists of four band-pass windows centered at frequencies that can be tailored to the function of the spectral free range of the optical source, the chromatic dispersion parameter of the optical fiber used, as well as the length of the optical link. In particular, filtering effect is obtained by the interaction of an externally modulated multimode laser diode emitting at 1.5 μm associated to the length of a dispersive optical fiber. Filtered microwave signals are used as electrical carriers to transmit TV-signal over long-haul optical links point-to-point. Transmission of TV-signal coded on the microwave band-pass windows located at 4.62, 6.86, 4.0 and 6.0 GHz are achieved over optical links of 25.25 km and 28.25 km, respectively. Practical applications for this approach lie in the field of the FTTH access network for distribution of services as video, voice, and data.

Polarization division multiplexing for optical data communications

NASA Astrophysics Data System (ADS)

Ivanovich, Darko; Powell, Samuel B.; Gruev, Viktor; Chamberlain, Roger D.

2018-02-01

Multiple parallel channels are ubiquitous in optical communications, with spatial division multiplexing (separate physical paths) and wavelength division multiplexing (separate optical wavelengths) being the most common forms. Here, we investigate the viability of polarization division multiplexing, the separation of distinct parallel optical communication channels through the polarization properties of light. Two or more linearly polarized optical signals (at different polarization angles) are transmitted through a common medium, filtered using aluminum nanowire optical filters fabricated on-chip, and received using individual silicon photodetectors (one per channel). The entire receiver (including optics) is compatible with standard CMOS fabrication processes. The filter model is based upon an input optical signal formed as the sum of the Stokes vectors for each individual channel, transformed by the Mueller matrix that models the filter proper, resulting in an output optical signal that impinges on each photodiode. The results show that two- and three-channel systems can operate with a fixed-threshold comparator in the receiver circuit, but four-channel systems (and larger) will require channel coding of some form. For example, in the four-channel system, 10 of 16 distinct bit patterns are separable by the receiver. The model supports investigation of the range of variability tolerable in the fabrication of the on-chip polarization filters.

Probing Atomic Dynamics and Structures Using Optical Patterns

NASA Astrophysics Data System (ADS)

Schmittberger, Bonnie L.; Gauthier, Daniel J.

2015-05-01

Pattern formation is a widely studied phenomenon that can provide fundamental insights into nonlinear systems. Emergent patterns in cold atoms are of particular interest in condensed matter physics and quantum information science because one can relate optical patterns to spatial structures in the atoms. In our experimental system, we study multimode optical patterns generated from a sample of cold, thermal atoms. We observe this nonlinear optical phenomenon at record low input powers due to the highly nonlinear nature of the spatial bunching of atoms in an optical lattice. We present a detailed study of the dynamics of these bunched atoms during optical pattern formation. We show how small changes in the atomic density distribution affect the symmetry of the generated patterns as well as the nature of the nonlinearity that describes the light-atom interaction. We gratefully acknowledge the financial support of the National Science Foundation through Grant #PHY-1206040.

Optical Fourier filtering for whole lens assessment of progressive power lenses.

PubMed

Spiers, T; Hull, C C

2000-07-01

Four binary filter designs for use in an optical Fourier filtering set-up were evaluated when taking quantitative measurements and when qualitatively mapping the power variation of progressive power lenses (PPLs). The binary filters tested were concentric ring, linear grating, grid and "chevron" designs. The chevron filter was considered best for quantitative measurements since it permitted a vernier acuity task to be used for measuring the fringe spacing, significantly reducing errors, and it also gave information on the polarity of the lens power. The linear grating filter was considered best for qualitatively evaluating the power variation. Optical Fourier filtering and a Nidek automatic focimeter were then used to measure the powers in the distance and near portions of five PPLs of differing design. Mean measurement error was 0.04 D with a maximum value of 0.13 D. Good qualitative agreement was found between the iso-cylinder plots provided by the manufacturer and the Fourier filter fringe patterns for the PPLs indicating that optical Fourier filtering provides the ability to map the power distribution across the entire lens aperture without the need for multiple point measurements. Arguments are presented that demonstrate that it should be possible to derive both iso-sphere and iso-cylinder plots from the binary filter patterns.

Velocity filtering applied to optical flow calculations

NASA Technical Reports Server (NTRS)

Barniv, Yair

1990-01-01

Optical flow is a method by which a stream of two-dimensional images obtained from a forward-looking passive sensor is used to map the three-dimensional volume in front of a moving vehicle. Passive ranging via optical flow is applied here to the helicopter obstacle-avoidance problem. Velocity filtering is used as a field-based method to determine range to all pixels in the initial image. The theoretical understanding and performance analysis of velocity filtering as applied to optical flow is expanded and experimental results are presented.

Determination of tailored filter sets to create rayfiles including spatial and angular resolved spectral information.

PubMed

Rotscholl, Ingo; Trampert, Klaus; Krüger, Udo; Perner, Martin; Schmidt, Franz; Neumann, Cornelius

2015-11-16

To simulate and optimize optical designs regarding perceived color and homogeneity in commercial ray tracing software, realistic light source models are needed. Spectral rayfiles provide angular and spatial varying spectral information. We propose a spectral reconstruction method with a minimum of time consuming goniophotometric near field measurements with optical filters for the purpose of creating spectral rayfiles. Our discussion focuses on the selection of the ideal optical filter combination for any arbitrary spectrum out of a given filter set by considering measurement uncertainties with Monte Carlo simulations. We minimize the simulation time by a preselection of all filter combinations, which bases on factorial design.

Cyclic additional optical true time delay for microwave beam steering with spectral filtering.

PubMed

Cao, Z; Lu, R; Wang, Q; Tessema, N; Jiao, Y; van den Boom, H P A; Tangdiongga, E; Koonen, A M J

2014-06-15

Optical true time delay (OTTD) is an attractive way to realize microwave beam steering (MBS) due to its inherent features of broadband, low-loss, and compactness. In this Letter, we propose a novel OTTD approach named cyclic additional optical true time delay (CAO-TTD). It applies additional integer delays of the microwave carrier frequency to achieve spectral filtering but without disturbing the spatial filtering (beam steering). Based on such concept, a broadband MBS scheme for high-capacity wireless communication is proposed, which allows the tuning of both spectral filtering and spatial filtering. The experimental results match well with the theoretical analysis.

Mach-Zehnder atom interferometer inside an optical fiber

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

An integrated charge exchange recombination spectroscopy/beam emission spectroscopy diagnostic for Alcator C-Mod tokamak.

PubMed

Bespamyatnov, I O; Rowan, W L; Liao, K T; Granetz, R S

2010-10-01

A novel integrated charge exchange recombination spectroscopy (CXRS)/beam emission spectroscopy (BES) system is proposed for C-Mod, in which both measurements are taken from a shared viewing geometry. The supplementary BES system serves to quantify local beam densities and supplants the common calculation of beam attenuation. The new system employs two optical viewing arrays, 20 poloidal and 22 toroidal channels. A dichroic filter splits the light between two spectrometers operating at different wavelengths for impurity ion and beam neutrals emission. In this arrangement, the impurity density is inferred from the electron density, measured BES and CXRS spectral radiances, and atomic emission rates.

Integrated Optical Dipole Trap for Cold Neutral Atoms with an Optical Waveguide Coupler

NASA Astrophysics Data System (ADS)

Lee, J.; Park, D. H.; Mittal, S.; Meng, Y.; Dagenais, M.; Rolston, S. L.

2013-05-01

Using an optical waveguide, an integrated optical dipole trap uses two-color (red and blue-detuned) traveling evanescent wave fields for trapping cold neutral atoms. To achieve longitudinal confinement, we propose using an integrated optical waveguide coupler, which provides a potential gradient along the beam propagation direction sufficient to confine atoms. This integrated optical dipole trap can support an atomic ensemble with a large optical depth due to its small mode area. Its quasi-TE0 waveguide mode has an advantage over the HE11 mode of a nanofiber, with little inhomogeneous Zeeman broadening at the trapping region. The longitudinal confinement eliminates the need for a 1D optical lattice, reducing collisional blockaded atomic loading, potentially producing larger ensembles. The waveguide trap allows for scalability and integrability with nano-fabrication technology. We analyze the potential performance of such integrated atom traps and present current research progress towards a fiber-coupled silicon nitride optical waveguide integrable with atom chips. Work is supported by the ARO Atomtronics MURI. Work is supported by the ARO Atomtronics MURI.

Detecting an atomic clock frequency anomaly using an adaptive Kalman filter algorithm

NASA Astrophysics Data System (ADS)

Song, Huijie; Dong, Shaowu; Wu, Wenjun; Jiang, Meng; Wang, Weixiong

2018-06-01

The abnormal frequencies of an atomic clock mainly include frequency jump and frequency drift jump. Atomic clock frequency anomaly detection is a key technique in time-keeping. The Kalman filter algorithm, as a linear optimal algorithm, has been widely used in real-time detection for abnormal frequency. In order to obtain an optimal state estimation, the observation model and dynamic model of the Kalman filter algorithm should satisfy Gaussian white noise conditions. The detection performance is degraded if anomalies affect the observation model or dynamic model. The idea of the adaptive Kalman filter algorithm, applied to clock frequency anomaly detection, uses the residuals given by the prediction for building ‘an adaptive factor’ the prediction state covariance matrix is real-time corrected by the adaptive factor. The results show that the model error is reduced and the detection performance is improved. The effectiveness of the algorithm is verified by the frequency jump simulation, the frequency drift jump simulation and the measured data of the atomic clock by using the chi-square test.

Study of the spectral bandwidth of a double-pass acousto-optic system [Invited].

PubMed

Champagne, Justine; Kastelik, Jean-Claude; Dupont, Samuel; Gazalet, Joseph

2018-04-01

Acousto-optic tunable filters are known as efficient instruments for spectral and spatial filtering of light. In this paper, we analyze the bandwidth dependence of a double-pass filter. The interaction geometry chosen allows the simultaneous diffraction of the ordinary and the extraordinary optical modes by a single ultrasonic frequency. We present the main parameters of a custom device (design, optical range, driving frequency) and experimental results concerning the angular deviation of the beams including the effect of optical birefringence. The spectral resolution and the side lobes' significance are discussed. Spectral bandwidth of such a system is analyzed.

Tune-out wavelengths and landscape-modulated polarizabilities of alkali-metal Rydberg atoms in infrared optical lattices

NASA Astrophysics Data System (ADS)

Topcu, Turker; Derevianko, Andrei

2013-11-01

Intensity-modulated optical lattice potentials can change sign for an alkali-metal Rydberg atom, and the atoms are not always attracted to intensity minima in optical lattices with wavelengths near the CO2 laser band. Here we demonstrate that such IR lattices can be tuned so that the trapping potential experienced by the Rydberg atom can be made to vanish for atoms in “targeted” Rydberg states. Such state-selective trapping of Rydberg atoms can be useful in controlled cold Rydberg collisions, cooling Rydberg states, and species-selective trapping and transport of Rydberg atoms in optical lattices. We tabulate wavelengths at which the trapping potential vanishes for the ns, np, and nd Rydberg states of Na and Rb atoms and discuss advantages of using such optical lattices for state-selective trapping of Rydberg atoms. We also develop exact analytical expressions for the lattice-induced polarizability for the mz=0 Rydberg states and derive an accurate formula predicting tune-out wavelengths at which the optical trapping potential becomes invisible to Rydberg atoms in targeted l=0 states.

Optical filters for the Multispectral Instrument (MSI) on Sentinel-2

NASA Astrophysics Data System (ADS)

Merschdorf, M.; Camus, F.; Kirschner, V.

2017-11-01

Multi-spectral optical filters are essential parts of spaceborne optical imagers such as the Multispectral Instrument (MSI) for the Sentinel-2 satellite in the framework of ESA's GMES programme for earth observation. In this development, Jena-Optronik is responsible for the design, manufacturing and test of the spectral filter assemblies. They are the key elements that define the spectral quality of the instrument. Besides the challenging spectral requirements straylight aspects are of crucial importance due to the close neighbourhood of the filter elements to the detector. Results will be presented of the extensive analyses and measurements that have been performed on component and assembly level to ensure the optical performance.

Integrated optical dipole trap for cold neutral atoms with an optical waveguide coupler

NASA Astrophysics Data System (ADS)

Lee, J.; Park, D. H.; Mittal, S.; Dagenais, M.; Rolston, S. L.

2013-04-01

An integrated optical dipole trap uses two-color (red and blue-detuned) traveling evanescent wave fields for trapping cold neutral atoms. To achieve longitudinal confinement, we propose using an integrated optical waveguide coupler, which provides a potential gradient along the beam propagation direction sufficient to confine atoms. This integrated optical dipole trap can support an atomic ensemble with a large optical depth due to its small mode area. Its quasi-TE0 waveguide mode has an advantage over the HE11 mode of a nanofiber, with little inhomogeneous Zeeman broadening at the trapping region. The longitudinal confinement eliminates the need for a one dimensional optical lattice, reducing collisional blockaded atomic loading, potentially producing larger ensembles. The waveguide trap allows for scalability and integrability with nano-fabrication technology. We analyze the potential performance of such integrated atom traps.

The Multi-Spectral Imaging Diagnostic on Alcator C-MOD and TCV

NASA Astrophysics Data System (ADS)

Linehan, B. L.; Mumgaard, R. T.; Duval, B. P.; Theiler, C. G.; TCV Team

2017-10-01

The Multi-Spectral Imaging (MSI) diagnostic is a new instrument that captures simultaneous spectrally filtered images from a common sight view while maintaining a large tendue and high spatial resolution. The system uses a polychromator layout where each image is sequentially filtered. This procedure yields a high transmission for each spectral channel with minimal vignetting and aberrations. A four-wavelength system was installed on Alcator C-Mod and then moved to TCV. The system uses industrial cameras to simultaneously image the divertor region at 95 frames per second at f/# 2.8 via a coherent fiber bundle (C-Mod) or a lens-based relay optic (TCV). The images are absolutely calibrated and spatially registered enabling accurate measurement of atomic line ratios and absolute line intensities. The images will be used to study divertor detachment by imaging impurities and Balmer series emissions. Furthermore, the large field of view and an ability to support many types of detectors opens the door for other novel approaches to optically measuring plasma with high temporal, spatial, and spectral resolution. Such measurements will allow for the study of Stark broadening and divertor turbulence. Here, we present the first measurements taken with this cavity imaging system. USDoE awards DE-FC02-99ER54512 and award DE-AC05-06OR23100, ORISE, administered by ORAU.

Exposure to space radiation of high-performance infrared multilayer filters and materials technology experiment (A0056)

NASA Technical Reports Server (NTRS)

Hawkins, Gary J.; Seeley, John S.; Hunneman, Roger

1992-01-01

Infrared optical multilayer filters and materials were exposed to the space environment of low Earth orbit on LDEF. The effects are summarized of that environment on the physical and optical properties of the filters and materials flown.

The Engineer Topographic Laboratories /ETL/ hybrid optical/digital image processor

NASA Astrophysics Data System (ADS)

Benton, J. R.; Corbett, F.; Tuft, R.

1980-01-01

An optical-digital processor for generalized image enhancement and filtering is described. The optical subsystem is a two-PROM Fourier filter processor. Input imagery is isolated, scaled, and imaged onto the first PROM; this input plane acts like a liquid gate and serves as an incoherent-to-coherent converter. The image is transformed onto a second PROM which also serves as a filter medium; filters are written onto the second PROM with a laser scanner in real time. A solid state CCTV camera records the filtered image, which is then digitized and stored in a digital image processor. The operator can then manipulate the filtered image using the gray scale and color remapping capabilities of the video processor as well as the digital processing capabilities of the minicomputer.

A 10-Gbit/s EML link using detuned narrowband optical filtering.

PubMed

Ebrahimi, P; Jones, R; Wang, Y; Yan, L; Mader, T; Paniccia, M; Willner, A E; Paraschis, L

2007-08-20

In this paper, the effects of asymmetric narrowband optical filtering are investigated in a 10-Gbit/s optical communication link using integrated electro-absorption modulated lasers (EML). We investigate the effect of EML chirp on link performance as well as the optimal filter bandwidth and wavelength detuning. We show that both the phase response and the spectral narrowing of the filter will enable a longer distance transmission by interacting with the EML transient chirp and compensating for the fiber chromatic dispersion. Experimentally, an 8.75-GHz filter is shown to improve the link distance by 40 km from 65 to 105 km, when transmitting over standard single mode fiber.

Synthesis of highly integrated optical network based on microdisk-resonator add-drop filters in silicon-on-insulator technology

NASA Astrophysics Data System (ADS)

Kaźmierczak, Andrzej; Dortu, Fabian; Giannone, Domenico; Bogaerts, Wim; Drouard, Emmanuel; Rojo-Romeo, Pedro; Gaffiot, Frederic

2009-10-01

We analyze a highly compact optical add-drop filter topology based on a pair of microdisk resonators and a bus waveguide intersection. The filter is further assessed on an integrated optical 4×4 network for optical on-chip communication. The proposed network structure, as compact as 50×50 μm, is fabricated in a CMOS-compatible process on a silicon-on-insulator (SOI) substrate. Finally, the experimental results demonstrate the proper operation of the fabricated devices.

Grayscale Optical Correlator Workbench

NASA Technical Reports Server (NTRS)

Hanan, Jay; Zhou, Hanying; Chao, Tien-Hsin

2006-01-01

Grayscale Optical Correlator Workbench (GOCWB) is a computer program for use in automatic target recognition (ATR). GOCWB performs ATR with an accurate simulation of a hardware grayscale optical correlator (GOC). This simulation is performed to test filters that are created in GOCWB. Thus, GOCWB can be used as a stand-alone ATR software tool or in combination with GOC hardware for building (target training), testing, and optimization of filters. The software is divided into three main parts, denoted filter, testing, and training. The training part is used for assembling training images as input to a filter. The filter part is used for combining training images into a filter and optimizing that filter. The testing part is used for testing new filters and for general simulation of GOC output. The current version of GOCWB relies on the mathematical software tools from MATLAB binaries for performing matrix operations and fast Fourier transforms. Optimization of filters is based on an algorithm, known as OT-MACH, in which variables specified by the user are parameterized and the best filter is selected on the basis of an average result for correct identification of targets in multiple test images.

Photothermally tunable silicon-microring-based optical add-drop filter through integrated light absorber.

PubMed

Chen, Xi; Shi, Yuechun; Lou, Fei; Chen, Yiting; Yan, Min; Wosinski, Lech; Qiu, Min

2014-10-20

An optically pumped thermo-optic (TO) silicon ring add-drop filter with fast thermal response is experimentally demonstrated. We propose that metal-insulator-metal (MIM) light absorber can be integrated into silicon TO devices, acting as a localized heat source which can be activated remotely by a pump beam. The MIM absorber design introduces less thermal capacity to the device, compared to conventional electrically-driven approaches. Experimentally, the absorber-integrated add-drop filter shows an optical response time of 13.7 μs following the 10%-90% rule (equivalent to a exponential time constant of 5 μs) and a wavelength shift over pump power of 60 pm/mW. The photothermally tunable add-drop filter may provide new perspectives for all-optical routing and switching in integrated Si photonic circuits.

Self-assembly micro optical filter

NASA Astrophysics Data System (ADS)

Zhang, Ping (Cerina); Le, Kevin; Malalur-Nagaraja-Rao, Smitha; Hsu, Lun-Chen; Chiao, J.-C.

2006-01-01

Optical communication and sensor industry face critical challenges in manufacturing for system integration. Due to the assembly complexity and integration platform variety, micro optical components require costly alignment and assembly procedures, in which many required manual efforts. Consequently, self-assembly device architectures have become a great interest and could provide major advantages over the conventional optical devices. In this paper, we discussed a self-assembly integration platform for micro optical components. To demonstrate the adaptability and flexibility of the proposed optical device architectures, we chose a commercially available MEMS fabrication foundry service - MUMPs (Multi-User MEMS Process). In this work, polysilicon layers of MUMPS are used as the 3-D structural material for construction of micro component framework and actuators. However, because the polysilicon has high absorption in the visible and near infrared wavelength ranges, it is not suitable for optical interaction. To demonstrate the required optical performance, hybrid integration of materials was proposed and implemented. Organic compound materials were applied on the silicon-based framework to form the required optical interfaces. Organic compounds provide good optical transparency, flexibility to form filters or lens and inexpensive manufacturing procedures. In this paper, we have demonstrated a micro optical filter integrated with self-assembly structures. We will discuss the self-assembly mechanism, optical filter designs, fabrication issues and results.

Computerized design and generation of space-variant holographic filters. II - Applications of space-variant filters to optical computing

NASA Technical Reports Server (NTRS)

Ambs, P.; Fainman, Y.; Esener, S.; Lee, S. H.

1988-01-01

Holographic optical elements (HOEs) of space-variant impulse response have been designed and generated using a computerized optical system. HOEs made of dichromated gelatin have been produced and used for spatial light modulator defect removal and optical interconnects. Experimental performance and characteristics are presented.

Monolithically Integrated Reconfigurable Filters for Microwave Photonic Links

NASA Astrophysics Data System (ADS)

Norberg, Erik J.

For the purposes of commercial communication and military electronic warfare and radar alike, there is an increasing interest in RF systems that can handle very wide instantaneous bandwidths at high center frequencies. Optical signal processing has the capability to reduce latency, improve size, weight and power (SwAP) performance, and overcome the inherent bandwidth limitations of electronic counterparts. By rapidly pre-filtering wide bandwidth microwave signals in the optical domain, the analog-to-digital conversion (ADC) and subsequent digital signal processing (DSP) can be significantly relieved. Compared to channelizing and add/drop filters for wavelength division multiplexing (WDM) applications, the microwave filter application is much more challenging as it requires a more versatile filter, ideally with tunability in both frequency and bandwidth. In this work such a filter was developed using integrated photonics. By integrating the filter on a single InP chip, the stability required for coherent filtering is met, while the active integration platform offers a flexible filter design and higher tolerance in the coupler and fabrication specifications. Using an entirely deep etched fabrication with a single blanket regrowth, a simple fabrication with high yield is achieved. The reconfigurable filter is designed as an array of uncoupled filter stages with each filter stage reconfigurable as a filter pole or zero with arbitrary magnitude and phase. This gives rise to a flexible ffilter synthesis, much like an optical version of DSP filters. Flat-topped bandpass filters are demonstrated with frequency tunability over 30 GHz, bandwidth adjustable between 1.9 and 5.4 GHz, and stopband rejection >32 dB. In order to meet the stringent spurious-free dynamic range (SFDR) requirements of the microwave application, a novel epitaxial layer integration platform is developed. Optimized for high optical saturation power and low propagation loss, it produces semiconductor optical amplifiers (SOAs) with low distortion and noise. Utilizing a novel characterization method of RF signal distortion for photonic devices, SOAs with state-of-the art SFDR in the range of 115 dB--Hz2/3 and a noise figure of 3.8 dB for 6 dB gain, is demonstrated. It is projected that this platform could ultimately provide integration for photonic microwave filter applications.

Lifetime Fluorescence and Raman Imaging for Detection of Wound Failure and Heterotopic Ossification

DTIC Science & Technology

2015-12-01

containing ten bandpass filters ( Semrock Fluorescence filters) centered at: 407nm, 434 nm, 465 nm, 494 nm, 520 nm, 542 nm, 572 nm, 605 nm, 652 nm, 676 nm...meat (~2 - 3 mm thickness), and a bottom piece (~8 mm). The system was built around an 852 nm tunable narrow-band optical filter ( Semrock , LL01-852...optical filters to block light that falls outside the detection band: 785 nm notch filter ( Semrock , NF03-785E-25), and a bandpass filter at 842 nm

Optical restoration of images blurred by atmospheric turbulence using optimum filter theory.

PubMed

Horner, J L

1970-01-01

The results of optimum filtering from communications theory have been applied to an image restoration problem. Photographic film imagery, degraded by long-term artificial atmospheric turbulence, has been restored by spatial filters placed in the Fourier transform plane. The time-averaged point spread function was measured and used in designing the filters. Both the simple inverse filter and the optimum least-mean-square filters were used in the restoration experiments. The superiority of the latter is conclusively demonstrated. An optical analog processor was used for the restoration.

LSST Camera Optics Design

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

Riot, V J; Olivier, S; Bauman, B

2012-05-24

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, telescope design feeding a camera system that includes a set of broad-band filters and three refractive corrector lenses to produce a flat field at the focal plane with a wide field of view. Optical design of the camera lenses and filters is integrated in with the optical design of telescope mirrors to optimize performance. We discuss the rationale for the LSST camera optics design, describe the methodology for fabricating, coating, mounting and testing the lenses and filters, and present the results of detailed analyses demonstrating that the camera optics willmore » meet their performance goals.« less

Sensitivity and specificity of monochromatic photography of the ocular fundus in differentiating optic nerve head drusen and optic disc oedema: optic disc drusen and oedema.

PubMed

Gili, Pablo; Flores-Rodríguez, Patricia; Yangüela, Julio; Orduña-Azcona, Javier; Martín-Ríos, María Dolores

2013-03-01

Evaluation of the efficacy of monochromatic photography of the ocular fundus in differentiating optic nerve head drusen (ONHD) and optic disc oedema (ODE). Sixty-six patients with ONHD, 31 patients with ODE and 70 healthy subjects were studied. Colour and monochromatic fundus photography with different filters (green, red and autofluorescence) were performed. The results were analysed blindly by two observers. The sensitivity, specificity and interobserver agreement (k) of each test were assessed. Colour photography offers 65.5 % sensitivity and 100 % specificity for the diagnosis of ONHD. Monochromatic photography improves sensitivity and specificity and provides similar results: green filter (71.20 % sensitivity, 96.70 % specificity), red filter (80.30 % sensitivity, 96.80 % specificity), and autofluorescence technique (87.8 % sensitivity, 100 % specificity). The interobserver agreement was good with all techniques used: autofluorescence (k = 0.957), green filter (k = 0.897), red filter (k = 0.818) and colour (k = 0.809). Monochromatic fundus photography permits ONHD and ODE to be differentiated, with good sensitivity and very high specificity. The best results were obtained with autofluorescence and red filter study.

Micromachined Tunable Fabry-Perot Filters for Infrared Astronomy

NASA Technical Reports Server (NTRS)

Barclay, Richard; Bier, Alexander; Chen, Tina; DiCamillo, Barbara; Deming, Drake; Greenhouse, Matthew; Henry, Ross; Hewagama, Tilak; Jacobson, Mindy; Loughlin, James;

Gas refractometry based on an all-fiber spatial optical filter.

PubMed

Silva, Susana; Coelho, L; André, R M; Frazão, O

2012-08-15

A spatial optical filter based on splice misalignment between optical fibers with different diameters is proposed for gas refractometry. The sensing head is formed by a 2 mm long optical fiber with 50 μm diameter that is spliced with a strong misalignment between two single-mode fibers (SMF28) and interrogated in transmission. The misalignment causes a Fabry-Perot behavior along the reduced-size fiber and depending on the lead-out SMF28 position, it is possible to obtain different spectral responses, namely, bandpass or band-rejection filters. It is shown that the spatial filter device is highly sensitive to refractive index changes on a nitrogen environment by means of the gas pressure variation. A maximum sensitivity of -1390 nm/RIU for the bandpass filter was achieved. Both devices have shown similar temperature responses with an average sensitivity of 25.7 pm/°C.

Multiplexing and Filtering of Optical Signals.

DTIC Science & Technology

1977-06-01

A0-A017 22« SPERRY RESEARCH CENTER SUOBURY MASS MULTIPLEXING ANO FILTERING OF OPTICAL SIGNALS.(U) JUN 77 A R NELSON UNCLASSIFIED SCRC-CR-77...0 F/G 20/6 Nil <r Research and Development Technical Report ECOM -76-1343-F MULTIPLEXING AND FILTERING OF OPTICAL SIGNALS A. R...Nelson SPERRY RESEARCH CENTER 100 North Road Sudbury, MA 01776 June 1977 Final Report for Period 29 April 1976 - 29 April 1977 DISTRIBUTION

Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

DOEpatents

Brown, Edward J.; Baldasaro, Paul F.; Dziendziel, Randolph J.

1997-01-01

A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength .lambda..sub.IF approximately equal to the bandgap wavelength .lambda..sub.g of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5.lambda..sub.IF to .lambda..sub.IF and reflect from .lambda..sub.IF to about 2.lambda..sub.IF ; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5.lambda..sub.IF.

Zero-phonon-line emission of single molecules for applications in quantum information processing

NASA Astrophysics Data System (ADS)

Kiraz, Alper; Ehrl, M.; Mustecaplioglu, O. E.; Hellerer, T.; Brauchle, C.; Zumbusch, A.

2005-07-01

A single photon source which generates transform limited single photons is highly desirable for applications in quantum optics. Transform limited emission guarantees the indistinguishability of the emitted single photons. This, in turn brings groundbreaking applications in linear optics quantum information processing within an experimental reach. Recently, self-assembled InAs quantum dots and trapped atoms have successfully been demonstrated as such sources for highly indistinguishable single photons. Here, we demonstrate that nearly transform limited zero-phonon-line (ZPL) emission from single molecules can be obtained by using vibronic excitation. Furthermore we report the results of coincidence detection experiments at the output of a Michelson-type interferometer. These experiments reveal Hong-Ou-Mandel correlations as a proof of the indistinguishability of the single photons emitted consecutively from a single molecule. Therefore, single molecules constitute an attractive alternative to single InAs quantum dots and trapped atoms for applications in linear optics quantum information processing. Experiments were performed with a home-built confocal microscope keeping the sample in a superfluid liquid Helium bath at 1.4K. We investigated terrylenediimide (TDI) molecules highly diluted in hexadecane (Shpol'skii matrix). A continuous wave single mode dye laser was used for excitation of vibronic transitions of individual molecules. From the integral fluorescence, the ZPL of single molecules was selected with a spectrally narrow interference filter. The ZPL emission was then sent to a scanning Fabry-Perot interferometer for linewidth measurements or a Michelson-type interferometer for coincidence detection.

Theoretical model for a Faraday anomalous dispersion optical filter

NASA Technical Reports Server (NTRS)

Yin, B.; Shay, T. M.

1991-01-01

A model for the Faraday anomalous dispersion optical filter is presented. The model predicts a bandwidth of 0.6 GHz and a transmission peak of 0.98 for a filter operating on the Cs (D2) line. The model includes hyperfine effects and is valid for arbitrary magnetic fields.

Advances in optical information processing IV; Proceedings of the Meeting, Orlando, FL, Apr. 18-20, 1990

NASA Astrophysics Data System (ADS)

Pape, Dennis R.

1990-09-01

The present conference discusses topics in optical image processing, optical signal processing, acoustooptic spectrum analyzer systems and components, and optical computing. Attention is given to tradeoffs in nonlinearly recorded matched filters, miniature spatial light modulators, detection and classification using higher-order statistics of optical matched filters, rapid traversal of an image data base using binary synthetic discriminant filters, wideband signal processing for emitter location, an acoustooptic processor for autonomous SAR guidance, and sampling of Fresnel transforms. Also discussed are an acoustooptic RF signal-acquisition system, scanning acoustooptic spectrum analyzers, the effects of aberrations on acoustooptic systems, fast optical digital arithmetic processors, information utilization in analog and digital processing, optical processors for smart structures, and a self-organizing neural network for unsupervised learning.

Simple route to (NH4)xWO3 nanorods for near infrared absorption

NASA Astrophysics Data System (ADS)

Guo, Chongshen; Yin, Shu; Dong, Qiang; Sato, Tsugio

2012-05-01

Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows.Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30612c

Spectroscopy, Manipulation and Trapping of Neutral Atoms, Molecules, and Other Particles Using Optical Nanofibers: A Review

PubMed Central

Morrissey, Michael J.; Deasy, Kieran; Frawley, Mary; Kumar, Ravi; Prel, Eugen; Russell, Laura; Truong, Viet Giang; Chormaic, Síle Nic

2013-01-01

The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining interest in recent years. In this review, we briefly introduce the optical nanofiber, its fabrication, and optical mode propagation within. We discuss recent progress on the integration of optical nanofibers into laser-cooled atom and vapor systems, paying particular attention to spectroscopy, cold atom cloud characterization, and optical trapping schemes. Next, a natural extension of this work to molecules is introduced. Finally, we consider several alternatives to optical nanofibers that display some advantages for specific applications. PMID:23945738

A polymer-based Fabry-Perot filter integrated with 3-D MEMS structures

NASA Astrophysics Data System (ADS)

Zhang, Ping (Cerina); Le, Kevin; Malalur-Nagaraja-Rao, Smitha; Hsu, Lun-Chen; Chiao, J.-C.

2006-01-01

Polymers have been considered as one of the most versatile materials in making optical devices for communication and sensor applications. They provide good optical transparency to form filters, lenses and many optical components with ease of fabrication. They are scalable and compatible in dimensions with requirements in optics and can be fabricated on inorganic substrates, such as silicon and quartz. Recent polymer synthesis also made great progresses on conductive and nonlinear polymers, opening opportunities for new applications. In this paper, we discussed hybrid-material integration of polymers on silicon-based microelectromechanical system (MEMS) devices. The motivation is to combine the advantages of demonstrated silicon-based MEMS actuators and excellent optical performance of polymers. We demonstrated the idea with a polymer-based out-of-plane Fabry-Perot filter that can be self-assembled by scratch drive actuators. We utilized a fabrication foundry service, MUMPS (Multi-User MEMS Process), to demonstrate the feasibility and flexibility of integration. The polysilicon, used as the structural material for construction of 3-D framework and actuators, has high absorption in the visible and near infrared ranges. Therefore, previous efforts using a polysilicon layer as optical interfaces suffer from high losses. We applied the organic compound materials on the silicon-based framework within the optical signal propagation path to form the optical interfaces. In this paper, we have shown low losses in the optical signal processing and feasibility of building a thin-film Fabry-Perot filter. We discussed the optical filter designs, mechanical design, actuation mechanism, fabrication issues, optical measurements, and results.

Nebulization reflux concentrator

NASA Technical Reports Server (NTRS)

Collins, V. G.; Cofer, W. R., III

1986-01-01

A nebulization reflux concentrator for removing trace gas contaminants from a sample gas is described. Sample gas from a gas supply is drawn by a suction source into a vessel. The gas enters the vessel through an atomizing nozzle, thereby atomizing and entraining a scrubbing liquid solvent drawn through a siphon tube from a scrubbing liquid reservoir. The gas and entrained liquid rise through a concentrator and impinge upon a solvent phobic filter, whereby purified gas exits through the filter housing and contaminated liquid coalesces on the solvent phobic filter and falls into the reservoir.

Collecting Protein Biomarkers in Breath Using Electret Filters: A Preliminary Method on New Technical Model and Human Study.

PubMed

Li, Wang; Pi, Xitian; Qiao, Panpan; Liu, Hongying

2016-01-01

Biomarkers in exhaled breath are useful for respiratory disease diagnosis in human volunteers. Conventional methods that collect non-volatile biomarkers, however, necessitate an extensive dilution and sanitation processes that lowers collection efficiencies and convenience of use. Electret filter emerged in recent decade to collect virus biomarkers in exhaled breath given its simplicity and effectiveness. To investigate the capability of electret filters to collect protein biomarkers, a model that consists of an atomizer that produces protein aerosol and an electret filter that collects albumin and carcinoembryonic antigen-a typical biomarker in lung cancer development- from the atomizer is developed. A device using electret filter as the collecting medium is designed to collect human albumin from exhaled breath of 6 volunteers. Comparison of the collecting ability between the electret filter method and other 2 reported methods is finally performed based on the amounts of albumin collected from human exhaled breath. In conclusion, a decreasing collection efficiency ranging from 17.6% to 2.3% for atomized albumin aerosol and 42% to 12.5% for atomized carcinoembryonic antigen particles is found; moreover, an optimum volume of sampling human exhaled breath ranging from 100 L to 200 L is also observed; finally, the self-designed collecting device shows a significantly better performance in collecting albumin from human exhaled breath than the exhaled breath condensate method (p<0.05) but is not significantly more effective than reported 3-stage impactor method (p>0.05). In summary, electret filters are potential in collecting non-volatile biomarkers in human exhaled breath not only because it was simpler, cheaper and easier to use than traditional methods but also for its better collecting performance.

Real-time alkali monitoring system

DOEpatents

Goff, David R.; Romanosky, Robert R.; Hensel, Peter

1990-01-01

A fiber optics based optical emission line monitoring system is provided in which selected spectral emission lines, such as the sodium emission line, may be detected in the presence of interfering background radiation. A combustion flame is fed by a diverted portion of a process stream and the common end of a bifurcated or quadfurcated fiber optic light guide is adapted to collect light from the flame. The light is guided through the branches of the fiber optic cable to bandpass filters, one of which is adapted to each of the branches of the fiber optic light guide. The bandpass filters are centered at wavelengths corresponding to the emission lines to be detected and two separate filters are required for each species being detected. The first filter has a bandwidth of about 3 nms and the second filter has a bandwidth of about 10 nms. Light detectors are located to view the light passing through the bandpass filters and amplifiers are connected to receive signals from the light detectors. The amplifier corresponding to the bandpass filter having the narrower bandwidth is preset to scale the signal by a factor equal to the ratio of the wide and narrow bandwidths of the bandpass filters. This scaling produces a scaled signal from which the difference between the scaled signal on the other signal can be calculated to produce a signal having an amplitude directly proportional to the concentration of the species of interest and independent of background radiation.

A high-temperature fiber sensor using a low cost interrogation scheme.

PubMed

Barrera, David; Sales, Salvador

2013-09-04

Regenerated Fibre Bragg Gratings have the potential for high-temperature monitoring. In this paper, the inscription of Fibre Bragg Gratings (FBGs) and the later regeneration process to obtain Regenerated Fiber Bragg Gratings (RFBGs) in high-birefringence optical fiber is reported. The obtained RFBGs show two Bragg resonances corresponding to the slow and fast axis that are characterized in temperature terms. As the temperature increases the separation between the two Bragg resonances is reduced, which can be used for low cost interrogation. The proposed interrogation setup is based in the use of optical filters in order to convert the wavelength shift of each of the Bragg resonances into optical power changes. The design of the optical filters is also studied in this article. In first place, the ideal filter is calculated using a recursive method and defining the boundary conditions. This ideal filter linearizes the output of the interrogation setup but is limited by the large wavelength shift of the RFBG with temperature and the maximum attenuation. The response of modal interferometers as optical filters is also analyzed. They can be easily tuned shifting the optical spectrum. The output of the proposed interrogation scheme is simulated in these conditions improving the sensitivity.

A High-Temperature Fiber Sensor Using a Low Cost Interrogation Scheme

PubMed Central

Barrera, David; Sales, Salvador

2013-01-01

Regenerated Fibre Bragg Gratings have the potential for high-temperature monitoring. In this paper, the inscription of Fibre Bragg Gratings (FBGs) and the later regeneration process to obtain Regenerated Fiber Bragg Gratings (RFBGs) in high-birefringence optical fiber is reported. The obtained RFBGs show two Bragg resonances corresponding to the slow and fast axis that are characterized in temperature terms. As the temperature increases the separation between the two Bragg resonances is reduced, which can be used for low cost interrogation. The proposed interrogation setup is based in the use of optical filters in order to convert the wavelength shift of each of the Bragg resonances into optical power changes. The design of the optical filters is also studied in this article. In first place, the ideal filter is calculated using a recursive method and defining the boundary conditions. This ideal filter linearizes the output of the interrogation setup but is limited by the large wavelength shift of the RFBG with temperature and the maximum attenuation. The response of modal interferometers as optical filters is also analyzed. They can be easily tuned shifting the optical spectrum. The output of the proposed interrogation scheme is simulated in these conditions improving the sensitivity. PMID:24008282

Integration of Cold Atom Interferometry INS with Other Sensors

DTIC Science & Technology

2012-03-22

Kalman filtering 2.6.1 Linear Kalman filtering . Kalman filtering is used to estimate the solution to a linear... Kalman Filter . This filter will estimate the errors in the navigation grade measurement. Whenever an outage occurs the mechanization must be done using ...navigation solution, with periodic GPS measurements being brought into a Kalman Filter to estimate the errors in the INS solution. The results of

Robotic Vision, Tray-Picking System Design Using Multiple, Optical Matched Filters

NASA Astrophysics Data System (ADS)

Leib, Kenneth G.; Mendelsohn, Jay C.; Grieve, Philip G.

1986-10-01

The optical correlator is applied to a robotic vision, tray-picking problem. Complex matched filters (MFs) are designed to provide sufficient optical memory for accepting any orientation of the desired part, and a multiple holographic lens (MHL) is used to increase the memory for continuous coverage. It is shown that with appropriate thresholding a small part can be selected using optical matched filters. A number of criteria are presented for optimizing the vision system. Two of the part-filled trays that Mendelsohn used are considered in this paper which is the analog (optical) expansion of his paper. Our view in this paper is that of the optical correlator as a cueing device for subsequent, finer vision techniques.

Implementation theory of distortion-invariant pattern recognition for optical and digital signal processing systems

NASA Astrophysics Data System (ADS)

Lhamon, Michael Earl

A pattern recognition system which uses complex correlation filter banks requires proportionally more computational effort than single-real valued filters. This introduces increased computation burden but also introduces a higher level of parallelism, that common computing platforms fail to identify. As a result, we consider algorithm mapping to both optical and digital processors. For digital implementation, we develop computationally efficient pattern recognition algorithms, referred to as, vector inner product operators that require less computational effort than traditional fast Fourier methods. These algorithms do not need correlation and they map readily onto parallel digital architectures, which imply new architectures for optical processors. These filters exploit circulant-symmetric matrix structures of the training set data representing a variety of distortions. By using the same mathematical basis as with the vector inner product operations, we are able to extend the capabilities of more traditional correlation filtering to what we refer to as "Super Images". These "Super Images" are used to morphologically transform a complicated input scene into a predetermined dot pattern. The orientation of the dot pattern is related to the rotational distortion of the object of interest. The optical implementation of "Super Images" yields feature reduction necessary for using other techniques, such as artificial neural networks. We propose a parallel digital signal processor architecture based on specific pattern recognition algorithms but general enough to be applicable to other similar problems. Such an architecture is classified as a data flow architecture. Instead of mapping an algorithm to an architecture, we propose mapping the DSP architecture to a class of pattern recognition algorithms. Today's optical processing systems have difficulties implementing full complex filter structures. Typically, optical systems (like the 4f correlators) are limited to phase-only implementation with lower detection performance than full complex electronic systems. Our study includes pseudo-random pixel encoding techniques for approximating full complex filtering. Optical filter bank implementation is possible and they have the advantage of time averaging the entire filter bank at real time rates. Time-averaged optical filtering is computational comparable to billions of digital operations-per-second. For this reason, we believe future trends in high speed pattern recognition will involve hybrid architectures of both optical and DSP elements.

Deep cooling of optically trapped atoms implemented by magnetic levitation without transverse confinement.

PubMed

Li, Chen; Zhou, Tianwei; Zhai, Yueyang; Xiang, Jinggang; Luan, Tian; Huang, Qi; Yang, Shifeng; Xiong, Wei; Chen, Xuzong

2017-05-01

We report a setup for the deep cooling of atoms in an optical trap. The deep cooling is implemented by eliminating the influence of gravity using specially constructed magnetic coils. Compared to the conventional method of generating a magnetic levitating force, the lower trap frequency achieved in our setup provides a lower limit of temperature and more freedoms to Bose gases with a simpler solution. A final temperature as low as ∼6nK is achieved in the optical trap, and the atomic density is decreased by nearly two orders of magnitude during the second stage of evaporative cooling. This deep cooling of optically trapped atoms holds promise for many applications, such as atomic interferometers, atomic gyroscopes, and magnetometers, as well as many basic scientific research directions, such as quantum simulations and atom optics.

Deep cooling of optically trapped atoms implemented by magnetic levitation without transverse confinement

NASA Astrophysics Data System (ADS)

Li, Chen; Zhou, Tianwei; Zhai, Yueyang; Xiang, Jinggang; Luan, Tian; Huang, Qi; Yang, Shifeng; Xiong, Wei; Chen, Xuzong

2017-05-01

We report a setup for the deep cooling of atoms in an optical trap. The deep cooling is implemented by eliminating the influence of gravity using specially constructed magnetic coils. Compared to the conventional method of generating a magnetic levitating force, the lower trap frequency achieved in our setup provides a lower limit of temperature and more freedoms to Bose gases with a simpler solution. A final temperature as low as ˜ 6 nK is achieved in the optical trap, and the atomic density is decreased by nearly two orders of magnitude during the second stage of evaporative cooling. This deep cooling of optically trapped atoms holds promise for many applications, such as atomic interferometers, atomic gyroscopes, and magnetometers, as well as many basic scientific research directions, such as quantum simulations and atom optics.

Using optical masks to create and image sub-optical wavelength atomic structures in a MOT

NASA Astrophysics Data System (ADS)

Turlapov, Andrey; Tonyushkin, Aleksey; Sleator, Tycho

2002-05-01

We have used an ``optical mask'' for Rubidium atoms in a magneto-optical trap to create and image atomic density gratings with periodicities as small as 1/8th of an optical wavelength ( ˜ 100 nm). The mask consists of a pulse of an optical standing wave (wavelength λ) resonant to an open atomic transition. The interaction pumps all atoms except those near the nodes into another hyperfine ground state, leaving a grating of ``spikes'' in atomic density in the initial ground state. The nodes of the standing wave serve as slits of the mask. By applying two such masks separated by time T, we have created atomic gratings of period λ/(2n) (or smaller) at times (n+1)/n T after the first mask pulse. For T on the order of the Talbot time (or inverse recoil frequency), quantum effects are important for the dynamics of the atomic center of mass. Under appropriate conditions, these quantum effects led to a reduction of the period of the resulting density gratings (Talbot-Lau effect). The resulting density gratings of period λ/2n (for n=1 to 4) were imaged in real time using an additional optical mask.

Rectangular optical filter based on high-order silicon microring resonators

NASA Astrophysics Data System (ADS)

Bao, Jia-qi; Yu, Kan; Wang, Li-jun; Yin, Juan-juan

2017-07-01

The rectangular optical filter is one of the most important optical switching components in the dense wavelength division multiplexing (DWDM) fiber-optic communication system and the intelligent optical network. The integrated highorder silicon microring resonator (MRR) is one of the best candidates to achieve rectangular filtering spectrum response. In general, the spectrum response rectangular degree of the single MRR is very low, so it cannot be used in the DWDM system. Using the high-order MRRs, the bandwidth of flat-top pass band, the out-of-band rejection degree and the roll-off coefficient of the edge will be improved obviously. In this paper, a rectangular optical filter based on highorder MRRs with uniform couplers is presented and demonstrated. Using 15 coupled race-track MRRs with 10 μm in radius, the 3 dB flat-top pass band of 2 nm, the out-of-band rejection ratio of 30 dB and the rising and falling edges of 48 dB/nm can be realized successfully.

Mode-filtered large-core fiber for optical coherence tomography

PubMed Central

Moon, Sucbei; Chen, Zhongping

2013-01-01

We have investigated the use of multimode fiber in optical coherence tomography (OCT) with a mode filter that selectively suppresses the power of the high-order modes (HOMs). A large-core fiber (LCF) that has a moderate number of guiding modes was found to be an attractive alternative to the conventional single-mode fiber for its large mode area and the consequentially wide Rayleigh range of the output beam if the HOMs of the LCF were efficiently filtered out by a mode filter installed in the middle. For this, a simple mode filtering scheme of a fiber-coil mode filter was developed in this study. The LCF was uniformly coiled by an optimal bend radius with a fiber winder, specially devised for making a low-loss mode filter. The feasibility of the mode-filtered LCF in OCT imaging was tested with a common-path OCT system. It has been successfully demonstrated that our mode-filtered LCF can provide a useful imaging or sensing probe without an objective lens that greatly simplifies the structure of the probing optics. PMID:23207399

Radon detection

DOEpatents

MacArthur, D.W.; Allander, K.S.; Bounds, J.A.

1994-01-25

A detector for atmospheric radon using a long range alpha detector as its sensing element is described. An electrostatic filter removes ions from ambient air, while allowing radon atoms to pass into a decay cavity. Here, radon atoms are allowed to decay, creating air ions. These air ions are drawn by a fan through a second electrostatic filter which can be activated or deactivated, and into the long range alpha detector. With the second electrostatic filter activated, no air ions are allowed to pass, and the signal output from the long range alpha detector consists of only the electronic background. With the second electrostatic filter deactivated, air ions and cosmic rays will be detected. The cosmic ray contribution can be minimized by shielding. 3 figures.

Radon detection

DOEpatents

MacArthur, Duncan W.; Allander, Krag S.; Bounds, John A.

1994-01-01

A detector for atmospheric radon using a long range alpha detector as its sensing element. An electrostatic filter removes ions from ambient air, while allowing radon atoms to pass into a decay cavity. Here, radon atoms are allowed to decay, creating air ions. These air ions are drawn by a fan through a second electrostatic filter which can be activated or deactivated, and into the long range alpha detector. With the second electrostatic filter activated, no air ions are allowed to pass, and the signal output from the long range alpha detector consists of only the electronic background. With the second electrostatic filter deactivated, air ions and cosmic rays will be detected. The cosmic ray contribution can be minimized by shielding.

Deposition and characterization of titania-silica optical multilayers by asymmetric bipolar pulsed dc sputtering of oxide targets

NASA Astrophysics Data System (ADS)

Sagdeo, P. R.; Shinde, D. D.; Misal, J. S.; Kamble, N. M.; Tokas, R. B.; Biswas, A.; Poswal, A. K.; Thakur, S.; Bhattacharyya, D.; Sahoo, N. K.; Sabharwal, S. C.

2010-02-01

Titania-silica (TiO2/SiO2) optical multilayer structures have been conventionally deposited by reactive sputtering of metallic targets. In order to overcome the problems of arcing, target poisoning and low deposition rates encountered there, the application of oxide targets was investigated in this work with asymmetric bipolar pulsed dc magnetron sputtering. In order to evaluate the usefulness of this deposition methodology, an electric field optimized Fabry Perot mirror for He-Cd laser (λ = 441.6 nm) spectroscopy was deposited and characterized. For comparison, this mirror was also deposited by the reactive electron beam (EB) evaporation technique. The mirrors developed by the two complementary techniques were investigated for their microstructural and optical reflection properties invoking atomic force microscopy, ellipsometry, grazing incidence reflectometry and spectrophotometry. From these measurements the layer geometry, optical constants, mass density, topography, surface and interface roughness and disorder parameters were evaluated. The microstructural properties and spectral functional characteristics of the pulsed dc sputtered multilayer mirror were found to be distinctively superior to the EB deposited mirror. The knowledge gathered during this study has been utilized to develop a 21-layer high-pass edge filter for radio photoluminescence dosimetry.

Controle des proprietes des couches optiques par bombardement ionique

NASA Astrophysics Data System (ADS)

Marushka, Viktor

The manufacture of optical coatings presents many challenges such as the control over the film properties and microstructure, the optimization for the production of thin films with high quality, and the research on new materials. Ion-assisted evaporation is one of the principal methods used for the fabrication of optical coatings as a response to these challenges. It allows for good process control, and it permits us to predict and put on an industrial scale the deposition process by considering the direct and quantitative relation between the energies of the incident ions, and the performance of the deposited materials. This work is devoted to the study of the effect of ion bombardment on the microstructure and properties of optical thin films of silicon dioxide and titanium dioxide, which are widely used in optical interference filters, in particular with the use of a Hall effect ion source. These studies include a systematic evaluation of the mechanical and optical properties and of the density of thin films using different complementary techniques - the Quartz Crystal Microbalance, Rutherford Backscattering Spectroscopy, and Infrared Variable Angle Spectroscopic Ellipsometry among others. Different approaches (Spectroscopic Ellipsometry and Infrared Ellipsometry, the measurement of mechanical stress) have been used to evaluate the amount of water in thin films. The results on the density of films and the presence of water in the films obtained by the different methods are in good agreement. It was found that the critical energy values giving rise to dense and stable optical coatings of silicon dioxide and titanium dioxide are 25 eV/atom and 45 eV/atom, respectively. Moreover, this work presents the methodology developed to determine the ion current density distribution on the surface of a substrate holder of a dome shape for different positions relative to the ion source. The proposed analysis can be used as an effective tool for the construction of an industrial reactor and for its appropriate optimization.

Optical Precursor with Four-Wave Mixing and Storage Based on a Cold-Atom Ensemble

NASA Astrophysics Data System (ADS)

Ding, Dong-Sheng; Jiang, Yun Kun; Zhang, Wei; Zhou, Zhi-Yuan; Shi, Bao-Sen; Guo, Guang-Can

2015-03-01

We observed optical precursors in four-wave mixing based on a cold-atom gas. Optical precursors appear at the edges of pulses of the generated optical field, and propagate through the atomic medium without absorption. Theoretical analysis suggests that these precursors correspond to high-frequency components of the signal pulse, which means the atoms cannot respond quickly to rapid changes in the electromagnetic field. In contrast, the low-frequency signal components are absorbed by the atoms during transmission. We also showed experimentally that the backward precursor can be stored using a Raman transition of the atomic ensemble and retrieved later.

Tunable electro-optic filter stack

DOEpatents

Fontecchio, Adam K.; Shriyan, Sameet K.; Bellingham, Alyssa

2017-09-05

A holographic polymer dispersed liquid crystal (HPDLC) tunable filter exhibits switching times of no more than 20 microseconds. The HPDLC tunable filter can be utilized in a variety of applications. An HPDLC tunable filter stack can be utilized in a hyperspectral imaging system capable of spectrally multiplexing hyperspectral imaging data acquired while the hyperspectral imaging system is airborne. HPDLC tunable filter stacks can be utilized in high speed switchable optical shielding systems, for example as a coating for a visor or an aircraft canopy. These HPDLC tunable filter stacks can be fabricated using a spin coating apparatus and associated fabrication methods.

A simple system for 160GHz optical terahertz wave generation and data modulation

NASA Astrophysics Data System (ADS)

Li, Yihan; He, Jingsuo; Sun, Xueming; Shi, Zexia; Wang, Ruike; Cui, Hailin; Su, Bo; Zhang, Cunlin

2018-01-01

A simple system based on two cascaded Mach-Zehnder modulators, which can generate 160GHz optical terahertz waves from 40GHz microwave sources, is simulated and tested in this paper. Fiber grating filter is used in the system to filter out optical carrier. By properly adjusting the modulator DC bias voltages and the signal voltages and phases, 4-tupling optical terahertz wave can be generated with fiber grating. This notch fiber grating filter is greatly suitable for terahertz over fiber (TOF) communication system. This scheme greatly reduces the cost of long-distance terahertz communication. Furthermore, 10Gbps digital signal is modulated in the 160GHz optical terahertz wave.

Rugged fiber optic probe for raman measurement

DOEpatents

O'Rourke, Patrick E.; Toole, Jr., William R.; Nave, Stanley E.

1998-01-01

An optical probe for conducting light scattering analysis is disclosed. The probe comprises a hollow housing and a probe tip. A fiber assembly made up of a transmitting fiber and a receiving bundle is inserted in the tip. A filter assembly is inserted in the housing and connected to the fiber assembly. A signal line from the light source and to the spectrometer also is connected to the filter assembly and communicates with the fiber assembly. By using a spring-loaded assembly to hold the fiber connectors together with the in-line filters, complex and sensitive alignment procedures are avoided. The close proximity of the filter assembly to the probe tip eliminates or minimizes self-scattering generated by the optical fiber. Also, because the probe can contact the sample directly, sensitive optics can be eliminated.

Backscattering spectrometry device for identifying unknown elements present in a workpiece

DOEpatents

Doyle, Barney L.; Knapp, James A.

1991-01-01

A backscattering spectrometry method and device for identifying and quantifying impurities in a workpiece during processing and manufacturing of that workpiece. While the workpiece is implanted with an ion beam, that same ion beam backscatters resulting from collisions with known atoms and with impurities within the workpiece. Those ions backscatter along a predetermined scattering angle and are filtered using a self-supporting filter to stop the ions with a lower energy because they collided with the known atoms of the workpiece of a smaller mass. Those ions which pass through the filter have a greater energy resulting from impact with impurities having a greater mass than the known atoms of the workpiece. A detector counts the number and measures the energy of the ions which pass through the filter. From the energy determination and knowledge of the scattering angle, a mass calculation determines the identity, and from the number and solid angle of the scattering angle, a relative concentration of the impurity is obtained.

Tunable and reconfigurable microwave filter by use of a Bragg-grating-based acousto-optic superlattice modulator.

PubMed

Delgado-Pinar, M; Mora, J; Díez, A; Andrés, M V; Ortega, B; Capmany, J

2005-01-01

We present an all-optical novel configuration for implementing multitap transversal filters by use of a broadband source sliced by fiber Bragg grating arrays generated by propagating an acoustic wave along a strong uniform fiber Bragg grating. The tunability and reconfigurability of the microwave filter are demonstrated.

Active probing of cloud multiple scattering, optical depth, vertical thickness, and liquid water content using wide-angle imaging lidar

NASA Astrophysics Data System (ADS)

Love, Steven P.; Davis, Anthony B.; Rohde, Charles A.; Tellier, Larry; Ho, Cheng

2002-09-01

At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60-degree full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer, and, from there, estimate the volume-averaged liquid water content. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Here we present recent WAIL data on various clouds and discuss the extension of WAIL to full diurnal monitoring by means of an ultra-narrow magneto-optic atomic line filter for daytime measurements.

Covert laser remote sensing and vibrometry

NASA Technical Reports Server (NTRS)

Maleki, Lutfollah (Inventor); Yu, Nan (Inventor); Matsko, Andrey B. (Inventor); Savchenkov, Anatoliy (Inventor)

2012-01-01

Designs of single-beam laser vibrometry systems and methods. For example, a method for detecting vibrations of a target based on optical sensing is provided to include operating a laser to produce a laser probe beam at a laser frequency and modulated at a modulation frequency onto a target; collecting light at or near the laser to collect light from the target while the target is being illuminated by the laser probe beam through an optical receiver aperture; using a narrow-band optical filter centered at the laser frequency to filter light collected from the optical receiver aperture to transmit light at the laser frequency while blocking light at other frequencies; using an optical detector to convert filtered light from the narrow-band optical filter to produce a receiver electrical signal; using a lock-in amplifier to detect and amplify the receiver electrical signal at the modulation frequency while rejecting signal components at other frequencies to produce an amplified receiver electrical signal; processing the amplified receiver electrical signal to extract information on vibrations of the target carried by reflected laser probe beam in the collected light; and controlling optical power of the laser probe beam at the target to follow optical power of background illumination at the target.

A System for Compressive Spectral and Polarization Imaging at Short Wave Infrared (SWIR) Wavelengths

DTIC Science & Technology

2017-10-18

2016). H. Rueda, H. Arguello and G. R. Arce, “DMD-based implementation of patterned optical filter arrays for compressive spectral imaging”, Journal...3)  a  set  of   optical   filters  which   allow   to   discriminate   spectrally   the   coded   and   sheared...system   that   includes   objective   lens,   spatial   light   modulator,   dispersive   element,   optical   filters

Photonic integrated circuit implementation of a sub-GHz-selectivity frequency comb filter for optical clock multiplication.

PubMed

Geng, Zihan; Xie, Yiwei; Zhuang, Leimeng; Burla, Maurizio; Hoekman, Marcel; Roeloffzen, Chris G H; Lowery, Arthur J

2017-10-30

We report a photonic integrated circuit implementation of an optical clock multiplier, or equivalently an optical frequency comb filter. The circuit comprises a novel topology of a ring-resonator-assisted asymmetrical Mach-Zehnder interferometer in a Sagnac loop, providing a reconfigurable comb filter with sub-GHz selectivity and low complexity. A proof-of-concept device is fabricated in a high-index-contrast stoichiometric silicon nitride (Si 3 N 4 /SiO 2 ) waveguide, featuring low loss, small size, and large bandwidth. In the experiment, we show a very narrow passband for filters of this kind, i.e. a -3-dB bandwidth of 0.6 GHz and a -20-dB passband of 1.2 GHz at a frequency interval of 12.5 GHz. As an application example, this particular filter shape enables successful demonstrations of five-fold repetition rate multiplication of optical clock signals, i.e. from 2.5 Gpulses/s to 12.5 Gpulses/s and from 10 Gpulses/s to 50 Gpulses/s. This work addresses comb spectrum processing on an integrated platform, pointing towards a device-compact solution for optical clock multipliers (frequency comb filters) which have diverse applications ranging from photonic-based RF spectrum scanners and photonic radars to GHz-granularity WDM switches and LIDARs.

Non-Hermitian optics in atomic systems

NASA Astrophysics Data System (ADS)

Zhang, Zhaoyang; Ma, Danmeng; Sheng, Jiteng; Zhang, Yiqi; Zhang, Yanpeng; Xiao, Min

2018-04-01

A wide class of non-Hermitian Hamiltonians can possess entirely real eigenvalues when they have parity-time (PT) symmetric potentials. Recently, this family of non-Hermitian systems has attracted considerable attention in diverse areas of physics due to their extraordinary properties, especially in optical systems based on solid-state materials, such as coupled gain-loss waveguides and microcavities. Considering the desired refractive index can be effectively manipulated through atomic coherence, it is important to realize such non-Hermitian optical potentials and further investigate their distinct properties in atomic systems. In this paper, we review the recent theoretical and experimental progress of non-Hermitian optics with coherently prepared multi-level atomic configurations. The realizations of (anti-) PT symmetry with different schemes have extensively demonstrated the special optical properties of non-Hermitian optical systems with atomic coherence.

Nonlinear electro-optic tuning of plasmonic nano-filter

NASA Astrophysics Data System (ADS)

Kotb, Rehab; Ismail, Yehea; Swillam, Mohamed A.

2015-03-01

Efficient, easy and accurate tuning techniques to a plasmonic nano-filter are investigated. The proposed filter supports both blue and red shift in the resonance wavelength. By varying the refractive index with a very small change (in the order of 10-3), the resonance wavelength can be controlled efficiently. Using Pockels material, an electrical tuning to the response of the filter is demonstrated. In addition, the behavior of the proposed filter can be controlled optically using Kerr material. A new approach of multi-stage electro-optic controlling is introduced. By cascading two stages and filling the first stage with pockels material and the second stage with kerr material, the output response of the second stage can be controlled by controlling the output response of the first stage electrically. Due to the sharp response of the proposed filter, 60nm shift in the resonance wavelength per 10 voltages is achieved. This nano-filter has compact size, low loss, sharp response and wide range of tunabilty which is highly demandable in many biological and sensing applications.

Frequency agile microwave photonic notch filter with anomalously high stopband rejection.

PubMed

Marpaung, David; Morrison, Blair; Pant, Ravi; Eggleton, Benjamin J

2013-11-01

We report a novel class microwave photonic (MWP) notch filter with a very narrow isolation bandwidth (10 MHz), an ultrahigh stopband rejection (>60 dB), a wide frequency tuning (1-30 GHz), and flexible bandwidth reconfigurability (10-65 MHz). This performance is enabled by a new concept of sideband amplitude and phase controls using an electro-optic modulator and an optical filter. This concept enables energy efficient operation in active MWP notch filters, and opens up a pathway toward enabling low-power nanophotonic devices as high-performance RF filters.

Optical Absorption Spectra of Nuclear Filters Modified by Deposition of Silver Nano- and Microparticles

NASA Astrophysics Data System (ADS)

Smolyanskii, A. S.; Kozlova, N. V.; Zheltova, A. V.; Aksyutina, A. S.; Shvedov, A. S.; Lakeev, S. G.

2015-07-01

Light scattering and interference patterns are studied in the optical absorption spectra of nuclear filters based on polyethylene terephthalate fi lms modifi ed by dry aerosol deposition of silver nano- and microparticles. Surface plasmon polaritons and localized plasmons formed by the passage of light through porous silver films are found to have an effect on the diffraction and interference modes. The thickness of silver nano- and microparticle coatings on the surface of the nuclear fi lters was determined from the shift in the interference patterns in the optical absorption spectra of the modified nuclear filters relative to the original nuclear filters. A correlation was found between the estimated coating thickness and the average surface roughness of the nuclear filters modified by layers of silver nano- and microparticles.

Prototyping of MWIR MEMS-based optical filter combined with HgCdTe detector

NASA Astrophysics Data System (ADS)

Kozak, Dmitry A.; Fernandez, Bautista; Velicu, Silviu; Kubby, Joel

2010-02-01

In the past decades, there have been several attempts to create a tunable optical detector with operation in the infrared. The drive for creating such a filter is its wide range of applications, from passive night vision to biological and chemical sensors. Such a device would combine a tunable optical filter with a wide-range detector. In this work, we propose using a Fabry-Perot interferometer centered in the mid-wave infrared (MWIR) spectrum with an HgCdTe detector. Using a MEMS-based interferometer with an integrated Bragg stack will allow in-plane operation over a wide range. Because such devices have a tendency to warp, creating less-than-perfect optical surfaces, the Fabry-Perot interferometer is prototyped using the SOI-MUMPS process to ensure desirable operation. The mechanical design is aimed at optimal optical flatness of the moving membranes and a low operating voltage. The prototype is tested for these requirements. An HgCdTe detector provides greater performance than a pyroelectic detector used in some previous work, allowing for lower noise, greater detection speed and higher sensitivity. Both a custom HgCdTe detector and commercially available pyroelectric detector are tested with commercial optical filter. In previous work, monolithic integration of HgCdTe detectors with optical filters proved to be problematic. Part of this work investigates the best approach to combining these two components, either monolithically in HgCdTe or using a hybrid packaging approach where a silicon MEMS Fabry-Perot filter is bonded at low temperature to a HgCdTe detector.

Analysis and design of planar waveguide elements for use in filters and sensors

NASA Astrophysics Data System (ADS)

Chen, Guangzhou

In this dissertation we present both theoretical analysis and practical design considerations for planar optical waveguide devices. The analysis takes into account both transverse dimensions of the waveguides and is based on supermode theory combined with the resonance method for the determination of the propagation constants and field profiles of the supermodes. An improved accuracy has been achieved by including corrections due to the fields in the corner regions of the waveguides using perturbation theory. We analyze in detail two particular devices, an optical filter/combiner and an optical sensor. An optical wavelength filter/combiner is a common element in an integrated optical circuit. A new "bend free" filter/combiner is proposed and analyzed. The new wavelength filter consists of only straight parallel channels, which considerably simplify both the analysis and fabrication of the device. We show in detail how the operation of the device depends upon each of the design parameters. The intrinsic power loss in the proposed filter/combiner is minimized. The optical sensor is another important device and the sensitivity of measurement is an important issue in its design. Two operating mechanisms used in prior optical sensors are evanescent wave sensing or surface plasmon excitation. In this dissertation, we present a sensor with a directional coupler structure in which a measurand to be detected is interfaced with one side of the cladding. The analysis shows that it is possible to make a high resolution device by adjusting the design parameters. The dimensions and materials used in an optimized design are presented.

Sub-Doppler two-photon absorption induced by the combination of a single-mode laser and a frequency comb

NASA Astrophysics Data System (ADS)

Moreno, Marco P.; Nogueira, Giovana T.; Felinto, Daniel; Vianna, Sandra S.

2017-08-01

The two-photon transition 5 S -5 P -5 D in rubidium vapor is investigated by detecting the fluorescence from the 6 P3 /2 state when the atomic system is excited by the combined action of a cw diode laser and a frequency comb. The cw laser plays a role as a velocity-selective filter and allows for sub-Doppler spectroscopy over a large spectral range including the 5 D3 /2 and 5 D5 /2 states. For a counterpropagating beam configuration, the response of each atomic velocity group is well characterized within the Doppler profile and the excited hyperfine levels are clearly resolved. The contribution of the optical pumping to the direct two-photon process is also revealed. The results are well described in a frequency domain picture by considering the interaction of each velocity group with the cw laser and the modes of the frequency comb.

Hyperfine Structure Constants of Energetically High-lying Levels of Odd Parity of Atomic Vanadium

NASA Astrophysics Data System (ADS)

Güzelçimen, F.; Yapıcı, B.; Demir, G.; Er, A.; Öztürk, I. K.; Başar, Gö.; Kröger, S.; Tamanis, M.; Ferber, R.; Docenko, D.; Başar, Gü.

2014-09-01

High-resolution Fourier transform spectra of a vanadium-argon plasma have been recorded in the wavelength range of 365-670 nm (15,000-27,400 cm-1). Optical bandpass filters were used in the experimental setup to enhance the sensitivity of the Fourier transform spectrometer. In total, 138 atomic vanadium spectral lines showing resolved or partially resolved hyperfine structure have been analyzed to determine the magnetic dipole hyperfine structure constants A of the involved energy levels. One of the investigated lines has not been previously classified. As a result, the magnetic dipole hyperfine structure constants A for 90 energy levels are presented: 35 of them belong to the configuration 3d 34s4p and 55 to the configuration 3d 44p. Of these 90 constants, 67 have been determined for the first time, with 23 corresponding to the configuration 3d 34s4p and 44 to 3d 44p.

Improved graphite furnace atomizer

DOEpatents

Siemer, D.D.

1983-05-18

A graphite furnace atomizer for use in graphite furnace atomic absorption spectroscopy is described wherein the heating elements are affixed near the optical path and away from the point of sample deposition, so that when the sample is volatilized the spectroscopic temperature at the optical path is at least that of the volatilization temperature, whereby analyteconcomitant complex formation is advantageously reduced. The atomizer may be elongated along its axis to increase the distance between the optical path and the sample deposition point. Also, the atomizer may be elongated along the axis of the optical path, whereby its analytical sensitivity is greatly increased.

Power Flow Angles for Slanted Finger Surface Acoustic Wave Filters on Langasite Substrate

NASA Astrophysics Data System (ADS)

Goto, Mikihiro; Yatsuda, Hiromi; Chiba, Takao

2007-07-01

Power flow angles (PFAs) on a langasite (LGS) substrate with Euler angles of (0{\\degree}, 138.5{\\degree}, \\psi), \\psi=25.7 to 27.7° are investigated for slanted finger interdigital transducer (SFIT) surface acoustic wave (SAW) filters by an electrical and optical methods. In the electrical method, several tilted SFIT SAW filters with different tilt angles for (0{\\degree}, 138.5{\\degree}, \\psi) LGS substrates were designed, and the frequency responses of the filters were measured. In the optical method, the PFAs were directly measured by optical probing for a parallel interdigital transducer (IDT) with wide propagation area on the substrate. As a result, a good correlation between electrical and optical measurements of the PFAs is obtained, but the calculated PFAs are slightly different from the measured PFAs. A good frequency response of a tilted 380 MHz SFIT SAW filter with an appropriate tilt angle corresponding to the PFA on the substrate is obtained even though the aperture is small.

Space Vehicle Pose Estimation via Optical Correlation and Nonlinear Estimation

NASA Technical Reports Server (NTRS)

Rakoczy, John M.; Herren, Kenneth A.

2008-01-01

A technique for 6-degree-of-freedom (6DOF) pose estimation of space vehicles is being developed. This technique draws upon recent developments in implementing optical correlation measurements in a nonlinear estimator, which relates the optical correlation measurements to the pose states (orientation and position). For the optical correlator, the use of both conjugate filters and binary, phase-only filters in the design of synthetic discriminant function (SDF) filters is explored. A static neural network is trained a priori and used as the nonlinear estimator. New commercial animation and image rendering software is exploited to design the SDF filters and to generate a large filter set with which to train the neural network. The technique is applied to pose estimation for rendezvous and docking of free-flying spacecraft and to terrestrial surface mobility systems for NASA's Vision for Space Exploration. Quantitative pose estimation performance will be reported. Advantages and disadvantages of the implementation of this technique are discussed.

PN-type carrier-induced filter with modulatable extinction ratio.

PubMed

Fang, Qing; Tu, Xiaoguang; Song, Junfeng; Jia, Lianxi; Luo, Xianshu; Yang, Yan; Yu, Mingbin; Lo, Guoqiang

2014-12-01

We demonstrate the first PN-type carrier-induced silicon waveguide Bragg grating filter on a SOI wafer. The optical extinction ratio of this kind of filter can be efficiently modulated under both reverse and forward biases. The carrier-induced Bragg grating based on a PN junction is fabricated on the silicon waveguide using litho compensation technology. The measured optical bandwidth and the extinction ratio of the filter are 0.45 nm and 19 dB, respectively. The optical extinction ratio modulation under the reverse bias is more than 11.5 dB and it is more than 10 dB under the forward bias. Only 1-dB optical transmission loss is realized in this Bragg grating under a reverse bias. The shifting rates of the central wavelength under forward and reverse biases are ~-1.25 nm/V and 0.01 nm/V, respectively. The 3-dB modulation bandwidth of this filter is 5.1 GHz at a bias of -10 V.

Space Vehicle Pose Estimation via Optical Correlation and Nonlinear Estimation

NASA Technical Reports Server (NTRS)

Rakoczy, John; Herren, Kenneth

2007-01-01

A technique for 6-degree-of-freedom (6DOF) pose estimation of space vehicles is being developed. This technique draws upon recent developments in implementing optical correlation measurements in a nonlinear estimator, which relates the optical correlation measurements to the pose states (orientation and position). For the optical correlator, the use of both conjugate filters and binary, phase-only filters in the design of synthetic discriminant function (SDF) filters is explored. A static neural network is trained a priori and used as the nonlinear estimator. New commercial animation and image rendering software is exploited to design the SDF filters and to generate a large filter set with which to train the neural network. The technique is applied to pose estimation for rendezvous and docking of free-flying spacecraft and to terrestrial surface mobility systems for NASA's Vision for Space Exploration. Quantitative pose estimation performance will be reported. Advantages and disadvantages of the implementation of this technique are discussed.

Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

DOEpatents

Brown, E.J.; Baldasaro, P.F.; Dziendziel, R.J.

1997-12-23

A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength {lambda}{sub IF} approximately equal to the bandgap wavelength {lambda}{sub g} of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5{lambda}{sub IF} to {lambda}{sub IF} and reflect from {lambda}{sub IF} to about 2{lambda}{sub IF}; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5{lambda}{sub IF}. 10 figs.

Optical Correlation of Images With Signal-Dependent Noise Using Constrained-Modulation Filter Devices

NASA Technical Reports Server (NTRS)

Downie, John D.

1995-01-01

Images with signal-dependent noise present challenges beyond those of images with additive white or colored signal-independent noise in terms of designing the optimal 4-f correlation filter that maximizes correlation-peak signal-to-noise ratio, or combinations of correlation-peak metrics. Determining the proper design becomes more difficult when the filter is to be implemented on a constrained-modulation spatial light modulator device. The design issues involved for updatable optical filters for images with signal-dependent film-grain noise and speckle noise are examined. It is shown that although design of the optimal linear filter in the Fourier domain is impossible for images with signal-dependent noise, proper nonlinear preprocessing of the images allows the application of previously developed design rules for optimal filters to be implemented on constrained-modulation devices. Thus the nonlinear preprocessing becomes necessary for correlation in optical systems with current spatial light modulator technology. These results are illustrated with computer simulations of images with signal-dependent noise correlated with binary-phase-only filters and ternary-phase-amplitude filters.

Towards Polarized Antiprotons at FAIR

NASA Astrophysics Data System (ADS)

Rathmann, Frank

2007-06-01

Understanding the interplay of the nuclear interaction with polarized protons and the electromagnetic interaction with polarized electrons in polarized atoms is crucial to progress towards the PAX goal to eventually produce stored polarized antiproton beams at FAIR. Presently, there exist two competing theoretical scenarios: one with substantial spin filtering of (anti)protons by atomic electrons, and a second one suggesting a self-cancellation of the electron contribution to spin filtering. After a brief review of the PAX physics case for polarized antiprotons at FAIR, a detailed discussion of future investigations, including spin-filtering experiments at COSY-Jülich and at the AD of CERN is presented.

MANTECH Project Book, 1992

DTIC Science & Technology

1992-01-01

RUGATE FILTER PROCESS AND PRODUCTION ................ 111 MANUFACTURING SCIENCE FOR TITANIUM ALUMINIDE COMPOSITE ENGINE STRU CTURES...rejection and mission filters , anti-reflection coatings, and dichroic layers which can have demanding optical requirements. Rugate m coatings can be used to...SCIENCE RUGATE FILTER PROCESS AND PRODUCTION CONTRACT NUMBER: F33615-86-C-5059STATEMENT OF NEED Achieving the optical performance specifications for

Optical microwave filter based on spectral slicing by use of arrayed waveguide gratings.

PubMed

Pastor, Daniel; Ortega, Beatriz; Capmany, José; Sales, Salvador; Martinez, Alfonso; Muñoz, Pascual

2003-10-01

We have experimentally demonstrated a new optical signal processor based on the use of arrayed waveguide gratings. The structure exploits the concept of spectral slicing combined with the use of an optical dispersive medium. The approach presents increased flexibility from previous slicing-based structures in terms of tunability, reconfiguration, and apodization of the samples or coefficients of the transversal optical filter.

Design issues for directional coupler- and MMI-based optical microring resonator filters on InP

NASA Astrophysics Data System (ADS)

Themistos, Christos; Kalli, Kyriacos; Komodromos, Michalis; Rajarajan, Muttukrishnan; Rahman, B. M. A.; Grattan, Kenneth T. V.

2004-08-01

The characterization and optimization of optical microring resonator-based optical filters on deeply etched GaInAsP-Inp waveguides, using the finite element-based beam propagation approach is presented here. Design issues for directional coupler- and multimode interference coupler-based devices, such as field evolution, optical power, phase, fabrication tolerance and wavelength dependence have been investigated.

Fiber-Coupled Acousto-Optical-Filter Spectrometer

NASA Technical Reports Server (NTRS)

Levin, Kenneth H.; Li, Frank Yanan

1993-01-01

Fiber-coupled acousto-optical-filter spectrometer steps rapidly through commanded sequence of wavelengths. Sample cell located remotely from monochromator and associated electronic circuitry, connected to them with optical fibers. Optical-fiber coupling makes possible to monitor samples in remote, hazardous, or confined locations. Advantages include compactness, speed, and no moving parts. Potential applications include control of chemical processes, medical diagnoses, spectral imaging, and sampling of atmospheres.

Quantum memory with optically trapped atoms.

PubMed

Chuu, Chih-Sung; Strassel, Thorsten; Zhao, Bo; Koch, Markus; Chen, Yu-Ao; Chen, Shuai; Yuan, Zhen-Sheng; Schmiedmayer, Jörg; Pan, Jian-Wei

2008-09-19

We report the experimental demonstration of quantum memory for collective atomic states in a far-detuned optical dipole trap. Generation of the collective atomic state is heralded by the detection of a Raman scattered photon and accompanied by storage in the ensemble of atoms. The optical dipole trap provides confinement for the atoms during the quantum storage while retaining the atomic coherence. We probe the quantum storage by cross correlation of the photon pair arising from the Raman scattering and the retrieval of the atomic state stored in the memory. Nonclassical correlations are observed for storage times up to 60 mus.

Magneto-optical cooling of atoms.

PubMed

Raizen, Mark G; Budker, Dmitry; Rochester, Simon M; Narevicius, Julia; Narevicius, Edvardas

2014-08-01

We propose an alternative method to laser cooling. Our approach utilizes the extreme brightness of a supersonic atomic beam, and the adiabatic atomic coilgun to slow atoms in the beam or to bring them to rest. We show how internal-state optical pumping and stimulated optical transitions, combined with magnetic forces, can be used to cool the translational motion of atoms. This approach does not rely on momentum transfer from photons to atoms, as in laser cooling. We predict that our method can surpass laser cooling in terms of flux of ultracold atoms and phase-space density, with lower required laser power.

Nanophotonic Optical Isolator Controlled by the Internal State of Cold Atoms

NASA Astrophysics Data System (ADS)

Sayrin, Clément; Junge, Christian; Mitsch, Rudolf; Albrecht, Bernhard; O'Shea, Danny; Schneeweiss, Philipp; Volz, Jürgen; Rauschenbeutel, Arno

2015-10-01

The realization of nanophotonic optical isolators with high optical isolation even at ultralow light levels and low optical losses is an open problem. Here, we employ the link between the local polarization of strongly confined light and its direction of propagation to realize low-loss nonreciprocal transmission through a silica nanofiber at the single-photon level. The direction of the resulting optical isolator is controlled by the spin state of cold atoms. We perform our experiment in two qualitatively different regimes, i.e., with an ensemble of cold atoms where each atom is weakly coupled to the waveguide and with a single atom strongly coupled to the waveguide mode. In both cases, we observe simultaneously high isolation and high forward transmission. The isolator concept constitutes a nanoscale quantum optical analog of microwave ferrite resonance isolators, can be implemented with all kinds of optical waveguides and emitters, and might enable novel integrated optical devices for fiber-based classical and quantum networks.

Tunable radio-frequency photonic filter based on an actively mode-locked fiber laser.

PubMed

Ortigosa-Blanch, A; Mora, J; Capmany, J; Ortega, B; Pastor, D

2006-03-15

We propose the use of an actively mode-locked fiber laser as a multitap optical source for a microwave photonic filter. The fiber laser provides multiple optical taps with an optical frequency separation equal to the external driving radio-frequency signal of the laser that governs its repetition rate. All the optical taps show equal polarization and an overall Gaussian apodization, which reduces the sidelobes. We demonstrate continuous tunability of the filter by changing the external driving radio-frequency signal of the laser, which shows good fine tunability in the operating range of the laser from 5 to 10 GHz.

Progress in electron- and ion-interferometry

NASA Astrophysics Data System (ADS)

Hasselbach, Franz

2010-01-01

In the 1970s the prominent goal was to overcome the limitations of electron microscopy caused by aberrations of electron lenses by the development of electron holography. In the meantime this problem has been solved, not only in the roundabout way of holography, but directly by correcting the aberrations of the lenses. Nevertheless, many quantitative electron microscopical measurement methods—e.g. mapping and visualization of electric and magnetic fields—were developed within the context of holography and have become fields of their own. In this review we focus on less popular electron interferometric experiments which complement the field of electron holography. The paper is organized as follows. After a short sketch of the development of electron biprism interferometry after its invention in 1954, recent advances in technology are discussed that made electron biprism interferometry an indispensable tool for solving fundamental and applied questions in physics: the development and preparation of conventional and single-atom field electron and field ion sources with their extraordinary properties. Single- and few-atom sources exhibit spectacular features: their brightness at 100 keV exceeds that of conventional field emitters by two orders in magnitude. Due to the extremely small aberrations of diode field emitter extraction optics, the virtual source size of single-atom tips is on the order of 0.2 nm. As a consequence it illuminates an area 7 cm in diameter on a screen at a distance of 15 cm coherently. Projection electron micrographs taken with these sources reach spatial resolutions of atomic dimensions and in-line holograms are—due to the absence of lenses with their aberrations—not blurred. Their reconstruction is straightforward. By addition of a carbon nanotube biprism into the beam path of a projection microscope a lensless electron interferometer has been realized. In extremely ultrahigh vacuum systems flicker noise is practically absent in the new sources. In the context of holography, methods have been developed to record holograms without modulation of the biprism fringes by waves diffracted at the edges of the biprism filament. This simplifies the reconstruction of holograms and the evaluation of interferograms (taken, e.g. to extract a spectrum by Fourier analysis of the fringe system) significantly. A major section is devoted to the influence of electromagnetic and gravito-inertial potentials and fields on the quantum mechanical phase of matter waves: the Aharonov-Bohm effect, the inertial Aharonov-Bohm effect and its realization, the Sagnac effect and Sagnac experiments with atoms, superfluid helium, Bose-Einstein condensates, electrons and ions and their potential as rotation sensors are discussed. Möllenstedt and Wohland discovered in a crossed beam analyzer (Wien filter) an optical element for charged particles that shifts wave packets longitudinally that transverse a Wien filter on laterally separated paths. This new optical element rendered it possible to measure coherence lengths and the spectrum of charged particle waves by visibility- and Fourier-spectroscopy, to perform a 'Welcher Weg' experiment, to re-establish seemingly lost longitudinal coherence in an interferometer for charged particles and to realize a decoherence free quantum eraser. A precision test of decoherence according to a proposal from Anglin and Zurek and biprism interferences with helium atoms close the section on first-order coherence experiments. The topics of the last section are Hanbury Brown-Twiss correlations and an antibuching experiment of free electrons.

Optical filtering in directly modulated/detected OOFDM systems.

PubMed

Sánchez, C; Ortega, B; Wei, J L; Capmany, J

2013-12-16

This work presents a theoretical investigation on the performance of directly modulated/detected (DM/DD) optical orthogonal frequency division multiplexed (OOFDM) systems subject to optical filtering. The impact of both linear and nonlinear distortion effects are taken into account to calculate the effective signal-to-noise ratio of each subcarrier. These results are then employed to optimize the design parameters of two simple optical filtering structures: a Mach Zehnder interferometer and a uniform fiber Bragg grating, leading to a significant optical power budget improvement given by 3.3 and 3dB, respectively. These can be further increased to 5.5 and 4.2dB respectively when balanced detection configurations are employed. We find as well that this improvement is highly dependent on the clipping ratio.

Generalised optical differentiation wavefront sensor: a sensitive high dynamic range wavefront sensor.

PubMed

Haffert, S Y

2016-08-22

Current wavefront sensors for high resolution imaging have either a large dynamic range or a high sensitivity. A new kind of wavefront sensor is developed which can have both: the Generalised Optical Differentiation wavefront sensor. This new wavefront sensor is based on the principles of optical differentiation by amplitude filters. We have extended the theory behind linear optical differentiation and generalised it to nonlinear filters. We used numerical simulations and laboratory experiments to investigate the properties of the generalised wavefront sensor. With this we created a new filter that can decouple the dynamic range from the sensitivity. These properties make it suitable for adaptive optic systems where a large range of phase aberrations have to be measured with high precision.

Frequency-Domain Characterization of Optic Flow and Vision-Based Ocellar Sensing for Rotational Motion

DTIC Science & Technology

2017-04-01

complementary fusion: Fourth-order Butterworth filter was used to high -pass ocelli and low-pass optic flow. The normalized cutoff frequency had to be kept...information introduced by luminance change. The high - frequency cutoff was added to reject the flickering noise for indoor usage. The filtered signals from the...function of the low- pass filter is to attenuate high - frequency noise. The final band-pass filter transfer function is in Eq. 2. (()

Quadratic correlation filters for optical correlators

NASA Astrophysics Data System (ADS)

Mahalanobis, Abhijit; Muise, Robert R.; Vijaya Kumar, Bhagavatula V. K.

2003-08-01

Linear correlation filters have been implemented in optical correlators and successfully used for a variety of applications. The output of an optical correlator is usually sensed using a square law device (such as a CCD array) which forces the output to be the squared magnitude of the desired correlation. It is however not a traditional practice to factor the effect of the square-law detector in the design of the linear correlation filters. In fact, the input-output relationship of an optical correlator is more accurately modeled as a quadratic operation than a linear operation. Quadratic correlation filters (QCFs) operate directly on the image data without the need for feature extraction or segmentation. In this sense, the QCFs retain the main advantages of conventional linear correlation filters while offering significant improvements in other respects. Not only is more processing required to detect peaks in the outputs of multiple linear filters, but choosing a winner among them is an error prone task. In contrast, all channels in a QCF work together to optimize the same performance metric and produce a combined output that leads to considerable simplification of the post-processing. In this paper, we propose a novel approach to the design of quadratic correlation based on the Fukunaga Koontz transform. Although quadratic filters are known to be optimum when the data is Gaussian, it is expected that they will perform as well as or better than linear filters in general. Preliminary performance results are provided that show that quadratic correlation filters perform better than their linear counterparts.

Application of optical broadband monitoring to quasi-rugate filters by ion-beam sputtering

NASA Astrophysics Data System (ADS)

Lappschies, Marc; Görtz, Björn; Ristau, Detlev

2006-03-01

Methods for the manufacture of rugate filters by the ion-beam-sputtering process are presented. The first approach gives an example of a digitized version of a continuous-layer notch filter. This method allows the comparison of the basic theory of interference coatings containing thin layers with practical results. For the other methods, a movable zone target is employed to fabricate graded and gradual rugate filters. The examples demonstrate the potential of broadband optical monitoring in conjunction with the ion-beam-sputtering process. First-characterization results indicate that these types of filter may exhibit higher laser-induced damage-threshold values than those of classical filters.

Multi-function all optical packet switch by periodic wavelength arrangement in an arrayed waveguide grating and wideband optical filters.

PubMed

Feng, Kai-Ming; Wu, Chung-Yu; Wen, Yu-Hsiang

2012-01-16

By utilizing the cyclic filtering function of an NxN arrayed waveguide grating (AWG), we propose and experimentally demonstrate a novel multi-function all optical packet switching (OPS) architecture by applying a periodical wavelength arrangement between the AWG in the optical routing/buffering unit and a set of wideband optical filters in the switched output ports to achieve the desired routing and buffering functions. The proposed OPS employs only one tunable wavelength converter at the input port to convert the input wavelength to a designated wavelength which reduces the number of active optical components and thus the complexity of the traffic control is simplified in the OPS. With the proposed OPS architecture, multiple optical packet switching functions, including arbitrary packet switching and buffering, first-in-first-out (FIFO) packet multiplexing, packet demultiplexing and packet add/drop multiplexing, have been successfully demonstrated.

Atom optics in the time domain

NASA Astrophysics Data System (ADS)

Arndt, M.; Szriftgiser, P.; Dalibard, J.; Steane, A. M.

1996-05-01

Atom-optics experiments are presented using a time-modulated evanescent light wave as an atomic mirror in the trampoline configuration, i.e., perpendicular to the direction of the atomic free fall. This modulated mirror is used to accelerate cesium atoms, to focus their trajectories, and to apply a ``multiple lens'' to separately focus different velocity classes of atoms originating from a point source. We form images of a simple two-slit object to show the resolution of the device. The experiments are modelled by a general treatment analogous to classical ray optics.

Continuously tunable optical notch filter and band-pass filter systems that cover the visible to near-infrared spectral ranges.

PubMed

Jeong, Mi-Yun; Mang, Jin Yeob

2018-03-10

Spatially continuous tunable optical notch and band-pass filter systems that cover the visible (VIS) and near-infrared (NIR) spectral ranges from ∼460  nm to ∼1,000  nm are realized by combining left- and right-handed circular cholesteric liquid crystal (CLC) wedge cells with continuous pitch gradient. The notch filter system is polarization independent in all of the spectral ranges. The band-pass filter system, when the left- and right-handed CLCs are arranged in a row, is polarization independent, while when they are arranged at right angles, they are polarization dependent; furthermore, the full-width at half-maximum of the band-pass filter can be changed reversibly from the original bandwidth of 36 nm to 16 nm. Depending on the CLC materials, this strategy could be applied to the UV, VIS, and IR spectral ranges. Due to the high performance in the broad spectral range, cost-effective facile fabrication process, simple mechanical control, and small size, it is expected that our optical tunable filter strategies could become one of the key parts of laser-based Raman spectroscopy, fluorescence, life science devices, optical communication systems, astronomical telescopes, and so forth.

Daytime adaptive optics for deep space optical communications

NASA Technical Reports Server (NTRS)

Wilson, Keith; Troy, M.; Srinivasan, M.; Platt, B.; Vilnrotter, V.; Wright, M.; Garkanian, V.; Hemmati, H.

2003-01-01

The deep space optical communications subsystem offers a higher bandwidth communications link in smaller size, lower mass, and lower power consumption subsystem than does RF. To demonstrate the benefit of this technology to deep space communications NASA plans to launch an optical telecommunications package on the 2009 Mars Telecommunications orbiter spacecraft. Current performance goals are 30-Mbps from opposition, and 1-Mbps near conjunction (-3 degrees Sun-Earth-Probe angle). Yet, near conjunction the background noise from the day sky will degrade the performance of the optical link. Spectral and spatial filtering and higher modulation formats can mitigate the effects of background sky. Narrowband spectral filters can result in loss of link margin, and higher modulation formats require higher transmitted peak powers. In contrast, spatial filtering at the receiver has the potential of being lossless while providing the required sky background rejection. Adaptive optics techniques can correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope. Such performance facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.

Application of velocity filtering to optical-flow passive ranging

NASA Technical Reports Server (NTRS)

Barniv, Yair

1992-01-01

The performance of the velocity filtering method as applied to optical-flow passive ranging under real-world conditions is evaluated. The theory of the 3-D Fourier transform as applied to constant-speed moving points is reviewed, and the space-domain shift-and-add algorithm is derived from the general 3-D matched filtering formulation. The constant-speed algorithm is then modified to fit the actual speed encountered in the optical flow application, and the passband of that filter is found in terms of depth (sensor/object distance) so as to cover any given range of depths. Two algorithmic solutions for the problems associated with pixel interpolation and object expansion are developed, and experimental results are presented.

Improved test time evaluation in an expansion tube

NASA Astrophysics Data System (ADS)

James, Christopher M.; Cullen, Timothy G.; Wei, Han; Lewis, Steven W.; Gu, Sangdi; Morgan, Richard G.; McIntyre, Timothy J.

2018-05-01

Traditionally, expansion tube test times have been experimentally evaluated using test section mounted impact pressure probes. This paper proposes two new methods which can be performed using a high-speed camera and a simple circular cylinder test model. The first is the use of a narrow bandpass optical filter to allow time-resolved radiative emission from an important species to be captured, and the second is using edge detection to track how the model shock standoff changes with time. Experimental results are presented for two test conditions using an air test gas and an optical filter aimed at capturing emission from the 777 nm atomic oxygen triplet. It is found that the oxygen emission is the most reliable experimental method, because it is shown to exhibit significant changes at the end of the test time. It is also proposed that, because the camera footage is spatially resolved, the radiative emission method can be used to examine the `effective' test time in multiple regions of the flow. For one of the test conditions, it is found that the effective test time away from the stagnation region for the cylindrical test model is at most 45% of the total test time. For the other test condition, it is found that the effective test time of a 54° wedge test model is at most a third of the total test time.

Architectural design of a ground-based deep-space optical reception antenna

NASA Technical Reports Server (NTRS)

Kerr, E. L.

1989-01-01

An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

Programmable optical processor chips: toward photonic RF filters with DSP-level flexibility and MHz-band selectivity

NASA Astrophysics Data System (ADS)

Xie, Yiwei; Geng, Zihan; Zhuang, Leimeng; Burla, Maurizio; Taddei, Caterina; Hoekman, Marcel; Leinse, Arne; Roeloffzen, Chris G. H.; Boller, Klaus-J.; Lowery, Arthur J.

2017-12-01

Integrated optical signal processors have been identified as a powerful engine for optical processing of microwave signals. They enable wideband and stable signal processing operations on miniaturized chips with ultimate control precision. As a promising application, such processors enables photonic implementations of reconfigurable radio frequency (RF) filters with wide design flexibility, large bandwidth, and high-frequency selectivity. This is a key technology for photonic-assisted RF front ends that opens a path to overcoming the bandwidth limitation of current digital electronics. Here, the recent progress of integrated optical signal processors for implementing such RF filters is reviewed. We highlight the use of a low-loss, high-index-contrast stoichiometric silicon nitride waveguide which promises to serve as a practical material platform for realizing high-performance optical signal processors and points toward photonic RF filters with digital signal processing (DSP)-level flexibility, hundreds-GHz bandwidth, MHz-band frequency selectivity, and full system integration on a chip scale.

Optical atomic magnetometer

DOEpatents

Budker, Dmitry; Higbie, James; Corsini, Eric P.

2013-11-19

An optical atomic magnetometers is provided operating on the principles of nonlinear magneto-optical rotation. An atomic vapor is optically pumped using linearly polarized modulated light. The vapor is then probed using a non-modulated linearly polarized light beam. The resulting modulation in polarization angle of the probe light is detected and used in a feedback loop to induce self-oscillation at the resonant frequency.

Enhancing light-atom interactions via atomic bunching

NASA Astrophysics Data System (ADS)

Schmittberger, Bonnie L.; Gauthier, Daniel J.

2014-07-01

There is a broad interest in enhancing the strength of light-atom interactions to the point where injecting a single photon induces a nonlinear material response. Here we show theoretically that sub-Doppler-cooled two-level atoms that are spatially organized by weak optical fields give rise to a nonlinear material response that is greatly enhanced beyond that attainable in a homogeneous gas. Specifically, in the regime where the intensity of the applied optical fields is much less than the off-resonance saturation intensity, we show that the third-order nonlinear susceptibility scales inversely with atomic temperature and, due to this scaling, can be two orders of magnitude larger than that of a homogeneous gas for typical experimental parameters. As a result, we predict that spatially bunched two-level atoms can exhibit single-photon nonlinearities. Our model is valid for all regimes of atomic bunching and simultaneously accounts for the backaction of the atoms on the optical fields. Our results agree with previous theoretical and experimental results for light-atom interactions that have considered only limited regimes of atomic bunching. For lattice beams tuned to the low-frequency side of the atomic transition, we find that the nonlinearity transitions from a self-focusing type to a self-defocusing type at a critical intensity. We also show that higher than third-order nonlinear optical susceptibilities are significant in the regime where the dipole potential energy is on the order of the atomic thermal energy. We therefore find that it is crucial to retain high-order nonlinearities to accurately predict interactions of laser fields with spatially organized ultracold atoms. The model presented here is a foundation for modeling low-light-level nonlinear optical processes for ultracold atoms in optical lattices.

Experimental nonlinear dynamical studies in cesium magneto-optical trap using time-series analysis

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

Anwar, M., E-mail: mamalik2000@gmail.com; Islam, R.; Faisal, M.

2015-03-30

A magneto-optical trap of neutral atoms is essentially a dissipative quantum system. The fast thermal atoms continuously dissipate their energy to the environment via spontaneous emissions during the cooling. The atoms are, therefore, strongly coupled with the vacuum reservoir and the laser field. The vacuum fluctuations as well as the field fluctuations are imparted to the atoms as random photon recoils. Consequently, the external and internal dynamics of atoms becomes stochastic. In this paper, we have investigated the stochastic dynamics of the atoms in a magneto-optical trap during the loading process. The time series analysis of the fluorescence signal showsmore » that the dynamics of the atoms evolves, like all dissipative systems, from deterministic to the chaotic regime. The subsequent disappearance and revival of chaos was attributed to chaos synchronization between spatially different atoms in the magneto-optical trap.« less

Procedure for rapid determination of nickel, cobalt, and chromium in airborne particulate samples

NASA Technical Reports Server (NTRS)

Davis, W. F.; Graab, J. W.

1972-01-01

A rapid, selective procedure for the determination of 1 to 20 micrograms of nickel, chromium, and cobalt in airborne particulates is described. The method utilizes the combined techniques of low temperature ashing and atomic absorption spectroscopy. The airborne particulates are collected on analytical filter paper. The filter papers are ashed, and the residues are dissolved in hydrochloric acid. Nickel, chromium, and cobalt are determined directly with good precision and accuracy by means of atomic absorption. The effects of flame type, burner height, slit width, and lamp current on the atomic absorption measurements are reported.

77 FR 28353 - Foreign-Trade Zone 45-Portland, OR, Notification of Proposed Production Activity, Shimadzu USA...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-14

...; filter paper; technical books and manuals; textile-covered foam shielding; ceramic hardware and fittings... cables (including fiber optic cable); insulators; filters; lenses; mirrors; prisms; other optical...

Intelligent vision system for autonomous vehicle operations

NASA Technical Reports Server (NTRS)

Scholl, Marija S.

1991-01-01

A complex optical system consisting of a 4f optical correlator with programmatic filters under the control of a digital on-board computer that operates at video rates for filter generation, storage, and management is described.

A Filtering Method to Reveal Crystalline Patterns from Atom Probe Microscopy Desorption Maps

DTIC Science & Technology

2016-03-26

Gault, S.P. Ringer, J.M. Cairney, Atom probe crystallography : characterization of grain boundary orientation relationships in nanocrystalline...J.M. Cairney, Atom probe crystallography : atomic- scale 3-D orientation mapping, Scr. Mater. 66 (11) (2012) 907. L. Yao /MethodsX 3 (2016) 268–273 273

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

An, Yipeng, E-mail: ypan@htu.edu.cn; Zhang, Mengjun; Wang, Tianxing

Very recently, boron nitride atomic chains were successively prepared and observed in experiments [O. Cretu et al., ACS Nano 8, 11950 (2015)]. Herein, using a first-principles technique, we study the magnetism and spin-dependent electronic transport properties of three types of BN atomic chains whose magnetic moment is 1 μ{sub B} for B{sub n}N{sub n−1}, 2 μ{sub B} for B{sub n}N{sub n}, and 3 μ{sub B} for B{sub n}N{sub n+1} type atomic chains, respectively. The spin-dependent electronic transport results demonstrate that the short B{sub n}N{sub n+1} chain presents an obvious spin-filtering effect with high spin polarization ratio (>90%) under low biasmore » voltages. Yet, this spin-filtering effect does not occur for long B{sub n}N{sub n+1} chains under high bias voltages and other types of BN atomic chains (B{sub n}N{sub n−1} and B{sub n}N{sub n}). The proposed short B{sub n}N{sub n+1} chain is predicted to be an effective low-bias spin filters. Moreover, the length-conductance relationships of these BN atomic chains were also studied.« less

Optical determination of material abundances by using neural networks for the derivation of spectral filters

NASA Astrophysics Data System (ADS)

Krippner, Wolfgang; Wagner, Felix; Bauer, Sebastian; Puente León, Fernando

2017-06-01

Using appropriately designed spectral filters allows to optically determine material abundances. While an infinite number of possibilities exist for determining spectral filters, we take advantage of using neural networks to derive spectral filters leading to precise estimations. To overcome some drawbacks that regularly influence the determination of material abundances using hyperspectral data, we incorporate the spectral variability of the raw materials into the training of the considered neural networks. As a main result, we successfully classify quantized material abundances optically. Thus, the main part of the high computational load, which belongs to the use of neural networks, is avoided. In addition, the derived material abundances become invariant against spatially varying illumination intensity as a remarkable benefit in comparison with spectral filters based on the Moore-Penrose pseudoinverse, for instance.

Solid colloidal optical wavelength filter

DOEpatents

Alvarez, Joseph L.

1992-01-01

A solid colloidal optical wavelength filter includes a suspension of spheal particles dispersed in a coagulable medium such as a setting plastic. The filter is formed by suspending spherical particles in a coagulable medium; agitating the particles and coagulable medium to produce an emulsion of particles suspended in the coagulable medium; and allowing the coagulable medium and suspended emulsion of particles to cool.

Dynamics of trapped atoms around an optical nanofiber probed through polarimetry.

PubMed

Solano, Pablo; Fatemi, Fredrik K; Orozco, Luis A; Rolston, S L

2017-06-15

The evanescent field outside an optical nanofiber (ONF) can create optical traps for neutral atoms. We present a non-destructive method to characterize such trapping potentials. An off-resonance linearly polarized probe beam that propagates through the ONF experiences a slow axis of polarization produced by trapped atoms on opposite sides along the ONF. The transverse atomic motion is imprinted onto the probe polarization through the changing atomic index of refraction. By applying a transient impulse, we measure a time-dependent polarization rotation of the probe beam that provides both a rapid and non-destructive measurement of the optical trapping frequencies.

Practical method for transversely measuring the spin polarization of optically pumped alkali atoms

NASA Astrophysics Data System (ADS)

Ding, Zhichao; Yuan, Jie; Long, Xingwu

2018-06-01

A practical method to measure the spin polarization of optically pumped alkali atoms is demonstrated. In order to realize transverse measurement, the transverse spin component of spin-polarized alkali atoms is created by a rotating exciting magnetic field, and detected using the optical rotation of a near-resonant probe beam for realizing a high detection sensitivity. The dependency of the optical rotation on the spin polarization of 133Cs atoms is derived theoretically and verified experimentally. By changing the direction of the rotating magnetic field, we realize the transverse measurement of the spin polarization of 133Cs atoms in either ground-state hyperfine level.

Integrated optic single-ring filter for narrowband phase demodulation

NASA Astrophysics Data System (ADS)

Madsen, C. K.

2017-05-01

Integrated optic notch filters are key building blocks for higher-order spectral filter responses and have been demonstrated in many technology platforms from dielectrics (such as Si3N4) to semiconductors (Si photonics). Photonic-assisted RF processing applications for notch filters include identifying and filtering out high-amplitude, narrowband signals that may be interfering with the desired signal, including undesired frequencies detected in radar and free-space optical links. The fundamental tradeoffs for bandwidth and rejection depth as a function of the roundtrip loss and coupling coefficient are investigated along with the resulting spectral phase response for minimum-phase and maximum-phase responses compared to the critical coupling condition and integration within a Mach Zehnder interferometer. Based on a full width at half maximum criterion, it is shown that maximum-phase responses offer the smallest bandwidths for a given roundtrip loss. Then, a new role for passive notch filters in combination with high-speed electro-optic phase modulation is explored around narrowband phase-to-amplitude demodulation using a single ring operating on one sideband. Applications may include microwave processing and instantaneous frequency measurement (IFM) for radar, space and defense applications.

Tunable microwave photonic filter free from baseband and carrier suppression effect not requiring single sideband modulation using a Mach-Zenhder configuration.

PubMed

Mora, José; Ortigosa-Blanch, Arturo; Pastor, Daniel; Capmany, José

2006-08-21

We present a full theoretical and experimental analysis of a novel all-optical microwave photonic filter combining a mode-locked fiber laser and a Mach-Zenhder structure in cascade to a 2x1 electro-optic modulator. The filter is free from the carrier suppression effect and thus it does not require single sideband modulation. Positive and negative coefficients are obtained inherently in the system and the tunability is achieved by controlling the optical path difference of the Mach-Zenhder structure.

Physics through the 1990s: Atomic, molecular and optical physics

NASA Technical Reports Server (NTRS)

1986-01-01

The volume presents a program of research initiatives in atomic, molecular, and optical physics. The current state of atomic, molecular, and optical physics in the US is examined with respect to demographics, education patterns, applications, and the US economy. Recommendations are made for each field, with discussions of their histories and the relevance of the research to government agencies. The section on atomic physics includes atomic theory, structure, and dynamics; accelerator-based atomic physics; and large facilities. The section on molecular physics includes spectroscopy, scattering theory and experiment, and the dynamics of chemical reactions. The section on optical physics discusses lasers, laser spectroscopy, and quantum optics and coherence. A section elucidates interfaces between the three fields and astrophysics, condensed matter physics, surface science, plasma physics, atmospheric physics, and nuclear physics. Another section shows applications of the three fields in ultra-precise measurements, fusion, national security, materials, medicine, and other topics.

Adaptive Filter Techniques for Optical Beam Jitter Control and Target Tracking

DTIC Science & Technology

2008-12-01

OPTICAL BEAM JITTER CONTROL AND TARGET TRACKING Michael J. Beerer Civilian, United States Air Force B.S., University of California Irvine, 2006...TECHNIQUES FOR OPTICAL BEAM JITTER CONTROL AND TARGET TRACKING by Michael J. Beerer December 2008 Thesis Advisor: Brij N. Agrawal Co...DATE December 2008 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Adaptive Filter Techniques for Optical Beam Jitter

WDM hybrid microoptical transceiver with Bragg volume grating

NASA Astrophysics Data System (ADS)

Jeřábek, Vitezslav; Armas, Julio; Mareš, David; Prajzler, Václav

2012-02-01

The paper presents the design, simulation and construction results of the wavelength division multiplex bidirectional transceiver module (WDM transceiver) for the passive optical network (PON) of a fiber to the home (FTTH) topology network. WDM transceiver uses a microoptical hybrid integration technology with volume holographic Bragg grating triplex filter -VHGT and a collimation lenses imagine system for wavelength multiplexing/ demultiplexing. This transmission type VHGT filter has high diffraction angle, very low insertion loses and optical crosstalk, which guide to very good technical parameters of transceiver module. WDM transceiver has been constructed using system of a four micromodules in the new circle topology. The optical micromodule with VHGT filter and collimation and decollimation lenses, two optoelectronics microwave receiver micromodules for receiving download information (internet and digital TV signals) and optoelectronic transmitter micromodule for transmitting upload information. In the paper is presented the optical analysis of the optical imagine system by ray-transfer matrix. We compute and measure VHGT characteristics such as diffraction angle, diffraction efficiency and diffraction crosstalk of the optical system for 1310, 1490 and 1550 nm wavelength radiation. For the design of optoelectronic receiver micromodule was used the low signal electrical equivalent circuit for the dynamic performance signal analysis. In the paper is presented the planar form WDM transceiver with polymer optical waveguides and two stage interference demultiplexing optical filter as well.

WDM hybrid microoptical transceiver with Bragg volume grating

NASA Astrophysics Data System (ADS)

Jeřábek, Vitezslav; Armas, Julio; Mareš, David; Prajzler, Václav

2011-09-01

The paper presents the design, simulation and construction results of the wavelength division multiplex bidirectional transceiver module (WDM transceiver) for the passive optical network (PON) of a fiber to the home (FTTH) topology network. WDM transceiver uses a microoptical hybrid integration technology with volume holographic Bragg grating triplex filter -VHGT and a collimation lenses imagine system for wavelength multiplexing/ demultiplexing. This transmission type VHGT filter has high diffraction angle, very low insertion loses and optical crosstalk, which guide to very good technical parameters of transceiver module. WDM transceiver has been constructed using system of a four micromodules in the new circle topology. The optical micromodule with VHGT filter and collimation and decollimation lenses, two optoelectronics microwave receiver micromodules for receiving download information (internet and digital TV signals) and optoelectronic transmitter micromodule for transmitting upload information. In the paper is presented the optical analysis of the optical imagine system by ray-transfer matrix. We compute and measure VHGT characteristics such as diffraction angle, diffraction efficiency and diffraction crosstalk of the optical system for 1310, 1490 and 1550 nm wavelength radiation. For the design of optoelectronic receiver micromodule was used the low signal electrical equivalent circuit for the dynamic performance signal analysis. In the paper is presented the planar form WDM transceiver with polymer optical waveguides and two stage interference demultiplexing optical filter as well.

Jammed-array wideband sawtooth filter.

PubMed

Tan, Zhongwei; Wang, Chao; Goda, Keisuke; Malik, Omer; Jalali, Bahram

2011-11-21

We present an all-optical passive low-cost spectral filter that exhibits a high-resolution periodic sawtooth spectral pattern without the need for active optoelectronic components. The principle of the filter is the partial masking of a phased array of virtual light sources with multiply jammed diffraction orders. We utilize the filter's periodic linear map between frequency and intensity to demonstrate fast sensitive interrogation of fiber Bragg grating sensor arrays and ultrahigh-frequency electrical sawtooth waveform generation. © 2011 Optical Society of America

Photonic crystal ring resonator based optical filters for photonic integrated circuits

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

Robinson, S., E-mail: mail2robinson@gmail.com

In this paper, a two Dimensional (2D) Photonic Crystal Ring Resonator (PCRR) based optical Filters namely Add Drop Filter, Bandpass Filter, and Bandstop Filter are designed for Photonic Integrated Circuits (PICs). The normalized output response of the filters is obtained using 2D Finite Difference Time Domain (FDTD) method and the band diagram of periodic and non-periodic structure is attained by Plane Wave Expansion (PWE) method. The size of the device is minimized from a scale of few tens of millimeters to the order of micrometers. The overall size of the filters is around 11.4 μm × 11.4 μm which ismore » highly suitable of photonic integrated circuits.« less

Silicon photonic filters with high rejection of both TE and TM modes for on-chip four wave mixing applications.

PubMed

Cantarella, Giuseppe; Klitis, Charalambos; Sorel, Marc; Strain, Michael J

2017-08-21

Wavelength selective filters represent one of the key elements for photonic integrated circuits (PIC) and many of their applications in linear and non-linear optics. In devices optimised for single polarisation operation, cross-polarisation scattering can significantly limit the achievable filter rejection. An on-chip filter consisting of elements to filter both TE and TM polarisations is demonstrated, based on a cascaded ring resonator geometry, which exhibits a high total optical rejection of over 60 dB. Monolithic integration of a cascaded ring filter with a four-wave mixing micro-ring device is also experimentally demonstrated with a FWM efficiency of -22dB and pump filter extinction of 62dB.

Reducing uncertainties associated with filter-based optical measurements of light absorbing carbon particles with chemical information

NASA Astrophysics Data System (ADS)

Engström, J. E.; Leck, C.

2011-08-01

The presented filter-based optical method for determination of soot (light absorbing carbon or Black Carbon, BC) can be implemented in the field under primitive conditions and at low cost. This enables researchers with small economical means to perform monitoring at remote locations, especially in the Asia where it is much needed. One concern when applying filter-based optical measurements of BC is that they suffer from systematic errors due to the light scattering of non-absorbing particles co-deposited on the filter, such as inorganic salts and mineral dust. In addition to an optical correction of the non-absorbing material this study provides a protocol for correction of light scattering based on the chemical quantification of the material, which is a novelty. A newly designed photometer was implemented to measure light transmission on particle accumulating filters, which includes an additional sensor recording backscattered light. The choice of polycarbonate membrane filters avoided high chemical blank values and reduced errors associated with length of the light path through the filter. Two protocols for corrections were applied to aerosol samples collected at the Maldives Climate Observatory Hanimaadhoo during episodes with either continentally influenced air from the Indian/Arabian subcontinents (winter season) or pristine air from the Southern Indian Ocean (summer monsoon). The two ways of correction (optical and chemical) lowered the particle light absorption of BC by 63 to 61 %, respectively, for data from the Arabian Sea sourced group, resulting in median BC absorption coefficients of 4.2 and 3.5 Mm-1. Corresponding values for the South Indian Ocean data were 69 and 97 % (0.38 and 0.02 Mm-1). A comparison with other studies in the area indicated an overestimation of their BC levels, by up to two orders of magnitude. This raises the necessity for chemical correction protocols on optical filter-based determinations of BC, before even the sign on the radiative forcing based on their effects can be assessed.

Wavelength-tunable filter utilizing non-cyclic arrayed waveguide grating to create colorless, directionless, contentionless ROADMs

NASA Astrophysics Data System (ADS)

Niwa, Masaki; Takashina, Shoichi; Mori, Yojiro; Hasegawa, Hiroshi; Sato, Ken-ichi; Watanabe, Toshio

2015-01-01

With the continuous increase in Internet traffic, reconfigurable optical add-drop multiplexers (ROADMs) have been widely adopted in the core and metro core networks. Current ROADMs, however, allow only static operation. To realize future dynamic optical-network services, and to minimize any human intervention in network operation, the optical signal add/drop part should have colorless/directionless/contentionless (C/D/C) capabilities. This is possible with matrix switches or a combination of splitter-switches and optical tunable filters. The scale of the matrix switch increases with the square of the number of supported channels, and hence, the matrix-switch-based architecture is not suitable for creating future large-scale ROADMs. In contrast, the numbers of splitter ports, switches, and tunable filters increase linearly with the number of supported channels, and hence the tunable-filter-based architecture will support all future traffic. So far, we have succeeded in fabricating a compact tunable filter that consists of multi-stage cyclic arrayed-waveguide gratings (AWGs) and switches by using planar-lightwave-circuit (PLC) technologies. However, this multistage configuration suffers from large insertion loss and filter narrowing. Moreover, power-consuming temperature control is necessary since it is difficult to make cyclic AWGs athermal. We propose here novel tunable-filter architecture that sandwiches a single-stage non-cyclic athermal AWG having flatter-topped passbands between small-scale switches. With this configuration, the optical tunable filter attains low insertion loss, large passband bandwidths, low power consumption, compactness, and high cost-effectiveness. A prototype is monolithically fabricated with PLC technologies and its excellent performance is experimentally confirmed utilizing 80-channel 30-GBaud dual-polarization quadrature phase-shift-keying (QPSK) signals.

An electron impact emission spectroscopy flux sensor for monitoring deposition rate at high background gas pressure with improved accuracy

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

Lu, C.; Blissett, C. D.; Diehl, G.

2008-07-15

Electron impact emission spectroscopy (EIES) has been proven to be a critical tool for film composition control during codeposition processes for the fabrication of multicomponent thin film materials including the high-efficiency copper-indium-gallium-diselenide photovoltaic cells. This technique is highly specific to atomic species because the emission spectrum of each element is unique, and the typical width of atomic emission lines is very narrow. Noninterfering emission lines can generally be allocated to different atomic species. However, the electron impact emission spectra of many molecular species are often broadband in nature. When the optical emission from an EIES sensor is measured by usingmore » a wavelength selection device with a modest resolution, such as an optical filter or monochromator, the emissions from common residual gases may interfere with that from the vapor flux and cause erroneous flux measurement. The interference is most pronounced when measuring low flux density with the presence of gases such as in reactive deposition processes. This problem is solved by using a novel EIES sensor that has two electron impact excitation sources in separate compartments but with one common port for optical output. The vapor flux is allowed to pass through one compartment only. Using a tristate excitation scheme and appropriate signal processing technique, the interfering signals from residual gases can be completely eliminated from the output signal of the EIES monitor for process control. Data obtained from Cu and Ga evaporations with the presence of common residual gases such as CO{sub 2} and H{sub 2}O are shown to demonstrate the improvement in sensor performance. The new EIES sensor is capable of eliminating the effect of interfering residual gases with pressure as high as in the upper 10{sup -5} Torr range.« less

All-optical NRZ wavelength conversion based on a single hybrid III-V/Si SOA and optical filtering.

PubMed

Wu, Yingchen; Huang, Qiangsheng; Keyvaninia, Shahram; Katumba, Andrew; Zhang, Jing; Xie, Weiqiang; Morthier, Geert; He, Jian-Jun; Roelkens, Gunther

2016-09-05

We demonstrate all-optical wavelength conversion (AOWC) of non-return-to-zero (NRZ) signal based on cross-gain modulation in a single heterogeneously integrated III-V-on-silicon semiconductor optical amplifier (SOA) with an optical bandpass filter. The SOA is 500 μm long and consumes less than 250 mW electrical power. We experimentally demonstrate 12.5 Gb/s and 40 Gb/s AOWC for both wavelength up and down conversion.

Updates to WFC3/UVIS Filter-Dependent and Filter-Distinct Distortion Corrections

NASA Astrophysics Data System (ADS)

Martlin, Catherine; Kozhurina-Platais, Vera; McKay, Myles; Sabbi, Elena

2018-06-01

The WFC3/UVIS filter wheel contains 63 filters that cover a large range of wavelengths from near ultraviolet to the near infrared. Previously, analysis was completed on the 14 most used UVIS filters to calibrate geometric distortions. These distortions are due to a combination of the optical assembly of HST as well as the variabilities in the composition of individual filters. We report recent updates to reference files that aid in correcting for these distortions of an additional 22 UVIS narrow and medium band filters and 4 unique UVIS filters. They were created following a calibration of the large-scale optical distortions and fine-scale filter-dependent distortions. Furthermore, we present results on a study into a selection of unique polynomial coefficient terms from all solved filters which allows us to better investigate the filter-dependent patterns across a large range of wavelengths.These updates will provide important enhancements for HST/WFC3 users as they allow more accurate alignment of images across the range of UVIS filters.

Optical properties behavior of three optical filters and a mirror used in the internal optical head of a Raman laser spectrometer after exposed to proton radiation

NASA Astrophysics Data System (ADS)

Guembe, V.; Alvarado, C. G.; Fernández-Rodriguez, M.; Gallego, P.; Belenguer, T.; Díaz, E.

2017-11-01

The Raman Laser Spectrometer is one of the ExoMars Pasteur Rover's payload instruments that is devoted to the analytical analysis of the geochemistry content and elemental composition of the observed minerals provided by the Rover through Raman spectroscopy technique. One subsystem of the RLS instrument is the Internal Optical Head unit (IOH), which is responsible for focusing the light coming from the laser onto the mineral under analysis and for collecting the Raman signal emitted by the excited mineral. The IOH is composed by 4 commercial elements for Raman spectroscopy application; 2 optical filters provided by Iridian Spectral Technologies Company and 1 optical filter and 1 mirror provided by Semrock Company. They have been exposed to proton radiation in order to analyze their optical behaviour due to this hostile space condition. The proton irradiation test was performed following the protocol of LINES lab (INTA). The optical properties have been studied through transmittance, reflectance and optical density measurements, the final results and its influence on optical performances are presented.

Demodulation of an optical fiber MEMS pressure sensor based on single bandpass microwave photonic filter.

PubMed

Wang, Yiping; Ni, Xiaoqi; Wang, Ming; Cui, Yifeng; Shi, Qingyun

2017-01-23

In this paper, a demodulation method for optic fiber micro-electromechanical systems (MEMS) extrinsic Fabry-Perot interferometer (EFPI) pressure sensor exploiting microwave photonics filter technique is firstly proposed and experimentally demonstrated. A single bandpass microwave photonic filter (MPF) which mainly consists of a spectrum-sliced light source, a pressurized optical fiber MEMS EFPI, a phase modulator (PM) and a length of dispersion compensating fiber (DCF) is demonstrated. The frequency response of the filter with respect to the pressure is studied. By detecting the resonance frequency shifts of the MPF, the pressure can be determined. The theoretical and experimental results show that the proposed EFPI pressure demodulation method has a higher resolution and higher speed than traditional methods based on optical spectrum analysis. The sensitivity of the sensor is measured to be as high as 86 MHz/MPa in the range of 0-4Mpa. Moreover, the sensitivity can be easily adjusted.

All optical controlled photonic integrated circuits using azo dye functionized sol-gel material

NASA Astrophysics Data System (ADS)

Ke, Xianjun

The main focus of this dissertation is development and characterization of all-optical controllable azo dye functionized sol gel material, demonstrating a PIC fabrication technique on glass substrate using such material, and exploration and feasibility demonstration of three PIC functional devices namely optical variable attenuator, optical switches, and optical tunable filters using the material. The realization of all the devices in this dissertation are based on one material: dye functionalized sol-gel material. A photochromic sol-gel material functionalized with azo dye was synthesized and characterized. It possesses a photochromic characteristic under the control of green laser beam illumination. The material characteristics suggest the possibility of a new promising material platform candidate for the fabrication of alloptical controlled photonic integrated circuits. As the first potential application of the dye functionalized sol-gel material, an alloptical variable attenuator was designed and demonstrated. The optical variable attenuation is achieved in Mach-Zehnder interferometric configuration through all-optical modulation of sol-gel waveguide phase shifters. A 2 x 2 optical switch based on multimode interference (MMI) waveguide structure is proposed in the dissertation. The schematic configuration of the optical switch consists of a cascade of two identical MMIs with two all-optical controlled phase shifters realized by using the photochromic sol-gel material. The cross or bar switch state of the optical switch is determined by the phase difference between the two sol-gel waveguide phase shifters. An all-optical tunable filter is designed and its feasibility demonstrated by using the sol-gel photochromic material. Except for the phase change demonstrated on sol-gel waveguide phase shifters, dynamic gratings were observed on sol-gel film when exposed to two interference beams. This reveals the possibility of realizing Bragg grating-based tunable filters. The schematic configuration of proposed tunable filters consists of a single straight waveguide embedded with a sol-gel waveguide. The wavelength tuning of the tunable filters is accomplished by varying the grating period.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: The 2P1/2 → 2P3/2 laser transition in atomic iodine and the problem of search for signals from extraterrestrial intelligence

NASA Astrophysics Data System (ADS)

Kutaev, Yu F.; Mankevich, S. K.; Nosach, O. Yu; Orlov, E. P.

2007-07-01

It is proposed to search for signals from extraterrestrial intelligence (ETI) at a wavelength of 1.315 μm of the laser 2P1/2 → 2P3/2 transition in the atomic iodine, which can be used for this purpose as the natural frequency reference. The search at this wavelength is promising because active quantum filters (AQFs) with the quantum sensitivity limit have been developed for this wavelength, which are capable of receiving laser signals, consisting of only a few photons, against the background of emission from a star under study. In addition, high-power iodine lasers emitting diffraction-limited radiation at 1.315 μm have been created, which highly developed ETI also can have. If a ETI sends in our direction a diffraction-limited 10-ns, 1-kJ laser pulse with the beam diameter of 10 m, a receiver with an AQF mounted on a ten-meter extra-atmospheric optical telescope can detect this signal at a distance of up to 300 light years, irrespective of the ETI position on the celestial sphere. The realisation of the projects for manufacturing optical telescopes of diameter 30 m will increase the research range up to 2700 light years. A weak absorption of the 1.315-μm radiation in the Earth atmosphere (the signal is attenuated by less than 20%) allows the search for ETI signals by using ground telescopes equipped with adaptive optical systems.

Spectral Filtering Criteria for U-Band Test Light for In-Service Line Monitoring in Optical Fiber Networks

NASA Astrophysics Data System (ADS)

Honda, Nazuki; Izumita, Hisashi; Nakamura, Minoru

2006-06-01

In the fiber-to-the-home era, thousands of optical fibers will have to be accommodated in the central offices of optical access networks. To reduce maintenance costs and improve the service reliability of optical fiber networks, the authors must develop an optical fiber line testing system with a function for in-service line monitoring that uses a test light with a wavelength different from the communication light wavelength. To monitor an in-service line in an optical network, the effective rejection ratio of the test light must be taken into account. This ratio depends on the spectrum of the test light from the optical time-domain reflectometer and the rejection band of the filter in front of the optical network unit. The dependence of the effective rejection ratio as a function of the sideband suppression ratio (SBSR) and of the ratio of the rejection band to the bandwidth of the sideband noise d/D is clarified. When d/D =0.1 and the target effective rejection ratio of the filter is -40 dB, the SBSR and the filter loss of the termination cable must be -70 and -43 dB, respectively, or the SBSR must be -80 dB. When d/D < 0.5 and the target effective rejection ratio of the filter is -40 dB, the SBSR is also required to be -80 dB. In-service line monitoring for a 10-Gb/s transmission using a 1650-nm test light with an SBSR of -80 dB is also demonstrated.

Fiber-optic apparatus and method for measurement of luminescence and raman scattering

DOEpatents

Myrick, Michael L.; Angel, Stanley M.

1993-01-01

A dual fiber forward scattering optrode for Raman spectroscopy with the remote ends of the fibers in opposed, spaced relationship to each other to form a analyte sampling space therebetween and the method of measuring Raman spectra utilizing same. One optical fiber is for sending an exciting signal to the remote sampling space and, at its remote end, has a collimating microlens and an optical filter for filtering out background emissions generated in the fiber. The other optical fiber is for collecting the Raman scattering signal at the remote sampling space and, at its remote end, has a collimating microlens and an optical filter to prevent the exciting signal from the exciting fiber from entering the collection fiber and to thereby prevent the generation of background emissions in the collecting fiber.

Optical filters for UV to near IR space applications

NASA Astrophysics Data System (ADS)

Begou, T.; Krol, H.; Hecquet, Christophe; Bondet, C.; Lumeau, J.; Grèzes-Besset, C.; Lequime, M.

2017-11-01

We present hereafter the results on the fabrication of complex optical filters within the Institut Fresnel in close collaboration with CILAS. Bandpass optical filters dedicated to astronomy and space applications, with central wavelengths ranging from ultraviolet to near infrared, were deposited on both sides of glass substrates with performances in very good congruence with theoretical designs. For these applications, the required functions are particularly complex as they must present a very narrow bandwidth as well as a high level of rejection over a broad spectral range. In addition to those severe optical performances, insensitivity to environmental conditions is necessary. For this purpose, robust solutions with particularly stable performances have to be proposed.

Thermo-optically tunable thin film devices

NASA Astrophysics Data System (ADS)

Domash, Lawrence H.

2003-10-01

We report advances in tunable thin film technology and demonstration of multi-cavity tunable filters. Thin film interference coatings are the most widely used optical technology for telecom filtering, but until recently no tunable versions have been known except for mechanically rotated filters. We describe a new approach to broadly tunable components based on the properties of semiconductor thin films with large thermo-optic coefficients. The technology is based on amorphous silicon deposited by plasma-enhanced chemical vapor deposition (PECVD), a process adapted for telecom applications from its origins in the flat-panel display and solar cell industries. Unlike MEMS devices, tunable thin films can be constructed in sophisticated multi-cavity, multi-layer optical designs.

Polymer based resonant waveguide grating photonic filter with on-chip thermal tuning

NASA Astrophysics Data System (ADS)

Chaudhuri, Ritesh Ray; Enemuo, Amarachukwu N.; Song, Youngsik; Seo, Sang-Woo

2018-07-01

In this paper, we present the development of a multilayer polymer resonant waveguide grating (RWG)-based optical filter with an integrated microheater for on-chip thermal spectral tuning. RWG optical filter is fabricated using polymer-based materials. Therefore, its integration can be applied to different material platforms. Typical RWG structure is sensitive to back optical reflection from the structures below. To reduce the effect of back reflection from the metal heater and improve the quality of the integrated RWG filter output, an intermediate absorption layer was implemented utilizing an epoxy based carbon coating. This approach effectively suppresses the background noise in the RWG characteristics. The central wavelength of the reported filter was designed around 1550 nm. Experimentally, wavelength tuning of 21.96 nm was achieved for operating temperature range of 81 °C with approximately 150mW power consumption. Based on the layer-by-layer fabrication approach, the presented thermally tunable RWG filter on a chip has potential for use in low cost hybrid communication systems and spectral sensing applications.

Super-resolution pupil filtering for visual performance enhancement using adaptive optics

NASA Astrophysics Data System (ADS)

Zhao, Lina; Dai, Yun; Zhao, Junlei; Zhou, Xiaojun

2018-05-01

Ocular aberration correction can significantly improve visual function of the human eye. However, even under ideal aberration correction conditions, pupil diffraction restricts the resolution of retinal images. Pupil filtering is a simple super-resolution (SR) method that can overcome this diffraction barrier. In this study, a 145-element piezoelectric deformable mirror was used as a pupil phase filter because of its programmability and high fitting accuracy. Continuous phase-only filters were designed based on Zernike polynomial series and fitted through closed-loop adaptive optics. SR results were validated using double-pass point spread function images. Contrast sensitivity was further assessed to verify the SR effect on visual function. An F-test was conducted for nested models to statistically compare different CSFs. These results indicated CSFs for the proposed SR filter were significantly higher than the diffraction correction (p < 0.05). As such, the proposed filter design could provide useful guidance for supernormal vision optical correction of the human eye.

Semiconductor ring lasers subject to both on-chip filtered optical feedback and external conventional optical feedback

NASA Astrophysics Data System (ADS)

Khoder, Mulham; Van der Sande, Guy; Danckaert, Jan; Verschaffelt, Guy

2016-05-01

It is well known that the performance of semiconductor lasers is very sensitive to external optical feedback. This feedback can lead to changes in lasing characteristics and a variety of dynamical effects including chaos and coherence collapse. One way to avoid this external feedback is by using optical isolation, but these isolators and their packaging will increase the cost of the total system. Semiconductor ring lasers nowadays are promising sources in photonic integrated circuits because they do not require cleaved facets or mirrors to form a laser cavity. Recently, some of us proposed to combine semiconductor ring lasers with on chip filtered optical feedback to achieve tunable lasers. The feedback is realized by employing two arrayed waveguide gratings to split/recombine light into different wavelength channels. Semiconductor optical amplifier gates are used to control the feedback strength. In this work, we investigate how such lasers with filtered feedback are influenced by an external conventional optical feedback. The experimental results show intensity fluctuations in the time traces in both the clockwise and counterclockwise directions due to the conventional feedback. We quantify the strength of the conventional feedback induced dynamics be extracting the standard deviation of the intensity fluctuations in the time traces. By using filtered feedback, we can shift the onset of the conventional feedback induced dynamics to larger values of the feedback rate [ Khoder et al, IEEE Photon. Technol. Lett. DOI: 10.1109/LPT.2016.2522184]. The on-chip filtered optical feedback thus makes the semiconductor ring laser less senstive to the effect of (long) conventional optical feedback. We think these conclusions can be extended to other types of lasers.

Method and apparatus for noble gas atom detection with isotopic selectivity

DOEpatents

Hurst, G. Samuel; Payne, Marvin G.; Chen, Chung-Hsuan; Parks, James E.

1984-01-01

Apparatus and methods of operation are described for determining, with isotopic selectivity, the number of noble gas atoms in a sample. The analysis is conducted within an evacuated chamber which can be isolated by a valve from a vacuum pumping system capable of producing a pressure of 10.sup.-8 Torr. Provision is made to pass pulses of laser beams through the chamber, these pulses having wavelengths appropriate for the resonance ionization of atoms of the noble gas under analysis. A mass filter within the chamber selects ions of a specific isotope of the noble gas, and means are provided to accelerate these selected ions sufficiently for implantation into a target. Specific types of targets are discussed. An electron measuring device produces a signal relatable to the number of ions implanted into the target and thus to the number of atoms of the selected isotope of the noble gas removed from the gas sample. The measurement can be continued until a substantial fraction, or all, of the atoms in the sample have been counted. Furthermore, additional embodiments of the apparatus are described for bunching the atoms of a noble gas for more rapid analysis, and for changing the target for repetitive cycling of the gas in the chamber. The number of repetitions of the cyclic steps depend upon the concentration of the isotope of interest, the separative efficiency of the mass filter, etc. The cycles are continued until a desired selectivity is achieved. Also described are components and a method of operation for a pre-enrichment operation for use when an introduction of a total sample would elevate the pressure within the chamber to levels in excess of those for operation of the mass filter, specifically a quadrupole mass filter. Specific examples of three noble gas isotope analyses are described.

Narrow bandpass steep edge optical filter for the JAST/T80 telescope instrumentation

NASA Astrophysics Data System (ADS)

Reichel, S.; Brauneck, U.; Bourquin, S.; Marín-Franch, A.

2013-09-01

The Observatorio Astrofisico de Javalambre in Spain observes with its JAST/T80 telescope galaxies in the Local Universe in a systematic study. This is accomplished with a multi-band photometric all sky survey called Javalambre Photometric Local Universe Survey (J-PLUS). A wide field camera receives the signals from universe via optical filters. In this presentation the development and design of a narrow bandpass steep edge filter with wide suppression will be shown. The filter has a full width half maximum in the range of 13-15 nm (with <1 nm tolerance) with central wavelengths in the range 350-860nm and an average transmission larger than 90% in the passband. Signals beyond the passband (blocking range) have to be suppressed down to 250nm and up to 1050nm (spectral regime), where a blocking of OD 5 (transmission < 10-5) is required. The edges have to be steep for a small transition width from 5% to 80%. The spectral requirements result in a large number of layers which are deposited with magnetron sputtering. The transmitted wavefront error of the optical filter must be less than lambda/2 over the 100mm aperture and the central wavelength uniformity must be better than +/- 0.4% over the clear aperture. The filter consists of optical filter glass and a coated substrate in order to reach the spectral requirements. The substrate is coated with more than 120 layers. The total filter thickness was specified to be 8.0mm. Results of steep edge narrow bandpass filters will be demonstrated fulfilling all these demanding requirements.

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR EXTRACTION OF METALS FROM SOIL, DUST, AIR FILTER, AND SURFACE AND DERMAL SAMPLES FOR AA (GRAPHITE FURNACE OR FLAME) OR ICP-AES ANALYSIS (BCO-L-3.1)

EPA Science Inventory

The purpose of this SOP is to describe the acid digestion of soil, house dust, air filter, and surface or dermal wipe samples for analysis using inductively coupled plasma atomic emissions spectrometry (ICP-AES) and/or graphite furnace atomic absorption spectrometry (GFAAS) or fl...

Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures

DOE PAGES

Song, Tiancheng; Cai, Xinghan; Tu, Matisse Wei-Yuan; ...

2018-05-03

Magnetic multilayer devices that exploit magnetoresistance are the backbone of magnetic sensing and data storage technologies. Here, we report multiple-spin-filter magnetic tunnel junctions (sf-MTJs) based on van der Waals (vdW) heterostructures in which atomically thin chromium triiodide (CrI3) acts as a spin-filter tunnel barrier sandwiched between graphene contacts. We demonstrate tunneling magnetoresistance which is drastically enhanced with increasing CrI 3 layer thickness, reaching a record 19,000% for magnetic multilayer structures using four-layer sf-MTJs at low temperatures. Using magnetic circular dichroism measurements, we attribute these effects to the intrinsic layer-by-layer antiferromagnetic ordering of the atomically thin CrI 3. In conclusion, ourmore » work reveals the possibility to push magnetic information storage to the atomically thin limit and highlights CrI 3 as a superlative magnetic tunnel barrier for vdW heterostructure spintronic devices.« less

Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures

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

Song, Tiancheng; Cai, Xinghan; Tu, Matisse Wei-Yuan

Magnetic multilayer devices that exploit magnetoresistance are the backbone of magnetic sensing and data storage technologies. Here, we report multiple-spin-filter magnetic tunnel junctions (sf-MTJs) based on van der Waals (vdW) heterostructures in which atomically thin chromium triiodide (CrI3) acts as a spin-filter tunnel barrier sandwiched between graphene contacts. We demonstrate tunneling magnetoresistance which is drastically enhanced with increasing CrI 3 layer thickness, reaching a record 19,000% for magnetic multilayer structures using four-layer sf-MTJs at low temperatures. Using magnetic circular dichroism measurements, we attribute these effects to the intrinsic layer-by-layer antiferromagnetic ordering of the atomically thin CrI 3. In conclusion, ourmore » work reveals the possibility to push magnetic information storage to the atomically thin limit and highlights CrI 3 as a superlative magnetic tunnel barrier for vdW heterostructure spintronic devices.« less

Electropolishing effect on roughness metrics of ground stainless steel: a length scale study

NASA Astrophysics Data System (ADS)

Nakar, Doron; Harel, David; Hirsch, Baruch

2018-03-01

Electropolishing is a widely-used electrochemical surface finishing process for metals. The electropolishing of stainless steel has vast commercial application, such as improving corrosion resistance, improving cleanness, and brightening. The surface topography characterization is performed using several techniques with different lateral resolutions and length scales, from atomic force microscopy in the nano-scale (<0.1 µm) to stylus and optical profilometry in the micro- and mesoscales (0.1 µm-1 mm). This paper presents an experimental length scale study of the surface texture of ground stainless steel followed by an electropolishing process in the micro and meso lateral scales. Both stylus and optical profilometers are used, and multiple cut-off lengths of the standard Gaussian filter are adopted. While the commonly used roughness amplitude parameters (Ra, Rq and Rz) fail to characterize electropolished textures, the root mean square slope (RΔq) is found to better describe the electropolished surfaces and to be insensitive to scale.

Broadly tunable thin-film intereference coatings: active thin films for telecom applications

NASA Astrophysics Data System (ADS)

Domash, Lawrence H.; Ma, Eugene Y.; Lourie, Mark T.; Sharfin, Wayne F.; Wagner, Matthias

2003-06-01

Thin film interference coatings (TFIC) are the most widely used optical technology for telecom filtering, but until recently no tunable versions have been known except for mechanically rotated filters. We describe a new approach to broadly tunable TFIC components based on the thermo-optic properties of semiconductor thin films with large thermo-optic coefficients 3.6X10[-4]/K. The technology is based on amorphous silicon thin films deposited by plasma-enhanced chemical vapor deposition (PECVD), a process adapted for telecom applications from its origins in the flat-panel display and solar cell industries. Unlike MEMS devices, tunable TFIC can be designed as sophisticated multi-cavity, multi-layer optical designs. Applications include flat-top passband filters for add-drop multiplexing, tunable dispersion compensators, tunable gain equalizers and variable optical attenuators. Extremely compact tunable devices may be integrated into modules such as optical channel monitors, tunable lasers, gain-equalized amplifiers, and tunable detectors.

Logarithmic r-θ mapping for hybrid optical neural network filter for multiple objects recognition within cluttered scenes

NASA Astrophysics Data System (ADS)

Kypraios, Ioannis; Young, Rupert C. D.; Chatwin, Chris R.; Birch, Phil M.

2009-04-01

θThe window unit in the design of the complex logarithmic r-θ mapping for hybrid optical neural network filter can allow multiple objects of the same class to be detected within the input image. Additionally, the architecture of the neural network unit of the complex logarithmic r-θ mapping for hybrid optical neural network filter becomes attractive for accommodating the recognition of multiple objects of different classes within the input image by modifying the output layer of the unit. We test the overall filter for multiple objects of the same and of different classes' recognition within cluttered input images and video sequences of cluttered scenes. Logarithmic r-θ mapping for hybrid optical neural network filter is shown to exhibit with a single pass over the input data simultaneously in-plane rotation, out-of-plane rotation, scale, log r-θ map translation and shift invariance, and good clutter tolerance by recognizing correctly the different objects within the cluttered scenes. We record in our results additional extracted information from the cluttered scenes about the objects' relative position, scale and in-plane rotation.

Simulation of synthetic discriminant function optical implementation

NASA Astrophysics Data System (ADS)

Riggins, J.; Butler, S.

1984-12-01

The optical implementation of geometrical shape and synthetic discriminant function matched filters is computer modeled. The filter implementation utilizes the Allebach-Keegan computer-generated hologram algorithm. Signal-to-noise and efficiency measurements were made on the resultant correlation planes.

Magneto-optical trap for thulium atoms

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

Sukachev, D.; Sokolov, A.; Chebakov, K.

2010-07-15

Thulium atoms are trapped in a magneto-optical trap using a strong transition at 410 nm with a small branching ratio. We trap up to 7x10{sup 4} atoms at a temperature of 0.8(2) mK after deceleration in a 40-cm-long Zeeman slower. Optical leaks from the cooling cycle influence the lifetime of atoms in the magneto-optical trap which varies between 0.3 and 1.5 s in our experiments. The lower limit for the leaking rate from the upper cooling level is measured to be 22(6) s{sup -1}. The repumping laser transferring the atomic population out of the F=3 hyperfine ground-state sublevel gives amore » 30% increase for the lifetime and the number of atoms in the trap.« less

Software-defined microwave photonic filter with high reconfigurable resolution

PubMed Central

Wei, Wei; Yi, Lilin; Jaouën, Yves; Hu, Weisheng

2016-01-01

Microwave photonic filters (MPFs) are of great interest in radio frequency systems since they provide prominent flexibility on microwave signal processing. Although filter reconfigurability and tunability have been demonstrated repeatedly, it is still difficult to control the filter shape with very high precision. Thus the MPF application is basically limited to signal selection. Here we present a polarization-insensitive single-passband arbitrary-shaped MPF with ~GHz bandwidth based on stimulated Brillouin scattering (SBS) in optical fibre. For the first time the filter shape, bandwidth and central frequency can all be precisely defined by software with ~MHz resolution. The unprecedented multi-dimensional filter flexibility offers new possibilities to process microwave signals directly in optical domain with high precision thus enhancing the MPF functionality. Nanosecond pulse shaping by implementing precisely defined filters is demonstrated to prove the filter superiority and practicability. PMID:27759062

Software-defined microwave photonic filter with high reconfigurable resolution.

PubMed

Wei, Wei; Yi, Lilin; Jaouën, Yves; Hu, Weisheng

2016-10-19

Microwave photonic filters (MPFs) are of great interest in radio frequency systems since they provide prominent flexibility on microwave signal processing. Although filter reconfigurability and tunability have been demonstrated repeatedly, it is still difficult to control the filter shape with very high precision. Thus the MPF application is basically limited to signal selection. Here we present a polarization-insensitive single-passband arbitrary-shaped MPF with ~GHz bandwidth based on stimulated Brillouin scattering (SBS) in optical fibre. For the first time the filter shape, bandwidth and central frequency can all be precisely defined by software with ~MHz resolution. The unprecedented multi-dimensional filter flexibility offers new possibilities to process microwave signals directly in optical domain with high precision thus enhancing the MPF functionality. Nanosecond pulse shaping by implementing precisely defined filters is demonstrated to prove the filter superiority and practicability.

Frequency Standards and Metrology

NASA Astrophysics Data System (ADS)

Maleki, Lute

2009-04-01

Preface / Lute Maleki -- Symposium history / Jacques Vanier -- Symposium photos -- pt. I. Fundamental physics. Variation of fundamental constants from the big bang to atomic clocks: theory and observations (Invited) / V. V. Flambaum and J. C. Berengut. Alpha-dot or not: comparison of two single atom optical clocks (Invited) / T. Rosenband ... [et al.]. Variation of the fine-structure constant and laser cooling of atomic dysprosium (Invited) / N. A. Leefer ... [et al.]. Measurement of short range forces using cold atoms (Invited) / F. Pereira Dos Santos ... [et al.]. Atom interferometry experiments in fundamental physics (Invited) / S. W. Chiow ... [et al.]. Space science applications of frequency standards and metrology (Invited) / M. Tinto -- pt. II. Frequency & metrology. Quantum metrology with lattice-confined ultracold Sr atoms (Invited) / A. D. Ludlow ... [et al.]. LNE-SYRTE clock ensemble: new [symbol]Rb hyperfine frequency measurement - spectroscopy of [symbol]Hg optical clock transition (Invited) / M. Petersen ... [et al.]. Precise measurements of S-wave scattering phase shifts with a juggling atomic clock (Invited) / S. Gensemer ... [et al.]. Absolute frequency measurement of the [symbol] clock transition (Invited) / M. Chwalla ... [et al.]. The semiclassical stochastic-field/atom interaction problem (Invited) / J. Camparo. Phase and frequency noise metrology (Invited) / E. Rubiola ... [et al.]. Optical spectroscopy of atomic hydrogen for an improved determination of the Rydberg constant / J. L. Flowers ... [et al.] -- pt. III. Clock applications in space. Recent progress on the ACES mission (Invited) / L. Cacciapuoti and C. Salomon. The SAGAS mission (Invited) / P. Wolf. Small mercury microwave ion clock for navigation and radioScience (Invited) / J. D. Prestage ... [et al.]. Astro-comb: revolutionizing precision spectroscopy in astrophysics (Invited) / C. E. Kramer ... [et al.]. High frequency very long baseline interferometry: frequency standards and imaging an event horizon (Invited) / S. Doeleman. Optically-pumped space cesium clock for Galileo: results of the breadboard / R. Ruffieux ... [et al.] -- pt. IV. Optical clocks I: lattice clocks. Optical lattice clock: seven years of progress and next steps (Invited) / H. Katori, M. Takamoto and T. Akatsuka. The Yb optical lattice clock (Invited) / N. D. Demke ... [et al.]. Optical Lattice clock with Sr atoms (Invited) / P. G. Westergaard ... [et al.]. Development of an optical clock based on neutral strontium atoms held in a lattice trap / E. A. Curtis ... [et al.]. Decoherence and losses by collisions in a [symbol]Sr lattice clock / J. S. R. Vellore Winfred ... [et al.]. Lattice Yb optical clock and cryogenic Cs fountain at INRIM / F. Levi ... [et al.] -- pt. V. Optical clocks II: ion clocks. [Symbol]Yb+ single-ion optical frequency standards (Invited) / Chr. Tamm ... [et al.]. An optical clock based on a single trapped [symbol]Sr+ ion (Invited) / H. S. Margolis ... [et al.]. A trapped [symbol]Yb+ ion optical frequency standard based on the [symbol] transition (Invited) / P. Gill ... [et al.]. Overview of highly accurate RF and optical frequency standards at the National Research Council of Canada (Invited) / A. A. Madej ... [et al.] -- pt. VI. Optical frequency combs. Extreme ultraviolet frequency combs for spectroscopy (Invited) / A. Ozawa ... [et al.]. Development of an optical clockwork for the single trapped strontium ion standard at 445 THz / J. E. Bernard ... [et al.]. A phase-coherent link between the visible and infrared spectral ranges using a combination of CW OPO and femtosecond laser frequency comb / E. V. Kovalchuk and A. Peters. Improvements to the robustness of a TI: sapphire-based femtosecond comb at NPL / V. Tsatourian ... [et al.] -- pt. VII. Atomic microwave standards. NIST FI and F2 (Invited) / T. P. Heavner ... [et al.]. Atomic fountains for the USNO master clock (Invited) / C. Ekstrom ... [et al.]. The transportable cesium fountain clock NIM5: its construction and performance (Invited) / T. Li ... [et al.].Compensated multi-pole mercury trapped ion frequency standard and stability evaluation of systematic effects (Invited) / E. A. Burt ... [et al.]. Research of frequency standards in SIOM - atomic frequency standards based on coherent storage (Invited) / B. Yan ... [et al.]. The PTB fountain clock ensemble preliminary characterization of the new fountain CSF2 / N. Nemitz ... [et al.]. The pulsed optically pumped clock: microwave and optical detection / S. Micalizio ... [et al.]. Research on characteristics of pulsed optically pumped rubidium frequency standard / J. Deng ... [et al.]. Status of the continuous cold fountain clocks at METAS-LTF / A. Joyet ... [et al.]. Experiments with a new [symbol]Hg+ ion clock / E. A. Burt ... [et al.]. Optimising a high-stability CW laser-pumped rubidium gas-cell frequency standard / C. Affolderbach ... [et al.]. Raman-Ramsey Cs cell atomic clock / R. Boudot ... [et al.] -- pt. VIII. Microwave resonators & oscillators. Solutions and ultimate limits in temperature compensation of metallic cylindrical microwave resonators (Invited) / A. De Marchi. Cryogenic sapphire oscillators (Invited) / J. G. Hartnett, E. N. Ivanov and M. E. Tobar. Ultra-stable optical cavity: design and experiments / J. Millo ... [et al.]. New results for whispering gallery mode cryogenic sapphire maser oscillators / K. Benmessai ... [et al.] -- pt. IX. Advanced techniques. Fundamental noise-limited optical phase locking at Femtowatt light levels (Invited) / J. Dick ... [et al.]. Microwave and optical frequency transfer via optical fibre / G. Marra ... [et al.]. Ultra-stable laser source for the [symbol]Sr+ single-ion optical frequency standard at NRC / P. Dubé, A. A. Madej and J. E. Bernard. Clock laser system for a strontium lattice clock / T. Legero ... [et al.]. Measurement noise floor for a long-distance optical carrier transmission via fiber / G. Grosche ... [et al.]. Optical frequency transfer over 172 KM of installed fiber / S. Crane -- pt. X. Miniature systems. Chip-scale atomic devices: precision atomic instruments based on MEMS (Invited) / J. Kitching ... [et al.]. CSAC - the chip-scale atomic clock (Invited) / R. Lutwak ... [et al.]. Reaching a few 10[symbol] stability level with a compact cold atom clock / F. X. Esnault ... [et al.]. Evaluation of Lin||Lin CPT for compact and high performance frequency standard / E. Breschi ... [et al.] -- pt. XI. Time scales. Atomic time scales TAI and TI(BIPM): present status and prospects (Invited) / G. Petit. Weight functions for biases in atomic frequency standards / J. H. Shirley -- pt. XII. Interferometers. Definition and construction of noise budget in atom interferometry (Invited) / E. D'Ambriosio. Characterization of a cold atom gyroscope (Invited) / A. Landragin ... [et al.]. A mobile atom interferometer for high precision measurements of local gravity / M. Schmidt ... [et al.]. Demonstration of atom interferometer comprised of geometric beam splitters / Hiromitsu Imai and Atsuo Morinaga -- pt. XIII. New directions. Active optical clocks (Invited) / J. Chen. Prospects for a nuclear optical frequency standard based on Thorium-229 (Invited) / E. Peik ... [et al.]. Whispering gallery mode oscillators and optical comb generators (Invited) / A. B. Matsko ... [et al.]. Frequency comparison using energy-time entangled photons / A. Stefanov -- List of participants.

Scheme for generating the singlet state of three atoms trapped in distant cavities coupled by optical fibers

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

Wang, Dong-Yang; Wen, Jing-Ji; Bai, Cheng-Hua

2015-09-15

An effective scheme is proposed to generate the singlet state with three four-level atoms trapped in three distant cavities connected with each other by three optical fibers, respectively. After a series of appropriate atom–cavity interactions, which can be arbitrarily controlled via the selective pairing of Raman transitions and corresponding optical switches, a three-atom singlet state can be successfully generated. The influence of atomic spontaneous decay, photon leakage of cavities and optical fibers on the fidelity of the state is numerically simulated showing that the three-atom singlet state can be generated with high fidelity by choosing the experimental parameters appropriately.

Hidden symmetry and nonlinear paraxial atom optics

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

Impens, Francois

2009-12-15

A hidden symmetry of the nonlinear wave equation is exploited to analyze the propagation of paraxial and uniform atom-laser beams in time-independent and quadratic transverse potentials with cylindrical symmetry. The quality factor and the paraxial ABCD formalism are generalized to account exactly for mean-field interaction effects in such beams. Using an approach based on moments, these theoretical tools provide a simple yet exact picture of the interacting beam profile evolution. Guided atom laser experiments are discussed. This treatment addresses simultaneously optical and atomic beams in a unified manner, exploiting the formal analogy between nonlinear optics, nonlinear paraxial atom optics, andmore » the physics of two-dimensional Bose-Einstein condensates.« less

Fabrication of artificially stacked ultrathin ZnS/MgF2 multilayer dielectric optical filters.

PubMed

Kedawat, Garima; Srivastava, Subodh; Jain, Vipin Kumar; Kumar, Pawan; Kataria, Vanjula; Agrawal, Yogyata; Gupta, Bipin Kumar; Vijay, Yogesh K

2013-06-12

We report a design and fabrication strategy for creating an artificially stacked multilayered optical filters using a thermal evaporation technique. We have selectively chosen a zinc sulphide (ZnS) lattice for the high refractive index (n = 2.35) layer and a magnesium fluoride (MgF2) lattice as the low refractive index (n = 1.38) layer. Furthermore, the microstructures of the ZnS/MgF2 multilayer films are also investigated through TEM and HRTEM imaging. The fabricated filters consist of high and low refractive 7 and 13 alternating layers, which exhibit a reflectance of 89.60% and 99%, respectively. The optical microcavity achieved an average transmittance of 85.13% within the visible range. The obtained results suggest that these filters could be an exceptional choice for next-generation antireflection coatings, high-reflection mirrors, and polarized interference filters.

Lasing by driven atoms-cavity system in collective strong coupling regime.

PubMed

Sawant, Rahul; Rangwala, S A

2017-09-12

The interaction of laser cooled atoms with resonant light is determined by the natural linewidth of the excited state. An optical cavity is another optically resonant system where the loss from the cavity determines the resonant optical response of the system. The near resonant combination of an optical Fabry-Pérot cavity with laser cooled and trapped atoms couples two distinct optical resonators via light and has great potential for precision measurements and the creation of versatile quantum optics systems. Here we show how driven magneto-optically trapped atoms in collective strong coupling regime with the cavity leads to lasing at a frequency red detuned from the atomic transition. Lasing is demonstrated experimentally by the observation of a lasing threshold accompanied by polarization and spatial mode purity, and line-narrowing in the outcoupled light. Spontaneous emission into the cavity mode by the driven atoms stimulates lasing action, which is capable of operating as a continuous wave laser in steady state, without a seed laser. The system is modeled theoretically, and qualitative agreement with experimentally observed lasing is seen. Our result opens up a range of new measurement possibilities with this system.

Optical Pattern Formation in Spatially Bunched Atoms: A Self-Consistent Model and Experiment

NASA Astrophysics Data System (ADS)

Schmittberger, Bonnie L.; Gauthier, Daniel J.

2014-05-01

The nonlinear optics and optomechanical physics communities use different theoretical models to describe how optical fields interact with a sample of atoms. There does not yet exist a model that is valid for finite atomic temperatures but that also produces the zero temperature results that are generally assumed in optomechanical systems. We present a self-consistent model that is valid for all atomic temperatures and accounts for the back-action of the atoms on the optical fields. Our model provides new insights into the competing effects of the bunching-induced nonlinearity and the saturable nonlinearity. We show that it is crucial to keep the fifth and seventh-order nonlinearities that arise when there exists atomic bunching, even at very low optical field intensities. We go on to apply this model to the results of our experimental system where we observe spontaneous, multimode, transverse optical pattern formation at ultra-low light levels. We show that our model accurately predicts our experimentally observed threshold for optical pattern formation, which is the lowest threshold ever reported for pattern formation. We gratefully acknowledge the financial support of the NSF through Grant #PHY-1206040.

Passband switchable microwave photonic multiband filter

PubMed Central

Ge, Jia; Fok, Mable P.

2015-01-01

A reconfigurable microwave photonic (MWP) multiband filter with selectable and switchable passbands is proposed and experimentally demonstrated, with a maximum of 12 simultaneous passbands evenly distributed from 0 to 10 GHz. The scheme is based on the generation of tunable optical comb lines using a two-stage Lyot loop filter, such that various filter tap spacings and spectral combinations are obtained for the configuration of the MWP filter. Through polarization state adjustment inside the Lyot loop filter, an optical frequency comb with 12 different comb spacings is achieved, which corresponds to a MWP filter with 12 selectable passbands. Center frequencies of the filter passbands are switchable, while the number of simultaneous passbands is tunable from 1 to 12. Furthermore, the MWP multiband filter can either work as an all-block, single-band or multiband filter with various passband combinations, which provide exceptional operation flexibility. All the passbands have over 30 dB sidelobe suppression and 3-dB bandwidth of 200 MHz, providing good filter selectivity. PMID:26521693

Passband switchable microwave photonic multiband filter.

PubMed

Ge, Jia; Fok, Mable P

2015-11-02

A reconfigurable microwave photonic (MWP) multiband filter with selectable and switchable passbands is proposed and experimentally demonstrated, with a maximum of 12 simultaneous passbands evenly distributed from 0 to 10 GHz. The scheme is based on the generation of tunable optical comb lines using a two-stage Lyot loop filter, such that various filter tap spacings and spectral combinations are obtained for the configuration of the MWP filter. Through polarization state adjustment inside the Lyot loop filter, an optical frequency comb with 12 different comb spacings is achieved, which corresponds to a MWP filter with 12 selectable passbands. Center frequencies of the filter passbands are switchable, while the number of simultaneous passbands is tunable from 1 to 12. Furthermore, the MWP multiband filter can either work as an all-block, single-band or multiband filter with various passband combinations, which provide exceptional operation flexibility. All the passbands have over 30 dB sidelobe suppression and 3-dB bandwidth of 200 MHz, providing good filter selectivity.

Design and manufacture of super-multilayer optical filters based on PARMS technology

NASA Astrophysics Data System (ADS)

Lü, Shaobo; Wang, Ruisheng; Ma, Jing; Jiang, Chao; Mu, Jiali; Zhao, Shuaifeng; Yin, Xiaojun

2018-04-01

Three multilayer interference optical filters, including a UV band-pass, a VIS dual-band-pass and a notch filter, were designed by using Ta2O5, Nb2O5, Al2O3 and SiO2 as high- and low-index materials. During the design of the coating process, a hybrid optical monitoring and RATE-controlled layer thickness control scheme was adopted. The coating process was simulated by using the optical monitoring system (OMS) Simulator, and the simulation result indicated that the layer thickness can be controlled within an error of less than ±0.1%. The three filters were manufactured on a plasma-assisted reactive magnetic sputtering (PARMS) coating machine. The measurements indicate that for the UV band-pass filter, the peak transmittance is higher than 95% and the blocking density is better than OD6 in the 300-1100 nm region, whereas for the dual-band-pass filter, the center wavelength positioning accuracy of the two passbands are less than ±2 nm, the peak transmittance is higher than 95% and blocking density is better than OD6 in the 300-950 nm region. Finally, for the notch filter, the minimum transmittance rates are >90% and >94% in the visible and near infrared, respectively, and the blocking density is better than OD5.5 at 808 nm.

Simulation of a 3D MOT-Optical Molasses Hybrid for Potassium-41 Atoms

NASA Astrophysics Data System (ADS)

Peterson, W. A.; Wrubel, Jonathan

2017-04-01

We report a design and numerical model for a 3D magneto-optical trap (MOT)-optical molasses hybrid for potassium-41 atoms. In this arrangement, the usual quadrupole magnetic field is replaced by an octupole field. The octupole field has a central region of very low magnetic field where our simulations show that the atoms experience an optical molasses, resulting in sub-doppler cooling not possible in a quadrupole MOT. The simulations also show that the presence of the magneto-optical trapping force at the edge of the cooling beams provides a restoring force which cycles atoms through the molasses region. We plan to use this hybrid trap to directly load a far off-resonance optical dipole trap. Because the atoms are recycled for multiple passes through the molasses, we expect a higher phase-space density of atoms loaded into the dipole trap. Similar hybrid cooling schemes should be relevant for lithium-6 and lithium-7, which also have poorly resolved D2 hyperfine structure. Research Corporation for Science Advancement, Cottrell College Science Award.

Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre

PubMed Central

Okaba, Shoichi; Takano, Tetsushi; Benabid, Fetah; Bradley, Tom; Vincetti, Luca; Maizelis, Zakhar; Yampol'skii, Valery; Nori, Franco; Katori, Hidetoshi

2014-01-01

Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom–atom and atom–wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kagome-lattice hollow-core photonic crystal fibre are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom–atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the 1S0−3P1(m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibres improve the optical depth while preserving atomic coherence time. PMID:24934478

All-optical transistor based on Rydberg atom-assisted optomechanical system.

PubMed

Liu, Yi-Mou; Tian, Xue-Dong; Wang, Jing; Fan, Chu-Hui; Gao, Feng; Bao, Qian-Qian

2018-04-30

We study the optical response of a double optomechanical cavity system assisted by two Rydberg atoms. The target atom is only coupled with one side cavity by a single cavity mode, and gate one is outside the cavities. It has been realized that a long-range manipulation of optical properties of a hybrid system, by controlling the Rydberg atom decoupled with the optomechanical cavity. Switching on the coupling between atoms and cavity mode, the original spatial inversion symmetry of the double cavity structure has been broken. Combining the controllable optical non-reciprocity with the coherent perfect absorption/transmission/synthesis effect (CPA/CPT/CPS reported by [ X.-B.Yan Opt. Express 22, 4886 (2014)], we put forward the theoretical schemes of an all-optical transistor which contains functions such as a controllable diode, rectifier, and amplifier by controlling a single gate photon.

Effects of fixture rotation on coating uniformity for high-performance optical filter fabrication

NASA Astrophysics Data System (ADS)

Rubin, Binyamin; George, Jason; Singhal, Riju

2018-04-01

Coating uniformity is critical in fabricating high-performance optical filters by various vacuum deposition methods. Simple and planetary rotation systems with shadow masks are used to achieve the required uniformity [J. B. Oliver and D. Talbot, Appl. Optics 45, 13, 3097 (2006); O. Lyngnes, K. Kraus, A. Ode and T. Erguder, in `Method for Designing Coating Thickness Uniformity Shadow Masks for Deposition Systems with a Planetary Fixture', 2014 Technical Conference Proceedings, Optical Coatings, August 13, 2014, DOI: 10.14332/svc14.proc.1817.]. In this work, we discuss the effect of rotation pattern and speed on thickness uniformity in an ion beam sputter deposition system. Numerical modeling is used to determine statistical distribution of random thickness errors in coating layers. The relationship between thickness tolerance and production yield are simulated theoretically and demonstrated experimentally. Production yields for different optical filters produced in an ion beam deposition system with planetary rotation are presented. Single-wavelength and broadband optical monitoring systems were used for endpoint monitoring during filter deposition. Limitations of thickness tolerances that can be achieved in systems with planetary rotation are shown. Paths for improving production yield in an ion beam deposition system are described.

Optical implementation of the synthetic discriminant function

NASA Astrophysics Data System (ADS)

Butler, S.; Riggins, J.

1984-10-01

Much attention is focused on the use of coherent optical pattern recognition (OPR) using matched spatial filters for robotics and intelligent systems. The OPR problem consists of three aspects -- information input, information processing, and information output. This paper discusses the information processing aspect which consists of choosing a filter to provide robust correlation with high efficiency. The filter should ideally be invariant to image shift, rotation and scale, provide a reasonable signal-to-noise (S/N) ratio and allow high throughput efficiency. The physical implementation of a spatial matched filter involves many choices. These include the use of conventional holograms or computer-generated holograms (CGH) and utilizing absorption or phase materials. Conventional holograms inherently modify the reference image by non-uniform emphasis of spatial frequencies. Proper use of film nonlinearity provides improved filter performance by emphasizing frequency ranges crucial to target discrimination. In the case of a CGH, the emphasis of the reference magnitude and phase can be controlled independently of the continuous tone or binary writing processes. This paper describes computer simulation and optical implementation of a geometrical shape and a Synthetic Discriminant Function (SDF) matched filter. The authors chose the binary Allebach-Keegan (AK) CGH algorithm to produce actual filters. The performances of these filters were measured to verify the simulation results. This paper provides a brief summary of the matched filter theory, the SDF, CGH algorithms, Phase-Only-Filtering, simulation procedures, and results.

Frequency chirped light at large detuning with an injection-locked diode laser

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

Teng, K.; Disla, M.; Dellatto, J.

2015-04-15

We have developed a laser system to generate frequency-chirped light at rapid modulation speeds (∼100 MHz) with a large frequency offset. Light from an external cavity diode laser with its frequency locked to an atomic resonance is passed through a lithium niobate electro-optical phase modulator. The phase modulator is driven by a ∼6 GHz signal whose frequency is itself modulated with a RF MHz signal (<200 MHz). A second injection locked diode laser is used to filter out all of the light except the frequency-chirped ±1 order by more than 30 dB. Using this system, it is possible to generatemore » a 1 GHz frequency chirp in 5 ns.« less

Differential collision cross-sections for atomic oxygen: Analysis of space flight instruments for solar terrestrial physics

NASA Technical Reports Server (NTRS)

Torr, Douglas G.

1991-01-01

A summary of the status of the Cross-section Facility at MSFC is presented. A facility was designed, fabricated, assembled, tested, and operated for measurement of differential scattering cross sections important to understand the induced environment for a vehicle (e.g., Space Station) in low earth orbit. A user's manual for the facility is also presented. The performance of the facility was evaluated and found to be satisfactory in all the essential areas. Differential scattering cross sections were measured and results for the scattering measurements are included. Input to the development of the Ultraviolet Imager Optical System is also discussed. Design, fabrication, and evaluation of UV filters using a four-layer aluminum base are reported.

Exploring Novel Crystals and Designs for Acousto-Optic Devices

NASA Astrophysics Data System (ADS)

Pfeiffer, Jonathan B.

Acousto-optic devices are a versatile technology that are driven electronically to precisely and rapidly control the intensity, frequency, and propagation direction of a laser beam. Applications include acousto-optic scanners, filters, mode lockers, and modulators. Despite the popularity of acousto-optic devices, there currently is no UV transparent device that can satisfy the requirements of the atomic clock and quantum computing communities. In this thesis, I describe my experimental efforts for discovering a new UV transparent, acousto-optic crystal that can meet the experimental requirements. I also present my graphical representations for locating practical and efficient acousto-optic designs in a given medium. The first part of this thesis describes how to measure the elastic-stiffness and photoelastic coefficients of a given crystal. The elastic-stiffness coefficients are essential for designing acousto-optic devices because they determine the velocity, diffraction, and polarization of acoustic waves in a given medium. I used both resonant ultrasound spectroscopy and a modified version of Schaefer-Bergman diffraction to measure elastic coefficients. I discuss in detail the strengths, differences, and similarities of the two experiments. The photoelastic coefficients are necessary for determining the diffraction efficiency of a given acousto-optic geometry. Similar to the elastic coefficients, I employ a modified version of the Schaefer-Bergmann experiment to measure the photoelastic coefficients. I corroborate the measured results with the well established Dixon experiment. The second part of this thesis describes four different graphical representations that help locate practical and efficient acousto-optic designs. I describe in detail each algorithm and how to interpret the calculated results. Several examples are provided for commonly used acosuto-optic materials. The thesis concludes by describing the design and performance of an acousto-optic frequency shifter that was designed based on the culmination my research effort.

METHANOL MEASUREMENT IN AUTO EXHAUST USING A GAS-FILTER CORRELATION SPECTROMETER

EPA Science Inventory

Spectroscopic methods offer an alternative to wet chemical methods for analysis of methanol emissions from automobiles. The gas filter correlation infrared optical analysis approach appears very promising. The report describes the gas correlation optical system constructed to ana...

Optical monitoring of rugate filters

NASA Astrophysics Data System (ADS)

Lappschies, Marc; Görtz, Björn; Ristau, Detlev

2005-09-01

Rugate filters have a high potential for solving specific design problems in many applications of modern optics and lighting technology. However, the exact manufacture of these gradual layer systems is still a challenge which could not be solved completely until today. One of the prominent approaches for the production of rugate filters is based on independent quartz crystal devices measuring the rate of the different coating materials. As an alternative, optical broadband monitoring has been already qualified for controlling the deposition of complicated non quarterwave stacks. In the present study, promising results of this deposition control concept as a direct monitoring of rugate filters will be presented. In a first attempt, the continuous change of refractive indices in the graded layers was transformed to a set of discrete homogeneous sub-layers with thicknesses values of around 5 nm. These discrete layers are realized by defined mixtures of two materials. A data base for the dispersion behavior was created for the different mixing ratios and is employed for the production of such quasi-rugate filters. The optical monitor is operated in the routine mode determining the switching points of the layers. Selected examples will be presented for quasi rugate coatings produced by ion beam sputtering from a movable zone target. Different designs will be discussed considering production problems as well as achievable optical properties.

Page Oriented Holographic Memories And Optical Pattern Recognition

NASA Astrophysics Data System (ADS)

Caulfield, H. J.

1987-08-01

In the twenty-two years since VanderLugt's introduction of holographic matched filtering, the intensive research carried out throughout the world has led to no applications in complex environment. This leads one to the suspicion that the VanderLugt filter technique is insufficiently complex to handle truly complex problems. Therefore, it is of great interest to increase the complexity of the VanderLugt filtering operation. We introduce here an approach to the real time filter assembly: use of page oriented holographic memories and optically addressed SLMs to achieve intelligent and fast reprogramming of the filters using a 10 4 to 10 6 stored pattern base.

A technique for synergistic atomic oxygen and vacuum ultraviolet radiation durability evaluation of materials for use in LEO

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Banks, Bruce A.

1996-01-01

Material erosion data collected during flight experiments such as the Environmental Oxygen Interaction with Materials (EOIM)-3 and the Long Duration Exposure Facility (LDEF) have raised questions as to the sensitivity of material erosion to levels of atomic oxygen exposure and vacuum ultraviolet (VUV) radiation. The erosion sensitivity of some materials such as FEP Teflon used as a thermal control material on satellites in low Earth orbit (LEO), is particularly important but difficult to determine. This is in large part due to the inability to hold all but one exposure parameter constant during a flight experiment. This is also difficult to perform in a ground based facility, because often the variation of the level of atomic oxygen or VUV radiation also results in a change in the level of the other parameter. A facility has been developed which allows each parameter to be changed almost independently and offer broad area exposure. The resulting samples can be made large enough for mechanical testing. The facility uses an electron cyclotron resonance plasma source to provide the atomic oxygen. A series of glass plates is used to focus the atomic oxygen while filtering the VUV radiation from the plasma source. After filtering, atomic oxygen effective flux levels can still be measured which are as high as 7 x 10(exp 15) atoms/cm(exp 2)-sec which is adequate for accelerated testing. VUV radiation levels after filtering can be as low as 0.3 suns. Additional VUV suns can be added with the use of deuterium lamps which allow the VUV level to be changed while keeping the flux of atomic oxygen constant. This paper discusses the facility, and results from exposure of Kapton and FEP at pre-determined atomic oxygen flux and VUV sun levels.

High resolution on-chip optical filter array based on double subwavelength grating reflectors

DOE PAGES

Horie, Yu; Arbabi, Amir; Han, Seunghoon; ...

2015-11-05

An optical filter array consisting of vertical narrow-band Fabry-Pèrot (FP) resonators formed by two highly reflective high contrast subwavelength grating mirrors is reported. The filters are designed to cover a wide range of operation wavelengths ( Δλ/λ=5%) just by changing the in-plane grating parameters while the device thickness is maintained constant. In conclusion, operation in the telecom band with transmission efficiencies greater than 40% and quality factors greater than 1,000 are measured experimentally for filters fabricated on the same substrate.

High resolution on-chip optical filter array based on double subwavelength grating reflectors

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

Horie, Yu; Arbabi, Amir; Han, Seunghoon

An optical filter array consisting of vertical narrow-band Fabry-Pèrot (FP) resonators formed by two highly reflective high contrast subwavelength grating mirrors is reported. The filters are designed to cover a wide range of operation wavelengths ( Δλ/λ=5%) just by changing the in-plane grating parameters while the device thickness is maintained constant. In conclusion, operation in the telecom band with transmission efficiencies greater than 40% and quality factors greater than 1,000 are measured experimentally for filters fabricated on the same substrate.

Formation of bimetallic clusters in superfluid helium nanodroplets analysed by atomic resolution electron tomography

PubMed Central

Haberfehlner, Georg; Thaler, Philipp; Knez, Daniel; Volk, Alexander; Hofer, Ferdinand; Ernst, Wolfgang E.; Kothleitner, Gerald

2015-01-01

Structure, shape and composition are the basic parameters responsible for properties of nanoscale materials, distinguishing them from their bulk counterparts. To reveal these in three dimensions at the nanoscale, electron tomography is a powerful tool. Advancing electron tomography to atomic resolution in an aberration-corrected transmission electron microscope remains challenging and has been demonstrated only a few times using strong constraints or extensive filtering. Here we demonstrate atomic resolution electron tomography on silver/gold core/shell nanoclusters grown in superfluid helium nanodroplets. We reveal morphology and composition of a cluster identifying gold- and silver-rich regions in three dimensions and we estimate atomic positions without using any prior information and with minimal filtering. The ability to get full three-dimensional information down to the atomic scale allows understanding the growth and deposition process of the nanoclusters and demonstrates an approach that may be generally applicable to all types of nanoscale materials. PMID:26508471

Fundamental Interactions for Atom Interferometry with Ultracold Quantum Gases in a Microgravity Environment

NASA Astrophysics Data System (ADS)

D'Incao, Jose P.; Willians, Jason R.

2015-05-01

Precision atom interferometers (AI) in space are a key element for several applications of interest to NASA. Our proposal for participating in the Cold Atom Laboratory (CAL) onboard the International Space Station is dedicated to mitigating the leading-order systematics expected to corrupt future high-precision AI-based measurements of fundamental physics in microgravity. One important focus of our proposal is to enhance initial state preparation for dual-species AIs. Our proposed filtering scheme uses Feshbach molecular states to create highly correlated mixtures of heteronuclear atomic gases in both their position and momentum distributions. We will detail our filtering scheme along with the main factors that determine its efficiency. We also show that the atomic and molecular heating and loss rates can be mitigated at the unique temperature and density regimes accessible on CAL. This research is supported by the National Aeronautics and Space Administration.

Fiber-optic apparatus and method for measurement of luminescence and Raman scattering

DOEpatents

Myrick, M.L.; Angel, S.M.

1993-03-16

A dual fiber forward scattering optrode for Raman spectroscopy with the remote ends of the fibers in opposed, spaced relationship to each other to form a analyte sampling space therebetween and the method of measuring Raman spectra utilizing same are described. One optical fiber is for sending an exciting signal to the remote sampling space and, at its remote end, has a collimating microlens and an optical filter for filtering out background emissions generated in the fiber. The other optical fiber is for collecting the Raman scattering signal at the remote sampling space and, at its remote end, has a collimating microlens and an optical filter to prevent the exciting signal from the exciting fiber from entering the collection fiber and to thereby prevent the generation of background emissions in the collecting fiber.

Optical Design of the LSST Camera

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

Olivier, S S; Seppala, L; Gilmore, K

2008-07-16

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, modified Paul-Baker design, with an 8.4-meter primary mirror, a 3.4-m secondary, and a 5.0-m tertiary feeding a camera system that includes a set of broad-band filters and refractive corrector lenses to produce a flat focal plane with a field of view of 9.6 square degrees. Optical design of the camera lenses and filters is integrated with optical design of telescope mirrors to optimize performance, resulting in excellent image quality over the entire field from ultra-violet to near infra-red wavelengths. The LSST camera optics design consists of three refractive lenses withmore » clear aperture diameters of 1.55 m, 1.10 m and 0.69 m and six interchangeable, broad-band, filters with clear aperture diameters of 0.75 m. We describe the methodology for fabricating, coating, mounting and testing these lenses and filters, and we present the results of detailed tolerance analyses, demonstrating that the camera optics will perform to the specifications required to meet their performance goals.« less

Solid State Spin-Wave Quantum Memory for Time-Bin Qubits.

PubMed

Gündoğan, Mustafa; Ledingham, Patrick M; Kutluer, Kutlu; Mazzera, Margherita; de Riedmatten, Hugues

2015-06-12

We demonstrate the first solid-state spin-wave optical quantum memory with on-demand read-out. Using the full atomic frequency comb scheme in a Pr(3+):Y2SiO5 crystal, we store weak coherent pulses at the single-photon level with a signal-to-noise ratio >10. Narrow-band spectral filtering based on spectral hole burning in a second Pr(3+):Y2SiO5 crystal is used to filter out the excess noise created by control pulses to reach an unconditional noise level of (2.0±0.3)×10(-3) photons per pulse. We also report spin-wave storage of photonic time-bin qubits with conditional fidelities higher than achievable by a measure and prepare strategy, demonstrating that the spin-wave memory operates in the quantum regime. This makes our device the first demonstration of a quantum memory for time-bin qubits, with on-demand read-out of the stored quantum information. These results represent an important step for the use of solid-state quantum memories in scalable quantum networks.

Dual-Mode Operation of an Optical Lattice Clock Using Strontium and Ytterbium Atoms.

PubMed

Akamatsu, Daisuke; Kobayashi, Takumi; Hisai, Yusuke; Tanabe, Takehiko; Hosaka, Kazumoto; Yasuda, Masami; Hong, Feng-Lei

2018-06-01

We have developed an optical lattice clock that can operate in dual modes: a strontium (Sr) clock mode and an ytterbium (Yb) clock mode. Dual-mode operation of the Sr-Yb optical lattice clock is achieved by alternately cooling and trapping 87 Sr and 171 Yb atoms inside the vacuum chamber of the clock. Optical lattices for Sr and Yb atoms were arranged with horizontal and vertical configurations, respectively, resulting in a small distance of the order of between the trapped Sr and Yb atoms. The 1 S 0 - 3 P 0 clock transitions in the trapped atoms were interrogated in turn and the clock lasers were stabilized to the transitions. We demonstrated the frequency ratio measurement of the Sr and Yb clock transitions by using the dual-mode operation of the Sr-Yb optical lattice clock. The dual-mode operation can reduce the uncertainty of the blackbody radiation shift in the frequency ratio measurement, because both Sr and Yb atoms share the same blackbody radiation.

Highly Concentrated Seed-Mediated Synthesis of Monodispersed Gold Nanorods (Postprint)

DTIC Science & Technology

2017-07-17

imaging, therapeutics and sensors, to large area coatings, filters , and optical attenuators. Development of the latter technologies has been hindered by...sensors, to large area coatings, filters , and optical attenuators. Development of the latter technologies has been hindered by the lack of cost-effective...challenges the utilization of Au-NRs in a diverse array of technologies, ranging from therapeutics, imaging and sensors, to large area coatings, filters and

Liquid crystal photonic bandgap fiber components

NASA Astrophysics Data System (ADS)

Scolari, L.; Alkeskjold, T. T.; Noordegraaf, D.; Tartarini, G.; Bassi, P.; Bjarklev, A.

2007-11-01

Liquid crystal photonic bandgap fibers represent a promising platform for the design of all-in-fiber optical devices, which show a high degree of tunability and exhibit novel optical properties for the manipulation of guided light. In this review paper we present tunable fiber devices for spectral filtering, such as Gaussian filters and notch filters, and devices for polarization control and analysis, such as birefringence control devices and switchable and rotatable polarizers.

Narrowband spectral filter based on biconical tapered fiber

NASA Astrophysics Data System (ADS)

Celaschi, Sergio; Malheiros-Silveira, Gilliard N.

2018-02-01

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

Tunable Filter Made From Three Coupled WGM Resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Iltchenko, Vladimir; Maleki, Lute; Matsko, Andrey

2006-01-01

A tunable third-order band-pass optical filter has been constructed as an assembly of three coupled, tunable, whispering-gallery-mode resonators similar to the one described in Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter (NPO-30896), NASA Tech Briefs, Vol. 28, No. 4 (April 2004), page 5a. This filter offers a combination of four characteristics that are desirable for potential applications in photonics: (1) wide real-time tunability accompanied by a high-order filter function, (2) narrowness of the passband, (3) relatively low loss between input and output coupling optical fibers, and (4) a sparse spectrum. In contrast, prior tunable band-pass optical filters have exhibited, at most, two of these four characteristics. As described in several prior NASA Tech Briefs articles, a whispering-gallery-mode (WGM) resonator is a spheroidal, disklike, or toroidal body made of a highly transparent material. It is so named because it is designed to exploit whispering-gallery electromagnetic modes, which are waveguide modes that propagate circumferentially and are concentrated in a narrow toroidal region centered on the equatorial plane and located near the outermost edge. Figure 1 depicts the optical layout of the present filter comprising an assembly of three coupled, tunable WGM resonators. Each WGM resonator is made from a disk of Z-cut LiNbO3 of 3.3-mm diameter and 50-m thickness. The perimeter of the disk is polished and rounded to a radius of curvature of 40 microns. The free spectral range of each WGM resonator is about 13.3 GHz. Gold coats on the flat faces of the disk serve as electrodes for exploiting the electro-optical effect in LiNbO3 for tuning. There is no metal coat on the rounded perimeter region, where the whispering-gallery modes propagate. Light is coupled from an input optical fiber into the whispering-gallery-modes of the first WGM resonator by means of a diamond prism. Another diamond prism is used to couple light from the whispering-gallery-modes of the third WGM resonator to an output optical fiber. The filter operates at a nominal wavelength of 1,550 nm and can be tuned over a frequency range of plus or minus 12 GHz by applying a potential in the range of plus or minus 150 V to the electrodes. The insertion loss (the loss between the input and output coupling optical fibers) was found to be repeatable at 6 dB. The resonance quality factor (Q) of the main sequence of resonator modes was found to be 5 x 10(exp 6), which corresponds to a bandwidth of 30 MHz. The filter can be shifted from one operating frequency to another within a tuning time less than or equal to 30 micro seconds. The transmission curve of the filter at frequencies near the middle of the passband closely approximates a theoretical third-order Butterworth filter profile, as shown in Figure 2.

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR EXTRACTION OF METALS FROM SOIL, DUST, AIR FILTER, AND SURFACE AND DERMAL WIPE SAMPLES FOR AA (GRAPHITE FURNACE OR FLAME) OR ICP-AES ANALYSIS (BCO-L-3.1)

EPA Science Inventory

The purpose of this SOP is to describe the acid digestion of soil, house dust, air filter, and surface or dermal wipe samples for analysis using inductively coupled plasma atomic emissions spectrometry (ICP-AES) and/or graphite furnace atomic absorption spectrometry (GFAAS) or fl...

A High Spectral Resolution Lidar Based on Absorption Filter

NASA Technical Reports Server (NTRS)

Piironen, Paivi

1996-01-01

A High Spectral Resolution Lidar (HSRL) that uses an iodine absorption filter and a tunable, narrow bandwidth Nd:YAG laser is demonstrated. The iodine absorption filter provides better performance than the Fabry-Perot etalon that it replaces. This study presents an instrument design that can be used a the basis for a design of a simple and robust lidar for the measurement of the optical properties of the atmosphere. The HSRL provides calibrated measurements of the optical properties of the atmospheric aerosols. These observations include measurements of aerosol backscatter cross sections, optical depth, backscatter phase function depolarization, and multiple scattering. The errors in the HSRL data are discussed and the effects of different errors on the measured optical parameters are shown.

Optical security system for the protection of personal identification information.

PubMed

Doh, Yang-Hoi; Yoon, Jong-Soo; Choi, Kyung-Hyun; Alam, Mohammad S

2005-02-10

A new optical security system for the protection of personal identification information is proposed. First, authentication of the encrypted personal information is carried out by primary recognition of a personal identification number (PIN) with the proposed multiplexed minimum average correlation energy phase-encrypted (MMACE_p) filter. The MMACE_p filter, synthesized with phase-encrypted training images, can increase the discrimination capability and prevent the leak of personal identification information. After the PIN is recognized, speedy authentication of personal information can be achieved through one-to-one optical correlation by means of the optical wavelet filter. The possibility of information counterfeiting can be significantly decreased with the double-identification process. Simulation results demonstrate the effectiveness of the proposed technique.

Wide-Field Optic for Autonomous Acquisition of Laser Link

NASA Technical Reports Server (NTRS)

Page, Norman A.; Charles, Jeffrey R.; Biswas, Abhijit

2011-01-01

An innovation reported in Two-Camera Acquisition and Tracking of a Flying Target, NASA Tech Briefs, Vol. 32, No. 8 (August 2008), p. 20, used a commercial fish-eye lens and an electronic imaging camera for initially locating objects with subsequent handover to an actuated narrow-field camera. But this operated against a dark-sky background. An improved solution involves an optical design based on custom optical components for the wide-field optical system that directly addresses the key limitations in acquiring a laser signal from a moving source such as an aircraft or a spacecraft. The first challenge was to increase the light collection entrance aperture diameter, which was approximately 1 mm in the first prototype. The new design presented here increases this entrance aperture diameter to 4.2 mm, which is equivalent to a more than 16 times larger collection area. One of the trades made in realizing this improvement was to restrict the field-of-view to +80 deg. elevation and 360 azimuth. This trade stems from practical considerations where laser beam propagation over the excessively high air mass, which is in the line of sight (LOS) at low elevation angles, results in vulnerability to severe atmospheric turbulence and attenuation. An additional benefit of the new design is that the large entrance aperture is maintained even at large off-axis angles when the optic is pointed at zenith. The second critical limitation for implementing spectral filtering in the design was tackled by collimating the light prior to focusing it onto the focal plane. This allows the placement of the narrow spectral filter in the collimated portion of the beam. For the narrow band spectral filter to function properly, it is necessary to adequately control the range of incident angles at which received light intercepts the filter. When this angle is restricted via collimation, narrower spectral filtering can be implemented. The collimated beam (and the filter) must be relatively large to reduce the incident angle down to only a few degrees. In the presented embodiment, the filter diameter is more than ten times larger than the entrance aperture. Specifically, the filter has a clear aperture of about 51 mm. The optical design is refractive, and is comprised of nine custom refractive elements and an interference filter. The restricted maximum angle through the narrow-band filter ensures the efficient use of a 2-nm noise equivalent bandwidth spectral width optical filter at low elevation angles (where the range is longest), at the expense of less efficiency for high elevations, which can be tolerated because the range at high elevation angles is shorter. The image circle is 12 mm in diameter, mapped to 80 x 360 of sky, centered on the zenith.

Does partial occlusion promote normal binocular function?

PubMed

Li, Jingrong; Thompson, Benjamin; Ding, Zhaofeng; Chan, Lily Y L; Chen, Xiang; Yu, Minbin; Deng, Daming; Hess, Robert F

2012-10-03

There is growing evidence that abnormal binocular interactions play a key role in the amblyopia syndrome and represent a viable target for treatment interventions. In this context the use of partial occlusion using optical devices such as Bangerter filters as an alternative to complete occlusion is of particular interest. The aims of this study were to understand why Bangerter filters do not result in improved binocular outcomes compared to complete occlusion, and to compare the effects of Bangerter filters, optical blur and neutral density (ND) filters on normal binocular function. The effects of four strengths of Bangerter filters (0.8, 0.6, 0.4, 0.2) on letter and vernier acuity, contrast sensitivity, stereoacuity, and interocular suppression were measured in 21 observers with normal vision. In a subset of 14 observers, the partial occlusion effects of Bangerter filters, ND filters and plus lenses on stereopsis and interocular suppression were compared. Bangerter filters did not have graded effect on vision and induced significant disruption to binocular function. This disruption was greater than that of monocular defocus but weaker than that of ND filters. The effect of the Bangerter filters on stereopsis was more pronounced than their effect on monocular acuity, and the induced monocular acuity deficits did not predict the induced deficits in stereopsis. Bangerter filters appear to be particularly disruptive to binocular function. Other interventions, such as optical defocus and those employing computer generated dichoptic stimulus presentation, may be more appropriate than partial occlusion for targeting binocular function during amblyopia treatment.

A Novel Gravito-Optical Surface Trap for Neutral Atoms

NASA Astrophysics Data System (ADS)

Xie, Chun-Xia; Wang, Zhengling; Yin, Jian-Ping

2006-04-01

We propose a novel gravito-optical surface trap (GOST) for neutral atoms based on one-dimensional intensity gradient cooling. The surface optical trap is composed of a blue-detuned reduced semi-Gaussian laser beam (SGB), a far-blue-detuned dark hollow beam and the gravity field. The SGB is produced by the diffraction of a collimated Gaussian laser beam passing through the straight edge of a semi-infinite opaque plate and then is reduced by an imaging lens. We calculate the intensity distribution of the reduced SGB, and study the dynamic process of the SGB intensity-gradient induced Sisyphus cooling for 87Rb atoms by using Monte Carlo simulations. Our study shows that the proposed GOST can be used not only to trap cold atoms loaded from a standard magneto-optical trap, but also to cool the trapped atoms to an equilibrium temperature of 3.47 μK from ~120 μK, even to realize an all-optical two-dimensional Bose-Einstein condensation by using optical-potential evaporative cooling.

Feasibility of a feedback control of atomic self-organization in an optical cavity

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

Ivanov, D. A., E-mail: ivanov-den@yandex.ru; Ivanova, T. Yu.

Many interesting nonlinear effects are based on the strong interaction of motional degrees of freedom of atoms with an optical cavity field. Among them is the spatial self-organization of atoms in a pattern where the atoms group in either odd or even sites of the cavity-induced optical potential. An experimental observation of this effect can be simplified by using, along with the original cavity-induced feedback, an additional electronic feedback based on the detection of light leaking the cavity and the control of the optical potential for the atoms. Following our previous study, we show that this approach is more efficientmore » from the laser power perspective than the original scheme without the electronic feedback.« less

Atom detection and photon production in a scalable, open, optical microcavity.

PubMed

Trupke, M; Goldwin, J; Darquié, B; Dutier, G; Eriksson, S; Ashmore, J; Hinds, E A

2007-08-10

A microfabricated Fabry-Perot optical resonator has been used for atom detection and photon production with less than 1 atom on average in the cavity mode. Our cavity design combines the intrinsic scalability of microfabrication processes with direct coupling of the cavity field to single-mode optical waveguides or fibers. The presence of the atom is seen through changes in both the intensity and the noise characteristics of probe light reflected from the cavity input mirror. An excitation laser passing transversely through the cavity triggers photon emission into the cavity mode and hence into the single-mode fiber. These are first steps toward building an optical microcavity network on an atom chip for applications in quantum information processing.

Toward Directly-Deposited Optical Blocking Filters for High-performance, Back-illuminated Imaging X-ray Detectors

NASA Astrophysics Data System (ADS)

Bautz, Mark W.; Kissel, S. E.; Ryu, K.; Suntharalingam, V.

2014-01-01

Silicon X-ray detectors require optical blocking filters to prevent out-of-band (UV, visible and near-IR) radiation from corrupting the X-ray signal. Traditionally, blocking filters have been deposited on thin, free-standing membranes suspended over the detector. Free-standing filters are fragile, however, and in past instruments have required heavy and complex vacuum housings to protect them from acoustic loads during ground operations and launch. A directly-deposited blocking filter greatly simplifies the instrument and in principle permits better soft X-ray detection efficiency than a traditional free-standing filter. Directly-deposited filters have flown in previous generation instruments (e.g. the XMM/Newton Reflection Grating Spectrometer) but none has yet been demonstrated on a modern, high-performance back-illuminated X-ray CCD. We report here on the status of our NASA-funded Strategic Astrophysics Technology program to demonstrate such filters.

Investigation of magnesium fluoride crystals for imaging acousto-optic tunable filter applications.

PubMed

Voloshinov, Vitaly B; Gupta, Neelam

2006-05-01

Results of an investigation of acousto-optic (AO) cells using single crystals of magnesium fluoride (MgF2) are presented. Two acousto-optic tunable filter (AOTF) cells for imaging application have been designed and tested in the visible and ultraviolet (UV) regions of the spectrum from 190 to 490 nm. The two imaging filters were developed by using the wide-angle AO interaction geometry in the (010) and (11 0) planes of the crystal. These filters were used to obtain spectral images at the shortest wavelengths achieved so far. Advantages and drawbacks of this crystal are discussed and photoelastic, acoustic, and AO properties of MgF2 are examined. The investigation confirmed that MgF2-based AOTF cells can be used in the deep UV region up to 110 nm.

Compact Single Site Resolution Cold Atom Experiment for Adiabatic Quantum Computing

DTIC Science & Technology

2016-02-03

goal of our scientific investigation is to demonstrate high fidelity and fast atom-atom entanglement between physically 1. REPORT DATE (DD-MM-YYYY) 4...of our scientific investigation is to demonstrate high fidelity and fast atom-atom entanglement between physically separated and optically addressed...Specifically, we will design and construct a set of compact single atom traps with integrated optics, suitable for heralded entanglement and loophole

Evaluation of the OSC-TV iterative reconstruction algorithm for cone-beam optical CT

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

Matenine, Dmitri, E-mail: dmitri.matenine.1@ulaval.ca; Mascolo-Fortin, Julia, E-mail: julia.mascolo-fortin.1@ulaval.ca; Goussard, Yves, E-mail: yves.goussard@polymtl.ca

Purpose: The present work evaluates an iterative reconstruction approach, namely, the ordered subsets convex (OSC) algorithm with regularization via total variation (TV) minimization in the field of cone-beam optical computed tomography (optical CT). One of the uses of optical CT is gel-based 3D dosimetry for radiation therapy, where it is employed to map dose distributions in radiosensitive gels. Model-based iterative reconstruction may improve optical CT image quality and contribute to a wider use of optical CT in clinical gel dosimetry. Methods: This algorithm was evaluated using experimental data acquired by a cone-beam optical CT system, as well as complementary numericalmore » simulations. A fast GPU implementation of OSC-TV was used to achieve reconstruction times comparable to those of conventional filtered backprojection. Images obtained via OSC-TV were compared with the corresponding filtered backprojections. Spatial resolution and uniformity phantoms were scanned and respective reconstructions were subject to evaluation of the modulation transfer function, image uniformity, and accuracy. The artifacts due to refraction and total signal loss from opaque objects were also studied. Results: The cone-beam optical CT data reconstructions showed that OSC-TV outperforms filtered backprojection in terms of image quality, thanks to a model-based simulation of the photon attenuation process. It was shown to significantly improve the image spatial resolution and reduce image noise. The accuracy of the estimation of linear attenuation coefficients remained similar to that obtained via filtered backprojection. Certain image artifacts due to opaque objects were reduced. Nevertheless, the common artifact due to the gel container walls could not be eliminated. Conclusions: The use of iterative reconstruction improves cone-beam optical CT image quality in many ways. The comparisons between OSC-TV and filtered backprojection presented in this paper demonstrate that OSC-TV can potentially improve the rendering of spatial features and reduce cone-beam optical CT artifacts.« less

Evaluation of the OSC-TV iterative reconstruction algorithm for cone-beam optical CT.

PubMed

Matenine, Dmitri; Mascolo-Fortin, Julia; Goussard, Yves; Després, Philippe

2015-11-01

The present work evaluates an iterative reconstruction approach, namely, the ordered subsets convex (OSC) algorithm with regularization via total variation (TV) minimization in the field of cone-beam optical computed tomography (optical CT). One of the uses of optical CT is gel-based 3D dosimetry for radiation therapy, where it is employed to map dose distributions in radiosensitive gels. Model-based iterative reconstruction may improve optical CT image quality and contribute to a wider use of optical CT in clinical gel dosimetry. This algorithm was evaluated using experimental data acquired by a cone-beam optical CT system, as well as complementary numerical simulations. A fast GPU implementation of OSC-TV was used to achieve reconstruction times comparable to those of conventional filtered backprojection. Images obtained via OSC-TV were compared with the corresponding filtered backprojections. Spatial resolution and uniformity phantoms were scanned and respective reconstructions were subject to evaluation of the modulation transfer function, image uniformity, and accuracy. The artifacts due to refraction and total signal loss from opaque objects were also studied. The cone-beam optical CT data reconstructions showed that OSC-TV outperforms filtered backprojection in terms of image quality, thanks to a model-based simulation of the photon attenuation process. It was shown to significantly improve the image spatial resolution and reduce image noise. The accuracy of the estimation of linear attenuation coefficients remained similar to that obtained via filtered backprojection. Certain image artifacts due to opaque objects were reduced. Nevertheless, the common artifact due to the gel container walls could not be eliminated. The use of iterative reconstruction improves cone-beam optical CT image quality in many ways. The comparisons between OSC-TV and filtered backprojection presented in this paper demonstrate that OSC-TV can potentially improve the rendering of spatial features and reduce cone-beam optical CT artifacts.

Development of low optical cross talk filters for VIIRS (JPSS)

NASA Astrophysics Data System (ADS)

Murgai, Vijay; Hendry, Derek; Downing, Kevin; Carbone, David; Potter, John

2016-09-01

The Visible/Infrared Imaging Radiometer Suite (VIIRS) is a key sensor on Suomi National Polar-orbiting Partnership (S-NPP) satellite launched on October 28, 2011 into a polar orbit of 824 km nominal altitude and the JPSS sensors currently being built and integrated. VIIRS collects radiometric and imagery data of the Earth's atmosphere, oceans, and land surfaces in 22 spectral bands spanning the visible and infrared spectrum from 0.4 to 12.5 μm. Interference filters assembled in `butcher-block' arrays mounted adjacent to focal plane arrays provide spectral definition. Out-of-band signal and out-of-band optical cross-talk was observed for bands in the 0.4 to 1 μm range in testing of VIIRS for S-NPP. Optical cross-talk is in-band or out-of-band light incident on an adjacent filter or adjacent region of the same filter reaching the detector. Out-of-band optical cross-talk results in spectral and spatial `impurities' in the signal and consequent errors in the calculated environmental parameters such as ocean color that rely on combinations of signals from more than one band. This paper presents results of characterization, specification, and coating process improvements that enabled production of filters with significantly reduced out of band light for Joint Polar Satellite System (JPSS) J1 and subsequent sensors. Total transmission and scatter measurements at a wavelength within the pass band can successfully characterize filter performance prior to dicing and assembling filters into butcher block assemblies. Coating and process development demonstrated performance on test samples followed by production of filters for J1 and J2. Results for J1 and J2 filters are presented.

Optimization of flow cytometric detection and cell sorting of transgenic Plasmodium parasites using interchangeable optical filters

PubMed Central

2012-01-01

Background Malaria remains a major cause of morbidity and mortality worldwide. Flow cytometry-based assays that take advantage of fluorescent protein (FP)-expressing malaria parasites have proven to be valuable tools for quantification and sorting of specific subpopulations of parasite-infected red blood cells. However, identification of rare subpopulations of parasites using green fluorescent protein (GFP) labelling is complicated by autofluorescence (AF) of red blood cells and low signal from transgenic parasites. It has been suggested that cell sorting yield could be improved by using filters that precisely match the emission spectrum of GFP. Methods Detection of transgenic Plasmodium falciparum parasites expressing either tdTomato or GFP was performed using a flow cytometer with interchangeable optical filters. Parasitaemia was evaluated using different optical filters and, after optimization of optics, the GFP-expressing parasites were sorted and analysed by microscopy after cytospin preparation and by imaging cytometry. Results A new approach to evaluate filter performance in flow cytometry using two-dimensional dot blot was developed. By selecting optical filters with narrow bandpass (BP) and maximum position of filter emission close to GFP maximum emission in the FL1 channel (510/20, 512/20 and 517/20; dichroics 502LP and 466LP), AF was markedly decreased and signal-background improve dramatically. Sorting of GFP-expressing parasite populations in infected red blood cells at 90 or 95% purity with these filters resulted in 50-150% increased yield when compared to the standard filter set-up. The purity of the sorted population was confirmed using imaging cytometry and microscopy of cytospin preparations of sorted red blood cells infected with transgenic malaria parasites. Discussion Filter optimization is particularly important for applications where the FP signal and percentage of positive events are relatively low, such as analysis of parasite-infected samples with in the intention of gene-expression profiling and analysis. The approach outlined here results in substantially improved yield of GFP-expressing parasites, and requires decreased sorting time in comparison to standard methods. It is anticipated that this protocol will be useful for a wide range of applications involving rare events. PMID:22950515

Rapid, all-optical crystal orientation imaging of two-dimensional transition metal dichalcogenide monolayers

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

David, Sabrina N.; Zhai, Yao; van der Zande, Arend M.

Two-dimensional (2D) atomic materials such as graphene and transition metal dichalcogenides (TMDCs) have attracted significant research and industrial interest for their electronic, optical, mechanical, and thermal properties. While large-area crystal growth techniques such as chemical vapor deposition have been demonstrated, the presence of grain boundaries and orientation of grains arising in such growths substantially affect the physical properties of the materials. There is currently no scalable characterization method for determining these boundaries and orientations over a large sample area. We here present a second-harmonic generation based microscopy technique for rapidly mapping grain orientations and boundaries of 2D TMDCs. We experimentallymore » demonstrate the capability to map large samples to an angular resolution of ±1° with minimal sample preparation and without involved analysis. A direct comparison of the all-optical grain orientation maps against results obtained by diffraction-filtered dark-field transmission electron microscopy plus selected-area electron diffraction on identical TMDC samples is provided. This rapid and accurate tool should enable large-area characterization of TMDC samples for expedited studies of grain boundary effects and the efficient characterization of industrial-scale production techniques.« less

Atomic hydrogen cleaning of EUV multilayer optics

NASA Astrophysics Data System (ADS)

Graham, Samuel, Jr.; Steinhaus, Charles A.; Clift, W. Miles; Klebanoff, Leonard E.; Bajt, Sasa

2003-06-01

Recent studies have been conducted to investigate the use of atomic hydrogen as an in-situ contamination removal method for EUV optics. In these experiments, a commercial source was used to produce atomic hydrogen by thermal dissociation of molecular hydrogen using a hot filament. Samples for these experiments consisted of silicon wafers coated with sputtered carbon, Mo/Si optics with EUV-induced carbon, and bare Si-capped and Ru-B4C-capped Mo/Si optics. Samples were exposed to an atomic hydrogen source at a distance of 200 - 500 mm downstream and angles between 0-90° with respect to the source. Carbon removal rates and optic oxidation rates were measured using Auger electron spectroscopy depth profiling. In addition, at-wavelength peak reflectance (13.4 nm) was measured using the EUV reflectometer at the Advanced Light Source. Data from these experiments show carbon removal rates up to 20 Ê/hr for sputtered carbon and 40 Ê/hr for EUV deposited carbon at a distance of 200 mm downstream. The cleaning rate was also observed to be a strong function of distance and angular position. Experiments have also shown that the carbon etch rate can be increased by a factor of 4 by channeling atomic hydrogen through quartz tubes in order to direct the atomic hydrogen to the optic surface. Atomic hydrogen exposures of bare optic samples show a small risk in reflectivity degradation after extended periods. Extended exposures (up to 20 hours) of bare Si-capped Mo/Si optics show a 1.2% loss (absolute) in reflectivity while the Ru-B4C-capped Mo/Si optics show a loss on the order of 0.5%. In order to investigate the source of this reflectivity degradation, optic samples were exposed to atomic deuterium and analyzed using low energy ion scattering direct recoil spectroscopy to determine any reactions of the hydrogen with the multilayer stack. Overall, the results show that the risk of over-etching with atomic hydrogen is much less than previous studies using RF discharge cleaning while providing cleaning rates suitable for EUV lithography operations.

Atomic hydrogen cleaning of EUV multilayer optics

NASA Astrophysics Data System (ADS)

Graham, Samuel, Jr.; Steinhaus, Charles A.; Clift, W. Miles; Klebanoff, Leonard E.; Bajt, Sasa

2003-06-01

Recent studies have been conducted to investigate the use of atomic hydrogen as an in-situ contamination removal method for EUV optics. In these experiments, a commercial source was used to produce atomic hydrogen by thermal dissociation of molecular hydrogen using a hot filament. Samples for these experiments consisted of silicon wafers coated with sputtered carbon, Mo/Si optics with EUV-induced carbon, and bare Si-capped and Ru-B4C-capped Mo/Si optics. Samples were exposed to an atomic hydrogen source at a distance of 200 - 500 mm downstream and angles between 0-90° with respect to the source. Carbon removal rates and optic oxidation rates were measured using Auger electron spectroscopy depth profiling. In addition, at-wavelength peak reflectance (13.4 nm) was measured using the EUV reflectometer at the Advanced Light Source. Data from these experiments show carbon removal rates up to 20 Å/hr for sputtered carbon and 40 Å/hr for EUV deposited carbon at a distance of 200 mm downstream. The cleaning rate was also observed to be a strong function of distance and angular position. Experiments have also shown that the carbon etch rate can be increased by a factor of 4 by channeling atomic hydrogen through quartz tubes in order to direct the atomic hydrogen to the optic surface. Atomic hydrogen exposures of bare optic samples show a small risk in reflectivity degradation after extended periods. Extended exposures (up to 20 hours) of bare Si-capped Mo/Si optics show a 1.2% loss (absolute) in reflectivity while the Ru-B4C-capped Mo/Si optics show a loss on the order of 0.5%. In order to investigate the source of this reflectivity degradation, optic samples were exposed to atomic deuterium and analyzed using low energy ion scattering direct recoil spectroscopy to determine any reactions of the hydrogen with the multilayer stack. Overall, the results show that the risk of over-etching with atomic hydrogen is much less than previous studies using RF discharge cleaning while providing cleaning rates suitable for EUV lithography operations.

Ultraviolet acousto-optic programmable dispersive filter laser pulse shaping in KDP.

PubMed

Coudreau, Sebastien; Kaplan, Daniel; Tournois, Pierre

2006-06-15

An acousto-optic programmable dispersive filter pulse shaper has been designed using KDP material for operation in the 200-500 nm wavelength range. With an acousto-optic interaction length of 72 mm, a spectral resolution of 0.15 nm has been measured to be consistent with theoretical predictions. Theory and experiments indicate that diffraction efficiencies up to 50% are expected in practical experimental conditions.

Improvement of LOD in Fluorescence Detection with Spectrally Nonuniform Background by Optimization of Emission Filtering.

PubMed

Galievsky, Victor A; Stasheuski, Alexander S; Krylov, Sergey N

2017-10-17

The limit-of-detection (LOD) in analytical instruments with fluorescence detection can be improved by reducing noise of optical background. Efficiently reducing optical background noise in systems with spectrally nonuniform background requires complex optimization of an emission filter-the main element of spectral filtration. Here, we introduce a filter-optimization method, which utilizes an expression for the signal-to-noise ratio (SNR) as a function of (i) all noise components (dark, shot, and flicker), (ii) emission spectrum of the analyte, (iii) emission spectrum of the optical background, and (iv) transmittance spectrum of the emission filter. In essence, the noise components and the emission spectra are determined experimentally and substituted into the expression. This leaves a single variable-the transmittance spectrum of the filter-which is optimized numerically by maximizing SNR. Maximizing SNR provides an accurate way of filter optimization, while a previously used approach based on maximizing a signal-to-background ratio (SBR) is the approximation that can lead to much poorer LOD specifically in detection of fluorescently labeled biomolecules. The proposed filter-optimization method will be an indispensable tool for developing new and improving existing fluorescence-detection systems aiming at ultimately low LOD.

A reflective-type, quasi-optical metasurface filter

NASA Astrophysics Data System (ADS)

Sima, Boyu; Momeni Hasan Abadi, Seyed Mohamad Amin; Behdad, Nader

2017-08-01

We introduce a new technique for designing quasi-optical, reflective-type spatial filters. The proposed filter is a reflective metasurface with a one dimensional, frequency-dependent phase gradient along the aperture. By careful design of each unit cell of the metasurface, the phase shift gradient provided by the adjacent unit cells can be engineered to steer the beam towards a desired, anomalous reflection direction over the passband region of the filter. Outside of that range, the phase shift gradient required to produce the anomalous reflection is not present and hence, the wave is reflected towards the specular reflection direction. This way, the metasurface acts as a reflective filter in a quasi-optical system where the detector is placed along the direction of anomalous reflection. The spectral selectivity of this filter is determined by the frequency dispersion of the metasurface's phase response. Based on this principle, a prototype of the proposed metasurface filter, which operates at 10 GHz and has a bandwidth of 3%, is designed. The device is modeled using a combination of theoretical analysis using the phased-array theory and full-wave electromagnetic simulations. A prototype of this device is also fabricated and characterized using a free-space measurement system. Experimental results agree well with the simulations.

Spatial filtering velocimetry of objective speckles for measuring out-of-plane motion.

PubMed

Jakobsen, M L; Yura, H T; Hanson, S G

2012-03-20

This paper analyzes the dynamics of objective laser speckles as the distance between the object and the observation plane continuously changes. With the purpose of applying optical spatial filtering velocimetry to the speckle dynamics, in order to measure out-of-plane motion in real time, a rotational symmetric spatial filter is designed. The spatial filter converts the speckle dynamics into a photocurrent with a quasi-sinusoidal response to the out-of-plane motion. The spatial filter is here emulated with a CCD camera, and is tested on speckles arising from a real application. The analysis discusses the selectivity of the spatial filter, the nonlinear response between speckle motion and observation distance, and the influence of the distance-dependent speckle size. Experiments with the emulated filters illustrate performance and potential applications of the technology. © 2012 Optical Society of America

Optical filter highlighting spectral features part II: quantitative measurements of cosmetic foundation and assessment of their spatial distributions under realistic facial conditions.

PubMed

Nishino, Ken; Nakamura, Mutsuko; Matsumoto, Masayuki; Tanno, Osamu; Nakauchi, Shigeki

2011-03-28

We previously proposed a filter that could detect cosmetic foundations with high discrimination accuracy [Opt. Express 19, 6020 (2011)]. This study extends the filter's functionality to the quantification of the amount of foundation and applies the filter for the assessment of spatial distributions of foundation under realistic facial conditions. Human faces that are applied with quantitatively controlled amounts of cosmetic foundations were measured using the filter. A calibration curve between pixel values of the image and the amount of foundation was created. The optical filter was applied to visualize spatial foundation distributions under realistic facial conditions, which clearly indicated areas on the face where foundation remained even after cleansing. Results confirm that the proposed filter could visualize and nondestructively inspect the foundation distributions.

[Determination of metals in waste bag filter of steel works by microwave digestion-flame atomic absorption spectrometry].

PubMed

Ning, Xun-An; Zhou, Yun; Liu, Jing-Yong; Wang, Jiang-Hui; Li, Lei; Ma, Xiao-Guo

2011-09-01

A method of microwave digestion technique-flame atomic absorption spectrometry was proposed to determine the total contents of Cu, Zn, Pb, Cd, Cr and Ni in five different kinds of waste bag filters from a steel plant. The digestion effects of the six acid systems on the heavy metals digestion were studied for the first time. The relative standard deviation (RSD) of the method was between 1.02% and 9.35%, and the recovery rates obtained by standard addition method ranged from 87.7% to 105.6%. The results indicated that the proposed method exhibited the advantages of simplicity, speediness, accuracy and repeatability, and it was suitable for determining the metal elements of the waste bag filter. The results also showed that different digestion systems should be used according to different waste bag filters. The waste bag filter samples from different production processes had different metal elements content. The Pb and Zn were the highest in the waste bag filters, while the Cu, Ni, Cd and Cr were relatively lower. These determination results provided the scientific data for further treatment and disposal of the waste bag filter.

Micro benchtop optics by bulk silicon micromachining

DOEpatents

Lee, Abraham P.; Pocha, Michael D.; McConaghy, Charles F.; Deri, Robert J.

2000-01-01

Micromachining of bulk silicon utilizing the parallel etching characteristics of bulk silicon and integrating the parallel etch planes of silicon with silicon wafer bonding and impurity doping, enables the fabrication of on-chip optics with in situ aligned etched grooves for optical fibers, micro-lenses, photodiodes, and laser diodes. Other optical components that can be microfabricated and integrated include semi-transparent beam splitters, micro-optical scanners, pinholes, optical gratings, micro-optical filters, etc. Micromachining of bulk silicon utilizing the parallel etching characteristics thereof can be utilized to develop miniaturization of bio-instrumentation such as wavelength monitoring by fluorescence spectrometers, and other miniaturized optical systems such as Fabry-Perot interferometry for filtering of wavelengths, tunable cavity lasers, micro-holography modules, and wavelength splitters for optical communication systems.

Development of Flight Slit-Jaw Optics for Chromospheric Lyman-Alpha SpectroPolarimeter

NASA Technical Reports Server (NTRS)

Kubo, Masahito; Suematsu, Yoshinori; Kano, Ryohei; Bando, Takamasa; Hara, Hirohisa; Narukage, Noriyuki; Katsukawa, Yukio; Ishikawa, Ryoko; Ishikawa, Shin-nosuke; Kobiki, Toshihiko;

Development of Flight Slit-Jaw Optics for Chromospheric Lyman-Alpha SpectroPolarimeter

NASA Technical Reports Server (NTRS)

Kubo, Masahito; Suematsu, Yoshinori; Kano, Ryohei; Bando, Takamasa; Hara, Hirohisa; Narukage, Noriyuki; Katsukawa, Yukio; Ishikawa, Ryoko; Ishikawa, Shin-nosuke; Kobiki, Toshihiko;

Angle-selective optical filter for highly sensitive reflection photoplethysmogram

PubMed Central

Hwang, Chan-Sol; Yang, Sung-Pyo; Jang, Kyung-Won; Park, Jung-Woo; Jeong, Ki-Hun

2017-01-01

We report an angle-selective optical filter (ASOF) for highly sensitive reflection photoplethysmography (PPG) sensors. The ASOF features slanted aluminum (Al) micromirror arrays embedded in transparent polymer resin, which effectively block scattered light under human tissue. The device microfabrication was done by using geometry-guided resist reflow of polymer micropatterns, polydimethylsiloxane replica molding, and oblique angle deposition of thin Al film. The angular transmittance through the ASOF is precisely controlled by the angle of micromirrors. For the mirror angle of 30 degrees, the ASOF accepts an incident light between - 90 to + 50 degrees and the maximum transmittance at - 55 degrees. The ASOF exhibits the substantial reduction of both the in-band noise of PPG signals over a factor of two and the low-frequency noise by three times. Consequently, this filter allows distinguishing the diastolic peak that allows miscellaneous parameters with diverse vascular information. This optical filter provides a new opportunity for highly sensitive PPG monitoring or miscellaneous optical tomography. PMID:29082070

Measurement device for high-precision spectral transmittance of solar blind filter

NASA Astrophysics Data System (ADS)

Wang, Yan; Qian, Yunsheng; Lv, Yang; Feng, Cheng; Liu, Jian

2017-02-01

In order to measure spectral transmittance of solar-blind filter ranging from ultraviolet to visible light accurately, a high-precision filter transmittance measuring system based on the ultraviolet photomultiplier is developed. The calibration method is mainly used to measure transmittance in this system, which mainly consists of an ultraviolet photomultiplier as core of the system and a lock-in amplifier combined with an optical modulator as the aided measurement for the system. The ultraviolet photomultiplier can amplify the current signal through the filter and have the characteristics of low dark current and high luminance gain. The optical modulator and the lock-in amplifier can obtain the signal from the photomultiplier and inhibit dark noise and spurious signal effectively. Through these two parts, the low light passing through the filters can be detected and we can calculate the transmittance by the optical power detected. Based on the proposed system, the limit detection of the transmittance can reach 10-12, while the result of the conventional approach is merely 10-6. Therefore, the system can make an effective assessment of solar blind ultraviolet filters.

Kalman filter based control for Adaptive Optics

NASA Astrophysics Data System (ADS)

Petit, Cyril; Quiros-Pacheco, Fernando; Conan, Jean-Marc; Kulcsár, Caroline; Raynaud, Henri-François; Fusco, Thierry

2004-12-01

Classical Adaptive Optics suffer from a limitation of the corrected Field Of View. This drawback has lead to the development of MultiConjugated Adaptive Optics. While the first MCAO experimental set-ups are presently under construction, little attention has been paid to the control loop. This is however a key element in the optimization process especially for MCAO systems. Different approaches have been proposed in recent articles for astronomical applications : simple integrator, Optimized Modal Gain Integrator and Kalman filtering. We study here Kalman filtering which seems a very promising solution. Following the work of Brice Leroux, we focus on a frequential characterization of kalman filters, computing a transfer matrix. The result brings much information about their behaviour and allows comparisons with classical controllers. It also appears that straightforward improvements of the system models can lead to static aberrations and vibrations filtering. Simulation results are proposed and analysed thanks to our frequential characterization. Related problems such as model errors, aliasing effect reduction or experimental implementation and testing of Kalman filter control loop on a simplified MCAO experimental set-up could be then discussed.

Fiber-Optic Gratings for Lidar Measurements of Water Vapor

NASA Technical Reports Server (NTRS)

Vann, Leila B.; DeYoung, Russell J.

2006-01-01

Narrow-band filters in the form of phase-shifted Fabry-Perot Bragg gratings incorporated into optical fibers are being developed for differential-absorption lidar (DIAL) instruments used to measure concentrations of atmospheric water vapor. The basic idea is to measure the relative amounts of pulsed laser light scattered from the atmosphere at two nearly equal wavelengths, one of which coincides with an absorption spectral peak of water molecules and the other corresponding to no water vapor absorption. As part of the DIAL measurement process, the scattered light is made to pass through a filter on the way to a photodetector. Omitting other details of DIAL for the sake of brevity, what is required of the filter is to provide a stop band that: Surrounds the water-vapor spectral absorption peaks at a wavelength of 946 nm, Has a spectral width of at least a couple of nanometers, Contains a pass band preferably no wider than necessary to accommodate the 946.0003-nm-wavelength water vapor absorption peak [which has 8.47 pm full width at half maximum (FWHM)], and Contains another pass band at the slightly shorter wavelength of 945.9 nm, where there is scattering of light from aerosol particles but no absorption by water molecules. Whereas filters used heretofore in DIAL have had bandwidths of =300 pm, recent progress in the art of fiber-optic Bragg-grating filters has made it feasible to reduce bandwidths to less than or equal to 20 pm and thereby to reduce background noise. Another benefit of substituting fiber-optic Bragg-grating filters for those now in use would be significant reductions in the weights of DIAL instruments. Yet another advantage of fiber-optic Bragg-grating filters is that their transmission spectra can be shifted to longer wavelengths by heating or stretching: hence, it is envisioned that future DIAL instruments would contain devices for fine adjustment of transmission wavelengths through stretching or heating of fiber-optic Bragg-grating filters nominally designed and fabricated to have transmission wavelengths that, in the absence of stretching, would be slightly too short.

Optical memory based on quantized atomic center-of-mass motion.

PubMed

Lopez, J P; de Almeida, A J F; Felinto, D; Tabosa, J W R

2017-11-01

We report a new type of optical memory using a pure two-level system of cesium atoms cooled by the magnetically assisted Sisyphus effect. The optical information of a probe field is stored in the coherence between quantized vibrational levels of the atoms in the potential wells of a 1-D optical lattice. The retrieved pulse shows Rabi oscillations with a frequency determined by the reading beam intensity and are qualitatively understood in terms of a simple theoretical model. The exploration of the external degrees of freedom of an atom may add another capability in the design of quantum-information protocols using light.

Modeling and performance analysis of an all-optical photonic microwave filter in the frequency range of 0.01-15 GHz

NASA Astrophysics Data System (ADS)

Aguayo-Rodríguez, Gustavo; Zaldívar-Huerta, Ignacio E.; Rodríguez-Asomoza, Jorge; García-Juárez, Alejandro; Alonso-Rubio, Paul

2010-01-01

The generation, distribution and processing of microwave signals in the optical domain is a topic of research due to many advantages such as low loss, light weight, broadband width, and immunity to electromagnetic interference. In this sense, a novel all-optical microwave photonic filter scheme is proposed and experimentally demonstrated in the frequency range of 0.01-15.0 GHz. A microwave signal generated by optical mixing drives the microwave photonic filter. Basically, photonic filter is composed by a multimode laser diode, an integrated Mach- Zehnder intensity modulator, and 28.3-Km of single-mode standard fiber. Frequency response of the microwave photonic filter depends of the emission spectral characteristics of the multimode laser diode, the physical length of the single-mode standard fiber, and the chromatic dispersion factor associated to this type of fiber. Frequency response of the photonic filter is composed of a low-pass band centered at zero frequency, and several band-pass lobes located periodically on the microwave frequency range. Experimental results are compared by means of numerical simulations in Matlab exhibiting a small deviation in the frequency range of 0.01-5.0 GHz. However, this deviation is more evident when higher frequencies are reached. In this paper, we evaluate the causes of this deviation in the range of 5.0-15.0 GHz analyzing the parameters involved in the frequency response. This analysis permits to improve the performance of the photonic microwave filter to higher frequencies.

Laser controlled atom source for optical clocks.

PubMed

Kock, Ole; He, Wei; Świerad, Dariusz; Smith, Lyndsie; Hughes, Joshua; Bongs, Kai; Singh, Yeshpal

2016-11-18

Precision timekeeping has been a driving force in innovation, from defining agricultural seasons to atomic clocks enabling satellite navigation, broadband communication and high-speed trading. We are on the verge of a revolution in atomic timekeeping, where optical clocks promise an over thousand-fold improvement in stability and accuracy. However, complex setups and sensitivity to thermal radiation pose limitations to progress. Here we report on an atom source for a strontium optical lattice clock which circumvents these limitations. We demonstrate fast (sub 100 ms), cold and controlled emission of strontium atomic vapours from bulk strontium oxide irradiated by a simple low power diode laser. Our results demonstrate that millions of strontium atoms from the vapour can be captured in a magneto-optical trap (MOT). Our method enables over an order of magnitude reduction in scale of the apparatus. Future applications range from satellite clocks testing general relativity to portable clocks for inertial navigation systems and relativistic geodesy.

Controllable vacuum-induced diffraction of matter-wave superradiance using an all-optical dispersive cavity

NASA Astrophysics Data System (ADS)

Su, Shih-Wei; Lu, Zhen-Kai; Gou, Shih-Chuan; Liao, Wen-Te

2016-10-01

Cavity quantum electrodynamics (CQED) has played a central role in demonstrating the fundamental principles of the quantum world, and in particular those of atom-light interactions. Developing fast, dynamical and non-mechanical control over a CQED system is particularly desirable for controlling atomic dynamics and building future quantum networks at high speed. However conventional mirrors do not allow for such flexible and fast controls over their coupling to intracavity atoms mediated by photons. Here we theoretically investigate a novel all-optical CQED system composed of a binary Bose-Einstein condensate (BEC) sandwiched by two atomic ensembles. The highly tunable atomic dispersion of the CQED system enables the medium to act as a versatile, all-optically controlled atomic mirror that can be employed to manipulate the vacuum-induced diffraction of matter-wave superradiance. Our study illustrates a innovative all-optical element of atomtroics and sheds new light on controlling light-matter interactions.

Laser controlled atom source for optical clocks

PubMed Central

Kock, Ole; He, Wei; Świerad, Dariusz; Smith, Lyndsie; Hughes, Joshua; Bongs, Kai; Singh, Yeshpal

2016-01-01

Precision timekeeping has been a driving force in innovation, from defining agricultural seasons to atomic clocks enabling satellite navigation, broadband communication and high-speed trading. We are on the verge of a revolution in atomic timekeeping, where optical clocks promise an over thousand-fold improvement in stability and accuracy. However, complex setups and sensitivity to thermal radiation pose limitations to progress. Here we report on an atom source for a strontium optical lattice clock which circumvents these limitations. We demonstrate fast (sub 100 ms), cold and controlled emission of strontium atomic vapours from bulk strontium oxide irradiated by a simple low power diode laser. Our results demonstrate that millions of strontium atoms from the vapour can be captured in a magneto-optical trap (MOT). Our method enables over an order of magnitude reduction in scale of the apparatus. Future applications range from satellite clocks testing general relativity to portable clocks for inertial navigation systems and relativistic geodesy. PMID:27857214

Single atom array to form a Rydberg ring

NASA Astrophysics Data System (ADS)

Zhan, Mingsheng; Xu, Peng; He, Xiaodong; Liu, Min; Wang, Jin

2012-02-01

Single atom arrays are ideal quantum systems for studying few-body quantum simulation and quantum computation [1]. Towards realizing a fully controllable array we did a lot of experimental efforts, which include rotating single atoms in a ring optical lattice generated by a spatial light modulator [2], high efficient loading of two atoms into a microscopic optical trap by dynamically reshaping the trap with a spatial light modulator [3], and trapping a single atom in a blue detuned optical bottle beam trap [4]. Recently, we succeeded in trapping up to 6 atoms in a ring optical lattice with one atom in each site. Further laser cooling the array and manipulation of the inner states will provide chance to form Ryberg rings for quantum simulation. [4pt] [1] M. Saffman et al., Rev. Mod. Phys. 82, 2313 (2010)[0pt] [2] X.D. He et al., Opt. Express 17, 21014 (2009)[0pt] [3] X.D. He et al., Opt. Express 18, 13586 (2010)[0pt] [4] P. Xu et al., Opt. Lett. 35, 2164 (2010)

Optical atomic clocks

NASA Astrophysics Data System (ADS)

Poli, N.; Oates, C. W.; Gill, P.; Tino, G. M.

2013-12-01

In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femtosecond optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today's best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in 1018. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

Aperiodic nanoplasmonic devices for directional colour filtering and sensing.

PubMed

Davis, Matthew S; Zhu, Wenqi; Xu, Ting; Lee, Jay K; Lezec, Henri J; Agrawal, Amit

2017-11-07

Exploiting the wave-nature of light in its simplest form, periodic architectures have enabled a panoply of tunable optical devices with the ability to perform useful functions such as filtering, spectroscopy, and multiplexing. Here, we remove the constraint of structural periodicity to enhance, simultaneously, the performance and functionality of passive plasmonic devices operating at optical frequencies. By using a physically intuitive, first-order interference model of plasmon-light interactions, we demonstrate a simple and efficient route towards designing devices with flexible, multi-spectral optical response, fundamentally not achievable using periodic architectures. Leveraging this approach, we experimentally implement ultra-compact directional light-filters and colour-sorters exhibiting angle- or spectrally-tunable optical responses with high contrast, and low spectral or spatial crosstalk. Expanding the potential of aperiodic systems to implement tailored spectral and angular responses, these results hint at promising applications in solar-energy harvesting, optical signal multiplexing, and integrated sensing.

Investigations on atomic-vapor-filter high-spectral-resolution lidar for temperature measurements

NASA Technical Reports Server (NTRS)

Voss, E.; Weitkamp, C.

1992-01-01

The temperature measurement by the analysis of Rayleigh scattered laser radiation with atomic vapor filters is investigated in both theory and laboratory experiments. Synthetic air is irradiated with a cw dye laser at 283 nano-meters, and the backscattered spectrum is analyzed with two lead vapor cells in one oven. Temperature measurements are carried out, and the effect of different parameters on the accuracy is investigated. Important aspects for the realization of a lidar are given.

Combined laser heating and tandem acousto-optical filter for two-dimensional temperature distribution on the surface of the heated microobject

NASA Astrophysics Data System (ADS)

Bykov, A. A.; Kutuza, I. B.; Zinin, P. V.; Machikhin, A. S.; Troyan, I. A.; Bulatov, K. M.; Batshev, V. I.; Mantrova, Y. V.; Gaponov, M. I.; Prakapenka, V. B.; Sharma, S. K.

2018-01-01

Recently it has been shown that it is possible to measure the two-dimensional distribution of the surface temperature of microscopic specimens. The main component of the system is a tandem imaging acousto-optical tunable filter synchronized with a video camera. In this report, we demonstrate that combining the laser heating system with a tandem imaging acousto-optical tunable filter allows measurement of the temperature distribution under laser heating of the platinum plates as well as a visualization of the infrared laser beam, that is widely used for laser heating in diamond anvil cells.

Real-Time Wavelength Discrimination for Improved Neutron Discrimination in CLYC

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

Hornback, Donald Eric; Hu, Michael Z.; Bell, Zane W.

We investigated the effects of optical filters on the pulse shape discrimination properties of Cs 2LiYCl 6:Ce (CLYC) scintillator crystals. By viewing the scintillation light through various optical filters, we attempted to better distinguish between neutron and gamma ray events in the crystal. We applied commercial interference and colored glass filters in addition to fabricating quantum dot (QD) filters by suspending QDs in plastic films and glass. QD filters ultimately failed because of instability of the QDs with respect to oxidation when exposed to ambient air, and the tendency of the QDs to aggregate in the plastic. Of the commercialmore » filters, the best results were obtained with a bandpass interference filter covering the spectral region containing core-valence luminescence (CVL) light. However, the PSD response of filtered CLYC light was always poorer than the response exhibited by unfiltered light because filters always reduced the amount of light available for signal processing.« less

3D Display Using Conjugated Multiband Bandpass Filters

NASA Technical Reports Server (NTRS)

Bae, Youngsam; White, Victor E.; Shcheglov, Kirill

2012-01-01

Stereoscopic display techniques are based on the principle of displaying two views, with a slightly different perspective, in such a way that the left eye views only by the left eye, and the right eye views only by the right eye. However, one of the major challenges in optical devices is crosstalk between the two channels. Crosstalk is due to the optical devices not completely blocking the wrong-side image, so the left eye sees a little bit of the right image and the right eye sees a little bit of the left image. This results in eyestrain and headaches. A pair of interference filters worn as an optical device can solve the problem. The device consists of a pair of multiband bandpass filters that are conjugated. The term "conjugated" describes the passband regions of one filter not overlapping with those of the other, but the regions are interdigitated. Along with the glasses, a 3D display produces colors composed of primary colors (basis for producing colors) having the spectral bands the same as the passbands of the filters. More specifically, the primary colors producing one viewpoint will be made up of the passbands of one filter, and those of the other viewpoint will be made up of the passbands of the conjugated filter. Thus, the primary colors of one filter would be seen by the eye that has the matching multiband filter. The inherent characteristic of the interference filter will allow little or no transmission of the wrong side of the stereoscopic images.

Toward a nanoscience emulator with two dimensional atomic gases

NASA Astrophysics Data System (ADS)

Wang, Ping; Ma, Q.; Dutta, S.; Chen, Yong P.

2009-05-01

We report our experimental progress in constructing a cold atom apparatus for emulating phenomena in nanoscience using low dimensional atom gases. Our first experiments will be performed with a 2D ^87Rb Bose-Einstein condensate created in an optical lattice. Our compact vacuum system consists of two AR-coated glass cells --- a low vacuum magneto-optical trap (MOT) chamber and a high vacuum ``science chamber'', connected by a 15cm-long tube for differential pumping. We have used elliptically shaped cooling laser beams and magnet field coils to realize an elongated MOT in the first chamber, and transferred the atoms to a second MOT in the science chamber by a push laser beam. In the science chamber, a 50W, 1550nm single frequency erbium fiber laser is used to produce an optical dipole trap and optical lattice.In addition, controllable disorder can be introduced with laser speckle and inter-atomic interactions can be tuned by atomic density or Feshbach resonance. We plan to explore important phenomena in nanoscience, such as 2D disorder-induced conductor-insulator transition, quantum Hall effect and graphene-like physics in such a tunable 2D atomic gas in optical lattices.

Tunable atom-light beam splitter using electromagnetically induced transparency

NASA Astrophysics Data System (ADS)

Zhu, Xinyu; Wen, Rong; Chen, J. F.

2018-06-01

With electromagnetically induced transmission (EIT), an optical field can be converted into collective atomic excitation and stored in the atomic medium through switching off the strong-coupling field adiabatically. By varying the power of the coupling pulse, we can control the ratio between the transmitted optical field and the stored atomic mode. We use a cloud of cold 85Rb atoms prepared in magneto-optical trap as the experimental platform. Based on a model of EIT dark-state polariton, we consider the real case where the atomic medium has a finite length. The theoretical calculation gives numerical results that agree well with the experimental data. The results show that the ratio can be changed approximately from 0 to 100%, when the maximum power of the coupling pulse (the pulse length is 100 ns) varies from 0 to 20 mW, in the cold atomic ensemble with an optical depth of 40. This process can be used to achieve an atom-light hybrid beam splitter with tunable splitting ratio and thus find potential application in interferometric measurement and quantum information processing.

Physical correction filter for improving the optical quality of an image

NASA Technical Reports Server (NTRS)

Lee, S. Y. (Inventor)

1975-01-01

A family of physical correction filters is described. Each filter is designed to correct image content of a photographed scene of limited resolution and includes a first filter element with a pinhole through which light passes to a differential amplifier. A second filter element through which light passes through one or more openings, whose geometric configuration is a function of the cause of the resolution loss included. The light, passing through the second filter element, is also supplied to the differential amplifier whose output is used to activate an optical display or recorder to reproduce a photograph or display of the scene in the original photograph or display of the scene in the original photograph with resolution which is significantly greater than that characterizing the original photograph.

A technique for individual atom delivery into a crossed vortex bottle beam trap using a dynamic 1D optical lattice.

PubMed

Dinardo, Brad A; Anderson, Dana Z

2016-12-01

We describe a system for loading a single atom from a reservoir into a blue-detuned crossed vortex bottle beam trap using a dynamic 1D optical lattice. The lattice beams are frequency chirped using acousto-optic modulators, which causes the lattice to move along its axial direction and behave like an optical conveyor belt. A stationary lattice is initially loaded with approximately 6000 atoms from a reservoir, and the conveyor belt transports them 1.1 mm from the reservoir to a bottle beam trap, where a single atom is loaded via light-assisted collisions. Photon counting data confirm that an atom can be delivered and loaded into the bottle beam trap 13.1% of the time.

Optical and digital pattern recognition; Proceedings of the Meeting, Los Angeles, CA, Jan. 13-15, 1987

NASA Technical Reports Server (NTRS)

Liu, Hua-Kuang (Editor); Schenker, Paul (Editor)

1987-01-01

The papers presented in this volume provide an overview of current research in both optical and digital pattern recognition, with a theme of identifying overlapping research problems and methodologies. Topics discussed include image analysis and low-level vision, optical system design, object analysis and recognition, real-time hybrid architectures and algorithms, high-level image understanding, and optical matched filter design. Papers are presented on synthetic estimation filters for a control system; white-light correlator character recognition; optical AI architectures for intelligent sensors; interpreting aerial photographs by segmentation and search; and optical information processing using a new photopolymer.

A landmark recognition and tracking experiment for flight on the Shuttle/Advanced Technology Laboratory (ATL)

NASA Technical Reports Server (NTRS)

Welch, J. D.

1975-01-01

The preliminary design of an experiment for landmark recognition and tracking from the Shuttle/Advanced Technology Laboratory is described. It makes use of parallel coherent optical processing to perform correlation tests between landmarks observed passively with a telescope and previously made holographic matched filters. The experimental equipment including the optics, the low power laser, the random access file of matched filters and the electro-optical readout device are described. A real time optically excited liquid crystal device is recommended for performing the input non-coherent optical to coherent optical interface function. A development program leading to a flight experiment in 1981 is outlined.

Tunable orbital angular momentum mode filter based on optical geometric transformation.

PubMed

Huang, Hao; Ren, Yongxiong; Xie, Guodong; Yan, Yan; Yue, Yang; Ahmed, Nisar; Lavery, Martin P J; Padgett, Miles J; Dolinar, Sam; Tur, Moshe; Willner, Alan E

2014-03-15

We present a tunable mode filter for spatially multiplexed laser beams carrying orbital angular momentum (OAM). The filter comprises an optical geometric transformation-based OAM mode sorter and a spatial light modulator (SLM). The programmable SLM can selectively control the passing/blocking of each input OAM beam. We experimentally demonstrate tunable filtering of one or multiple OAM modes from four multiplexed input OAM modes with vortex charge of ℓ=-9, -4, +4, and +9. The measured output power suppression ratio of the propagated modes to the blocked modes exceeds 14.5 dB.

FM and FSK response of tunable two-electrode DFB lasers and their performance with noncoherent detection

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

Willner, A.E.; Kuznetsov, M.; Kaminow, I.P.

1989-12-01

Two-electrode DFB lasers show promise for combining high speed and frequency tunability for FDM-FSK networks. The authors have measured the FM and FSK response of such lasers up to modulation frequencies of {approximately} GHz. Using these lasers in a noncoherent detection system in which a fiber Fabry-Perot tunable optical filter converts an FSK signal into ASK format, the authors demonstrate 10{sup {minus}9} BER up to 1 Gbit/s. Nonuniform FM response and consequent tone broadening of the optical-filtering FSK spectra can lead to system power penalties due to optical-filtering effects. Thus, for a given FM response, they can project the behaviormore » of these lasers in FSK optical systems.« less

Valley filters, accumulators, and switches induced in graphene quantum dots by lines of adsorbed hydrogen atoms

NASA Astrophysics Data System (ADS)

Azari, Mohammadhadi; Kirczenow, George

2018-06-01

We present electronic structure and quantum transport calculations that predict conducting channels induced in graphene quantum dots by lines of adsorbed hydrogen atoms to function as highly efficient, experimentally realizable valley filters, accumulators, and switches. The underlying physics is an interesting property of graphene Dirac point resonances (DPRs) that is revealed here, namely, that an electric current passing through a DPR-mediated conducting channel in a given direction is carried by electrons of only one of the two graphene valleys. Our predictions apply to lines of hydrogen atoms adsorbed on graphene quantum dots that are either free standing or supported on a hexagonal boron nitride substrate.

Filter performance parameters for vectorial high-aperture wave fields.

PubMed

Sheppard, Colin J R; Martinez-Corral, M

2008-03-01

Performance parameters have been presented that can be used to compare the focusing performance of different optical systems, including the effect of pupil filters. These were originally given for the paraxial case and recently extended to the high-aperture scalar regime. We generalize these parameters to the full vectorial case for an aplanatic optical system illuminated by a plane-polarized wave. The behavior of different optical systems is compared.

Acousto-optic filtering of lidar signals

NASA Technical Reports Server (NTRS)

Kolarov, G.; Deleva, A.; Mitsev, TS.

1992-01-01

The predominant part of the noise in lidar receivers is created by the background radiation; therefore, one of the most important elements of the receiving optics is a spectrally selecting filter placed in front of the photodetector. Interference filters are usually used to transmit a given wavelength. Specific properties of the interference filters, such as simple design, reliability, small size, and large aperture, combined with high transmission coefficient and narrow spectral band, make them the preferred spectral device in many cases. However, problems arise in applications such as the Differential Absorption Lidar (DIAL) technique, where fast tuning within a wide spectral region is necessary. Tunable acousto-optical filters (TAOF), used recently in astrophysical observations to suppress the background radiation, can be employed with success in lidar sounding. They are attractive due to the possibility for fast spectral scanning with a narrow transmission band. The TAOF's advantages are fully evident in DIAL lidars where one must simultaneously receive signals at two laser frequencies.

Design of coupled mace filters for optical pattern recognition using practical spatial light modulators

NASA Technical Reports Server (NTRS)

Rajan, P. K.; Khan, Ajmal

1993-01-01

Spatial light modulators (SLMs) are being used in correlation-based optical pattern recognition systems to implement the Fourier domain filters. Currently available SLMs have certain limitations with respect to the realizability of these filters. Therefore, it is necessary to incorporate the SLM constraints in the design of the filters. The design of a SLM-constrained minimum average correlation energy (SLM-MACE) filter using the simulated annealing-based optimization technique was investigated. The SLM-MACE filter was synthesized for three different types of constraints. The performance of the filter was evaluated in terms of its recognition (discrimination) capabilities using computer simulations. The correlation plane characteristics of the SLM-MACE filter were found to be reasonably good. The SLM-MACE filter yielded far better results than the analytical MACE filter implemented on practical SLMs using the constrained magnitude technique. Further, the filter performance was evaluated in the presence of noise in the input test images. This work demonstrated the need to include the SLM constraints in the filter design. Finally, a method is suggested to reduce the computation time required for the synthesis of the SLM-MACE filter.

Simulating Optical Correlation on a Digital Image Processing

NASA Astrophysics Data System (ADS)

Denning, Bryan

1998-04-01

Optical Correlation is a useful tool for recognizing objects in video scenes. In this paper, we explore the characteristics of a composite filter known as the equal correlation peak synthetic discriminant function (ECP SDF). Although the ECP SDF is commonly used in coherent optical correlation systems, the authors simulated the operation of a correlator using an EPIX frame grabber/image processor board to complete this work. Issues pertaining to simulating correlation using an EPIX board will be discussed. Additionally, the ability of the ECP SDF to detect objects that have been subjected to inplane rotation and small scale changes will be addressed by correlating filters against true-class objects placed randomly within a scene. To test the robustness of the filters, the results of correlating the filter against false-class objects that closely resemble the true class will also be presented.

Solid state electro-optic color filter and iris

NASA Technical Reports Server (NTRS)

1975-01-01

A pair of solid state electro-optic filters (SSEF) in a binocular holder were designed and fabricated for evaluation of field sequential stereo TV applications. The electronic circuitry for use with the stereo goggles was designed and fabricated, requiring only an external video input. A polarizing screen suitable for attachment to various size TV monitors for use in conjunction with the stereo goggles was designed and fabricated. An improved engineering model 2 filter was fabricated using the bonded holder technique developed previously and integrated to a GCTA color TV camera. An engineering model color filter was fabricated and assembled using PLZT control elements. In addition, a ruggedized holder assembly was designed, fabricated and tested. This assembly provides electrical contacts, high voltage protection, and support for the fragile PLZT disk, and also permits mounting and optical alignment of the associated polarizers.

Ultra-wide-range measurements of thin-film filter optical density over the visible and near-infrared spectrum.

PubMed

Lequime, Michel; Liukaityte, Simona; Zerrad, Myriam; Amra, Claude

2015-10-05

We present the improved structure and operating principle of a spectrophotometric mean that allows us for the recording of the transmittance of a thin-film filter over an ultra-wide range of optical densities (from 0 to 11) between 400 and 1000 nm. The operation of this apparatus is based on the combined use of a high power supercontinuum laser source, a tunable volume hologram filter, a standard monochromator and a scientific grade CCD camera. The experimentally recorded noise floor is in good accordance with the optical density values given by the theoretical approach. A demonstration of the sensitivity gain provided by this new set-up with respect to standard spectrophotometric means is performed via the characterization of various types of filters (band-pass, long-pass, short-pass, and notch).

All-optical VPN utilizing DSP-based digital orthogonal filters access for PONs

NASA Astrophysics Data System (ADS)

Zhang, Xiaoling; Zhang, Chongfu; Chen, Chen; Jin, Wei; Qiu, Kun

2018-04-01

Utilizing digital filtering-enabled signal multiplexing and de-multiplexing, a cost-effective all-optical virtual private network (VPN) system is proposed, for the first time to our best knowledge, in digital filter multiple access passive optical networks (DFMA-PONs). Based on the DFMA technology, the proposed system can be easily designed to meet the requirements of next generation network's flexibility, elasticity, adaptability and compatibility. Through dynamic digital filter allocation and recycling, the proposed all-optical VPN system can provide dynamic establishments and cancellations of multiple VPN communications with arbitrary traffic volumes. More importantly, due to the employment of DFMA technology, the system is not limited to a fixed signal format and different signal formats such as pulse amplitude modulation (PAM), quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexing (OFDM) can be used. Moreover, one transceiver is sufficient to simultaneously transmit upstream (US)/VPN data to optical line terminal (OLT) or other VPN optical network units (ONUs), thus leading to great reduction in network constructions and operation expenditures. The proposed all-optical VPN system is demonstrated with the transceiver incorporating the formats of QAM and OFDM, which can be made transparent to downstream (DS), US and VPN communications. The bit error rates (BERs) of DS, US and VPN for OFDM signals are below the forward-error-correction (FEC) limit of 3 . 8 × 10-3 when the received optical powers are about -16.8 dBm, -14.5 dBm and -15.7 dBm, respectively.

Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering

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

Ott, Dino; Oddershede, Lene B., E-mail: oddershede@nbi.dk; Reihani, S. Nader S.

2014-05-15

In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of themore » trapping beam introduced by the required high numerical aperture optics. Here we present a simple and easy-to-implement method to efficiently eliminate crosstalk. The method is based on spatial filtering by simply inserting a pinhole at the correct position and is highly compatible with standard back focal plane photodiode based detection of position and force. Our spatial filtering method reduces crosstalk up to five times better than polarization filtering alone. The effectiveness is dependent on pinhole size and distance between the traps and is here quantified experimentally and reproduced by theoretical modeling. The method here proposed will improve the accuracy of force-distance measurements, e.g., of single molecules, performed by dual-beam optical traps and hence give much more scientific value for the experimental efforts.« less

SPECIAL ISSUE ON OPTICAL PROCESSING OF INFORMATION: Realisation of video-frequency filters on the basis of a new mode of operation of an acousto-optical correlator with spatial integration

NASA Astrophysics Data System (ADS)

Ushakov, V. N.

1995-10-01

A video-frequency acousto-optical correlator with spatial integration, which widens the functional capabilities of correlation-type acousto-optical processors, is described. The correlator is based on a two-dimensional reference transparency and it can filter arbitrary video signals of spectral width limited by the pass band of an acousto-optical modulator. The calculated pulse characteristic is governed by the structure of the reference transparency. A procedure for the synthesis of this transparency is considered and experimental results are reported.

An approach to control tuning range and speed in 1D ternary photonic band gap material nano-layered optical filter structures electro-optically

NASA Astrophysics Data System (ADS)

Zia, Shahneel; Banerjee, Anirudh

2016-05-01

This paper demonstrates a way to control spectrum tuning capability in one-dimensional (1D) ternary photonic band gap (PBG) material nano-layered structures electro-optically. It is shown that not only tuning range, but also tuning speed of tunable optical filters based on 1D ternary PBG structures can be controlled Electro-optically. This approach finds application in tuning range enhancement of 1D Ternary PBG structures and compensating temperature sensitive transmission spectrum shift in 1D Ternary PBG structures.

Design of far-infrared acousto-optic tunable filter based on backward collinear interaction.

PubMed

Voloshinov, Vitaly B; Porokhovnichenko, Dmitriy L; Dyakonov, Evgeniy A

2018-04-10

The paper proposes a design of acousto-optic cell applying backward collinear interaction and acoustic mode transformation in a KRS-5 crystal. This cell may serve as an acousto-optic tunable filter for far-infrared spectral range and is able to operate both with collimated optical beams and with divergent beams forming images. The problem of acoustic mode transformation by wave reflection from the crystal facet away from symmetry planes has been solved. Polarization properties of the backward collinear interaction in optically isotropic media are discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

An approach to control tuning range and speed in 1D ternary photonic band gap material nano-layered optical filter structures electro-optically

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

Zia, Shahneel, E-mail: shahneelzia@gmail.com; Banerjee, Anirudh, E-mail: abanerjee@amity.edu

2016-05-06

This paper demonstrates a way to control spectrum tuning capability in one-dimensional (1D) ternary photonic band gap (PBG) material nano-layered structures electro-optically. It is shown that not only tuning range, but also tuning speed of tunable optical filters based on 1D ternary PBG structures can be controlled Electro-optically. This approach finds application in tuning range enhancement of 1D Ternary PBG structures and compensating temperature sensitive transmission spectrum shift in 1D Ternary PBG structures.

Micro-optical fiber probe for use in an intravascular Raman endoscope.

PubMed

Komachi, Yuichi; Sato, Hidetoshi; Aizawa, Katsuo; Tashiro, Hideo

2005-08-01

We believe that we have developed the narrowest optical-fiber Raman probe ever reported, 600 microm in total diameter, that can be inserted into coronary arteries. The selection of suitable optical fibers, filters, and a processing method is discussed. Custom-made filters attached to the front end of a probe eliminate the background Raman signals of the optical fiber itself. The experimental evaluation of various optical fibers is carried out for the selection of suitable fibers. Measurement of the Raman spectra of an atherosclerotic lesion of a rabbit artery in vitro demonstrates the excellent performance of the micro-Raman probe.

A model of optical trapping cold atoms using a metallic nano wire with surface plasmon effect

NASA Astrophysics Data System (ADS)

Thi Phuong Lan, Nguyen; Thi Nga, Do; Viet, Nguyen Ai

2016-06-01

In this work, we construct a new model of optical trapping cold atoms with a metallic nano wire by using surface plasmon effect generated by strong field of laser beams. Using the skin effect, we send a strong oscillated electromagnetic filed through the surface of a metallic nano wire. The local field generated by evanescent effect creates an effective attractive potential near the surface of metallic nano wires. The consideration of some possible boundary and frequency conditions might lead to non-trivial bound state solution for a cold atom. We discus also the case of the laser reflection optical trap with shell-core design, and compare our model with another recent schemes of cold atom optical traps using optical fibers and carbon nanotubes.

Defect of focus in two-line resolution with Hanning amplitude filters

NASA Astrophysics Data System (ADS)

Karunasagar, D.; Bhikshamaiah, G.; Keshavulu Goud, M.; Lacha Goud, S.

In the presence of defocusing the modified Sparrow limits of resolution for two-line objects have been investigated for a diffraction-limited coherent optical system apodized by generalized Hanning amplitude filters. These limits have been studied as a function of different parameters such as intensity ratio, the order of the filter for various amounts of apodization parameter. Results reveal that in some situations the defocusing is effective in enhancing the resolution of an optical system.

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.

Optical coupling of cold atoms to a levitated nanosphere

NASA Astrophysics Data System (ADS)

Montoya, Cris; Witherspoon, Apryl; Fausett, Jacob; Lim, Jason; Kitching, John; Geraci, Andrew

2017-04-01

Cooling mechanical oscillators to their quantum ground state enables the study of quantum phenomena at macroscopic levels. In many cases, the temperature required to cool a mechanical mode to the ground state is below what current cryogenic systems can achieve. As an alternative to cooling via cryogenic systems, it has been shown theoretically that optically trapped nanospheres could reach the ground state by sympathetically cooling the spheres via cold atoms. Such cooled spheres can be used in quantum limited sensing and matter-wave interferometry, and could also enable new hybrid quantum systems where mechanical oscillators act as transducers. In our setup, optical fields are used to couple a sample of cold Rubidium atoms to a nanosphere. The sphere is optically levitated in a separate vacuum chamber, while the atoms are trapped in a 1-D optical lattice and cooled using optical molasses. This work is partially supported by NSF, Grant No. PHY-1506431.

Multispectral interference filter arrays with compensation of angular dependence or extended spectral range.

PubMed

Frey, Laurent; Masarotto, Lilian; Armand, Marilyn; Charles, Marie-Lyne; Lartigue, Olivier

2015-05-04

Thin film Fabry-Perot filter arrays with high selectivity can be realized with a single patterning step, generating a spatial modulation of the effective refractive index in the optical cavity. In this paper, we investigate the ability of this technology to address two applications in the field of image sensors. First, the spectral tuning may be used to compensate the blue-shift of the filters in oblique incidence, provided the filter array is located in an image plane of an optical system with higher field of view than aperture angle. The technique is analyzed for various types of filters and experimental evidence is shown with copper-dielectric infrared filters. Then, we propose a design of a multispectral filter array with an extended spectral range spanning the visible and near-infrared range, using a single set of materials and realizable on a single substrate.

The {sup 2}P{sub 1/2} {yields} {sup 2}P{sub 3/2} laser transition in atomic iodine and the problem of search for signals from extraterrestrial intelligence

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

Kutaev, Yu F; Mankevich, S K; Nosach, O Yu

2007-07-31

It is proposed to search for signals from extraterrestrial intelligence (ETI) at a wavelength of 1.315 {mu}m of the laser {sup 2}P{sub 1/2} {yields} {sup 2}P{sub 3/2} transition in the atomic iodine, which can be used for this purpose as the natural frequency reference. The search at this wavelength is promising because active quantum filters (AQFs) with the quantum sensitivity limit have been developed for this wavelength, which are capable of receiving laser signals, consisting of only a few photons, against the background of emission from a star under study. In addition, high-power iodine lasers emitting diffraction-limited radiation at 1.315more » {mu}m have been created, which highly developed ETI also can have. If a ETI sends in our direction a diffraction-limited 10-ns, 1-kJ laser pulse with the beam diameter of 10 m, a receiver with an AQF mounted on a ten-meter extra-atmospheric optical telescope can detect this signal at a distance of up to 300 light years, irrespective of the ETI position on the celestial sphere. The realisation of the projects for manufacturing optical telescopes of diameter 30 m will increase the research range up to 2700 light years. A weak absorption of the 1.315-{mu}m radiation in the Earth atmosphere (the signal is attenuated by less than 20%) allows the search for ETI signals by using ground telescopes equipped with adaptive optical systems. (laser applications and other topics in quantum electronics)« less

Acousto-Optic Tunable Filter Hyperspectral Microscope Imaging Method for Characterizing Spectra from Foodborne Pathogens.

USDA-ARS?s Scientific Manuscript database

Hyperspectral microscope imaging (HMI) method, which provides both spatial and spectral characteristics of samples, can be effective for foodborne pathogen detection. The acousto-optic tunable filter (AOTF)-based HMI method can be used to characterize spectral properties of biofilms formed by Salmon...

Guided-mode resonance reflection and transmission filters in the optical and microwave spectral ranges

NASA Astrophysics Data System (ADS)

Tibuleac, Sorin

In this dissertation, new reflection and transmission filters are developed and characterized in the optical and microwave spectral regions. These guided-mode resonance (GMR) filters are implemented by integrating diffraction gratings into classical thin-film multilayers to produce high efficiency filter response and low sidebands extended over a large spectral range. Diffraction from phase-shifted gratings and gratings with different periods is analyzed using rigorous coupled-wave theory yielding a new approach to filter linewidth broadening, line-shaping, and multi-line filters at normal incidence. New single-grating transmission filters presented have narrow linewidth, high peak transmittance, and low sideband reflectance. A comparison with classical thin-film filters shows that GMR devices require significantly fewer layers to obtain narrow linewidth and high peak response. All-dielectric microwave frequency- selective surfaces operating in reflection or transmission are shown to be realizable with only a few layers using common microwave materials. Single-layer and multilayer waveguide gratings operating as reflection and transmission filters, respectively, were built and tested in the 4-20 GHz frequency range. The presence of GMR notches and peaks is clearly established by the experimental results, and their spectral location and lineshape found to be in excellent agreement with the theoretical predictions. A new computer program using genetic algorithms and rigorous coupled-wave analysis was developed for optimization of multilayer structures containing homogeneous and diffractive layers. This program was utilized to find GMR filters possessing features not previously known. Thus, numerous examples of transmission filters with peaks approaching 100%, narrow linewidths (~0.03%), and low sidebands have been found in structures containing only 1-3 layers. A new type of GMR device integrating a waveguide grating with subwavelength period on the endface of an optical fiber is developed for high-resolution biomedical or chemical sensors and spectral filtering applications. Diffraction gratings with submicron periods exhibiting high efficiencies have been recorded for the first time on coated and uncoated endfaces of single-mode and multimode fibers. Guided-mode resonance transmittance notches of ~18% were experimentally obtained with structures consisting of photoresist gratings on thin films of Si3N4 deposited on optical fiber endfaces.

A Compact, High-Flux Cold Atom Beam Source

NASA Technical Reports Server (NTRS)

Kellogg, James R.; Kohel, James M.; Thompson, Robert J.; Aveline, David C.; Yu, Nan; Schlippert, Dennis

2012-01-01

The performance of cold atom experiments relying on three-dimensional magneto-optical trap techniques can be greatly enhanced by employing a highflux cold atom beam to obtain high atom loading rates while maintaining low background pressures in the UHV MOT (ultra-high vacuum magneto-optical trap) regions. Several techniques exist for generating slow beams of cold atoms. However, one of the technically simplest approaches is a two-dimensional (2D) MOT. Such an atom source typically employs at least two orthogonal trapping beams, plus an additional longitudinal "push" beam to yield maximum atomic flux. A 2D atom source was created with angled trapping collimators that not only traps atoms in two orthogonal directions, but also provides a longitudinal pushing component that eliminates the need for an additional push beam. This development reduces the overall package size, which in turn, makes the 2D trap simpler, and requires less total optical power. The atom source is more compact than a previously published effort, and has greater than an order of magnitude improved loading performance.

Adiabatic Quantum Computing with Neutral Atoms

NASA Astrophysics Data System (ADS)

Hankin, Aaron; Biedermann, Grant; Burns, George; Jau, Yuan-Yu; Johnson, Cort; Kemme, Shanalyn; Landahl, Andrew; Mangan, Michael; Parazzoli, L. Paul; Schwindt, Peter; Armstrong, Darrell

2012-06-01

We are developing, both theoretically and experimentally, a neutral atom qubit approach to adiabatic quantum computation. Using our microfabricated diffractive optical elements, we plan to implement an array of optical traps for cesium atoms and use Rydberg-dressed ground states to provide a controlled atom-atom interaction. We will develop this experimental capability to generate a two-qubit adiabatic evolution aimed specifically toward demonstrating the two-qubit quadratic unconstrained binary optimization (QUBO) routine.

Limit on Excitation and Stabilization of Atoms in Intense Optical Laser Fields.

PubMed

Zimmermann, H; Meise, S; Khujakulov, A; Magaña, A; Saenz, A; Eichmann, U

2018-03-23

Atomic excitation in strong optical laser fields has been found to take place even at intensities exceeding saturation. The concomitant acceleration of the atom in the focused laser field has been considered a strong link to, if not proof of, the existence of the so-called Kramers-Henneberger (KH) atom, a bound atomic system in an intense laser field. Recent findings have moved the importance of the KH atom from being purely of theoretical interest toward real world applications; for instance, in the context of laser filamentation. Considering this increasing importance, we explore the limits of strong-field excitation in optical fields, which are basically imposed by ionization through the spatial field envelope and the field propagation.

Angle- and polarization-insensitive, small area, subtractive color filters via a-Si nanopillar arrays (Conference Presentation)

NASA Astrophysics Data System (ADS)

Fountaine, Katherine T.; Ito, Mikinori; Pala, Ragip; Atwater, Harry A.

2016-09-01

Spectrally-selective nanophotonic and plasmonic structures enjoy widespread interest for application as color filters in imaging devices, due to their potential advantages over traditional organic dyes and pigments. Organic dyes are straightforward to implement with predictable optical performance at large pixel size, but suffer from inherent optical cross-talk and stability (UV, thermal, humidity) issues and also exhibit increasingly unpredictable performance as pixel size approaches dye molecule size. Nanophotonic and plasmonic color filters are more robust, but often have polarization- and angle-dependent optical response and/or require large-range periodicity. Herein, we report on design and fabrication of polarization- and angle-insensitive CYM color filters based on a-Si nanopillar arrays as small as 1um2, supported by experiment, simulation, and analytic theory. Analytic waveguide and Mie theories explain the color filtering mechanism- efficient coupling into and interband transition-mediated attenuation of waveguide-like modes—and also guided the FDTD simulation-based optimization of nanopillar array dimensions. The designed a-Si nanopillar arrays were fabricated using e-beam lithography and reactive ion etching; and were subsequently optically characterized, revealing the predicted polarization- and angle-insensitive (±40°) subtractive filter responses. Cyan, yellow, and magenta color filters have each been demonstrated. The effects of nanopillar array size and inter-array spacing were investigated both experimentally and theoretically to probe the issues of ever-shrinking pixel sizes and cross-talk, respectively. Results demonstrate that these nanopillar arrays maintain their performance down to 1um2 pixel sizes with no inter-array spacing. These concepts and results along with color-processed images taken with a fabricated color filter array will be presented and discussed.

Focusing Light Beams To Improve Atomic-Vapor Optical Buffers

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatoliy

2010-01-01

Specially designed focusing of light beams has been proposed as a means of improving the performances of optical buffers based on cells containing hot atomic vapors (e.g., rubidium vapor). There is also a companion proposal to improve performance by use of incoherent optical pumping under suitable conditions. Regarding the proposal to use focusing: The utility of atomic-vapor optical buffers as optical storage and processing devices has been severely limited by nonuniform spatial distributions of intensity in optical beams, arising from absorption of the beams as they propagate in atomic-vapor cells. Such nonuniformity makes it impossible to optimize the physical conditions throughout a cell, thereby making it impossible to optimize the performance of the cell as an optical buffer. In practical terms simplified for the sake of brevity, "to optimize" as used here means to design the cell so as to maximize the group delay of an optical pulse while keeping the absorption and distortion of the pulse reasonably small. Regarding the proposal to use incoherent optical pumping: For reasons too complex to describe here, residual absorption of light is one of the main impediments to achievement of desirably long group delays in hot atomic vapors. The present proposal is directed toward suppressing residual absorption of light. The idea of improving the performance of slow-light optical buffers by use of incoherent pumping overlaps somewhat with the basic idea of Raman-based slow-light systems. However, prior studies of those systems did not quantitatively answer the question of whether the performance of an atomic vapor or other medium that exhibits electromagnetically induced transparency (EIT) with Raman gain is superior to that of a medium that exhibits EIT without Raman gain.

Fully tunable 360° microwave photonic phase shifter based on a single semiconductor optical amplifier.

PubMed

Sancho, Juan; Lloret, Juan; Gasulla, Ivana; Sales, Salvador; Capmany, José

2011-08-29

A fully tunable microwave photonic phase shifter involving a single semiconductor optical amplifier (SOA) is proposed and demonstrated. 360° microwave phase shift has been achieved by tuning the carrier wavelength and the optical input power injected in an SOA while properly profiting from the dispersion feature of a conveniently designed notch filter. It is shown that the optical filter can be advantageously employed to switch between positive and negative microwave phase shifts. Numerical calculations corroborate the experimental results showing an excellent agreement.

Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal.

PubMed

Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin

2016-07-01

A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application.

Cold Atom Source Containing Multiple Magneto-Optical Traps

NASA Technical Reports Server (NTRS)

Ramirez-Serrano, Jaime; Kohel, James; Kellogg, James; Lim, Lawrence; Yu, Nan; Maleki, Lute

2007-01-01

An apparatus that serves as a source of a cold beam of atoms contains multiple two-dimensional (2D) magneto-optical traps (MOTs). (Cold beams of atoms are used in atomic clocks and in diverse scientific experiments and applications.) The multiple-2D-MOT design of this cold atom source stands in contrast to single-2D-MOT designs of prior cold atom sources of the same type. The advantages afforded by the present design are that this apparatus is smaller than prior designs.

Low-cost space-varying FIR filter architecture for computational imaging systems

NASA Astrophysics Data System (ADS)

Feng, Guotong; Shoaib, Mohammed; Schwartz, Edward L.; Dirk Robinson, M.

2010-01-01

Recent research demonstrates the advantage of designing electro-optical imaging systems by jointly optimizing the optical and digital subsystems. The optical systems designed using this joint approach intentionally introduce large and often space-varying optical aberrations that produce blurry optical images. Digital sharpening restores reduced contrast due to these intentional optical aberrations. Computational imaging systems designed in this fashion have several advantages including extended depth-of-field, lower system costs, and improved low-light performance. Currently, most consumer imaging systems lack the necessary computational resources to compensate for these optical systems with large aberrations in the digital processor. Hence, the exploitation of the advantages of the jointly designed computational imaging system requires low-complexity algorithms enabling space-varying sharpening. In this paper, we describe a low-cost algorithmic framework and associated hardware enabling the space-varying finite impulse response (FIR) sharpening required to restore largely aberrated optical images. Our framework leverages the space-varying properties of optical images formed using rotationally-symmetric optical lens elements. First, we describe an approach to leverage the rotational symmetry of the point spread function (PSF) about the optical axis allowing computational savings. Second, we employ a specially designed bank of sharpening filters tuned to the specific radial variation common to optical aberrations. We evaluate the computational efficiency and image quality achieved by using this low-cost space-varying FIR filter architecture.

Electromagnetically Induced Absorption (EIA) and a ``Twist'' on Nonlinear Magneto-optical Rotation (NMOR) with Cold Atoms

NASA Astrophysics Data System (ADS)

Kunz, Paul; Meyer, David; Quraishi, Qudsia

2015-05-01

Within the class of nonlinear optical effects that exhibit sub-natural linewidth features, electromagnetically induced transparency (EIT) and nonlinear magneto-optical rotation (NMOR) stand out as having made dramatic impacts on various applications including atomic clocks, magnetometry, and single photon storage. A related effect, known as electromagnetically induced absorption (EIA), has received less attention in the literature. Here, we report on the first observation of EIA in cold atoms using the Hanle configuration, where a single laser beam is used to both pump and probe the atoms while sweeping a magnetic field through zero along the beam direction. We find that, associated with the EIA peak, a ``twist'' appears in the corresponding NMOR signal. A similar twist has been previously noted by Budker et al., in the context of warm vapor optical magnetometry, and was ascribed to optical pumping through nearby hyperfine levels. By studying this feature through numerical simulations and cold atom experiments, thus rendering the hyperfine levels well resolved, we enhance the understanding of the optical pumping mechanism behind it, and elucidate its relation to EIA. Finally, we demonstrate a useful application of these studies through a simple and rapid method for nulling background magnetic fields within our atom chip apparatus.

Tunable filters for multispectral imaging of aeronomical features

NASA Astrophysics Data System (ADS)

Goenka, C.; Semeter, J. L.; Noto, J.; Dahlgren, H.; Marshall, R.; Baumgardner, J.; Riccobono, J.; Migliozzi, M.

2013-10-01

Multispectral imaging of optical emissions in the Earth's upper atmosphere unravels vital information about dynamic phenomena in the Earth-space environment. Wavelength tunable filters allow us to accomplish this without using filter wheels or multiple imaging setups, but with identifiable caveats and trade-offs. We evaluate one such filter, a liquid crystal Fabry-Perot etalon, as a potential candidate for the next generation of imagers for aeronomy. The tunability of such a filter can be exploited in imaging features such as the 6300-6364 Å oxygen emission doublet, or studying the rotational temperature of N2+ in the 4200-4300 Å range, observations which typically require multiple instruments. We further discuss the use of this filter in an optical instrument, called the Liquid Crystal Hyperspectral Imager (LiCHI), which will be developed to make simultaneous measurements in various wavelength ranges.

Microwave photonic filters with negative coefficients based on phase inversion in an electro-optic modulator.

PubMed

Capmany, José; Pastor, Daniel; Martinez, Alfonso; Ortega, Beatriz; Sales, Salvador

2003-08-15

We report on a novel technical approach to the implementation of photonic rf filters that is based on the pi phase inversion that a rf modulating signal suffers in an electro-optic Mach-Zehnder modulator, which depends on whether the positive or the negative linear slope of the signal's modulation transfer function is employed. Experimental evidence is provided of the implementation of filters with negative coefficients that shows excellent agreement with results predicted by the theory.

Improved methods of performing coherent optical correlation

NASA Technical Reports Server (NTRS)

Husain-Abidi, A. S.

1972-01-01

Coherent optical correlators are described in which complex spatial filters are recorded by a quasi-Fourier transform method. The high-pass spatial filtering effects (due to the dynamic range of photographic films) normally encountered in Vander Lugt type complex filters are not present in this system. Experimental results for both transmittive as well as reflective objects are presented. Experiments are also performed by illuminating the object with diffused light. A correlator using paraboloidal mirror segments as the Fourier-transforming element is also described.

Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

NASA Astrophysics Data System (ADS)

Min, Rui; Marques, Carlos; Bang, Ole; Ortega, Beatriz

2018-03-01

We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured.

Secure optical generalized filter bank multi-carrier system based on cubic constellation masked method.

PubMed

Zhang, Lijia; Liu, Bo; Xin, Xiangjun

2015-06-15

A secure optical generalized filter bank multi-carrier (GFBMC) system with carrier-less amplitude-phase (CAP) modulation is proposed in this Letter. The security is realized through cubic constellation-masked method. Large key space and more flexibility masking can be obtained by cubic constellation masking aligning with the filter bank. An experiment of 18 Gb/s encrypted GFBMC/CAP system with 25-km single-mode fiber transmission is performed to demonstrate the feasibility of the proposed method.

Electronically tuned optical filters

NASA Technical Reports Server (NTRS)

Castellano, J. A.; Pasierb, E. F.; Oh, C. S.; Mccaffrey, M. T.

1972-01-01

A detailed account is given of efforts to develop a three layer, polychromic filter that can be tuned electronically. The operation of the filter is based on the cooperative alignment of pleochroic dye molecules by nematic liquid crystals activated by electric fields. This orientation produces changes in the optical density of the material and thus changes in the color of light transmitted through the medium. In addition, attempts to improve materials and devices which employ field induced changes of a cholesteric to a nematic liquid crystal are presented.

Filter Function for Wavefront Sensing Over a Field of View

NASA Technical Reports Server (NTRS)

Dean, Bruce H.

2007-01-01

A filter function has been derived as a means of optimally weighting the wavefront estimates obtained in image-based phase retrieval performed at multiple points distributed over the field of view of a telescope or other optical system. When the data obtained in wavefront sensing and, more specifically, image-based phase retrieval, are used for controlling the shape of a deformable mirror or other optic used to correct the wavefront, the control law obtained by use of the filter function gives a more balanced optical performance over the field of view than does a wavefront-control law obtained by use of a wavefront estimate obtained from a single point in the field of view.

Real-time optical correlator using computer-generated holographic filter on a liquid crystal light valve

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin; Yu, Jeffrey

1990-01-01

Limitations associated with the binary phase-only filter often used in optical correlators are presently circumvented in the writing of complex-valued data on a gray-scale spatial light modulator through the use of a computer-generated hologram (CGH) algorithm. The CGH encodes complex-valued data into nonnegative real CGH data in such a way that it may be encoded in any of the available gray-scale spatial light modulators. A CdS liquid-crystal light valve is used for the complex-valued CGH encoding; computer simulations and experimental results are compared, and the use of such a CGH filter as the synapse hologram in a holographic optical neural net is discussed.

Picosecond and sub-picosecond flat-top pulse generation using uniform long-period fiber gratings

NASA Astrophysics Data System (ADS)

Park, Y.; Kulishov, M.; Slavík, R.; Azaña, J.

2006-12-01

We propose a novel linear filtering scheme based on ultrafast all-optical differentiation for re-shaping of ultrashort pulses generated from a mode-locked laser into flat-top pulses. The technique is demonstrated using simple all-fiber optical filters, more specifically uniform long period fiber gratings (LPGs) operated in transmission. The large bandwidth typical for these fiber filters allows scaling the technique to the sub-picosecond regime. In the experiments reported here, 600-fs and 1.8-ps Gaussian-like optical pulses (@ 1535 nm) have been re-shaped into 1-ps and 3.2-ps flat-top pulses, respectively, using a single 9-cm long uniform LPG.

A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth.

PubMed

Zhang, Shanchao; Chen, J F; Liu, Chang; Zhou, Shuyu; Loy, M M T; Wong, G K L; Du, Shengwang

2012-07-01

We describe the apparatus of a dark-line two-dimensional (2D) magneto-optical trap (MOT) of (85)Rb cold atoms with high optical depth (OD). Different from the conventional configuration, two (of three) pairs of trapping laser beams in our 2D MOT setup do not follow the symmetry axes of the quadrupole magnetic field: they are aligned with 45° angles to the longitudinal axis. Two orthogonal repumping laser beams have a dark-line volume in the longitudinal axis at their cross over. With a total trapping laser power of 40 mW and repumping laser power of 18 mW, we obtain an atomic OD up to 160 in an electromagnetically induced transparency (EIT) scheme, which corresponds to an atomic-density-length product NL = 2.05 × 10(15) m(-2). In a closed two-state system, the OD can become as large as more than 600. Our 2D MOT configuration allows full optical access of the atoms in its longitudinal direction without interfering with the trapping and repumping laser beams spatially. Moreover, the zero magnetic field along the longitudinal axis allows the cold atoms maintain a long ground-state coherence time without switching off the MOT magnetic field, which makes it possible to operate the MOT at a high repetition rate and a high duty cycle. Our 2D MOT is ideal for atomic-ensemble-based quantum optics applications, such as EIT, entangled photon pair generation, optical quantum memory, and quantum information processing.

Relaxation method of compensation in an optical correlator

NASA Technical Reports Server (NTRS)

Juday, Richard D.; Daiuto, Brian J.

1987-01-01

An iterative method is proposed for the sharpening of programmable filters in a 4-f optical correlator. Continuously variable spatial light modulators (SLMs) permit the fine adjustment of optical processing filters so as to compensate for the departures from ideal behavior of a real optical system. Although motivated by the development of continuously variable phase-only SLMs, the proposed sharpening method is also applicable to amplitude modulators and, with appropriate adjustments, to binary modulators as well. A computer simulation is presented that illustrates the potential effectiveness of the method: an image is placed on the input to the correlator, and its corresponding phase-only filter is adjusted (allowed to relax) so as to produce a progressively brighter and more centralized peak in the correlation plane. The technique is highly robust against the form of the system's departure from ideal behavior.

Optical Correlation

NASA Technical Reports Server (NTRS)

Cotariu, Steven S.

1991-01-01

Pattern recognition may supplement or replace certain navigational aids on spacecraft in docking or landing activities. The need to correctly identify terrain features remains critical in preparation of autonomous planetary landing. One technique that may solve this problem is optical correlation. Correlation has been successfully demonstrated under ideal conditions; however, noise significantly affects the ability of the correlator to accurately identify input signals. Optical correlation in the presence of noise must be successfully demonstrated before this technology can be incorporated into system design. An optical correlator is designed and constructed using a modified 2f configuration. Liquid crystal televisions (LCTV) are used as the spatial light modulators (SLM) for both the input and filter devices. The filter LCTV is characterized and an operating curve is developed. Determination of this operating curve is critical for reduction of input noise. Correlation of live input with a programmable filter is demonstrated.

Flat-Passband 3 × 3 Interleaving Filter Designed With Optical Directional Couplers in Lattice Structure

NASA Astrophysics Data System (ADS)

Wang, Qi Jie; Zhang, Ying; Soh, Yeng Chai

2005-12-01

This paper presents a novel lattice optical delay-line circuit using 3 × 3 directional couplers to implement three-port optical interleaving filters. It is shown that the proposed circuit can deliver three channels of 2pi/3 phase-shifted interleaving transmission spectra if the coupling ratios of the last two directional couplers are selected appropriately. The other performance requirements of an optical interleaver can be achieved by designing the remaining part of the lattice circuit. A recursive synthesis design algorithm is developed to calculate the design parameters of the lattice circuit that will yield the desired filter response. As illustrative examples, interleavers with maximally flat-top passband transmission and with given transmission performance on passband ripples and passband bandwidth, respectively, are designed to verify the effectiveness of the proposed design scheme.

Nano-aquarium fabrication with cut-off filter for mechanism study of Phormidium assemblage

NASA Astrophysics Data System (ADS)

Hanada, Y.; Sugioka, K.; Ishikawa, I.; Kawano, H.; Miyawaki, A.; Midorikawa, K.

2010-02-01

We demonstrate fabrication of microfluidic chips integrated with different functional elements such as optical filters and optical waveguide for mechanism study of gliding movement of Phormidium to a seedling root using a femtosecond (fs) laser. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in formation of three dimensional (3D) hollow microstructures embedded in a photostructurable glass. The embedded microfludic structures enabled us to easily and efficiently observe Phormidium gliding to the seedling root, which accelerates growth of the seedling. In addition, fabrication of optical filter and optical waveguide integrated with the microfluidic structures in the microchip clarified the mechanism of the gliding movement. Such microchips, referred to as a nano-aquarium, realize the efficient and highly functional observation and analysis of the gliding movement of Phormidium.

Optical correlation

NASA Astrophysics Data System (ADS)

Cotariu, Steven S.

1991-12-01

Pattern recognition may supplement or replace certain navigational aids on spacecraft in docking or landing activities. The need to correctly identify terrain features remains critical in preparation of autonomous planetary landing. One technique that may solve this problem is optical correlation. Correlation has been successfully demonstrated under ideal conditions; however, noise significantly affects the ability of the correlator to accurately identify input signals. Optical correlation in the presence of noise must be successfully demonstrated before this technology can be incorporated into system design. An optical correlator is designed and constructed using a modified 2f configuration. Liquid crystal televisions (LCTV) are used as the spatial light modulators (SLM) for both the input and filter devices. The filter LCTV is characterized and an operating curve is developed. Determination of this operating curve is critical for reduction of input noise. Correlation of live input with a programmable filter is demonstrated.

Laser tweezer actuated microphotonic array devices for high resolution imaging and analysis in chip-based biosystems

NASA Astrophysics Data System (ADS)

Birkbeck, Aaron L.

A new technology is developed that functionally integrates arrays of lasers and micro-optics into microfluidic systems for the purpose of imaging, analyzing, and manipulating objects and biological cells. In general, the devices and technologies emerging from this area either lack functionality through the reliance on mechanical systems or provide a serial-based, time consuming approach. As compared to the current state of art, our all-optical design methodology has several distinguishing features, such as parallelism, high efficiency, low power, auto-alignment, and high yield fabrication methods, which all contribute to minimizing the cost of the integration process. The potential use of vertical cavity surface emitting lasers (VCSELs) for the creation of two-dimensional arrays of laser optical tweezers that perform independently controlled, parallel capture, and transport of large numbers of individual objects and biological cells is investigated. One of the primary biological applications for which VCSEL array sourced laser optical tweezers are considered is the formation of engineered tissues through the manipulation and spatial arrangement of different types of cells in a co-culture. Creating devices that combine laser optical tweezers with select micro-optical components permits optical imaging and analysis functions to take place inside the microfluidic channel. One such device is a micro-optical spatial filter whose motion and alignment is controlled using a laser optical tweezer. Unlike conventional spatial filter systems, our device utilizes a refractive optical element that is directly incorporated onto the lithographically patterned spatial filter. This allows the micro-optical spatial filter to automatically align itself in three-dimensions to the focal point of the microscope objective, where it then filters out the higher frequency additive noise components present in the laser beam. As a means of performing high resolution imaging in the microfluidic channel, we developed a novel technique that integrates the capacity of a laser tweezer to optically trap and manipulate objects in three-dimensions with the resolution-enhanced imaging capabilities of a solid immersion lens (SIL). In our design, the SIL is a free-floating device whose imaging beam, motion control and alignment is provided by a laser optical tweezer, which allows the microfluidic SIL to image in areas that are inaccessible to traditional solid immersion microscopes.

Production and characterization of a dual species magneto-optical trap of cesium and ytterbium.

PubMed

Kemp, S L; Butler, K L; Freytag, R; Hopkins, S A; Hinds, E A; Tarbutt, M R; Cornish, S L

2016-02-01

We describe an apparatus designed to trap and cool a Yb and Cs mixture. The apparatus consists of a dual species effusive oven source, dual species Zeeman slower, magneto-optical traps in a single ultra-high vacuum science chamber, and the associated laser systems. The dual species Zeeman slower is used to load sequentially the two species into their respective traps. Its design is flexible and may be adapted for other experiments with different mixtures of atomic species. The apparatus provides excellent optical access and can apply large magnetic bias fields to the trapped atoms. The apparatus regularly produces 10(8) Cs atoms at 13.3 μK in an optical molasses, and 10(9) (174)Y b atoms cooled to 22 μK in a narrowband magneto-optical trap.

[Application of AOTF in spectral analysis. 3. Application of AOTF in atomic emission spectral analysis].

PubMed

Chen, Ze-yong; Peng, Rong-fei; Zhang, Zhan-xia

2002-06-01

An atomic emission spectrometer based on acousto-optic tunable filter (AOTF) was self-constructed and was used to evaluate its practical use in atomic emission analysis. The AOTF used was of model TEAF5-0.36-0.52-S (Brimrose, USA) and the frequency of the direct digital RF synthesizer ranges from 100 MHz to 200 MHz. ICP and PMT were used as light source and detector respectively. The software, written in Visual C++ and running on the Windows 98 platform, is of an utility program system having two data banks and multiwindows. The wavelength calibration was performed with 14 emission lines of Ca, Y, Li, Eu, Sr and Ba using a tenth-order polynomial for line fitting method. The absolute error of the peak position was less than 0.1 nm, and the peak deviation was only 0.04 nm as the PMT varied from 337.5 V to 412.5 V. The scanning emission spectra and the calibration curves of Ba, Y, Eu, Sc and Sr are presented. Their average correlation coefficient was 0.9991 and their detection limits were in the range of 0.051 to 0.97 micrograms.mL-1 respectively. The detection limit can be improved under optimized operating conditions. However, the spectral resolution is only 2.1 nm at the wavelength of 488 nm. Evidently, this poor spectral resolution would restrict the application of AOTF in atomic emission spectral analysis, unless an enhancing techniques is integrated in it.

Analytical SuperSTEM for extraterrestrial materials research

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

Bradley, J P; Dai, Z R

2009-09-08

Electron-beam studies of extraterrestrial materials with significantly improved spatial resolution, energy resolution and sensitivity are enabled using a 300 keV SuperSTEM scanning transmission electron microscope with a monochromator and two spherical aberration correctors. The improved technical capabilities enable analyses previously not possible. Mineral structures can be directly imaged and analyzed with single-atomic-column resolution, liquids and implanted gases can be detected, and UV-VIS optical properties can be measured. Detection limits for minor/trace elements in thin (<100 nm thick) specimens are improved such that quantitative measurements of some extend to the sub-500 ppm level. Electron energy-loss spectroscopy (EELS) can be carried outmore » with 0.10-0.20 eV energy resolution and atomic-scale spatial resolution such that variations in oxidation state from one atomic column to another can be detected. Petrographic mapping is extended down to the atomic scale using energy-dispersive x-ray spectroscopy (EDS) and energy-filtered transmission electron microscopy (EFTEM) imaging. Technical capabilities and examples of the applications of SuperSTEM to extraterrestrial materials are presented, including the UV spectral properties and organic carbon K-edge fine structure of carbonaceous matter in interplanetary dust particles (IDPs), x-ray elemental maps showing the nanometer-scale distribution of carbon within GEMS (glass with embedded metal and sulfides), the first detection and quantification of trace Ti in GEMS using EDS, and detection of molecular H{sub 2}O in vesicles and implanted H{sub 2} and He in irradiated mineral and glass grains.« less

Miniaturized multi channel infrared optical gas sensor system

NASA Astrophysics Data System (ADS)

Wöllenstein, Jürgen; Eberhardt, Andre; Rademacher, Sven; Schmitt, Katrin

2011-06-01

Infrared spectroscopy uses the characteristic absorption of the molecules in the mid infrared and allows the determination of the gases and their concentration. Especially by the absorption at longer wavelengths between 8 μm and 12 μm, the so called "fingerprint" region, the molecules can be measured with highest selectivity. We present an infrared optical filter photometer for the analytical determination of trace gases in the air. The challenge in developing the filter photometer was the construction of a multi-channel system using a novel filter wheel concept - which acts as a chopper too- in order to measure simultaneously four gases: carbon monoxide, carbon dioxide, methane and ammonia. The system consists of a broadband infrared emitter, a long path cell with 1.7m optical path length, a filter wheel and analogue and digital signal processing. Multi channel filter photometers normally need one filter and one detector per target gas. There are small detection units with one, two or more detectors with integrated filters available on the market. One filter is normally used as reference at a wavelength without any cross-sensitivities to possible interfering gases (e.g. at 3.95 μm is an "atmospheric window" - a small spectral band without absorbing gases in the atmosphere). The advantage of a filter-wheel set-up is that a single IR-detector can be used, which reduces the signal drift enormously. Pyroelectric and thermopile detectors are often integrated in these kinds of spectrometers. For both detector types a modulation of the light is required and can be done - without an additional chopper - with the filter wheel.

Raman Laser Spectrometer internal Optical Head current status: opto-mechanical redesign to minimize the excitation laser trace

NASA Astrophysics Data System (ADS)

Sanz, Miguel; Ramos, Gonzalo; Moral, Andoni; Pérez, Carlos; Belenguer, Tomás; del Rosario Canchal, María; Zuluaga, Pablo; Rodriguez, Jose Antonio; Santiago, Amaia; Rull, Fernando; Instituto Nacional de Técnica Aeroespacial (INTA); Ingeniería de Sistemas para la Defesa de España S.A. (ISDEFE)

2016-10-01

Raman Laser Spectrometer (RLS) is the Pasteur Payload instruments of the ExoMars mission, within the ESA's Aurora Exploration Programme, that will perform for the first time in an out planetary mission Raman spectroscopy. RLS is composed by SPU (Spectrometer Unit), iOH (Internal Optical Head), and ICEU (Instrument Control and Excitation Unit). iOH focuses the excitation laser on the samples (excitation path), and collects the Raman emission from the sample (collection path, composed on collimation system and filtering system). The original design presented a high laser trace reaching to the detector, and although a certain level of laser trace was required for calibration purposes, the high level degrades the Signal to Noise Ratio confounding some Raman peaks.The investigation revealing that the laser trace was not properly filtered as well as the iOH opto-mechanical redesign are reported on. After the study of the Long Pass Filters Optical Density (OD) as a function of the filtering stage to the detector distance, a new set of filters (Notch filters) was decided to be evaluated. Finally, and in order to minimize the laser trace, a new collection path design (mainly consisting on that the collimation and filtering stages are now separated in two barrels, and on the kind of filters to be used) was required. Distance between filters and collimation stage first lens was increased, increasing the OD. With this new design and using two Notch filters, the laser trace was reduced to assumable values, as can be observed in the functional test comparison also reported on this paper.

External modes in quantum dot light emitting diode with filtered optical feedback

NASA Astrophysics Data System (ADS)

Al Husseini, Hussein B.; Al Naimee, Kais A.; Al-Khursan, Amin H.; Khedir, Ali. H.

2016-06-01

This research reports a theoretical investigation on the role of filtered optical feedback (FOF) in the quantum dot light emitting diode (QD-LED). The underlying dynamics is affected by a sidle node, which returns to an elliptical shape when the wetting layer (WL) is neglected. Both filter width and time delay change the appearance of different dynamics (chaotic and mixed mode oscillations, MMOs). The results agree with the experimental observations. Here, the fixed point analysis for QDs was done for the first time. For QD-LED with FOF, the system transits from the coherence collapse case in conventional optical feedback to a coherent case with a filtered mode in FOF. It was found that the WL washes out the modes which is an unexpected result. This may attributed to the longer capture time of WL compared with that between QD states. Thus, WL reduces the chaotic behavior.

Thermally controlled femtosecond pulse shaping using metasurface based optical filters

NASA Astrophysics Data System (ADS)

Rahimi, Eesa; Şendur, Kürşat

2018-02-01

Shaping of the temporal distribution of the ultrashort pulses, compensation of pulse deformations due to phase shift in transmission and amplification are of interest in various optical applications. To address these problems, in this study, we have demonstrated an ultra-thin reconfigurable localized surface plasmon (LSP) band-stop optical filter driven by insulator-metal phase transition of vanadium dioxide. A Joule heating mechanism is proposed to control the thermal phase transition of the material. The resulting permittivity variation of vanadium dioxide tailors spectral response of the transmitted pulse from the stack. Depending on how the pulse's spectrum is located with respect to the resonance of the band-stop filter, the thin film stack can dynamically compress/expand the output pulse span up to 20% or shift its phase up to 360°. Multi-stacked filters have shown the ability to dynamically compensate input carrier frequency shifts and pulse span variations besides their higher span expansion rates.

Evaluation of a Magneto-optical Filter and a Fabry-perot Interferometer for the Measurement of Solar Velocity Fields from Space

NASA Technical Reports Server (NTRS)

Rhodes, E. J., Jr.; Cacciani, A.; Blamont, J.; Tomczyk, S.; Ulrich, R. K.; Howard, R. F.

1984-01-01

A program was developed to evaluate the performance of three different devices as possible space-borne solar velocity field imagers. Two of these three devices, a magneto-optical filter and a molecular adherence Fabry-Perot interferometer were installed in a newly-constructed observing system located at the 60-foot tower telescope at the Mt. Wilson Observatory. Time series of solar filtergrams and Dopplergrams lasting up to 10 hours per day were obtained with the filter while shorter runs were obtained with the Fabry-Perot. Two-dimensional k (sub h)-omega power spectra which show clearly the well-known p-mode ridges were computed from the time series obtained with the magneto-optical filter. These power spectra were compared with similar power spectra obtained recently with the 13.7-m McMath spectrograph at Kitt Peak.

External modes in quantum dot light emitting diode with filtered optical feedback

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

Al Husseini, Hussein B.; Department of Physics, College of Science, University of Baghdad, Al Jadiriyah, Baghdad; Al Naimee, Kais A.

2016-06-14

This research reports a theoretical investigation on the role of filtered optical feedback (FOF) in the quantum dot light emitting diode (QD-LED). The underlying dynamics is affected by a sidle node, which returns to an elliptical shape when the wetting layer (WL) is neglected. Both filter width and time delay change the appearance of different dynamics (chaotic and mixed mode oscillations, MMOs). The results agree with the experimental observations. Here, the fixed point analysis for QDs was done for the first time. For QD-LED with FOF, the system transits from the coherence collapse case in conventional optical feedback to amore » coherent case with a filtered mode in FOF. It was found that the WL washes out the modes which is an unexpected result. This may attributed to the longer capture time of WL compared with that between QD states. Thus, WL reduces the chaotic behavior.« less

Air-mass flux measurement system using Doppler-shifted filtered Rayleigh scattering

NASA Technical Reports Server (NTRS)

Shirley, John A.; Winter, Michael

1993-01-01

An optical system has been investigated to measure mass flux distributions in the inlet of a high speed air-breathing propulsion system. Rayleigh scattered light from air is proportional to the number density of molecules and hence can be used to ascertain the gas density in a calibrated system. Velocity field measurements are achieved by spectrally filtering the elastically-scattered Doppler-shifted light with an absorbing molecular filter. A novel anamorphic optical collection system is used which allows optical rays from different scattering angles, that have different Doppler shifts, to be recorded separately. This is shown to obviate the need to tune the laser through the absorption to determine velocities, while retaining the ability to make spatially-resolved measurements along a line. By properly selecting the laser tuning and filter parameters, simultaneous density measurements can be made. These properties are discussed in the paper and experiments demonstrating the velocimetry capability are described.

Mechanical comparison of a polymer nanocomposite to a ceramic thin-film anti-reflective filter.

PubMed

Druffel, Thad; Geng, Kebin; Grulke, Eric

2006-07-28

Thin-film filters on optical components have been in use for decades and, for those industries utilizing a polymer substrate, the mismatch in mechanical behaviour has caused problems. Surface damage including scratches and cracks induces haze on the optical filter, reducing the transmission of the optical article. An in-mold anti-reflective (AR) filter incorporating 1/4-wavelength thin films based on a polymer nanocomposite is outlined here and compared with a traditional vacuum deposition AR coating. Nanoindentation and nanoscratch techniques are used to evaluate the mechanical properties of the thin films. Scanning electron microscopy (SEM) images of the resulting indentations and scratches are then compared to the force deflection curves to further explain the phenomena. The traditional coatings fractured by brittle mechanisms during testing, increasing the area of failure, whereas the polymer nanocomposite gave ductile failure with less surface damage.

Application of Kalman filter in frequency offset estimation for coherent optical quadrature phase-shift keying communication system

NASA Astrophysics Data System (ADS)

Jiang, Wen; Yang, Yanfu; Zhang, Qun; Sun, Yunxu; Zhong, Kangping; Zhou, Xian; Yao, Yong

2016-09-01

The frequency offset estimation (FOE) schemes based on Kalman filter are proposed and investigated in detail via numerical simulation and experiment. The schemes consist of a modulation phase removing stage and Kalman filter estimation stage. In the second stage, the Kalman filters are employed for tracking either differential angles or differential data between two successive symbols. Several implementations of the proposed FOE scheme are compared by employing different modulation removing methods and two Kalman algorithms. The optimal FOE implementation is suggested for different operating conditions including optical signal-to-noise ratio and the number of the available data symbols.

Computational Design of Tunable UV-Vis-IR Filters Based on Silver Nanoparticle Arrays

NASA Astrophysics Data System (ADS)

Waters, Michael; Shi, Guangsha; Kioupakis, Emmanouil

We propose design strategies to develop selective optical filters in the UV-Vis-IR spectrum using the surface plasmon response of silver nanoparticle arrays. Our finite-difference time-domain simulations allow us to rapidly evaluate many nanostructures comprising simple geometries while varying their shape, height, width, and spacing. Our results allow us to identify trends in the filtering spectra as well as the relative amount of absorption and reflection. Optical filtering with nanoparticles is applicable to any transparent substrate and can be easily adapted to existing manufacturing processes while keeping the total cost of materials low. This work was supported by Guardian Industries Corp.

Use of acousto-optic tunable filter in fluorescence imaging endoscopy

NASA Astrophysics Data System (ADS)

Bouhifd, Mounir; Whelan, Maurice; Aprahamian, Marc

2003-10-01

A prototype instrument for fluorescence-based medical diagnostics in vivo is described. The system consists of a rigid endoscope comprising a UV laser-source for fluorescence excitation and a white light source for direct imaging. An acousto-optic tuneable filter (AOTF) is employed as a full-field tuneable bandpass filter. This allows fast continuous or random-access tuning with high filtering efficiency. A study of the diagnostic potential of fluorescence imaging for pancreatitis was conducted on a rat model. In particular, the aim was to detect autofluorescence of endogenous protoporphyrin IX (PpIX) that has been shown to accumulate in early-stage diseased tissue undergoing an inflammatory response.

Wavelength-Filter Based Spectral Calibrated Wave number - Linearization in 1.3 mm Spectral Domain Optical Coherence.

PubMed

Wijeisnghe, Ruchire Eranga Henry; Cho, Nam Hyun; Park, Kibeom; Shin, Yongseung; Kim, Jeehyun

2013-12-01

In this study, we demonstrate the enhanced spectral calibration method for 1.3 μm spectral-domain optical coherence tomography (SD-OCT). The calibration method using wavelength-filter simplifies the SD-OCT system, and also the axial resolution and the entire speed of the OCT system can be dramatically improved as well. An externally connected wavelength-filter is utilized to obtain the information of the wavenumber and the pixel position. During the calibration process the wavelength-filter is placed after a broadband source by connecting through an optical circulator. The filtered spectrum with a narrow line width of 0.5 nm is detected by using a line-scan camera. The method does not require a filter or a software recalibration algorithm for imaging as it simply resamples the OCT signal from the detector array without employing rescaling or interpolation methods. One of the main drawbacks of SD-OCT is the broadened point spread functions (PSFs) with increasing imaging depth can be compensated by increasing the wavenumber-linearization order. The sensitivity of our system was measured at 99.8 dB at an imaging depth of 2.1 mm compared with the uncompensated case.

Metal-polymer nanocomposites for stretchable optics and plasmonics

NASA Astrophysics Data System (ADS)

Potenza, Marco A. C.; Minnai, Chloé; Milani, Paolo

2016-12-01

Stretchable and conformable optical devices open very exciting perspectives for the fabrication of systems incorporating diffracting and optical power in a single element and of tunable plasmonic filters and absorbers. The use of nanocomposites obtained by inserting metallic nanoparticles produced in the gas phase into polymeric matrices allows to effectively fabricate cheap and simple stretchable optical elements able to withstand thousands of deformations and stretching cycles without any degradation of their optical properties. The nanocomposite-based reflective optical devices show excellent performances and stability compared to similar devices fabricated with standard techniques. The nanocomposite-based devices can be therefore applied to arbitrary curved non-optical grade surfaces in order to achieve optical power and to minimize aberrations like astigmatism. Examples discussed here include stretchable reflecting gratings, plasmonic filters tunable by mechanical stretching and light absorbers.

Atom chip apparatus for experiments with ultracold rubidium and potassium gases

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

Ivory, M. K.; Ziltz, A. R.; Fancher, C. T.

2014-04-15

We present a dual chamber atom chip apparatus for generating ultracold {sup 87}Rb and {sup 39}K atomic gases. The apparatus produces quasi-pure Bose-Einstein condensates of 10{sup 4} {sup 87}Rb atoms in an atom chip trap that features a dimple and good optical access. We have also demonstrated production of ultracold {sup 39}K and subsequent loading into the chip trap. We describe the details of the dual chamber vacuum system, the cooling lasers, the magnetic trap, the multicoil magnetic transport system, the atom chip, and two optical dipole traps. Due in part to the use of light-induced atom desorption, the lasermore » cooling chamber features a sufficiently good vacuum to also support optical dipole trap-based experiments. The apparatus is well suited for studies of atom-surface forces, quantum pumping and transport experiments, atom interferometry, novel chip-based traps, and studies of one-dimensional many-body systems.« less

Mode-routed fiber-optic add-drop filter

NASA Technical Reports Server (NTRS)

Moslehi, Behzad (Inventor); Black, Richard James (Inventor); Shaw, Herbert John (Inventor)

2000-01-01

New elements mode-converting two-mode grating and mode-filtering two-mode coupler are disclosed and used as elements in a system for communications, add-drop filtering, and strain sensing. Methods of fabrication for these new two-mode gratings and mode-filtering two-mode couplers are also disclosed.

Transformation of Personal Computers and Mobile Phones into Genetic Diagnostic Systems

DTIC Science & Technology

2014-08-31

a Gel Logic System using UV transillumination and a 535 nm optical filter ( Kodak ). The positive control PCR was performed by taking an aliquot of the...described in the section above. Samples were excited by a UV transilluminator ( Kodak ). For imaging, a 520 ± 10 nm bandpass filter (Edmund Optics) was

Stereo Imaging Miniature Endoscope with Single Imaging Chip and Conjugated Multi-Bandpass Filters

NASA Technical Reports Server (NTRS)

Shahinian, Hrayr Karnig (Inventor); Bae, Youngsam (Inventor); White, Victor E. (Inventor); Shcheglov, Kirill V. (Inventor); Manohara, Harish M. (Inventor); Kowalczyk, Robert S. (Inventor)

2018-01-01

A dual objective endoscope for insertion into a cavity of a body for providing a stereoscopic image of a region of interest inside of the body including an imaging device at the distal end for obtaining optical images of the region of interest (ROI), and processing the optical images for forming video signals for wired and/or wireless transmission and display of 3D images on a rendering device. The imaging device includes a focal plane detector array (FPA) for obtaining the optical images of the ROI, and processing circuits behind the FPA. The processing circuits convert the optical images into the video signals. The imaging device includes right and left pupil for receiving a right and left images through a right and left conjugated multi-band pass filters. Illuminators illuminate the ROI through a multi-band pass filter having three right and three left pass bands that are matched to the right and left conjugated multi-band pass filters. A full color image is collected after three or six sequential illuminations with the red, green and blue lights.

Fabrication of optical filters using multilayered porous silicon

NASA Astrophysics Data System (ADS)

Gaber, Noha; Khalil, Diaa; Shaarawi, Amr

2011-02-01

In this work we describe a method for fabricating optical filters using multilayered porous silicon 1D photonic structure. An electrochemical cell is constructed to control the porosity of variable layers in p-type Si wafers. Porous silicon multilayered structures are formed of λ/4 (or multiples) thin films that construct optical interference filters. By changing the anodizing current density of the cell during fabrication, different porosities can be obtained as the optical refractive index is a direct function of the layer porosity. To determine the morphology, the wavelength dependent refractive index n and absorption coefficient α, first, porous silicon free standing mono-layers have been fabricated at different conditions and characterized in the near infrared region (from 1000 to 2500nm). Large difference in refractive index (between 1.6 and 2.6) is obtained. Subsequently, multilayer structures have been fabricated and tested. Their spectral response has been measured and it shows good agreement with numerical simulations. A technique based on inserting etching breaks is adopted to ensure the depth homogeneity. The effect of differing etching/break times on the reproducibility of the filters is studied.

Matched-filtering generalized phase contrast using LCoS pico-projectors for beam-forming.

PubMed

Bañas, Andrew; Palima, Darwin; Glückstad, Jesper

2012-04-23

We report on a new beam-forming system for generating high intensity programmable optical spikes using so-called matched-filtering Generalized Phase Contrast (mGPC) applying two consumer handheld pico-projectors. Such a system presents a low-cost alternative for optical trapping and manipulation, optical lattices and other beam-shaping applications usually implemented with high-end spatial light modulators. Portable pico-projectors based on liquid crystal on silicon (LCoS) devices are used as binary phase-only spatial light modulators by carefully setting the appropriate polarization of the laser illumination. The devices are subsequently placed into the object and Fourier plane of a standard 4f-setup according to the mGPC spatial filtering configuration. Having a reconfigurable spatial phase filter, instead of a fixed and fabricated one, allows the beam shaper to adapt to different input phase patterns suited for different requirements. Despite imperfections in these consumer pico-projectors, the mGPC approach tolerates phase aberrations that would have otherwise been hard to overcome by standard phase projection. © 2012 Optical Society of America

Achieving nonlinear optical modulation via four-wave mixing in a four-level atomic system

NASA Astrophysics Data System (ADS)

Li, Hai-Chao; Ge, Guo-Qin; Zubairy, M. Suhail

2018-05-01

We propose an accessible scheme for implementing tunable nonlinear optical amplification and attenuation via a synergetic mechanism of four-wave mixing (FWM) and optical interference in a four-level ladder-type atomic system. By constructing a cyclic atom-field interaction, we show that two reverse FWM processes can coexist via optical transitions in different branches. In the suitable input-field conditions, strong interference effects between the input fields and the generated FWM fields can be induced and result in large amplification and deep attenuation of the output fields. Moreover, such an optical modulation from enhancement to suppression can be controlled by tuning the relative phase. The quantum system can be served as a switchable optical modulator with potential applications in quantum nonlinear optics.

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

Kertzscher, G; Beddar, S

Purpose: To study the promising potential of inorganic scintillator detectors (ISDs) and investigate various unwanted luminescence properties which may compromise their accuracy. Methods: The ISDs were comprised of a ruby crystal coupled to a polymethyl methacrylate (PMMA) fiber-optic cable and a charged coupled device camera. A new type of ISD was manufactured and included a long-pass filter that was sandwiched between the crystal and the fiber-optic cable. The purpose of the filter was to suppress the Cerenkov and fluorescence background light induced in the PMMA (the stem signal) from striking the ruby crystal, generating unwanted ruby excitation. A variety ofmore » experiments were performed to characterize the ruby based ISDs. The relative contribution of the induced ruby signal and the stem signal were quantified while exposing the detector and a bare fiber-optic cable to a high dose rate (HDR) brachytherapy (BT) source, respectively. The unwanted ruby excitation was quantified while irradiating the fiber-optic cable with the detector volume shielded. Other experiments addressed time-dependent luminescence properties and a comparison to other commonly used organic scintillator detectors (BCF-12, BCF-60). Results: When the BT source dwelled 0.5 cm away from the fiber-optic cable, the unwanted ruby excitation amounted to >5% of the total signal if the source-distance from the scintillator was >7 cm. However, the unwanted excitation was suppressed to <1% if the ISD incorporated an optic filter. The stem signal was suppressed with a 20 nm band-pass filter and was <3% as long as the source-distance was <7 cm. The ruby based ISDs generated signal up to 20(40) times that of BCF-12(BCF-60). Conclusion: The study presents solutions to unwanted luminescence properties of ruby based ISDs for HDR BT. An optic filter should be sandwiched between the scintillator volume and the fiber-optic cable to prevent the stem signal to excite the ruby crystal.« less

First-principles study on silicon atom doped monolayer graphene

NASA Astrophysics Data System (ADS)

Rafique, Muhammad; Shuai, Yong; Hussain, Nayyar

2018-01-01

This paper illustrates the structural, electronic and optical properties of individual silicon (Si) atom-doped single layer graphene using density functional theory method. Si atom forms tight bonding with graphene layer. The effect of doping has been investigated by varying the concentration of Si atoms from 3.125% to 9.37% (i.e. From one to three Si atoms in 4 × 4 pure graphene supercell containing 32 carbon atoms), respectively. Electronic structure, partial density of states (PDOS) and optical properties of pure and Si atom-doped graphene sheet were calculated using VASP (Vienna ab-initio Simulation Package). The calculated results for pure graphene sheet were then compared with Si atom doped graphene. It is revealed that upon Si doping in graphene, a finite band gap appears at the high symmetric K-point, thereby making graphene a direct band gap semiconductor. Moreover, the band gap value is directly proportional to the concentration of impurity Si atoms present in graphene lattice. Upon analyzing the optical properties of Si atom-doped graphene structures, it is found that, there is significant change in the refractive index of the graphene after Si atom substitution in graphene. In addition, the overall absorption spectrum of graphene is decreased after Si atom doping. Although a significant red shift in absorption is found to occur towards visible range of radiation when Si atom is substituted in its lattice. The reflectivity of graphene improves in low energy region after Si atom substitution in graphene. These results can be useful for tuning the electronic structure and to manipulate the optical properties of graphene layer in the visible region.

Telescope Multi-Field Wavefront Control with a Kalman Filter

NASA Technical Reports Server (NTRS)

Lou, John Z.; Redding, David; Sigrist, Norbert; Basinger, Scott

2008-01-01

An effective multi-field wavefront control (WFC) approach is demonstrated for an actuated, segmented space telescope using wavefront measurements at the exit pupil, and the optical and computational implications of this approach are discussed. The integration of a Kalman Filter as an optical state estimator into the wavefront control process to further improve the robustness of the optical alignment of the telescope will also be discussed. Through a comparison of WFC performances between on-orbit and ground-test optical system configurations, the connection (and a possible disconnection) between WFC and optical system alignment under these circumstances are analyzed. Our MACOS-based computer simulation results will be presented and discussed.

Optical design of the lightning imager for MTG

NASA Astrophysics Data System (ADS)

Lorenzini, S.; Bardazzi, R.; Di Giampietro, M.; Feresin, F.; Taccola, M.; Cuevas, L. P.

2017-11-01

The Lightning Imager for Meteosat Third Generation is an optical payload with on-board data processing for the detection of lightning. The instrument will provide a global monitoring of lightning events over the full Earth disk from geostationary orbit and will operate in day and night conditions. The requirements of the large field of view together with the high detection efficiency with small and weak optical pulses superimposed to a much brighter and highly spatial and temporal variable background (full operation during day and night conditions, seasonal variations and different albedos between clouds oceans and lands) are driving the design of the optical instrument. The main challenge is to distinguish a true lightning from false events generated by random noise (e.g. background shot noise) or sun glints diffusion or signal variations originated by microvibrations. This can be achieved thanks to a `multi-dimensional' filtering, simultaneously working on the spectral, spatial and temporal domains. The spectral filtering is achieved with a very narrowband filter centred on the bright lightning O2 triplet line (777.4 nm +/- 0.17 nm). The spatial filtering is achieved with a ground sampling distance significantly smaller (between 4 and 5 km at sub satellite pointing) than the dimensions of a typical lightning pulse. The temporal filtering is achieved by sampling continuously the Earth disk within a period close to 1 ms. This paper presents the status of the optical design addressing the trade-off between different configurations and detailing the design and the analyses of the current baseline. Emphasis is given to the discussion of the design drivers and the solutions implemented in particular concerning the spectral filtering and the optimisation of the signal to noise ratio.

NASA Tech Briefs, October 2007

NASA Technical Reports Server (NTRS)

2007-01-01

Topics covered include; Wirelessly Interrogated Position or Displacement Sensors; Ka-Band Radar Terminal Descent Sensor; Metal/Metal Oxide Differential Electrode pH Sensors; Improved Sensing Coils for SQUIDs; Inductive Linear-Position Sensor/Limit-Sensor Units; Hilbert-Curve Fractal Antenna With Radiation- Pattern Diversity; Single-Camera Panoramic-Imaging Systems; Interface Electronic Circuitry for an Electronic Tongue; Inexpensive Clock for Displaying Planetary or Sidereal Time; Efficient Switching Arrangement for (N + 1)/N Redundancy; Lightweight Reflectarray Antenna for 7.115 and 32 GHz; Opto-Electronic Oscillator Using Suppressed Phase Modulation; Alternative Controller for a Fiber-Optic Switch; Strong, Lightweight, Porous Materials; Nanowicks; Lightweight Thermal Protection System for Atmospheric Entry; Rapid and Quiet Drill; Hydrogen Peroxide Concentrator; MMIC Amplifiers for 90 to 130 GHz; Robot Would Climb Steep Terrain; Measuring Dynamic Transfer Functions of Cavitating Pumps; Advanced Resistive Exercise Device; Rapid Engineering of Three-Dimensional, Multicellular Tissues With Polymeric Scaffolds; Resonant Tunneling Spin Pump; Enhancing Spin Filters by Use of Bulk Inversion Asymmetry; Optical Magnetometer Incorporating Photonic Crystals; WGM-Resonator/Tapered-Waveguide White-Light Sensor Optics; Raman-Suppressing Coupling for Optical Parametric Oscillator; CO2-Reduction Primary Cell for Use on Venus; Cold Atom Source Containing Multiple Magneto- Optical Traps; POD Model Reconstruction for Gray-Box Fault Detection; System for Estimating Horizontal Velocity During Descent; Software Framework for Peer Data-Management Services; Autogen Version 2.0; Tracking-Data-Conversion Tool; NASA Enterprise Visual Analysis; Advanced Reference Counting Pointers for Better Performance; C Namelist Facility; and Efficient Mosaicking of Spitzer Space Telescope Images.

All-semiconductor metamaterial-based optical circuit board at the microscale

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

Min, Li; Huang, Lirong, E-mail: lrhuang@hust.edu.cn

2015-07-07

The newly introduced metamaterial-based optical circuit, an analogue of electronic circuit, is becoming a forefront topic in the fields of electronics, optics, plasmonics, and metamaterials. However, metals, as the commonly used plasmonic elements in an optical circuit, suffer from large losses at the visible and infrared wavelengths. We propose here a low-loss, all-semiconductor metamaterial-based optical circuit board at the microscale by using interleaved intrinsic GaAs and doped GaAs, and present the detailed design process for various lumped optical circuit elements, including lumped optical inductors, optical capacitors, optical conductors, and optical insulators. By properly combining these optical circuit elements and arrangingmore » anisotropic optical connectors, we obtain a subwavelength optical filter, which can always hold band-stop filtering function for various polarization states of the incident electromagnetic wave. All-semiconductor optical circuits may provide a new opportunity in developing low-power and ultrafast components and devices for optical information processing.« less