Investigation of 100 mJ all solid state end-pumped 1064 nm Q-switched laser

NASA Astrophysics Data System (ADS)

Xie, Shiyong; Wang, Caili; Liu, Hui; Bo, Yong; Xu, Zuyan

2017-11-01

High energy 1064 nm Q-switched laser output is obtained by LD vertical array end pumping Nd:YAG. Cylindrical lens are used for beam shaping of LD array for different divergence angle of fast and slow axis. Based on the theoretical simulation of fundamental mode radius using ABCD transfer matrix, the resonant cavity is optimized and curvature radius of cavity mirrors is determined. The intracavity power density is calculated according to the output laser pulse energy and transmittance of output coupling mirror is optimized under the condition that optical device is not damaged. 1064 nm laser with a maximum output of 110 mJ is generated under LD pump energy of 600 mJ, corresponding to optical conversion efficiency of 18.3%. The laser pulse width is 11 ns and divergence angle is 1.2 mrad. For saturation phenomenon of Q-switched laser output, LD temperature is adjusted to make wavelength deviate from absorption peak of Nd:YAG crystal. The parasitic oscillation, which affects the enhancement of Q-switched laser energy, can be effectively suppressed by reducing gain of pump end of laser medium, which provides an effective technical means for obtaining high energy end-pumped Q-switched laser.

Optical displacement sensor

DOEpatents

Carr, Dustin W [Albuquerque, NM

2008-04-08

An optical displacement sensor is disclosed which uses a vertical-cavity surface-emitting laser (VCSEL) coupled to an optical cavity formed by a moveable membrane and an output mirror of the VCSEL. This arrangement renders the lasing characteristics of the VCSEL sensitive to any movement of the membrane produced by sound, vibrations, pressure changes, acceleration, etc. Some embodiments of the optical displacement sensor can further include a light-reflective diffractive lens located on the membrane or adjacent to the VCSEL to control the amount of lasing light coupled back into the VCSEL. A photodetector detects a portion of the lasing light from the VCSEL to provide an electrical output signal for the optical displacement sensor which varies with the movement of the membrane.

Internal Mirror Optical Fiber Couplers

NASA Astrophysics Data System (ADS)

Shin, Jong-Dug

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

Investigative study of a diode-pumped continuous-wave Tm:YAP laser as an efficient 1.94 μm pump source

NASA Astrophysics Data System (ADS)

Kwiatkowski, Jacek; Zendzian, Waldemar; Jabczynski, Jan K.

2016-12-01

A detailed study of a Tm:YAP laser in continuous-wave (CW), single-pass end-pumped by a 793 nm diode laser is presented. The laser based on c-cut 3 at. % Tm:YAP crystal was experimentally examined and presented in the dependence on transmittance and radius of curvature of output coupling mirrors. A detailed spectral analysis was presented. The influence of a heat-sink cooling water temperature on the laser performance was studied. At room temperature, for an output coupling transmission of 19.5%, the maximum CW output power of 4.53 W was achieved, corresponding to a slope efficiency of 41.5% and an optical-to-optical conversion efficiency of 25.7% with respect to the incident pump power, respectively. We have shown that the output spectrum at a certain wavelength (e.g. 1940 nm) for a given pump power can be realized via the change of resonator parameters (OC transmittance, mode size).

Multiple-wavelength tunable laser

NASA Technical Reports Server (NTRS)

Barnes, Norman P. (Inventor); Walsh, Brian M. (Inventor); Reichle, Donald J. (Inventor)

2010-01-01

A tunable laser includes dispersion optics for separating generated laser pulses into first and second wavelength pulses directed along first and second optical paths. First and second reflective mirrors are disposed in the first and second optical paths, respectively. The laser's output mirror is partially reflective and partially transmissive with respect to the first wavelength and the second wavelength in accordance with provided criteria. A first resonator length is defined between the output mirror and the first mirror, while a second resonator length is defined between the output mirror and the second mirror. The second resonator length is a function of the first resonator length.

Generalized design of a zero-geometric-loss, astigmatism-free, modified four-objective multipass matrix system.

PubMed

Guo, Yin; Sun, LiQun; Yang, Zheng; Liu, Zilong

2016-02-20

During this study we constructed a generalized parametric modified four-objective multipass matrix system (MMS). We used an optical system comprising four asymmetrical spherical mirrors to improve the alignment process. The use of a paraxial equation for the design of the front transfer optics yielded the initial condition for modeling our MMS. We performed a ray tracing simulation to calculate the significant aberration of the system (astigmatism). Based on the calculated meridional and sagittal focus positions, the complementary focusing mirror was easily designed to provide an output beam free of astigmatism. We have presented an example of a 108-transit multipass system (5×7 matrix arrangement) with a relatively larger numerical aperture source (xenon light source). The whole system exhibits zero theoretical geometrical loss when simulated with Zemax software. The MMS construction strategy described in this study provides an anastigmatic output beam and the generalized approach to design a controllable matrix spot pattern on the field mirrors. Asymmetrical reflective mirrors aid in aligning the whole system with high efficiency. With the generalized design strategy in terms of optics configuration and asymmetrical fabrication method in this paper, other kinds of multipass matrix system coupled with different sources and detector systems also can be achieved.

High-efficient Nd:YAG microchip laser for optical surface scanning

NASA Astrophysics Data System (ADS)

Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

2017-12-01

A CW operating, compact, high-power, high-efficient diode pumped 1064nm laser, based on Nd:YAG active medium, was developed for optical surface scanning and mapping applications. To enhance the output beam quality, laser stability, and compactness, a microchip configuration was used. In this arrangement the resonator mirrors were deposited directly on to the laser crystal faces. The Nd-doping concentration was 1 at.% Nd/Y. The Nd:YAG crystal was 5mm long. The laser resonator without pumping radiation recuperation was investigated {the output coupler was transparent for pumping radiation. For the generated laser radiation the output coupler reflectivity was 95%@1064 nm. The diameter of the samples was 5 mm. For the laser pumping two arrangements were investigated. Firstly, a fibre coupled laser diode operating at wavelength 808nm was used in CW mode. The 400 ¹m fiber was delivering up to 14W of pump power amplitude to the microchip laser. The maximum CW output power of 7.2W @ 1064nm in close to TEM00 beam was obtained for incident pumping power 13.7W @ 808 nm. The differential efficiency in respect to the incident pump power reached 56 %. Secondly, a single-emitter, 1W laser diode operating at 808nm was used for Nd:YAG microchip pumping. The laser pumping was directly coupled into the microchip laser using free-space lens optics. Slope efficiency up to 70% was obtained in stable, high-quality, 1064nm laser beam with CW power up to 350mW. The system was successfully used for scanning of super-Gaussian laser mirrors reflectivity profile.

Phasing surface emitting diode laser outputs into a coherent laser beam

DOEpatents

Holzrichter, John F [Berkeley, CA

2006-10-10

A system for generating a powerful laser beam includes a first laser element and at least one additional laser element having a rear laser mirror, an output mirror that is 100% reflective at normal incidence and <5% reflective at an input beam angle, and laser material between the rear laser mirror and the output mirror. The system includes an injector, a reference laser beam source, an amplifier and phase conjugater, and a combiner.

Model-Based Angular Scan Error Correction of an Electrothermally-Actuated MEMS Mirror

PubMed Central

Zhang, Hao; Xu, Dacheng; Zhang, Xiaoyang; Chen, Qiao; Xie, Huikai; Li, Suiqiong

2015-01-01

In this paper, the actuation behavior of a two-axis electrothermal MEMS (Microelectromechanical Systems) mirror typically used in miniature optical scanning probes and optical switches is investigated. The MEMS mirror consists of four thermal bimorph actuators symmetrically located at the four sides of a central mirror plate. Experiments show that an actuation characteristics difference of as much as 4.0% exists among the four actuators due to process variations, which leads to an average angular scan error of 0.03°. A mathematical model between the actuator input voltage and the mirror-plate position has been developed to predict the actuation behavior of the mirror. It is a four-input, four-output model that takes into account the thermal-mechanical coupling and the differences among the four actuators; the vertical positions of the ends of the four actuators are also monitored. Based on this model, an open-loop control method is established to achieve accurate angular scanning. This model-based open loop control has been experimentally verified and is useful for the accurate control of the mirror. With this control method, the precise actuation of the mirror solely depends on the model prediction and does not need the real-time mirror position monitoring and feedback, greatly simplifying the MEMS control system. PMID:26690432

Single frequency 1083nm ytterbium doped fiber master oscillator power amplifier laser.

PubMed

Huang, Shenghong; Qin, Guanshi; Shirakawa, Akira; Musha, Mitsuru; Ueda, Ken-Ichi

2005-09-05

Single frequency 1083nm ytterbium fiber master oscillator power amplifier system was demonstrated. The oscillator was a linear fiber cavity with loop mirror filter and polarization controller. The loop mirror with unpumped ytterbium fiber as a narrow bandwidth filter discriminated and selected laser longitudinal modes efficiently. Spatial hole burning effect was restrained by adjusting polarization controller appropriately in the linear cavity. The amplifier was 5 m ytterbium doped fiber pumped by 976nm pigtail coupled laser diode. The linewidth of the single frequency laser was about 2 KHz. Output power up to 177 mW was produced under the launched pump power of 332 mW.

Time-resolved spectra of dense plasma focus using spectrometer, streak camera, and CCD combination.

PubMed

Goldin, F J; Meehan, B T; Hagen, E C; Wilkins, P R

2010-10-01

A time-resolving spectrographic instrument has been assembled with the primary components of a spectrometer, image-converting streak camera, and CCD recording camera, for the primary purpose of diagnosing highly dynamic plasmas. A collection lens defines the sampled region and couples light from the plasma into a step index, multimode fiber which leads to the spectrometer. The output spectrum is focused onto the photocathode of the streak camera, the output of which is proximity-coupled to the CCD. The spectrometer configuration is essentially Czerny-Turner, but off-the-shelf Nikon refraction lenses, rather than mirrors, are used for practicality and flexibility. Only recently assembled, the instrument requires significant refinement, but has now taken data on both bridge wire and dense plasma focus experiments.

Pulse stretcher

DOEpatents

Horton, J.A.

1994-05-03

Apparatus for increasing the length of a laser pulse to reduce its peak power without substantial loss in the average power of the pulse is disclosed. The apparatus uses a White cell having a plurality of optical delay paths of successively increasing number of passes between the field mirror and the objective mirrors. A pulse from a laser travels through a multi-leg reflective path between a beam splitter and a totally reflective mirror to the laser output. The laser pulse is also simultaneously injected through the beam splitter to the input mirrors of the optical delay paths. The pulses from the output mirrors of the optical delay paths go simultaneously to the laser output and to the input mirrors of the longer optical delay paths. The beam splitter is 50% reflective and 50% transmissive to provide equal attenuation of all of the pulses at the laser output. 6 figures.

High efficiency and high-energy intra-cavity beam shaping laser

NASA Astrophysics Data System (ADS)

Yang, Hailong; Meng, Junqing; Chen, Weibiao

2015-09-01

We present a technology of intra-cavity laser beam shaping with theory and experiment to obtain a flat-top-like beam with high-pulse energy. A radial birefringent element (RBE) was used in a crossed Porro prism polarization output coupling resonator to modulate the phase delay radially. The reflectively of a polarizer used as an output mirror was variable radially. A flat-top-like beam with 72.5 mJ, 11 ns at 20 Hz was achieved by a side-pumped Nd:YAG zigzag slab laser, and the optical-to-optical conversion efficiency was 17.3%.

Efficient diode-end-pumped actively Q-switched Nd:YAG/SrWO4/KTP yellow laser.

PubMed

Cong, Zhenhua; Zhang, Xingyu; Wang, Qingpu; Liu, Zhaojun; Li, Shutao; Chen, Xiaohan; Zhang, Xiaolei; Fan, Shuzhen; Zhang, Huaijin; Tao, Xutang

2009-09-01

An efficient intracavity frequency-doubled Raman laser was obtained by using an SrWO(4) Raman medium, an Nd:YAG ceramic gain medium, and a KTP frequency-doubling medium. Three laser cavities, including a two-mirror cavity, a three-mirror coupled cavity, and a folded cavity, were investigated. With the coupled cavity, a 2.93 W, 590 nm laser was obtained at an incident pump power of 16.2 W and a pulse repetition frequency of 20 kHz; the corresponding conversion efficiency was 18.1%. The highest conversion efficiency of 19.2% was obtained at an incident pump power of 14.1 W and a pulse repetition frequency of 15 kHz. The obtained maximum output power and conversion efficiency were much higher than the results previously obtained with intracavity frequency-doubled solid-state Raman lasers.

Optical apparatus for conversion of whispering-gallery modes into a free space gaussian like beam

DOEpatents

Stallard, Barry W.; Makowski, Michael A.; Byers, Jack A.

1992-01-01

An optical converter for efficient conversion of millimeter wavelength whispering-gallery gyrotron output into a linearly polarized, free-space Gaussian-like beam. The converter uses a mode-converting taper and three mirror optics. The first mirror has an azimuthal tilt to eliminate the k.sub..phi. component of the propagation vector of the gyrotron output beam. The second mirror has a twist reflector to linearly polarize the beam. The third mirror has a constant phase surface so the converter output is in phase.

High stability wavefront reference source

DOEpatents

Feldman, M.; Mockler, D.J.

1994-05-03

A thermally and mechanically stable wavefront reference source which produces a collimated output laser beam is disclosed. The output beam comprises substantially planar reference wavefronts which are useful for aligning and testing optical interferometers. The invention receives coherent radiation from an input optical fiber, directs a diverging input beam of the coherent radiation to a beam folding mirror (to produce a reflected diverging beam), and collimates the reflected diverging beam using a collimating lens. In a class of preferred embodiments, the invention includes a thermally and mechanically stable frame comprising rod members connected between a front end plate and a back end plate. The beam folding mirror is mounted on the back end plate, and the collimating lens mounted to the rods between the end plates. The end plates and rods are preferably made of thermally stable metal alloy. Preferably, the input optical fiber is a single mode fiber coupled to an input end of a second single mode optical fiber that is wound around a mandrel fixedly attached to the frame of the apparatus. The output end of the second fiber is cleaved so as to be optically flat, so that the input beam emerging therefrom is a nearly perfect diverging spherical wave. 7 figures.

High stability wavefront reference source

DOEpatents

Feldman, Mark; Mockler, Daniel J.

1994-01-01

A thermally and mechanically stable wavefront reference source which produces a collimated output laser beam. The output beam comprises substantially planar reference wavefronts which are useful for aligning and testing optical interferometers. The invention receives coherent radiation from an input optical fiber, directs a diverging input beam of the coherent radiation to a beam folding mirror (to produce a reflected diverging beam), and collimates the reflected diverging beam using a collimating lens. In a class of preferred embodiments, the invention includes a thermally and mechanically stable frame comprising rod members connected between a front end plate and a back end plate. The beam folding mirror is mounted on the back end plate, and the collimating lens mounted to the rods between the end plates. The end plates and rods are preferably made of thermally stable metal alloy. Preferably, the input optical fiber is a single mode fiber coupled to an input end of a second single mode optical fiber that is wound around a mandrel fixedly attached to the frame of the apparatus. The output end of the second fiber is cleaved so as to be optically flat, so that the input beam emerging therefrom is a nearly perfect diverging spherical wave.

Effect of the influence function of deformable mirrors on laser beam shaping.

PubMed

González-Núñez, Héctor; Béchet, Clémentine; Ayancán, Boris; Neichel, Benoit; Guesalaga, Andrés

2017-02-20

The continuous membrane stiffness of a deformable mirror propagates the deformation of the actuators beyond their neighbors. When phase-retrieval algorithms are used to determine the desired shape of these mirrors, this cross-coupling-also known as influence function (IF)-is generally disregarded. We study this problem via simulations and bench tests for different target shapes to gain further insight into the phenomenon. Sound modeling of the IF effect is achieved as highlighted by the concurrence between the modeled and experimental results. In addition, we observe that the actuators IF is a key parameter that determines the accuracy of the output light pattern. Finally, it is shown that in some cases it is possible to achieve better shaping by modifying the input irradiance of the phase-retrieval algorithm. The results obtained from this analysis open the door to further improvements in this type of beam-shaping systems.

High-efficiency cyrogenic-cooled diode-pumped amplifier with relay imaging for nanosecond pulses

NASA Astrophysics Data System (ADS)

Körner, J.; Hein, J.; Kahle, M.; Liebetrau, H.; Kaluza, M.; Siebold, M.; Loeser, M.

2011-06-01

We present temperature dependent gain measurements with different Ytterbium doped laser media, such as Yb:YAG, Yb:FP15-glass and Yb:CaF2 in a multi-pass amplifier setup. The temperature of these materials was adjusted arbitrarily between 100K and 300K, while heat removal was realized by transverse cooling. In order to obtain a good beam profile throughout the amplification process, we used an all-mirror based relay imaging setup consisting of a telescope accomplishing a 4f-imaging with a plane mirror in each image plane. The amplification beam is then coupled into the cavity and doing several round trips wandering over the surface of the spherical mirrors. Hence the laser material is placed in one of the image planes, the beam quality of the amplifier was ruled by the intensity profile of the pumping laser diodes consisting of two stacks with 2.5kW peak output power each. Due to the given damage threshold fluence, the output energy of the amplifier was limited to about 1J at a beam diameter of 4.5 mm (FWHM). The seed pulses with a duration of 6 ns were generated in a Yb:FP15-glass cavity dumped oscillator with further amplification up to the 100mJ level by a room temperature Yb:YAG multi pass amplifier. The 1 Hz repetition rate of the system was limited by the repetition rate of the front-end. With Yb:YAG for instance an output energy of 1.1 J with an record high optical to optical efficiency of more than 35% was achieved, which was further increased to 45% for 500 mJ output energy.

Sensitivity of a three-mirror cavity to thermal and nonlinear lensing: Gaussian-beam analysis.

PubMed

Anctil, G; McCarthy, N; Piché, M

2000-12-20

We consider a compact three-mirror cavity consisting of a flat output coupler, a curved folding mirror, and an active medium with one facet cut at the Brewster angle and the other facet coated for unit reflectivity. We examine the sensitivity to thermal lensing and to self-focusing in the active medium of the Gaussian beam that is circulating in that cavity. We use a simple thin-lens model; the astigmatism of the beam that is circulating in the cavity and the nonlinear coupling between the field distributions along the two orthogonal axes are taken into account. We find configurations in which beam ellipticity is compensated for at either end of the cavity in the presence of thermal lensing. We have derived an analytical criterion that predicts the sensitivity of the beam size to nonlinear lensing. The ability of the cavity to favor self-mode locking is found to be sensitive to the strength of thermal lensing. In the absence of thermal lensing, cavities operated as telescopic systems (C = 0) or self-imaging systems (B = 0) are most appropriate for achieving self-mode locking, with nonlinear mode selection accomplished through saturation of the spatially varying laser gain. We identify conditions for which self-mode locking can be produced by variable-reflectivity output couplers with either maximum or minimum reflectivity at the center of the coupler. We use our model to estimate the nonlinear gain produced in laser cavities equipped with such output couplers. We identify a cavity configuration for which nonlinear lensing can simultaneously produce mode locking and correction of beam ellipticity at the output coupler.

Sensitivity of a Three-Mirror Cavity to Thermal and Nonlinear Lensing: Gaussian-Beam Analysis

NASA Astrophysics Data System (ADS)

Anctil, Geneviève; McCarthy, Nathalie; Piché, Michel

2000-12-01

We consider a compact three-mirror cavity consisting of a flat output coupler, a curved folding mirror, and an active medium with one facet cut at the Brewster angle and the other facet coated for unit reflectivity. We examine the sensitivity to thermal lensing and to self-focusing in the active medium of the Gaussian beam that is circulating in that cavity. We use a simple thin-lens model; the astigmatism of the beam that is circulating in the cavity and the nonlinear coupling between the field distributions along the two orthogonal axes are taken into account. We find configurations in which beam ellipticity is compensated for at either end of the cavity in the presence of thermal lensing. We have derived an analytical criterion that predicts the sensitivity of the beam size to nonlinear lensing. The ability of the cavity to favor self-mode locking is found to be sensitive to the strength of thermal lensing. In the absence of thermal lensing, cavities operated as telescopic systems ( C 0 ) or self-imaging systems ( B 0 ) are most appropriate for achieving self-mode locking, with nonlinear mode selection accomplished through saturation of the spatially varying laser gain. We identify conditions for which self-mode locking can be produced by variable-reflectivity output couplers with either maximum or minimum reflectivity at the center of the coupler. We use our model to estimate the nonlinear gain produced in laser cavities equipped with such output couplers. We identify a cavity configuration for which nonlinear lensing can simultaneously produce mode locking and correction of beam ellipticity at the output coupler.

Study of Avalanche Discharge Lasers.

DTIC Science & Technology

1983-09-30

tic a com ponents ued fosr . o sern tio of X e1 .~i fluorescence an l se S o u r cs wi t as o e r i r s p e s u r e s a n d c r r e n t obseT...R. P . Akins and S. C. Lin, Appl. Phys. Lett. 28, 221 (1976). A 4. C. P . Wang, H. Mirels, D. G. Sutton, and S. N . Suchard, Appl. Phys. Lett. 28 , 326...intensity at the output coupling mirror, Ia , which deter- mines the laser oscillator output power PL P viz., I + n [ exp(2. 303D)+ Raexp(-Z. 33D) f , (9

Super-Gaussian laser intensity output formation by means of adaptive optics

NASA Astrophysics Data System (ADS)

Cherezova, T. Y.; Chesnokov, S. S.; Kaptsov, L. N.; Kudryashov, A. V.

1998-10-01

An optical resonator using an intracavity adaptive mirror with three concentric rings of controlling electrodes, which produc low loss and large beamwidth super-Gaussian output of order 4, 6, 8, is analyzed. An inverse propagation method is used to determine the appropriate shape of the adaptive mirror. The mirror reproduces the shape with minimal RMS error by combining weights of experimentally measured response functions of the mirror sample. The voltages applied to each mirror electrode are calculated. Practical design parameters such as construction of an adaptive mirror, Fresnel numbers, and geometric factor are discussed.

Pulse stretcher

DOEpatents

Horton, James A.

1994-01-01

Apparatus (20) for increasing the length of a laser pulse to reduce its peak power without substantial loss in the average power of the pulse. The apparatus (20) uses a White cell (10) having a plurality of optical delay paths (18a-18d) of successively increasing number of passes between the field mirror (13) and the objective mirrors (11 and 12). A pulse (26) from a laser (27) travels through a multi-leg reflective path (28) between a beam splitter (21) and a totally reflective mirror (24) to the laser output (37). The laser pulse (26) is also simultaneously injected through the beam splitter (21) to the input mirrors (14a-14d) of the optical delay paths (18a-18d). The pulses from the output mirrors (16a-16d) of the optical delay paths (18a-18d) go simultaneously to the laser output (37) and to the input mirrors ( 14b-14d) of the longer optical delay paths. The beam splitter (21) is 50% reflective and 50% transmissive to provide equal attenuation of all of the pulses at the laser output (37).

Interferometric Polarization Control

NASA Technical Reports Server (NTRS)

Wollack, Edward J. (Inventor); Moseley, Samuel H. (Inventor); Chuss, David T. (Inventor); Novak, Giles A. (Inventor)

2008-01-01

A signal conditioning module provides a polarimeter capability in a photometric system. The module may include multiple variable delay polarization modulators. Each modulator may include an input port, and a first arm formed to include a first reflector and first rooftop mirror arranged in opposed relationship. The first reflector may direct an input radiation signal to the first rooftop mirror. Each modulator also may include an output port and a second arm formed to include a second reflector and second rooftop mirror arranged in opposed relationship. The second reflector can guide a signal from the second rooftop mirror towards the output port to provide an output radiation signal. A beamsplitting grid may be placed between the first reflector and the first rooftop mirror, and also between the second reflector and the second rooftop mirror. A translation apparatus can provide adjustment relative to optical path length vis-a-vis the first arm, the second arm and the grid.

Interferometric polarization control

NASA Technical Reports Server (NTRS)

Wollack, Edward J. (Inventor); Novak, Giles A. (Inventor); Moseley, Samuel H. (Inventor); Chuss, David T. (Inventor)

2009-01-01

A signal conditioning module provides a polarimeter capability in a photometric system. The module may include multiple variable delay polarization modulators. Each modulator may include an input port, and a first arm formed to include a first reflector and first rooftop mirror arranged in opposed relationship. The first reflector may direct an input radiation signal to the first rooftop mirror. Each modulator also may include an output port and a second arm formed to include a second reflector and second rooftop mirror arranged in opposed relationship. The second reflector can guide a signal from the second rooftop mirror towards the output port to provide an output radiation signal. A beamsplitting grid may be placed between the first reflector and the first rooftop mirror, and also between the second reflector and the second rooftop mirror. A translation apparatus can provide adjustment relative to optical path length vis-a-vis the first arm, the second arm and the grid.

650-nm-band high-power and highly reliable laser diodes with a window-mirror structure

NASA Astrophysics Data System (ADS)

Shima, Akihiro; Hironaka, Misao; Ono, Ken-ichi; Takemi, Masayoshi; Sakamoto, Yoshifumi; Kunitsugu, Yasuhiro; Yamashita, Koji

1998-05-01

An active layer structure with 658 nm-emission at 25 degrees Celsius has been optimized in order to reduce the operating current of the laser diodes (LD) under high temperature condition. For improvement of the maximum output power and the reliability limited by mirror degradation, we have applied a zinc-diffused-type window-mirror structure which prevents the optical absorption at the mirror facet. As a result, the CW output power of 50 mW is obtained even at 80 degrees Celsius for a 650 micrometer-long window-mirror LD. In addition, the maximum light output power over 150 mW at 25 degrees Celsius has been realized without any optical mirror damage. In the aging tests, the LDs have been operating for over 2,500 - 5,000 hours under the CW condition of 30 - 50 mW at 60 degrees Celsius. The window-mirror structure also enables reliable 60 degree Celsius, 30 mW, CW operation of the LDs with 651 nm- emission at 25 degrees Celsius. Moreover, the maximum output power of around 100 mW even at 80 degrees Celsius and reliable 2,000-hour operation at 60 degrees Celsius, 70 mW have been realized for the first time by 659 nm LDs with a long cavity length of 900 micrometers.

Method for separating FEL output beams from long wavelength radiation

DOEpatents

Neil, George; Shinn, Michelle D.; Gubeli, Joseph

2016-04-26

A method for improving the output beam quality of a free electron laser (FEL) by reducing the amount of emission at wavelengths longer than the electron pulse length and reducing the amount of edge radiation. A mirror constructed of thermally conductive material and having an aperture therein is placed at an oblique angle with respect to the beam downstream of the bending magnet but before any sensitive use of the FEL beam. The aperture in the mirror is sized to deflect emission longer than the wavelength of the FEL output while having a minor impact on the FEL output beam. A properly sized aperture will enable the FEL radiation, which is coherent and generally at a much shorter wavelength than the bending radiations, to pass through the aperture mirror. The much higher divergence bending radiations will subsequently strike the aperture mirror and be reflected safely out of the way.

Digital frequency offset-locked He–Ne laser system with high beat frequency stability, narrow optical linewidth and optical fibre output

NASA Astrophysics Data System (ADS)

Sternkopf, Christian; Manske, Eberhard

2018-06-01

We report on the enhancement of a previously-presented heterodyne laser source on the basis of two phase-locked loop (PLL) frequency coupled internal-mirror He–Ne lasers. Our new system consists of two digitally controlled He–Ne lasers with slightly different wavelengths, and offers high-frequency stability and very narrow optical linewidth. The digitally controlled system has been realized by using a FPGA controller and transconductance amplifiers. The light of both lasers was coupled into separate fibres for heterodyne interferometer applications. To enhance the laser performance we observed the sensitivity of both laser tubes to electromagnetic noise from various laser power supplies and frequency control systems. Furthermore, we describe how the linewidth of a frequency-controlled He–Ne laser can be reduced during precise frequency stabilisation. The digitally controlled laser source reaches a standard beat frequency deviation of less than 20 Hz (with 1 s gate time) and a spectral full width at half maximum (FWHM) of the beat signal less than 3 kHz. The laser source has enough optical output power to serve a fibre-coupled multi axis heterodyne interferometer. The system can be adjusted to output beat frequencies in the range of 0.1 MHz–20 MHz.

Capacitive label reader

DOEpatents

Arlowe, H. Duane

1985-01-01

A capacitive label reader includes an outer ring transmitting portion, an inner ring transmitting portion, and a plurality of insulated receiving portions. A label is the mirror-image of the reader except that identifying portions corresponding to the receiving portions are insulated from only one of two coupling elements. Positive and negative pulses applied, respectively, to the two transmitting rings biased a CMOS shift register positively to either a 1 or 0 condition. The output of the CMOS may be read as an indication of the label.

Capacitive label reader

DOEpatents

Arlowe, H.D.

1985-11-12

A capacitive label reader includes an outer ring transmitting portion, an inner ring transmitting portion, and a plurality of insulated receiving portions. A label is the mirror-image of the reader except that identifying portions corresponding to the receiving portions are insulated from only one of two coupling elements. Positive and negative pulses applied, respectively, to the two transmitting rings biased a CMOS shift register positively to either a 1 or 0 condition. The output of the CMOS may be read as an indication of the label. 5 figs.

Capacitive label reader

DOEpatents

Arlowe, H.D.

1983-07-15

A capacitive label reader includes an outer ring transmitting portion, an inner ring transmitting portion, and a plurality of insulated receiving portions. A label is the mirror-image of the reader except that identifying portions corresponding to the receiving portions are insulated from only one of two coupling elements. Positive and negative pulses applied, respectively, to the two transmitting rings biased a CMOS shift register positively to either a 1 or 0 condition. The output of the CMOS may be read as an indication of the label.

Initial results for a 170 GHz high power ITER waveguide component test stand

NASA Astrophysics Data System (ADS)

Bigelow, Timothy; Barker, Alan; Dukes, Carl; Killough, Stephen; Kaufman, Michael; White, John; Bell, Gary; Hanson, Greg; Rasmussen, Dave

2014-10-01

A high power microwave test stand is being setup at ORNL to enable prototype testing of 170 GHz cw waveguide components being developed for the ITER ECH system. The ITER ECH system will utilize 63.5 mm diameter evacuated corrugated waveguide and will have 24 >150 m long runs. A 170 GHz 1 MW class gyrotron is being developed by Communications and Power Industries and is nearing completion. A HVDC power supply, water-cooling and control system has been partially tested in preparation for arrival of the gyrotron. The power supply and water-cooling system are being designed to operate for >3600 second pulses to simulate the operating conditions planned for the ITER ECH system. The gyrotron Gaussian beam output has a single mirror for focusing into a 63.5 mm corrugated waveguide in the vertical plane. The output beam and mirror are enclosed in an evacuated duct with absorber for stray radiation. Beam alignment with the waveguide is a critical task so a combination of mirror tilt adjustments and a bellows for offsets will be provided. Analysis of thermal patterns on thin witness plates will provide gyrotron mode purity and waveguide coupling efficiency data. Pre-prototype waveguide components and two dummy loads are available for initial operational testing of the gyrotron. ORNL is managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under Contract DE-AC-05-00OR22725.

The Physics of Ultracold Sr2 Molecules: Optical Production and Precision Measurement

DTIC Science & Technology

2013-01-01

causing stimulated emission. The wavelength of the feedback light is determined by the angle of the feedback mirror . The zeroth order is the output from...with representative mirror , diffraction grating and diode housing (right). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.14 Schematic of...of the feedback light is determined by the angle of the feedback mirror . The zeroth order is the output from the ECDL. . . . . . . . . . . . 23 2.15

Influence of thermal deformation in cavity mirrors on beam propagation characteristics of high-power slab lasers

NASA Astrophysics Data System (ADS)

Wang, Zhen; Xiao, Longsheng; Wang, Wei; Wu, Chao; Tang, Xiahui

2018-01-01

Owing to their good diffusion cooling and low sensitivity to misalignment, slab-shape negative-branch unstable-waveguide resonators are widely used for high-power lasers in industry. As the output beam of the resonator is astigmatic, an external beam shaping system is required. However, the transverse dimension of the cavity mirrors in the resonator is large. For a long-time operation, the heating of cavity mirrors can be non-uniform. This results in micro-deformation and a change in the radius of curvature of the cavity mirrors, and leads to an output beam of an offset optical axis of the resonator. It was found that a change in the radius of curvature of 0.1% (1 mm) caused by thermal deformation generates a transverse displacement of 1.65 mm at the spatial filter of the external beam shaping system, and an output power loss of more than 80%. This can potentially burn out the spatial filter. In order to analyze the effect of the offset optical axis of the beam on the external optical path, we analyzed the transverse displacement and rotational misalignments of the spatial filter. For instance, if the transverse displacement was 0.3 mm, the loss in the output power was 9.6% and a sidelobe appeared in the unstable direction. If the angle of rotation was 5°, the loss in the output power was 2%, and the poles were in the direction of the waveguide. Based on these results, by adjusting the bending mirror, the deviation angle of the output beam of the resonator cavity was corrected, in order to obtain maximum output power and optimal beam quality. Finally, the propagation characteristics of the corrected output beam were analyzed.

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

Afonenko, A A; Dorogush, E S; Malyshev, S A

Using a system of coupled travelling wave equations, in the small-signal regime we analyse frequency and noise characteristics of index- or absorption-coupled distributed feedback laser diodes, as well as of Fabry – Perot (FP) laser diodes. It is shown that the weakest dependence of the direct modulation efficiency on the locking frequency in the regime of strong external optical injection locking is exhibited by a FP laser diode formed by highly reflective and antireflective coatings on the end faces of a laser structure. A reduction in the dependence of output characteristics of the laser diode on the locking frequency canmore » be attained by decreasing the reflection coefficient of the antireflective FP mirror. (control of laser radiation parameters)« less

Method and device for remotely monitoring an area using a low peak power optical pump

DOEpatents

Woodruff, Steven D.; Mcintyre, Dustin L.; Jain, Jinesh C.

2014-07-22

A method and device for remotely monitoring an area using a low peak power optical pump comprising one or more pumping sources, one or more lasers; and an optical response analyzer. Each pumping source creates a pumping energy. The lasers each comprise a high reflectivity mirror, a laser media, an output coupler, and an output lens. Each laser media is made of a material that emits a lasing power when exposed to pumping energy. Each laser media is optically connected to and positioned between a corresponding high reflectivity mirror and output coupler along a pumping axis. Each output coupler is optically connected to a corresponding output lens along the pumping axis. The high reflectivity mirror of each laser is optically connected to an optical pumping source from the one or more optical pumping sources via an optical connection comprising one or more first optical fibers.

NONLINEAR OPTICAL EFFECTS AND FIBER OPTICS: Pulsed neodymium amplifier with phase conjugation and direct amplification

NASA Astrophysics Data System (ADS)

Basov, N. G.; Efimkov, V. F.; Zubarev, I. G.; Kolobrodov, V. V.; Pastukhov, S. A.; Smirnov, M. G.; Sobolev, V. B.

1988-12-01

A study was made of the characteristics of an amplifier containing neodymium-activated silicate rods, 45 mm in diameter, used in direct amplification and phase conjugation systems. At low output energies the divergence of the output radiation in the presence of a phase-conjugating mirror was half ( ~ 10- 4 rad) that in the case of direct amplification. An increase in the output power caused the divergence to rise more rapidly in the presence of a phase-conjugating mirror, which was tentatively attributed to an earlier manifestation of large-scale self-focusing. Output energies of 130 J in the case of direct amplification and 80 J in the presence of a phase-conjugating mirror were obtained when the output pulse duration was ~ 2 ns and the fraction of the total energy contained within an angle of ~ 10- 4 rad was ~ 0.3.

Spectral singularities, threshold gain, and output intensity for a slab laser with mirrors

NASA Astrophysics Data System (ADS)

Doğan, Keremcan; Mostafazadeh, Ali; Sarısaman, Mustafa

2018-05-01

We explore the consequences of the emergence of linear and nonlinear spectral singularities in TE modes of a homogeneous slab of active optical material that is placed between two mirrors. We use the results together with two basic postulates regarding the behavior of laser light emission to derive explicit expressions for the laser threshold condition and output intensity for these modes of the slab and discuss their physical implications. In particular, we reveal the details of the dependence of the threshold gain and output intensity on the position and properties of the mirrors and on the real part of the refractive index of the gain material.

Multiple wavelength tunable surface-emitting laser arrays

NASA Astrophysics Data System (ADS)

Chang-Hasnain, Connie J.; Harbison, J. P.; Zah, Chung-En; Maeda, M. W.; Florez, L. T.; Stoffel, N. G.; Lee, Tien-Pei

1991-06-01

Techniques to achieve wavelength multiplexing and tuning capabilities in vertical-cavity surface-emitting lasers (VCSELs) are described, and experimental results are given. The authors obtained 140 unique, uniformly separated, single-mode wavelength emissions from a 7 x 20 VCSEL array. Large total wavelength span (about 430 A) and small wavelength separation (about 3 A) are obtained simultaneously with uncompromised laser performance. All 140 lasers have nearly the same threshold currents, voltages, and resistances. Wavelength tuning is obtained by using a three-mirror coupled-cavity configuration. The three-mirror laser is a two-terminal device and requires only one top contact. Discrete tuning with a range as large as 61 A is achieved with a small change in drive current of only 10.5 mA. The VCSEL output power variation is within 5 dB throughout the entire tuning range.

Global Radius of Curvature Estimation and Control System for Segmented Mirrors

NASA Technical Reports Server (NTRS)

Rakoczy, John M. (Inventor)

2006-01-01

An apparatus controls positions of plural mirror segments in a segmented mirror with an edge sensor system and a controller. Current mirror segment edge sensor measurements and edge sensor reference measurements are compared with calculated edge sensor bias measurements representing a global radius of curvature. Accumulated prior actuator commands output from an edge sensor control unit are combined with an estimator matrix to form the edge sensor bias measurements. An optimal control matrix unit then accumulates the plurality of edge sensor error signals calculated by the summation unit and outputs the corresponding plurality of actuator commands. The plural mirror actuators respond to the actuator commands by moving respective positions of the mixor segments. A predetermined number of boundary conditions, corresponding to a plurality of hexagonal mirror locations, are removed to afford mathematical matrix calculation.

Fiber Grating Coupled Light Source Capable of Tunable, Single Frequency Operation

NASA Technical Reports Server (NTRS)

Krainak, Michael A. (Inventor); Duerksen, Gary L. (Inventor)

2001-01-01

Fiber Bragg grating coupled light sources can achieve tunable single-frequency (single axial and lateral spatial mode) operation by correcting for a quadratic phase variation in the lateral dimension using an aperture stop. The output of a quasi-monochromatic light source such as a Fabry Perot laser diode is astigmatic. As a consequence of the astigmatism, coupling geometries that accommodate the transverse numerical aperture of the laser are defocused in the lateral dimension, even for apsherical optics. The mismatch produces the quadratic phase variation in the feedback along the lateral axis at the facet of the laser that excites lateral modes of higher order than the TM(sub 00). Because the instability entails excitation of higher order lateral submodes, single frequency operation also is accomplished by using fiber Bragg gratings whose bandwidth is narrower than the submode spacing. This technique is particularly pertinent to the use of lensed fiber gratings in lieu of discrete coupling optics. Stable device operation requires overall phase match between the fed-back signal and the laser output. The fiber Bragg grating acts as a phase-preserving mirror when the Bragg condition is met precisely. The phase-match condition is maintained throughout the fiber tuning range by matching the Fabry-Perot axial mode wavelength to the passband center wavelength of the Bragg grating.

Fiber optic laser-induced breakdown spectroscopy sensor for molten material analysis

DOEpatents

Zhang, Hansheng; Rai, Awadesh K.; Singh, Jagdish P.; Yueh, Fang-Yu

2004-07-13

A fiber optic laser-induced breakdown spectroscopy (LIBS) sensor, including a laser light source, a harmonic separator for directing the laser light, a dichroic mirror for reflecting the laser light, a coupling lens for coupling the laser light at an input of a multimode optical fiber, a connector for coupling the laser light from an output of the multimode optical fiber to an input of a high temperature holder, such as a holder made of stainless steel, and a detector portion for receiving emission signal and analyzing LIBS intensities. In one variation, the multimode optical fiber has silica core and silica cladding. The holder includes optical lenses for collimating and focusing the laser light in a molten alloy to produce a plasma, and for collecting and transmitting an emission signal to the multimode optical fiber.

Program Predicts Performance of Optical Parametric Oscillators

NASA Technical Reports Server (NTRS)

Cross, Patricia L.; Bowers, Mark

2006-01-01

A computer program predicts the performances of solid-state lasers that operate at wavelengths from ultraviolet through mid-infrared and that comprise various combinations of stable and unstable resonators, optical parametric oscillators (OPOs), and sum-frequency generators (SFGs), including second-harmonic generators (SHGs). The input to the program describes the signal, idler, and pump beams; the SFG and OPO crystals; and the laser geometry. The program calculates the electric fields of the idler, pump, and output beams at three locations (inside the laser resonator, just outside the input mirror, and just outside the output mirror) as functions of time for the duration of the pump beam. For each beam, the electric field is used to calculate the fluence at the output mirror, plus summary parameters that include the centroid location, the radius of curvature of the wavefront leaving through the output mirror, the location and size of the beam waist, and a quantity known, variously, as a propagation constant or beam-quality factor. The program provides a typical Windows interface for entering data and selecting files. The program can include as many as six plot windows, each containing four graphs.

IR Spectrometer Using 90-Degree Off-Axis Parabolic Mirrors

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

Robert M. Malone, Ian J. McKenna

2008-03-01

A gated spectrometer has been designed for real-time, pulsed infrared (IR) studies at the National Synchrotron Light Source at the Brookhaven National Laboratory. A pair of 90-degree, off-axis parabolic mirrors are used to relay the light from an entrance slit to an output recording camera. With an initial wavelength range of 1500–4500 nm required, gratings could not be used in the spectrometer because grating orders would overlap. A magnesium oxide prism, placed between these parabolic mirrors, serves as the dispersion element. The spectrometer is doubly telecentric. With proper choice of the air spacing between the prism and the second parabolicmore » mirror, any spectral region of interest within the InSb camera array’s sensitivity region can be recorded. The wavelengths leaving the second parabolic mirror are collimated, thereby relaxing the camera positioning tolerance. To set up the instrument, two different wavelength (visible) lasers are introduced at the entrance slit and made collinear with the optical axis via flip mirrors. After dispersion by the prism, these two laser beams are directed to tick marks located on the outside housing of the gated IR camera. This provides first-order wavelength calibration for the instrument. Light that is reflected off the front prism face is coupled into a high-speed detector to verify steady radiance during the gated spectral imaging. Alignment features include tick marks on the prism and parabolic mirrors. This instrument was designed to complement single-point pyrometry, which provides continuous time histories of a small collection of spots from shock-heated targets.« less

IR Spectrometer Using 90-degree Off-axis Parabolic Mirrors

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

Robert M. Malone, Richard, G. Hacking, Ian J. McKenna, and Daniel H. Dolan

2008-09-02

A gated spectrometer has been designed for real-time, pulsed infrared (IR) studies at the National Synchrotron Light ource at the Brookhaven National Laboratory. A pair of 90-degree, off-axis parabolic mirrors are used to relay the light from an entrance slit to an output IR recording camera. With an initial wavelength range of 1500–4500 nm required, gratings could not be used in the spectrometer because grating orders would overlap. A magnesium oxide prism, placed between these parabolic mirrors, serves as the dispersion element. The spectrometer is doubly telecentric. With proper choice of the air spacing between the prism and the secondmore » parabolic mirror, any spectral region of interest within the InSb camera array’s sensitivity region can be recorded. The wavelengths leaving the second parabolic mirror are collimated, thereby relaxing the camera positioning tolerance. To set up the instrument, two different wavelength (visible) lasers are introduced at the entrance slit and made collinear with the optical axis via flip mirrors. After dispersion by the prism, these two laser beams are directed to tick marks located on the outside housing of the gated IR camera. This provides first-order wavelength calibration for the instrument. Light that is reflected off the front prism face is coupled into a high-speed detector to verify steady radiance during the gated spectral imaging. Alignment features include tick marks on the prism and parabolic mirrors. This instrument was designed to complement singlepoint pyrometry, which provides continuous time histories of a small collection of spots from shock-heated targets.« less

Multistaged stokes injected Raman capillary waveguide amplifier

DOEpatents

Kurnit, Norman A.

1980-01-01

A multistaged Stokes injected Raman capillary waveguide amplifier for providing a high gain Stokes output signal. The amplifier uses a plurality of optically coupled capillary waveguide amplifiers and one or more regenerative amplifiers to increase Stokes gain to a level sufficient for power amplification. Power amplification is provided by a multifocused Raman gain cell or a large diameter capillary waveguide. An external source of CO.sub.2 laser radiation can be injected into each of the capillary waveguide amplifier stages to increase Raman gain. Devices for injecting external sources of CO.sub.2 radiation include: dichroic mirrors, prisms, gratings and Ge Brewster plates. Alternatively, the CO.sub.2 input radiation to the first stage can be coupled and amplified between successive stages.

Output-Mirror-Tuning Terahertz-Wave Parametric Oscillator with an Asymmetrical Porro-Prism Resonator Configuration

NASA Astrophysics Data System (ADS)

Zhang, Ruiliang; Qu, Yanchen; Zhao, Weijiang; Liu, Chuang; Chen, Zhenlei

2017-06-01

We demonstrate a terahertz-wave parametric oscillator (TPO) with an asymmetrical porro-prism (PP) resonator configuration, consisting of a close PP corner reflector and a distant output mirror relative to the MgO:LiNbO3 crystal. Based on this cavity, frequency tuning of Stokes and the accompanied terahertz (THz) waves is realized just by rotating the plane mirror. Furthermore, THz output with high efficiency and wide tuning range is obtained. Compared with a conventional TPO employing a plane-parallel resonator of the same cavity length and output loss, the low end of the frequency tuning range is extended to 0.96 THz from 1.2 THz. The highest output obtained at 1.28 THz is enhanced by about 25%, and the oscillation threshold pump energy measured at 1.66 THz is reduced by about 4.5%. This resonator configuration also shows some potential to simplify the structure and application for intracavity TPOs.

Point Relay Scanner Utilizing Ellipsoidal Mirrors

NASA Technical Reports Server (NTRS)

Manhart, Paul K. (Inventor); Pagano, Robert J. (Inventor)

1997-01-01

A scanning system uses a polygonal mirror assembly with each facet of the polygon having an ellipsoidal mirror located thereon. One focal point of each ellipsoidal mirror is located at a common point on the axis of rotation of the polygonal mirror assembly. As the mirror assembly rotates. a second focal point of the ellipsoidal mirrors traces out a scan line. The scanner can be utilized for scanned output display of information or for scanning information to be detected.

Over 10-watt pico-second diffraction-limited output from a Nd:YVO4 slab amplifier with a phase conjugate mirror.

PubMed

Ojima, Yasukuni; Nawata, Kouji; Omatsu, Takashige

2005-10-31

We have produced a high beam quality pico-second laser based on a continuous-wave diode pumped Nd:YVO4 slab amplifier with a photorefractive phase conjugate mirror. 12.8W diffraction-limited output with a pulse width of 8.7ps was obtained.

Integrated Lloyd's mirror on planar waveguide facet as a spectrometer.

PubMed

Morand, Alain; Benech, Pierre; Gri, Martine

2017-12-10

A low-cost and simple Fourier transform spectrometer based on the Lloyd's mirror configuration is proposed in order to have a very stable interferogram. A planar waveguide coupled to a fiber injection is used to spatially disperse the optical beam. A second beam superposed to the previous one is obtained by a total reflection of the incident beam on a vertical glass face integrated in the chip by dicing with a specific circular precision saw. The interferogram at the waveguide output is imaged on a near-infrared camera with an objective lens. The contrast and the fringe period are thus dependent on the type and the fiber position and can be optimized to the pixel size and the length of the camera. Spectral resolution close to λ/Δλ=80 is reached with a camera with 320 pixels of 25 μm width in a wavelength range from O to L bands.

Metasurface-assisted orbital angular momentum carrying Bessel-Gaussian Laser: proposal and simulation.

PubMed

Zhou, Nan; Wang, Jian

2018-05-23

Bessel-Gaussian beams have distinct properties of suppressed diffraction divergence and self-reconstruction. In this paper, we propose and simulate metasurface-assisted orbital angular momentum (OAM) carrying Bessel-Gaussian laser. The laser can be regarded as a Fabry-Perot cavity formed by one partially transparent output plane mirror and the other metasurface-based reflector mirror. The gain medium of Nd:YVO 4 enables the lasing wavelength at 1064 nm with a 808 nm laser serving as the pump. The sub-wavelength structure of metasurface facilitates flexible spatial light manipulation. The compact metasurface-based reflector provides combined phase functions of an axicon and a spherical mirror. By appropriately selecting the size of output mirror and inserting mode-selection element in the laser cavity, different orders of OAM-carrying Bessel-Gaussian lasing modes are achievable. The lasing Bessel-Gaussian 0 , Bessel-Gaussian 01 + , Bessel-Gaussian 02 + and Bessel-Gaussian 03 + modes have high fidelities of ~0.889, ~0.889, ~0.881 and ~0.879, respectively. The metasurface fabrication tolerance and the dependence of threshold power and output lasing power on the length of gain medium, beam radius of pump and transmittance of output mirror are also discussed. The obtained results show successful implementation of metasurface-assisted OAM-carrying Bessel-Gaussian laser with favorable performance. The metasurface-assisted OAM-carrying Bessel-Gaussian laser may find wide OAM-enabled communication and non-communication applications.

Coupling of a nanomechanical oscillator and an atomic three-level medium

NASA Astrophysics Data System (ADS)

Sanz-Mora, A.; Eisfeld, A.; Wüster, S.; Rost, J.-M.

2016-02-01

We theoretically investigate the coupling of an ultracold three-level atomic gas and a nanomechanical mirror via classical electromagnetic radiation. The radiation pressure on the mirror is modulated by absorption of a probe light field, caused by the atoms which are electromagnetically rendered nearly transparent, allowing the gas to affect the mirror. In turn, the mirror can affect the gas as its vibrations generate optomechanical sidebands in the control field. We show that the sidebands cause modulations of the probe intensity at the mirror frequency, which can be enhanced near atomic resonances. Through the radiation pressure from the probe beam onto the mirror, this results in resonant driving of the mirror. Controllable by the two-photon detuning, the phase relation of the driving to the mirror motion decides upon amplification or damping of mirror vibrations. This permits direct phase locking of laser amplitude modulations to the motion of a nanomechanical element opening a perspective for cavity-free cooling through coupling to an atomic gas.

High-power direct diode laser output by spectral beam combining

NASA Astrophysics Data System (ADS)

Tan, Hao; Meng, Huicheng; Ruan, Xu; Du, Weichuan; Wang, Zhao

2018-03-01

We demonstrate a spectral beam combining scheme based on multiple mini-bar stacks, which have more diode laser combining elements, to increase the combined diode laser power and realize equal beam quality in both the fast and slow axes. A spectral beam combining diode laser output of 1130 W is achieved with an operating current of 75 A. When a 9.6 X de-magnifying telescope is introduced between the output mirror and the diffraction grating, to restrain cross-talk among diode laser emitters, a 710 W spectral beam combining diode laser output is achieved at the operating current of 70 A, and the beam quality on the fast and slow axes of the combined beam is about 7.5 mm mrad and 7.3 mm mrad respectively. The power reduction is caused by the existence of a couple resonator between the rear facet of the diode laser and the fast axis collimation lens, and it should be eliminated by using diode laser chips with higher front facet transmission efficiency and a fast axis collimation lens with lower residual reflectivity.

Microchip laser based on Yb:YAG/V:YAG monolith crystal

NASA Astrophysics Data System (ADS)

Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav

2016-03-01

V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

Simultaneous calculation of three optical surfaces in the 3D SMS freeform RXI optic

NASA Astrophysics Data System (ADS)

Sorgato, Simone; Chaves, Julio; Mohedano, Rubén.; Hernández, Maikel; Blen, José; Benitez, Pablo; Miñano, Juan C.; Grabovickic, Dejan; Thienpont, Hugo; Duerr, Fabian

2016-09-01

The Freeform RXI collimator is a remarkable example of advanced nonimaging device designed with the 3D Simultaneous Multiple Surface (SMS) Method. In the original design, two (the front refracting surface and the back mirror) of the three optical surfaces of the RXI are calculated simultaneously and one (the cavity surrounding the source) is fixed by the designer. As a result, the RXI perfectly couples two input wavefronts (coming from the edges of the extended LED source) with two output wavefronts (defining the output beam). This allows for LED lamps able to produce controlled intensity distributions, which can and have been successfully applied to demanding applications like high- and low-beams for Automotive Lighting. Nevertheless, current trends in this field are moving towards smaller headlamps with more shape constraints driven by car design. We present an improved version of the 3D RXI in which also the cavity surface is computed during the design, so that there are three freeform surfaces calculated simultaneously and an additional degree of freedom for controlling the light emission: now the RXI can perfectly couple three input wavefronts with three output wavefronts. The enhanced control over ray beams allows for improved light homogeneity and better pattern definition.

MEMS micromirrors for optical switching in multichannel spectrophotometers

NASA Astrophysics Data System (ADS)

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

2004-04-01

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

Coupling structures for out-of-plane coupling in optical PCBs

NASA Astrophysics Data System (ADS)

Hendrickx, N.; Van Erps, J.; Bosman, E.; Thienpont, H.; Van Daele, P.

2008-04-01

Coupling structures are critical building blocks that have a big influence on the performance of board-level optical interconnections. 45° micro-mirrors deflect the light beam over 90° and are used for out-of-plane coupling in single layer structures and out-of-plane and inter-plane coupling in multilayer structures. Two different approaches are being presented: a micro-mirror that is directly integrated with the multimode waveguides and a discrete coupling element that can be plugged into a cavity in the optical layer. The advantage of the integrated micro-mirror is the high achievable alignment accuracy. The discrete couplers on the other hand have the advantage that they can be characterized and measured prior to the insertion into the optical layer. Both mirror configurations are discussed and the performance is evaluated at wavelength 850nm.

Fiber optic diffraction grating maker

DOEpatents

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

1991-05-21

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

Fiber optic diffraction grating maker

DOEpatents

Deason, Vance A.; Ward, Michael B.

1991-01-01

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

Large volume multiple-path nuclear pumped laser

NASA Technical Reports Server (NTRS)

Hohl, F.; Deyoung, R. J. (Inventor)

1981-01-01

Large volumes of gas are excited by using internal high reflectance mirrors that are arranged so that the optical path crosses back and forth through the excited gaseous medium. By adjusting the external dielectric mirrors of the laser, the number of paths through the laser cavity can be varied. Output powers were obtained that are substantially higher than the output powers of previous nuclear laser systems.

Redundantly piezo-actuated XYθ z compliant mechanism for nano-positioning featuring simple kinematics, bi-directional motion and enlarged workspace

NASA Astrophysics Data System (ADS)

Zhu, Wu-Le; Zhu, Zhiwei; To, Suet; Liu, Qiang; Ju, Bing-Feng; Zhou, Xiaoqin

2016-12-01

This paper presents a novel redundantly piezo-actuated three-degree-of-freedom XYθ z compliant mechanism for nano-positioning, driven by four mirror-symmetrically configured piezoelectric actuators (PEAs). By means of differential motion principle, linearized kinematics and physically bi-directional motions in all the three directions are achieved. Meanwhile, the decoupled delivering of three-directional independent motions at the output end is accessible, and the essential parallel and mirror symmetric configuration guarantees large output stiffness, high natural frequencies, high accuracy as well as high structural compactness of the mechanism. Accurate kinematics analysis with consideration of input coupling indicates that the proposed redundantly actuated compliant mechanism can generate three-dimensional (3D) symmetric polyhedral workspace envelope with enlarged reachable workspace, as compared with the most common parallel XYθ z mechanism driven by three PEAs. Keeping a high consistence with both analytical and numerical models, the experimental results show the working ranges of ±6.21 μm and ±12.41 μm in X- and Y-directions, and that of ±873.2 μrad in θ z-direction with nano-positioning capability can be realized. The superior performances and easily achievable structure well facilitate practical applications of the proposed XYθ z compliant mechanism in nano-positioning systems.

Compact optical multipass matrix system design based on slicer mirrors.

PubMed

Guo, Yin; Sun, Liqun

2018-02-10

High path-to-volume ratio (PVR) and low-aberration-output beams are the two main criteria to assess the performance of multipass absorption cells. However, no substantial progress has been reported for large-numerical-aperture-coupled multipass cells, which is due to the accumulated aberrations caused by a large number of off-axis reflections. Based on Chernin's design, in this study, we modified Chernin's four-objective multipass matrix cell by using slicer mirrors to eliminate alignment difficulty and decrease the system volume. A generalized design routine based on user requirements is also proposed. Based on the automatic modeling tool package (Pyzdde) connected with Zemax and boundary conditions of the parameters selection proposed, a low-aberration-output beam and a high PVR are easily obtained compared with other multipass cells schemes. In one demo design, 108 passes (5×7 matrix spots) in a base length of 300 mm are presented. The PVR and peak-to-valley value wavefront errors are 67.5 m/L and 0.92 μm, respectively. Finally, a tolerance analysis of this optical multipass system is also presented. This work may provide better broadband optical absorption cells in terms of response time and a better detection sensitivity in versatile applications.

A blackbody-pumped CO2-N2 transfer laser

NASA Astrophysics Data System (ADS)

Deyoung, R. J.; Higdon, N. S.

1984-08-01

A compact blackbody-pumped CO2-N2 transfer laser was constructed and the significant operating parameters were investigated. Lasing was achieved at 10.6 microns by passing preheated N2 through a 1.5-mm-diameter nozzle to a laser cavity where the N2 was mixed with CO2 and He. An intrinsic efficiency of 0.7 percent was achieved for an oven temperature of 1473 K and N2 oven pressure of 440 torr. The optimum laser cavity consisted of a back mirror with maximum reflectivity and an output mirror with 97.5-percent reflectivity. The optimum gas mixture was 1CO2/.5He/6N2. The variation of laser output was measured as a function of oven temperature, nozzle diameter, N2 oven pressure, He and CO2 partial pressures, nozzle-to-oven separation, laser cell temperature, and output laser mirror reflectivity. With these parameters optimized, outputs approaching 1.4 watts were achieved.

Laser diode side-pumped Nd:YVO4 microchip laser with film-etched microcavity mirrors.

PubMed

Li, Jiyang; Niu, Yanxiong; Chen, Sanbin; Tan, Yidong

2017-10-01

Microchip lasers are applied as the light sources on various occasions with the end-pumping scheme. However, the vibration, the temperature drift, or the mechanical deformation of the pumping light in laser diodes in the end-pumping scheme will lead to instability in the microchip laser output, which causes errors and malfunctioning in the optic systems. In this paper, the side-pumping scheme is applied for improving the disturbance-resisting ability of the microchip laser. The transverse mode and the frequency purity of the laser output are tested. To ensure unicity in the frequency of the laser output, numerical simulations based on Fresnel-Kirchhoff diffraction theory are conducted on the parameters of the microchip laser cavity. Film-etching technique is applied to restrain the area of the film and form the microcavity mirrors. The laser output with microcavity mirrors is ensured to be in single frequency and with good beam quality, which is significant in the applications of microchip lasers as the light sources in optical systems.

A blackbody-pumped CO2-N2 transfer laser

NASA Technical Reports Server (NTRS)

Deyoung, R. J.; Higdon, N. S.

1984-01-01

A compact blackbody-pumped CO2-N2 transfer laser was constructed and the significant operating parameters were investigated. Lasing was achieved at 10.6 microns by passing preheated N2 through a 1.5-mm-diameter nozzle to a laser cavity where the N2 was mixed with CO2 and He. An intrinsic efficiency of 0.7 percent was achieved for an oven temperature of 1473 K and N2 oven pressure of 440 torr. The optimum laser cavity consisted of a back mirror with maximum reflectivity and an output mirror with 97.5-percent reflectivity. The optimum gas mixture was 1CO2/.5He/6N2. The variation of laser output was measured as a function of oven temperature, nozzle diameter, N2 oven pressure, He and CO2 partial pressures, nozzle-to-oven separation, laser cell temperature, and output laser mirror reflectivity. With these parameters optimized, outputs approaching 1.4 watts were achieved.

Mathematical modeling and design of a novel 2-DOF micro attraction actuator for a micro optical switch

NASA Astrophysics Data System (ADS)

Kamiya, Daiki; Bagheri, Saeed; Horie, Mikio

2004-08-01

Many studies on optical switches have been performed in an attempt to develop optical information networks to speed information technology. In reality, however, mirror manipulators cannot be applied to multiple input and output systems due to both insufficient output displacements by the mirror parts inside the manipulator, and the difficulty of designing structures and mechanisms suitable for multi-dimensional manipulation. The principal reasons for insufficient displacement are the high rigidity of the elastic parts compared to the available driving forces and the pull-in effect. Therefore, in order to develop optical switches capable of multiple input and output switching, we suggest a novel 2-DOF(degree of freedom) electrostatic microactuator. The actuator is composed of one mirror with four beams laid about it in a corkscrew pattern, with four corkscrew electrodes on the substrate below and one mirror support pyramid situated under the mirror. Using electrostatic force, one or more of the beams are attracted from their outer ends toward the substrate. The mirror is then tilted by an angle proportional to the attracted length along the beam. The inclination and direction of the mirror are determined by the combined attracted length of the four beams. In this work we derive the mathematical model for the corkscrew beam microactuator for optical switches and show that this mathematical model accurately simulates the device by comparison with finite element analysis results. We use this mathematical model for design of the microactuator. Further we show that the designed optical switch microactuator is capable of rotating the mirror from +32 to -32 degrees about two axes with a maximum operating voltage of 163 volts. Finally, stress analysis of the actuator shows that the generated stress in the structure is at most 369 MPa.

Investigation of light source and scattering medium related to vapor-screen flow visualization in a supersonic wind tunnel

NASA Technical Reports Server (NTRS)

Snow, W. L.; Morris, O. A.

1984-01-01

Methods for increasing the radiant in light sheets used for vapor screen set-ups were investigated. Both high-pressure mercury arc lamps and lasers were considered. Pulsed operation of the air-cooled 1-kW lamps increased the light output but decreased reliability. An ellipsoidal mirror improved the output of the air-cooled lamps by concentrating the light but increased the complexity of the housing. Water-cooled-4-kW lamps coupled with high-aperture Fresnel lenses provided reasonable improvements over the air-cooled lamps. Fanned laser beams measurements of scattered light versus dew point made in conjunction with successful attempts to control the fluid injection. A number of smoke generators are described and test results comparing smoke and vapor screens are shown. Finally, one test included a periscope system to relay the image to a camera outside the flow.

Qubit assisted enhancement of quantum correlations in an optomechanical system

NASA Astrophysics Data System (ADS)

Chakraborty, Subhadeep; Sarma, Amarendra K.

2018-05-01

We perform a theoretical study on quantum correlations in an optomechanical system where the mechanical mirror is perturbatively coupled to an auxiliary qubit. In our study, we consider logarithmic negativity to quantify the degree of stationary entanglement between the cavity field and mechanical mirror, and, Gaussian quantum discord as a witness of the quantumness of the correlation beyond entanglement. Utilizing experimentally feasible parameters, we show that both entanglement and quantum discord enhance significantly with increase in mirror-qubit coupling. Moreover, we find that in presence of the mirror-qubit coupling entanglement could be generated at a considerably lower optomechanical coupling strength, which is also extremely robust against the environmental temperature. Overall, our proposed scheme offers some considerable advantages for realizing the continuous-variable quantum information and communication.

Reduction of parasitic lasing

NASA Technical Reports Server (NTRS)

Storm, Mark E. (Inventor)

1994-01-01

A technique was developed which carefully retro-reflects precisely controlled amounts of light back into a laser system thereby intentionally forcing the laser system components to oscillate in a new resonator called the parasitic oscillator. The parasitic oscillator uses the laser system to provide the gain and an external mirror is used to provide the output coupling of the new resonator. Any change of gain or loss inside the new resonator will directly change the lasing threshold of the parasitic oscillator. This change in threshold can be experimentally measured as a change in the absolute value of reflectivity, provided by the external mirror, necessary to achieve lasing in the parasitic oscillator. Discrepancies between experimental data and a parasitic oscillator model are direct evidence of optical misalignment or component performance problems. Any changes in the optical system can instantly be measured as a change in threshold for the parasitic oscillator. This technique also enables aligning the system for maximum parasitic suppression with the system fully operational.

Sub-20-ps pulses from a passively Q-switched microchip laser at 1  MHz repetition rate.

PubMed

Mehner, Eva; Bernard, Benjamin; Giessen, Harald; Kopf, Daniel; Braun, Bernd

2014-05-15

We present a 50 μm Nd3+:YVO4 microchip laser that is passively Q-switched by a semiconductor saturable absorber mirror. To reduce handling problems caused by the small crystal dimensions, the 50 μm Nd3+:YVO4 crystal is optically bonded to an undoped YVO4 crystal of a length of about 500 μm. By using a saturable absorber mirror with an effective modulation depth of >10% the system is able to deliver 16 ps pulses at a repetition rate of up to 1.0 MHz. The average laser power is 16 mW at 1064 nm. To our knowledge these are the shortest Q-switched pulses ever reported from a solid-state laser. The limits in terms of pulse width, repetition rate, output power, and system stability are discussed. Additionally, continuous-wave behavior is analyzed. Experimental data is compared with the simulation results of the coupled rate equations.

A Fiber-Optic Coupled Telescope for Water Vapor DIAL Receivers

NASA Technical Reports Server (NTRS)

DeYoung, Russell J.; Lonn, Frederick

1998-01-01

A fiber-optic coupled telescope of low complexity was constructed and tested. The major loss mechanisms of the optical system have been characterized. Light collected by the receiver mirror is focused onto an optical fiber, and the output of the fiber is filtered by an interference filter and then focused onto an APD detector. This system was used in lidar field measurements with a 532-nm Nd:YAG laser beam. The results were encouraging. A numerical model used for calculation of the expected return signal agreed with the lidar return signal obtained. The assembled system was easy to align and operate and weighed about 8 kg for a 30 cm (12") mirror system. This weight is low enough to allow mounting of the fiber-optic telescope receiver system in a UAV. Furthermore, the good agreement between the numerical lidar model and the performance of the actual receiver system, suggests that this model may be used for estimation of the performance of this and other lidar systems in the future. Such telescopes are relatively easy to construct and align. The fiber optic cable allows easy placement of the optical detector in any position. These telescope systems should find widespread use in aircraft and space home DIAL water vapor receiver systems.

Stability branching induced by collective atomic recoil in an optomechanical ring cavity

NASA Astrophysics Data System (ADS)

Ian, Hou

2017-02-01

In a ring cavity filled with an atomic condensate, self-bunching of atoms due to the cavity pump mode produce an inversion that re-emits into the cavity probe mode with an exponential gain, forming atomic recoil lasing. An optomechanical ring cavity is formed when one of the reflective mirrors is mounted on a mechanical vibrating beam. In this paper, we extend studies on the stability of linear optomechanical cavities to such ring cavities with two counter-propagating cavity modes, especially when the forward propagating pump mode is taken to its weak coupling limit. We find that when the atomic recoil is in action, stable states of the mechanical mode of the mirror converge into branch cuts, where the gain produced by the recoiling strikes balance with the multiple decay sources, such as cavity leakage in the optomechanical system. This balance is obtained when the propagation delay in the dispersive atomic medium matches in a periodic pattern to the frequencies and linewidths of the cavity mode and the collective bosonic mode of the atoms. We show an input-output hysteresis cycle between the atomic mode and the cavity mode to verify the multi-valuation of the stable states after branching at the weak coupling limit.

Design and fabrication of embedded micro-mirror inserts for out-of-plane coupling in PCB-level optical interconnections

NASA Astrophysics Data System (ADS)

Van Erps, Jurgen; Hendrickx, Nina; Bosman, Erwin; Van Daele, Peter; Debaes, Christof; Thienpont, Hugo

2010-05-01

Optical interconnections have gained interest over the last years, and several approaches have been presented for the integration of optics to the printed circuit board (PCB)-level. The use of a polymer optical waveguide layer appears to be the prevailing solution to route optical signals on the PCB. The most difficult issue is the efficient out-of-plane coupling of light between surface-normal optoelectronic devices (lasers and photodetectors) and PCB-integrated waveguides. The most common approach consists of using 45° reflecting micro-mirrors. The micro-mirror performance significantly affects the total insertion loss of the optical interconnect system, and hence has a crucial role on the system's bit error rate (BER) characteristics. Several technologies have been proposed for the fabrication of 45° reflector micro-mirrors directly into waveguides. Alternatively, it is possible to make use of discrete coupling components which have to be inserted into cavities formed in the PCB-integrated waveguides. In this paper, we present a hybrid approach where we try to combine the advantages of integrated and discrete coupling mirrors, i.e. low coupling loss and maintenance of the planararity of the top surface of the optical layer, allowing the lamination of additional layers or the mounting of optoelectronic devices. The micro-mirror inserts are designed through non-sequential ray tracing simulations, including a tolerance analysis, and subsequently prototyped with Deep Proton Writing (DPW). The DPW prototypes are compatible with mass fabrication at low cost in a wide variety of high-tech plastics. The DPW micro-mirror insert is metallized and inserted in a laser ablated cavity in the optical layer and in a next step covered with cladding material. Surface roughness measurements confirm the excellent quality of the mirror facet. An average mirror loss of 0.35-dB was measured in a receiver scheme, which is the most stringent configuration. Finally, the configuration is robust, since the mirror is embedded and thus protected from environmental contamination, like dust or moisture adsorption, which makes them interesting candidates for out-of-plane coupling in high-end boards.

Very short intracavity directional coupler for high-speed communication

NASA Astrophysics Data System (ADS)

Griffel, Giora

1993-07-01

We propose a novel intracavity modulator/switch that consists of a directional-coupler located inside a Fabry-Perot cavity. The back mirror of the cavity has a unit reflectivity so that both input and output signals are at the same side. In this way we obtain a two-port, single side element, with coupling length of 83.5 μm, which is the shortest modulation coupler proposed so far. The upper frequency limit due to photon lifetime is 275 GHz, which is well over the bandwidth constraints of microwave lumped structures. A unified approach for the analysis of this device and other similar structures is presented and discussed.

High efficiency laser spectrum conditioner

DOEpatents

Greiner, Norman R.

1980-01-01

A high efficiency laser spectrum conditioner for generating a collinear parallel output beam containing a predetermined set of frequencies from a multifrequency laser. A diffraction grating and spherical mirror are used in combination, to disperse the various frequencies of the input laser beam and direct these frequencies along various parallel lines spatially separated from one another to an apertured mask. Selection of the desired frequencies is accomplished by placement of apertures at locations on the mask where the desired frequencies intersect the mask. A recollimated parallel output beam with the desired set of frequencies is subsequently generated utilizing a mirror and grating matched and geometrically aligned in the same manner as the input grating and mirror.

Enhancement of slope efficiency and output power in GaN-based vertical-cavity surface-emitting lasers with a SiO2-buried lateral index guide

NASA Astrophysics Data System (ADS)

Kuramoto, Masaru; Kobayashi, Seiichiro; Akagi, Takanobu; Tazawa, Komei; Tanaka, Kazufumi; Saito, Tatsuma; Takeuchi, Tetsuya

2018-03-01

We have achieved a high output power of 6 mW from a 441 nm GaN-based vertical-cavity surface-emitting laser (VCSEL) under continuous wave (CW) operation, by reducing both the internal loss and the reflectivity of the front cavity mirror. A preliminary analysis of the internal loss revealed an enormously high transverse radiation loss in a conventional GaN-based VCSEL without lateral optical confinement (LOC). Introducing an LOC structure enhanced the slope efficiency by a factor of 4.7, with a further improvement to a factor of 6.7 upon reducing the front mirror reflectivity. The result was a slope efficiency of 0.87 W/A and an external differential quantum efficiency of 32% under pulsed operation. A flip-chip-bonded VCSEL also exhibited a high slope efficiency of 0.64 W/A and an external differential quantum efficiency of 23% for the front-side output under CW operation. The reflectivity of the cavity mirror was adjusted by varying the number of AlInN/GaN distributed Bragg reflector pairs from 46 to 42, corresponding to reflectivity values from 99.8% to 99.5%. These results demonstrate that a combination of internal loss reduction and cavity mirror control is a very effective way of obtaining a high output GaN-based VCSEL.

Direct-to-digital holography and holovision

DOEpatents

Thomas, Clarence E.; Baylor, Larry R.; Hanson, Gregory R.; Rasmussen, David A.; Voelkl, Edgar; Castracane, James; Simkulet, Michelle; Clow, Lawrence

2000-01-01

Systems and methods for direct-to-digital holography are described. An apparatus includes a laser; a beamsplitter optically coupled to the laser; a reference beam mirror optically coupled to the beamsplitter; an object optically coupled to the beamsplitter, a focusing lens optically coupled to both the reference beam mirror and the object; and a digital recorder optically coupled to the focusing lens. A reference beam is incident upon the reference beam mirror at a non-normal angle, and the reference beam and an object beam are focused by the focusing lens at a focal plane of the digital recorder to form an image. The systems and methods provide advantages in that computer assisted holographic measurements can be made.

Virtual mask digital electron beam lithography

DOEpatents

Baylor, L.R.; Thomas, C.E.; Voelkl, E.; Moore, J.A.; Simpson, M.L.; Paulus, M.J.

1999-04-06

Systems and methods for direct-to-digital holography are described. An apparatus includes a laser; a beamsplitter optically coupled to the laser; a reference beam mirror optically coupled to the beamsplitter; an object optically coupled to the beamsplitter, a focusing lens optically coupled to both the reference beam mirror and the object; and a digital recorder optically coupled to the focusing lens. A reference beam is incident upon the reference beam mirror at a non-normal angle, and the reference beam and an object beam are focused by the focusing lens at a focal plane of the digital recorder to form an image. The systems and methods provide advantages in that computer assisted holographic measurements can be made. 5 figs.

Virtual mask digital electron beam lithography

DOEpatents

Baylor, Larry R.; Thomas, Clarence E.; Voelkl, Edgar; Moore, James A.; Simpson, Michael L.; Paulus, Michael J.

1999-01-01

Systems and methods for direct-to-digital holography are described. An apparatus includes a laser; a beamsplitter optically coupled to the laser; a reference beam mirror optically coupled to the beamsplitter; an object optically coupled to the beamsplitter, a focusing lens optically coupled to both the reference beam mirror and the object; and a digital recorder optically coupled to the focusing lens. A reference beam is incident upon the reference beam mirror at a non-normal angle, and the reference beam and an object beam are focused by the focusing lens at a focal plane of the digital recorder to form an image. The systems and methods provide advantages in that computer assisted holographic measurements can be made.

High-Voltage-Input Level Translator Using Standard CMOS

NASA Technical Reports Server (NTRS)

Yager, Jeremy A.; Mojarradi, Mohammad M.; Vo, Tuan A.; Blalock, Benjamin J.

2011-01-01

proposed integrated circuit would translate (1) a pair of input signals having a low differential potential and a possibly high common-mode potential into (2) a pair of output signals having the same low differential potential and a low common-mode potential. As used here, "low" and "high" refer to potentials that are, respectively, below or above the nominal supply potential (3.3 V) at which standard complementary metal oxide/semiconductor (CMOS) integrated circuits are designed to operate. The input common-mode potential could lie between 0 and 10 V; the output common-mode potential would be 2 V. This translation would make it possible to process the pair of signals by use of standard 3.3-V CMOS analog and/or mixed-signal (analog and digital) circuitry on the same integrated-circuit chip. A schematic of the circuit is shown in the figure. Standard 3.3-V CMOS circuitry cannot withstand input potentials greater than about 4 V. However, there are many applications that involve low-differential-potential, high-common-mode-potential input signal pairs and in which standard 3.3-V CMOS circuitry, which is relatively inexpensive, would be the most appropriate circuitry for performing other functions on the integrated-circuit chip that handles the high-potential input signals. Thus, there is a need to combine high-voltage input circuitry with standard low-voltage CMOS circuitry on the same integrated-circuit chip. The proposed circuit would satisfy this need. In the proposed circuit, the input signals would be coupled into both a level-shifting pair and a common-mode-sensing pair of CMOS transistors. The output of the level-shifting pair would be fed as input to a differential pair of transistors. The resulting differential current output would pass through six standoff transistors to be mirrored into an output branch by four heterojunction bipolar transistors. The mirrored differential current would be converted back to potential by a pair of diode-connected transistors, which, by virtue of being identical to the input transistors, would reproduce the input differential potential at the output

940  mW 1564  nm multi-longitudinal-mode and 440  mW 1537  nm single-longitudinal-mode continuous-wave Er:Yb:Lu2Si2O7 microchip lasers.

PubMed

Huang, Jianhua; Chen, Yujin; Lin, Yanfu; Gong, Xinghong; Luo, Zundu; Huang, Yidong

2018-04-15

An Er:Yb:Lu 2 Si 2 O 7 microchip laser was constructed by placing a 1.2 mm thick, Y-cut Er:Yb:Lu 2 Si 2 O 7 microchip between two 1.2 mm thick sapphire crystals, in which input and output mirrors were directly deposited onto one face of each crystal. End-pumped by a continuous-wave 975.4 nm diode laser, a 1564 nm multi-longitudinal-mode laser with a maximum output power of 940 mW and slope efficiency of 20% was realized at an absorbed pump power of 5.5 W when the transmission of output mirror was 2.2%. When the transmission of the output mirror was increased to 6%, a 1537 nm single-longitudinal-mode laser with a maximum output power of 440 mW and slope efficiency of 12% was realized at an absorbed pump power of 4.3 W. The results indicate that the Er:Yb:Lu 2 Si 2 O 7 crystal is a promising microchip gain medium to realize a single-longitudinal-mode laser.

Miniature Tunable Laser Spectrometer for Detection of a Trace Gas

NASA Technical Reports Server (NTRS)

Christensen, Lance E. (Inventor)

2017-01-01

An open-path laser spectrometer (OPLS) for measuring a concentration of a trace gas, the OPLS including an open-path multi-pass analysis region including a first mirror, a second mirror at a distance and orientation from the first mirror, and a support structure for locating the mirrors, a laser coupled to the analysis region and configured to emit light of a wavelength range and to enable a plurality of reflections of the emitted light between the mirrors, a detector coupled to the analysis region and configured to detect a portion of the emitted light impinging on the detector and to generate a corresponding signal, and an electronic system coupled to the laser and the detector, and configured to adjust the wavelength range of the emitted light from the laser based on the generated signal, and to measure the concentration of the trace gas based on the generated signal.

Analysis of a single ring resonator with 2×2 90-degree multimode waveguide turning couplers

NASA Astrophysics Data System (ADS)

Chiu, C. L.; Liao, Yen-Hsun

2016-02-01

A novel design of a single ring resonator with two low-loss 2×2 90-degree multimode waveguide turning mirror couplers based on a InP structure. The coupling factor of the 2×2 90-degree multimode waveguide turning mirror coupler is inversed for K=0.85 to K=0.15 when one folding is achieved. The 2×2 90-degree turning mirror coupler for K=0.15 is (3/4)Lπ in length. Its length is reduced 3 times than the conventional straight 2×2 multimode waveguide interference coupler (9/4)Lπ in length for K=0.15. The cavity length of the curve waveguide (90-degree arc length) in this ring resonator with two 2×2 90-degree multimode waveguide turning couplers is decreased 1/2 times than with two 2×2 MMI couplers (180-degree arc length). The free spectral range (FSR) is increased 2 times. The output spectral response gets a FSR of 82 GHz for the device and a contrast of 4 dB and FWHM of 0.24 nm for the drop port. The results of numerical analysis calculated by the transfer functions in a single ring resonator are agreement with the experimental results.

Single laser pulse compression via strongly coupled stimulated Brillouin scattering in plasma

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

Peng, H.; Wu, Z. H.; Zhang, Z. M.

2016-07-15

Laser amplification in plasma, including stimulated Raman scattering amplification and strongly coupled stimulated Brillouin scattering (sc-SBS) amplification, is very promising to generate ultrahigh-power and ultrashort laser pulses. But both are quite complex in experiments: at least three different laser pulses must be prepared; temporal delay and spatial overlap of these three pulses are difficult. We propose a single pulse compression scheme based on sc-SBS in plasma. Only one moderately long laser is applied, the front part of which ionizes the gas to produced plasma, and gets reflected by a plasma mirror at the end of the gas channel. The reflectedmore » front quickly depletes the remaining part of the laser by sc-SBS in the self-similar regime. The output laser is much stronger and shorter. This scheme is at first considered theoretically, then validated by using 1D PIC simulations.« less

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

Read, Michael; Ives, Robert Lawrence; Marsden, David

The Phase II program developed an internal RF coupler that transforms the whispering gallery RF mode produced in gyrotron cavities to an HE11 waveguide mode propagating in corrugated waveguide. This power is extracted from the vacuum using a broadband, chemical vapor deposited (CVD) diamond, Brewster angle window capable of transmitting more than 1.5 MW CW of RF power over a broad range of frequencies. This coupling system eliminates the Mirror Optical Units now required to externally couple Gaussian output power into corrugated waveguide, significantly reducing system cost and increasing efficiency. The program simulated the performance using a broad range ofmore » advanced computer codes to optimize the design. Both a direct coupler and Brewster angle window were built and tested at low and high power. Test results confirmed the performance of both devices and demonstrated they are capable of achieving the required performance for scientific, defense, industrial, and medical applications.« less

Spectroscopy and lasing of Tm:SrMoO4 crystal near 1.5, 1.9, and 2.3-μm under 793-nm excitation

NASA Astrophysics Data System (ADS)

Šulc, Jan; Švejkar, Richard; Němec, Michal; Doroshenko, Maxim E.; Jelínková, Helena; Ivleva, Liudmila I.; Dunaeva, Elizaveta E.

2018-02-01

The spectroscopy properties and lasing of diode pumped Tm-doped strontium molybdate SrMoO4 single crystal were investigated at room temperature. The Tm:SrMoO4 crystal was grown by modified Stepanov method (2 wt.% of TmNbO4 in the melt). The tested Tm:SrMoO4 sample was cut from the grown crystal boule perpendicularly to growth direction 100. For spectroscopy and laser experiments 4.2mm thick plane-parallel face-polished plate (without AR coatings) was used. A fiber-coupled laser diode operating at wavelength 793nm was used for longitudinal Tm:SrMoO4 pumping which corresponds to 3H4 level excitation. Fluorescence spectra measurement showed strong emission in vicinity of 1.8 μm (3F4 -> 3H6 transition), and also significant emission close to wavelengths 1.45 μm (3H4 -> 3F4 transition) and 2.3 μm (3H4 -> 3H5 transition). The lasing was successfully reached for all these three transitions and output characteristics were measured. The pumping laser diode was operating in the pulsed regime with a low duty cycle. The 145mm long semi-hemispherical laser resonator consisted of flat pumping mirror (HT @ 0.79 μm) and curved (r = 150mm) output coupler. For each lasing transition the particular set of resonator mirrors was used to reach high reflexivity of pumping mirror and output coupler transmission 0.5% at laser operation wavelength. The obtained laser emission wavelengths were 1.95 μm, 1.45 & 1.49 μm, and 2.30 μm. In spite of low laser slope efficiency in respect to absorbed pumping power (0.45% for 3H4 -> 3F4 transition, 0.50% for 3F4 -> 3H6 transition and 0.83% for 3H4 -> 3H5 transition), results obtained are promising for further development of diode-pumped laser at 2.3 μm spectral region.

Maritime Adaptive Optics Beam Control

DTIC Science & Technology

2010-09-01

Liquid Crystal LMS Least Mean Square MIMO Multiple- Input Multiple-Output MMDM Micromachined Membrane Deformable Mirror MSE Mean Square Error...determine how the beam is distorted, a control computer to calculate the correction to be applied, and a corrective element, usually a deformable mirror ...during this research, an overview of the system modification is provided here. Using additional mirrors and reflecting the beam to and from an

The 100 cm solar telescope primary mirror study

NASA Technical Reports Server (NTRS)

1975-01-01

The manufacturing impact of primary mirror configuration on the performance of a 100 cm aperture solar telescope was studied. Three primary mirror configurations were considered: solid, standard lightweight, and mushroom. All of these are of low expansion material. Specifically, the study consisted of evaluating the mirrors with regard to: manufacturing metrology, manufacturing risk factors and ultimate quality assessment. As a result of this evaluation, a performance comparison of the configurations was made, and a recommendation of mirror configuration is the final output. These evaluations, comparisons and recommendations are discussed in detail. Other investigations were completed and are documented in the appendices.

Single mode terahertz quantum cascade amplifier

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

Ren, Y., E-mail: yr235@cam.ac.uk; Wallis, R.; Shah, Y. D.

2014-10-06

A terahertz (THz) optical amplifier based on a 2.9 THz quantum cascade laser (QCL) structure has been demonstrated. By depositing an antireflective coating on the QCL facet, the laser mirror losses are enhanced to fully suppress the lasing action, creating a THz quantum cascade (QC) amplifier. Terahertz radiation amplification has been obtained, by coupling a separate multi-mode THz QCL of the same active region design to the QC amplifier. A bare cavity gain is achieved and shows excellent agreement with the lasing spectrum from the original QCL without the antireflective coating. Furthermore, a maximum optical gain of ∼30 dB with single-modemore » radiation output is demonstrated.« less

Life problems of dc and RF-excited low-power CW CO2 waveguide lasers

NASA Technical Reports Server (NTRS)

Hochuli, U. E.; Haldemann, P. R.

1986-01-01

A number of different, RF-excited 3-W CW CO2 waveguide lasers have been built. Four of these lasers, after continuously working for 15,000-30,000 h, still yield about 70 percent of their original power output. The design variations cover N2and CO-bearing gas mixtures, as well as internal- and external-capacitively coupled excitation electrodes. A similar laser survived 50,000 5-min-ON/5-min-OFF cycles without significant mirror damage. It was not possible to find suitable cold cathodes that allow the building of longitudinally dc-excited CW CO2 waveguide lasers that work for such extended periods of time.

Production of ELZM mirrors: performance coupled with attractive schedule, cost, and risk factors

NASA Astrophysics Data System (ADS)

Leys, Antoine; Hull, Tony; Westerhoff, Thomas

2016-08-01

Extreme light weighted ZERODUR Mirrors (ELZM) have been developed to exploit the superb thermal characteristics of ZERODUR. Coupled with up to date mechanical and optical fabrication methods this becomes an attractive technical approach. However the process of making mirror substrates has demonstrated to be unusually rapid and especially cost-effective. ELZM is aimed at the knee of the cost as a function of light weighting curve. ELZM mirrors are available at 88% light weighted. Together with their low risk, low cost production methods, this is presented as a strong option for NASA Explorer and Probe class missions.

Laser Gyro Attitude Control System Feasibility Study.

DTIC Science & Technology

1987-04-24

GYROS (Distinguishable by method used to circumvent lock-in phenomenon) M ECHANICAL DITHER ,. MAGNETIC MIRROR DILAG (MULTI-OSCILLATOR) Figure 1...by a multiple transit of a light beam within a closed optical cavity (a three- mirror system). The beam traverses the cavity continuously; after each...circulation a small fraction of the beam intensity is output at one of the mirrors . Each transit incurs a phase % %0 ? % o I" us ol *..~% % %~*,~*)*f

A perfect spin filtering device through Mach-Zehnder interferometry in a GaAs/AlGaAs electron gas

NASA Astrophysics Data System (ADS)

López, Alexander; Medina, Ernesto; Bolívar, Nelson; Berche, Bertrand

2010-03-01

A spin filtering device based on quantum spin interference is addressed, for use with a two-dimensional GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit (SO) couplings and an applied external magnetic field. We propose an experimentally feasible electronic Mach-Zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions. We find two broad spin filtering regimes: one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non-Abelian nature of the spin rotations; and another where one needs a tilted preferential axis in order to observe the polarized output spinor. Both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. Including a full account of the beam splitter and mirror effects on spin yields solutions only for the tilted basis, but encompasses a broad range of filtering conditions.

A perfect spin filtering device through Mach-Zehnder interferometry in a GaAs/AlGaAs electron gas.

PubMed

López, Alexander; Medina, Ernesto; Bolívar, Nelson; Berche, Bertrand

2010-03-24

A spin filtering device based on quantum spin interference is addressed, for use with a two-dimensional GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit (SO) couplings and an applied external magnetic field. We propose an experimentally feasible electronic Mach-Zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions. We find two broad spin filtering regimes: one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non-Abelian nature of the spin rotations; and another where one needs a tilted preferential axis in order to observe the polarized output spinor. Both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. Including a full account of the beam splitter and mirror effects on spin yields solutions only for the tilted basis, but encompasses a broad range of filtering conditions.

Cavity-induced mirror-mirror entanglement in a single-atom Raman laser

NASA Astrophysics Data System (ADS)

Teklu, Berihu; Byrnes, Tim; Khan, Faisal Shah

2018-02-01

We address an experimental scheme to analyze the optical bistability and the entanglement of two movable mirrors coupled to a two-mode laser inside a doubly resonant cavity. With this aim we investigate the master equations of the atom-cavity subsystem in conjunction with the quantum Langevin equations that describe the interaction of the mirror cavity. The parametric amplification-type coupling induced by the two-photon coherence on the optical bistability of the intracavity mean photon numbers is found and investigated. Under this condition, the optical intensities exhibit bistability for all large values of cavity laser detuning. We also provide numerical evidence for the generation of strong entanglement between the movable mirrors and show that it is robust against environmental thermalization.

A 15kWe (nominal) solar thermal electric power conversion concept definition study: Steam Rankine reheat reciprocator system

NASA Technical Reports Server (NTRS)

Fuller, H.; Demler, R.; Poulin, E.; Dantowitz, P.

1979-01-01

An evaluation was made of the potential of a steam Rankine reheat reciprocator engine to operate at high efficiency in a point-focusing distributed receiver solar thermal-electric power system. The scope of the study included the engine system and electric generator; not included was the solar collector/mirror or the steam generator/receiver. A parametric analysis of steam conditions was completed leading to the selection of 973 K 12.1 MPa as the steam temperature/pressure for a conceptual design. A conceptual design was completed for a two cylinder/ opposed engine operating at 1800 rpm directly coupled to a commercially available induction generator. A unique part of the expander design is the use of carbon/graphite piston rings to eliminate the need for using oil as an upper cylinder lubricant. The evaluation included a system weight estimate of 230 kg at the mirror focal point with the condenser mounted separately on the ground. The estimated cost of the overall system is $1932 or $90/kW for the maximum 26 kW output.

The wavelength-tunable tapered surface plasmon resonance fiber sensor based on separated input-output channels

NASA Astrophysics Data System (ADS)

Chen, Shimeng; Liu, Yun; Gao, Xiaotong; Liu, Xiuxin; Peng, Wei

2014-11-01

We present a wavelength-tunable tapered optics fiber surface Plasmon resonance (SPR) sensor by polishing the end faces of multimode fibers(MMF).Two hard plastic clad optical fibers joint closely and are used as the light input and output channels. Their end faces are polished to produce two oblique planes, which are coated with gold film to be the sensing surface and the front mirror. The presence of the tapered geometry formed by the two oblique planes in the orthogonal directions makes it possible to adjust incident angle through changing the tilt angles of the two end faces, so as to achieve tuning the SPR coupling wavelength-angle pair. Compared with previous researches based a tapered optic fiber probe, we report the approach theoretically increase the signal noise ratio (SNR) by separating incident and emergent light propagating in the different coordinate fiber. Since fabricating the sensing surface and the front mirror on the two fibers to replace one single fiber tip, there is more incident light can reach the sensing surface and satisfy SPR effective. In addition, this improvement in structure has advantages of large grinding and sensing area, which can lead to high sensitivity and simple manufacture process of the sensor. Experimental measurement demonstrates the sensor has a favorable SPR resonanceabsorption and the ability of measuring refractive index (RI) of aqueous solution. This novel tapered SPR sensor has the potential to be applied to the biological sensing field.

Efficient excitations of radially and azimuthally polarized Nd3+:YAG ceramic microchip laser by use of subwavelength multilayer concentric gratings composed of Nb2O5/SiO2.

PubMed

Li, Jian-Lang; Ueda, Ken-ichi; Zhong, Lan-xiang; Musha, Mitsuru; Shirakawa, Akira; Sato, Takashi

2008-07-07

Cylindrical vector beams were produced from laser diode end-pumped Nd:YAG ceramic microchip laser by use of two types of subwavelength multilayer gratings as the axisymmetric-polarization output couplers respectively. The grating mirrors are composed of high- and low-refractive- index (Nb(2)O(5)/SiO(2)) layers alternately while each layer is shaped into triangle and concentric corrugations. For radially polarized laser output, the beam power reached 610mW with a polarization extinction ratio (PER) of 61:1 and a slope efficiency of 68.2%; for azimuthally polarized laser output, the beam power reached 626mW with a PER of 58:1 and a slope efficiency of 47.6%. In both cases, the laser beams had near-diffraction limited quality. Small differences of beam power, PER and slope efficiency between radially and azimuthally polarized laser outputs were not critical, and could be minimized by further optimized adjustment to laser cavity and the reflectances of respective grating mirrors. The results manifested, by use of the photonic crystal gratings mirrors and end-pumped microchip laser configuration, CVBs can be generated efficiently with high modal symmetry and polarization purity.

Latest Progress in High Power VECSELs

DTIC Science & Technology

2013-01-01

are more efficient, and can be tailored to an application. In this manuscript we lay out some advantages to VECSELs as compared to many in-plane...semiconductor lasers. We review common fabrication and packaging techniques in Section 2. In Section 3, we discuss both small- signal and large-signal... out LR coating MQW DBR VECSEL chip Heat Spreader output coupler HR flat mirror BF at Brewster’s angle HR flat mirror HR curved mirror signal beam out

Experimental results of the 140 GHz, 1 MW long-pulse gyrotron for W7-X

NASA Astrophysics Data System (ADS)

Koppenburg, K.; Arnold, A.; Borie, E.; Dammertz, G.; Giguet, E.; Heidinger, R.; Illy, S.; Kuntze, M.; Le Cloarec, G.; Legrand, F.; Leonhardt, W.; Lievin, C.; Neffe, G.; Piosczyk, B.; Schmid, M.; Thumm, M.

2003-02-01

Gyrotrons at high frequency with high output power are mainly developed for microwave heating and current drive in plasmas for thermonuclear fusion. For the stellarator Wendelstein 7-X now under construction at IPP Greifswald, Germany, a 10 MW ECRH system is foreseen. A 1 MW, 140 GHz long-pulse gyrotron has been designed and a pre-prototype (Maquette) has been constructed and tested in an European collaboration between FZK Karlsruhe, CRPP Lausanne, IPF Suttgart, IPP Greifswald, CEA Cadarache and TED Vélizy [1]. The cylindrical cavity is designed for operating in the TE28,8 mode. It is a standard tapered cavity with linear input downtaper and a non-linear uptaper. The diameter of the cylindrical part is 40.96 mm. The transitions between tapers and straight section are smoothly rounded to avoid mode conversion. The TE28,8-cavity mode is transformed to a Gaussian TEM0,0 output mode by a mode converter consisting of a rippled-wall waveguide launcher followed by a three mirror system. The output window uses a single, edge cooled CVD-diamond disk with an outer diameter of 106 mm, a window aperture of 88 mm and a thickness of 1.8 mm corresponding to four half wavelengths. The collector is at ground potential, and a depression voltage for energy recovery can be applied to the cavity and to the first two mirrors. Additional normal-conducting coils are employed to the collector in order to produce an axial magnetic field for sweeping the electron beam with a frequency of 7 Hz. A temperature limited magnetron injection gun without intermediate anode ( diode type ) is used. In short pulse operation at the design current of 40 A an output power of 1 MW could be achieved for an accelerating voltage of 82 kV without depression voltage and with a depression voltage of 25 kV an output power of 1.15 MW at an accelerating voltage of 84 kV has been measured. For these values an efficiency of 49% was obtained. At constant accelerating voltages, the output power did not change up to depression voltages of 33 kV. The output beam of the gyrotron is injected into an RF-tight microwave chamber which is equipped with two water-cooled mirrors directing the beam towards the 1 MW water load. The second mirror inside the microwave chamber contains a directional output coupler formed by a row of holes in the mirror surface. A diode detector is connected to the directional coupler and the forward power can be determined once the signal has been calibrated. This was performed by calorimetric measurement of the RF wave in short-pulse measurements. The mode purity of the Gaussian beam was measured by an IR camera and a thin dielectric target plate placed at different positions across the RF beam. The measured beam distribution agrees very well with the theoretical predictions. After some problems with the RF load, long-pulse operation was performed: The power measurements were done by the signal of the diode detector placed at the second mirror. The measured output power of the calorimetric RF-load normally shows values reduced by about 20%. Output powers of 1 MW could be achieved for 10 s, and an energy as high as 90 MJ per pulse has been produced with an output power of 0.64 MW. The pulse lengths were mainly determined by the preset values, and due to lack of experimental time no attempt was made to increase the pulse length. Only for a 100 s pulse with 0.74 MW output power, a limitation was found due to a pressure increase beyond about 10-7mbar. The gyrotron was sent back to the manufacturer Thales Electron Devices for a visual inspection, and an improved prototype was built and delivered to Forschungszentrum Karlsruhe in the middle of April 2002.

Unraveling mirror properties in time-delayed quantum feedback scenarios

NASA Astrophysics Data System (ADS)

Faulstich, Fabian M.; Kraft, Manuel; Carmele, Alexander

2018-06-01

We derive in the Heisenberg picture a widely used phenomenological coupling element to treat feedback effects in quantum optical platforms. Our derivation is based on a microscopic Hamiltonian, which describes the mirror-emitter dynamics based on a dielectric, a mediating fully quantized electromagnetic field and a single two-level system in front of the dielectric. The dielectric is modelled as a system of identical two-state atoms. The Heisenberg equation yields a system of describing differential operator equations, which we solve in the Weisskopf-Wigner limit. Due to a finite round-trip time between emitter and dielectric, we yield delay differential operator equations. Our derivation motivates and justifies the typical phenomenologicalassumed coupling element and allows, furthermore, a generalization to a variety of mirrors, such as dissipative mirrors or mirrors with gain dynamics.

Decreased oscillation threshold of a continuous-wave OPO using a semiconductor gain mirror.

PubMed

Siltanen, Mikael; Leinonen, Tomi; Halonen, Lauri

2011-09-26

We have constructed a singly resonant, continuous-wave optical parametric oscillator, where the signal beam resonates and is amplified by a semiconductor gain mirror. The gain mirror can significantly decrease the oscillation threshold compared to an identical system with conventional mirrors. The largest idler beam tuning range reached by changing the pump laser wavelength alone is from 3.6 to 4.7 µm. The single mode output power is limited but can be continuously scanned for at least 220 GHz by adding optical components in the oscillator cavity for increased stability. © 2011 Optical Society of America

Study on Dynamic Alignment Technology of COIL Resonator

NASA Astrophysics Data System (ADS)

Xiong, M. D.; Zou, X. J.; Guo, J. H.; Jia, S. N.; Zhang2, Z. B.

2006-10-01

The performance of great power chemical oxygen-iodine laser (COIL) beam is decided mostly by resonator mirror maladjustment and environment vibration. To improve the performance of light beam, an auto-alignment device is used in COIL resonator, the device can keep COIL resonator collimating by adjusting the optical components of resonator. So the coupling model of COIL resonator is present. The multivariable self study fuzzy uncoupling arithmetic and six-dimensional micro drive technology are used to design a six-input-three-output uncoupling controller, resulting in the realization of the high precision dynamic alignment. The experiments indicate that the collimating range of this system is 8 mrad, precision is 5 urad and frequency response is 20Hz, which meet the demand of resonator alignment system.

Optical apparatus for conversion of whispering-gallery modes into a free space gaussian like beam

DOEpatents

Stallard, B.W.; Makowski, M.A.; Byers, J.A.

1992-05-19

An optical converter for efficient conversion of millimeter wavelength whispering-gallery gyrotron output into a linearly polarized, free-space Gaussian-like beam is described. The converter uses a mode-converting taper and three mirror optics. The first mirror has an azimuthal tilt to eliminate the k[sub [phi

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Fabry—Perot interferometer with resonant mirrors

NASA Astrophysics Data System (ADS)

Troitskii, Yu V.

1995-06-01

An analysis is made of the task of construction of an interferometer with an output signal weakly dependent on the frequency of the incident light and yet highly sensitive to a change in the distance between the mirrors. This can be achieved by the use of resonant dielectric mirrors with the reflection phase and amplitude strongly dependent on the frequency within the width of the response function of the interferometer. The interferometer can be reduced to a four-mirror configuration in the case of the proposed types of mirrors. The relevant expressions are derived for this configuration. It is shown that the distance between the mirrors can be considerably greater than has been assumed earlier. A system of parameters is introduced and specific examples are considered.

Rapid-Scanning Fourier Transform Spectrometer for Studies of Propagation of Near-Millimeter-Wave Radiation through Clear Air and Fog.

DTIC Science & Technology

1988-03-01

parallel in the output beam . ’ , However, as will be seen, this function can be performed by auxiliary, non -moving mirrors. Our . design for a rapid... splitter used in our design is shown in Fig. 2. The mirror drive is somewhat novel for this type of interferometer in that one mirror in each beam . M3...features: * High interferometric efficiency, due to the Martin-Puplett type design 0 Ruggedness in photolithographically produced beam splitters

Development of optically pumped DBR-free semiconductor disk lasers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

2017-03-01

Semiconductor disk lasers (SDLs) are attractive for applications requiring good beam quality, wavelength versatility, and high output powers. Typical SDLs utilize the active mirror geometry, where a semiconductor DBR is integrated with the active region by growth or post-growth bonding. This imposes restrictions for the SDL design, like material system choice, thermal management, and effective gain bandwidth. In DBR-free geometry, these restrictions can be alleviated. An integrated gain model predicts DBR-free geometry with twice the gain bandwidth of typical SDLs, which has been experimentally verified with active regions near 1 μm and 1.15 μm. The lift-off and bonding technique enables the integration of semiconductor active regions with arbitrary high quality substrates, allowing novel monolithic geometries. Bonding an active region onto a straight side of a commercial fused silica right angle prism, and attaching a high reflectivity mirror onto the hypotenuse side, with quasi CW pumping at 780 nm, lasing operation was achieved at 1037 nm with 0.2 mW average power at 1.6 mW average pump power. Laser dynamics show that thermal lens generation in the active region bottlenecks the laser efficiency. Investigations on total internal reflection based monolithic ring cavities are ongoing. These geometries would allow the intracavity integration of 2D materials or other passive absorbers, which could be relevant for stable mode locking. Unlike typical monolithic microchip SDLs, with the evanescent wave coupling technique, these monolithic geometries allow variable coupling efficiency.

Social context rather than behavioral output or winning modulates post-conflict testosterone responses in Japanese quail (Coturnix japonica).

PubMed

Hirschenhauser, K; Wittek, M; Johnston, P; Möstl, E

2008-10-20

Testosterone regulates the expression of sexual and aggressive behavior in male vertebrates and treatments with testosterone may promote territorial aggression and winning in dyadic contests. Conversely, individual testosterone levels respond to sexual or aggressive interactions and the social environment. Post-conflict testosterone in winner males though appears to be more complex than simply reflecting conflict outcome. Expression and degree of post-conflict testosterone responses may adapt to additional modulators such as repeated winning experience, audience presence, opponent's fighting ability, and self-assessment. We present simulated intrusion experiments with male Japanese quail using mirror-elicited aggression and fights with real opponents ('direct challenge'). We recorded agonistic behavior and measured immunoreactive testosterone metabolites (TM) non-invasively from individual droppings. Frequencies of initiated agonistic behavior were similar whether towards the mirror or in direct challenge tests, although some of the males were behaviorally non-responsive to the mirror ('mirror submissives'). However, there was no TM response to the mirror test in both, mirror fighters and mirror submissives, thus independently of behavioral output. After direct challenges TM levels were elevated in all males (focal males winning or conflict unresolved after 30 min), hence independently of conflict outcome. Thus, in male quail a combination of physical stimuli and the individual perception of own and opponent's fighting ability explained the expression of post-conflict TM responses rather than behavioral performance, conflict outcome, or any of these factors alone. In sum, our results emphasize that the degree of androgen responsiveness to agonistic behavior is fine-tuned by components related with social context and environment.

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

PubMed

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

2012-10-08

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

Wave excitation by nonlinear coupling among shear Alfvén waves in a mirror-confined plasma

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

Ikezoe, R., E-mail: ikezoe@prc.tsukuba.ac.jp; Ichimura, M.; Okada, T.

2015-09-15

A shear Alfvén wave at slightly below the ion-cyclotron frequency overcomes the ion-cyclotron damping and grows because of the strong anisotropy of the ion temperature in the magnetic mirror configuration, and is called the Alfvén ion-cyclotron (AIC) wave. Density fluctuations caused by the AIC waves and the ion-cyclotron range of frequencies (ICRF) waves used for ion heating have been detected using a reflectometer in a wide radial region of the GAMMA 10 tandem mirror plasma. Various wave-wave couplings are clearly observed in the density fluctuations in the interior of the plasma, but these couplings are not so clear in themore » magnetic fluctuations at the plasma edge when measured using a pick-up coil. A radial dependence of the nonlinearity is found, particularly in waves with the difference frequencies of the AIC waves; bispectral analysis shows that such wave-wave coupling is significant near the core, but is not so evident at the periphery. In contrast, nonlinear coupling with the low-frequency background turbulence is quite distinct at the periphery. Nonlinear coupling associated with the AIC waves may play a significant role in the beta- and anisotropy-limits of a mirror-confined plasma through decay of the ICRF heating power and degradation of the plasma confinement by nonlinearly generated waves.« less

Enhancement of the beam quality of non-uniform output slab laser amplifier with a 39-actuator rectangular piezoelectric deformable mirror.

PubMed

Yang, Ping; Ning, Yu; Lei, Xiang; Xu, Bing; Li, Xinyang; Dong, Lizhi; Yan, Hu; Liu, Wenjing; Jiang, Wenhan; Liu, Lei; Wang, Chao; Liang, Xingbo; Tang, Xiaojun

2010-03-29

We present a slab laser amplifier beam cleanup experimental system based on a 39-actuator rectangular piezoelectric deformable mirror. Rather than use a wave-front sensor to measure distortions in the wave-front and then apply a conjugation wave-front for compensating them, the system uses a Stochastic Parallel Gradient Descent algorithm to maximize the power contained within a far-field designated bucket. Experimental results demonstrate that at the output power of 335W, more than 30% energy concentrates in the 1x diffraction-limited area while the beam quality is enhanced greatly.

Microscopic theory of Dzyaloshinsky-Moriya interaction in pyrochlore oxides with spin-orbit coupling

NASA Astrophysics Data System (ADS)

Arakawa, Naoya

2016-10-01

Pyrochlore oxides show several fascinating phenomena, such as the formation of heavy fermions and the thermal Hall effect. Although a key to understanding some phenomena may be the Dzyaloshinsky-Moriya (DM) interaction, its microscopic origin is unclear. To clarify the microscopic origin, we constructed a t2 g-orbital model with the kinetic energy, the trigonal-distortion potential, the multiorbital Hubbard interactions, and the L S coupling, and derived the low-energy effective Hamiltonian for a d1 Mott insulator with the weak L S coupling. We first show that lack of the inversion center of each nearest-neighbor V-V bond causes the odd-mirror interorbital hopping integrals. Those are qualitatively different from the even-mirror hopping integrals, existing even with the inversion center. We next show that the second-order perturbation using the kinetic terms leads to the ferromagnetic and the antiferromagnetic superexchange interactions, whose competition is controllable by tuning the Hubbard interactions. Then, we show the most important result: the third-order perturbation terms using the combination of the even-mirror hopping integral, the odd-mirror hopping integral, and the L S coupling causes the DM interaction due to the mirror-mixing effect, where those hopping integrals are necessary to obtain the antisymmetric kinetic exchange and the L S coupling is necessary to excite the orbital angular momentum at one of two sites. We also show that the magnitude and sign of the DM interaction can be controlled by changing the positions of the O ions and the strength of the Hubbard interactions. We discuss the advantages in comparison with the phenomenological theory and Moriya's microscopic theory, applicability of our mechanism, and the similarities and differences between our case and the strong-L S -coupling case.

One-way acoustic mirror based on anisotropic zero-index media

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

Gu, Zhong-ming; Liang, Bin, E-mail: liangbin@nju.edu.cn, E-mail: jccheng@nju.edu.cn; Yang, Jing

2015-11-23

We have designed a one-way acoustic mirror comprising anisotropic zero-index media. For acoustic beam incident at a particular angle, the designed structure behaves like a high-efficient mirror that redirects almost all the incident energy into another direction predicted by the Snell's law, while becoming virtually transparent to beams propagating reversely along this output path. Furthermore, the mirror can be tailored to work at arbitrary incident angle by simply adjusting its geometry. Our design, with undirectional reflection functionality and flexible working angle, may offer possibilities in space isolations and have deep implication in various scenarios like ultrasound imaging or noise control.

Robust entanglement between a movable mirror and atomic ensemble and entanglement transfer in coupled optomechanical system

PubMed Central

Bai, Cheng-Hua; Wang, Dong-Yang; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

2016-01-01

We propose a scheme for the creation of robust entanglement between a movable mirror and atomic ensemble at the macroscopic level in coupled optomechanical system. We numerically simulate the degree of entanglement of the bipartite macroscopic entanglement and show that it depends on the coupling strength between the cavities and is robust with respect to the certain environment temperature. Inspiringly and surprisingly, according to the reported relation between the mechanical damping rate and the mechanical frequency of the movable mirror, the numerical simulation result shows that such bipartite macroscopic entanglement persists for environment temperature up to 170 K, which breaks the liquid nitrogen cooling and liquid helium cooling and largely lowers down the experiment cost. We also investigate the entanglement transfer based on this coupled system. The scheme can be used for the realization of quantum memories for continuous variable quantum information processing and quantum-limited displacement measurements. PMID:27624534

Er:YAG laser technology for remote sensing applications

NASA Astrophysics Data System (ADS)

Chen, Moran; Burns, Patrick M.; Litvinovitch, Viatcheslav; Storm, Mark; Sawruk, Nicholas W.

2016-10-01

Fibertek has developed an injection locked, resonantly pumped Er:YAG solid-state laser operating at 1.6 μm capable of pulse repetition rates of 1 kHz to 10 kHz for airborne methane and water differential absorption lidars. The laser is resonantly pumped with a fiber-coupled 1532 nm diode laser minimizing the quantum defect and thermal loading generating tunable single-frequency output of 1645-1646 nm with a linewidth of < 100 MHz. The frequency-doubled 1.6 μm Er:YAG laser emits wavelengths in the 822-823 nm spectrum, coincident with water vapor lines. Various cavity designs were studied and optimized for compactness and performance, with the optimal design being an injection seeded and locked five-mirror ring cavity. The laser generated 4 W of average power at pulse repetition frequencies (PRFs) of 1 kHz and 10 kHz, corresponding to 4 mJ and 400 μJ pulse energies, respectively. The 1645 nm was subsequently frequency doubled to 822.5 nm with a 600 pm tuning range covering multiple water absorption lines, with a pulse energy of 1 mJ and a pulse repetition frequency of 1 kHz. The resonator cavity was locked to the seed wavelength via a Pound Drever Hall (PDH) technique and an analog Proportional Integral Derivative (PID) Controller driving a high-bandwidth piezoelectric (PZT)-mounted cavity mirror. Two seed sources lasing on and off the methane absorption line were optically switched to tune the resonator wavelength on and off the methane absorption line between each sequential output pulse. The cavity locking servo maintained the cavity resonance for each pulse.

Scattering (stochastic) recoupling of a coupled ten-stripe AlGaAs-GaAs-InGaAs quantum-well heterostructure laser

NASA Astrophysics Data System (ADS)

Kellogg, D. A.; Holonyak, N.

2001-04-01

Data are presented on coupled ten-stripe AlGaAs-GaAs-InGaAs quantum well heterostructure (QWH) lasers recoupled stochastically at the cleaved end mirrors. Recoupling of neighboring elements of a ten-stripe laser is accomplished by the scattering (random feedback) afforded by applying ˜10-μm-diam Al powder or 0.3 μm α-Al2O3 polishing compound in microscopy immersion oil or in epoxy at the cleaved ends (mirrors). Data on QWH samples with the end mirrors coated with the scatterer (Al or Al2O3 powder in "liquid") exhibit spectral and far-field broadening, as well as increased laser threshold because of the reduced cavity Q. Single mode operation is possible with the conventional evanescent wave coupling of the ten-stripe QWH and is destroyed, even the laser operation itself, with the scattering recoupling (dephasing) at the end mirrors, which is reversible (removable). The narrow ten-stripe QWH laser with strong end-mirror scattering, a long amplifier with random feedback, indicates that a photopumped III-V or II-VI powder (a random "wall" cavity) has little or no merit.

A new model of sensorimotor coupling in the development of speech.

PubMed

Westermann, Gert; Reck Miranda, Eduardo

2004-05-01

We present a computational model that learns a coupling between motor parameters and their sensory consequences in vocal production during a babbling phase. Based on the coupling, preferred motor parameters and prototypically perceived sounds develop concurrently. Exposure to an ambient language modifies perception to coincide with the sounds from the language. The model develops motor mirror neurons that are active when an external sound is perceived. An extension to visual mirror neurons for oral gestures is suggested.

Limits on amplification by Aharonov-Albert-Vaidman weak measurement

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

Koike, Tatsuhiko; Tanaka, Saki

2011-12-15

We analyze the amplification by the Aharonov-Albert-Vaidman weak quantum measurement on a Sagnac interferometer [Dixon et al., Phys. Rev. Lett. 102, 173601 (2009)] up to all orders of the coupling strength between the measured system and the measuring device. The amplifier transforms a small tilt of a mirror into a large transverse displacement of the laser beam. The conventional analysis has shown that the measured value is proportional to the weak value, so that the amplification can be made arbitrarily large in the cost of decreasing output laser intensity. It is shown that the measured displacement and the amplification factormore » are in fact not proportional to the weak value and rather vanish in the limit of infinitesimal output intensity. We derive the optimal overlap of the pre- and postselected states with which the amplification become maximum. We also show that the nonlinear effects begin to arise in the performed experiments so that any improvements in the experiment, typically with an amplification greater than 100, should require the nonlinear theory in translating the observed value to the original displacement.« less

Single- and dual-wavelength laser operation of a diode-pumped Nd:LaF3 single crystal around 1.05 μm and 1.32 μm

NASA Astrophysics Data System (ADS)

Xu, Bin; Huang, Xiaoxu; Lan, Jinglong; Lin, Zhi; Wang, Yi; Xu, Huiying; Cai, Zhiping; Moncorgé, Richard

2016-07-01

Calibrated room temperature polarized emission spectra recorded between 850 and 1400 nm and nearly free from any reabsorption effect are presented for the first time. A laser output power of 2.35 W is obtained at 1063.45 nm with a laser slope efficiency of about 56% by pumping an uncoated Nd:LaF3 single crystal with a fiber-coupled laser diode at 790 nm inside a standard two-mirror linear laser cavity. True dual-wavelength laser operation on two orthogonally polarized laser lines around 1040 and 1065 nm as well as continuous laser wavelength tuning around 1040 nm, 1048 nm and 1064 nm are also achieved for the first time by using either an intracavity etalon or a birefringent filter. Laser operation is finally obtained around 1330.73 nm with a maximum output power of 0.18 W and a laser slope efficiency of about 4% and simultaneous dual-wavelength laser operation at 1329.04 and 1359.67 nm is demonstrated by using a glass etalon.

Stable TEM00-mode Nd:YAG solar laser operation by a twisted fused silica light-guide

NASA Astrophysics Data System (ADS)

Bouadjemine, R.; Liang, D.; Almeida, J.; Mehellou, S.; Vistas, C. R.; Kellou, A.; Guillot, E.

2017-12-01

To improve the output beam stability of a TEM00-mode solar-pumped laser, a twisted fused silica light-guide was used to achieve uniform pumping along a 3 mm diameter and 50 mm length Nd:YAG rod. The concentrated solar power at the focal spot of a primary parabolic mirror with 1.18 m2 effective collection area was efficiently coupled to the entrance aperture of a 2D-CPC/2V-shaped pump cavity, within which the thin laser rod was pumped. Optimum solar laser design parameters were found through ZEMAX© non-sequential ray-tracing and LASCAD© laser cavity analysis codes. 2.3 W continuous-wave TEM00-mode 1064 nm laser power was measured, corresponding to 1.96 W/m2 collection efficiency and 2.2 W laser beam brightness figure of merit. Excellent TEM00-mode laser beam profile at M2 ≤ 1.05 and very good output power stability of less than 1.6% were achieved. Heliostat orientation error dependent laser power variation was considerably less than previous solar laser pumping schemes.

Development of a miniature multiple reference optical coherence tomography imaging device

NASA Astrophysics Data System (ADS)

McNamara, Paul M.; O'Riordan, Colm; Collins, Seán.; O'Brien, Peter; Wilson, Carol; Hogan, Josh; Leahy, Martin J.

2016-03-01

Multiple reference optical coherence tomography (MR-OCT) is a new technology ideally suited to low-cost, compact OCT imaging. This modality is an extension of time-domain OCT with the addition of a partial mirror in front of the reference mirror. This enables extended, simultaneous depth scanning with the relatively short sweep of a miniature voice coil motor on which the scanning mirror is mounted. Applications of this technology include biometric security, ophthalmology, personal health monitoring and non-destructive testing. This work details early-stage development of the first iteration of a miniature MR-OCT device. This device utilizes a fiber-coupled input from an off-board superluminescent diode (SLD). Typical dimensions of the module are 40 × 57 mm, but future designs are expected to be more compact. Off-the-shelf miniature optical components, voice coil motors and photodetectors are used, with the complexity of design depending on specific applications. The photonic module can be configured as either polarized or non-polarized and can include balanced detection. The photodetectors are directly connected to a printed circuit board under the module containing a transimpedance amplifier with complimentary outputs. The results shown in this work are from the non-polarized device. Assembly of the photonic modules requires extensive planning. In choosing the optical components, Zemax simulations are performed to model the beam characteristics. The physical layout is modeled using Solidworks and each component is placed and aligned via a well-designed alignment procedure involving an active-alignment pick-and-place assembly system.

Glass light pipes for solar concentration

NASA Astrophysics Data System (ADS)

Madsen, C. K.; Dogan, Y.; Morrison, M.; Hu, C.; Atkins, R.

2018-02-01

Glass waveguides are fabricated using laser processing techniques that have low optical loss with >90% optical throughput. Advanced light pipes are demonstrated, including angled facets for turning mirrors used for lens-to-light pipe coupling, tapers that increase the concentration, and couplers for combining the outputs from multiple lens array elements. Because they are fabricated from glass, these light pipes can support large optical concentrations and propagate broadband solar over long distances with minimal loss and degradation compared to polymer waveguides. Applications include waveguiding solar concentrators using multi-junction PV cells, solar thermal applications and remoting solar energy, such as for daylighting. Ray trace simulations are used to estimate the surface smoothness required to achieve low loss. Optical measurements for fabricated light pipes are reported for use in waveguiding solar concentrator architectures.

Time-delay signature of chaos in 1550 nm VCSELs with variable-polarization FBG feedback.

PubMed

Li, Yan; Wu, Zheng-Mao; Zhong, Zhu-Qiang; Yang, Xian-Jie; Mao, Song; Xia, Guang-Qiong

2014-08-11

Based on the framework of spin-flip model (SFM), the output characteristics of a 1550 nm vertical-cavity surface-emitting laser (VCSEL) subject to variable-polarization fiber Bragg grating (FBG) feedback (VPFBGF) have been investigated. With the aid of the self-correlation function (SF) and the permutation entropy (PE) function, the time-delay signature (TDS) of chaos in the VPFBGF-VCSEL is evaluated, and then the influences of the operation parameters on the TDS of chaos are analyzed. The results show that the TDS of chaos can be suppressed efficiently through selecting suitable coupling coefficient and feedback rate of the FBG, and is weaker than that of chaos generated by traditional variable-polarization mirror feedback VCSELs (VPMF-VCSELs) or polarization-preserved FBG feedback VCSELs (PPFBGF-VCSELs).

High-pulse energy-stabilized passively mode-locked external cavity inverse bow-tie 980nm laser diode for space applications

NASA Astrophysics Data System (ADS)

Krakowski, M.; Resneau, P.; Garcia, M.; Vinet, E.; Robert, Y.; Lecomte, M.; Parillaud, O.; Gerard, B.; Kundermann, S.; Torcheboeuf, N.; Boiko, D. L.

2018-02-01

We report on multi-section inverse bow-tie laser producing mode-locked pulses of 90 pJ energy and 6.5 ps width (895 fs after compression) at 1.3 GHz pulse repetition frequency (PRF) and consuming 2.9 W of electric power. The laser operates in an 80 mm long external cavity. By translation of the output coupling mirror, the PRF was continuously tuned over 37 MHz range without additional adjustments. Active stabilization with a phase lock loop actuating on the driving current has allowed us to reach the PRF relative stability at a 2·10-10 level on 10 s intervals, as required by the European Space Agency (ESA) for inter-satellite long distance measurements.

Graded Reflectivity Mirror for the Solid State Heat Capacity Laser Final Report CRADA No. TC-2085-04

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

Yamamoto, R.; Davis, J. A.

This was a collaborative effort between The Regents of the University of California, Lawrence Livermore National Laboratory (LLNL) and the Boeing Company, to develop a Graded Reflectivity Mirror (GRM) to achieve improved near field fill and higher brightness in the far field output of LLNL’s Solid State Heat Capacity Laser (SSHCL).

High Power Q-Switched Thulium Doped Fibre Laser using Carbon Nanotube Polymer Composite Saturable Absorber

PubMed Central

Chernysheva, Maria; Mou, Chengbo; Arif, Raz; AlAraimi, Mohammed; Rümmeli, Mark; Turitsyn, Sergei; Rozhin, Aleksey

2016-01-01

We have proposed and demonstrated a Q-switched Thulium doped fibre laser (TDFL) with a ‘Yin-Yang’ all-fibre cavity scheme based on a combination of nonlinear optical loop mirror (NOLM) and nonlinear amplified loop mirror (NALM). Unidirectional lasing operation has been achieved without any intracavity isolator. By using a carbon nanotube polymer composite based saturable absorber (SA), we demonstrated the laser output power of ~197 mW and pulse energy of 1.7 μJ. To the best of our knowledge, this is the highest output power from a nanotube polymer composite SA based Q-switched Thulium doped fibre laser. PMID:27063511

Analysis and design of optically pumped far infrared oscillators and amplifiers

NASA Technical Reports Server (NTRS)

Galantowicz, T. A.

1978-01-01

A waveguide laser oscillator was designed and experimental measurements made of relationships among output power, pressure, pump power, pump frequency, cavity tuning, output beam pattern, and cavity mirror properties for various active gases. A waveguide regenerative amplifier was designed and gain measurements were made for various active gases. An external Fabry-Perot interferometer was fabricated and used for accurate wavelength determination and for measurements of the refractive indices of solids transparent in the far infrared. An electronic system was designed and constructed to provide an appropriate error signal for use in feedback control of pump frequency. Pump feedback from the FIR laser was decoupled using a vibrating mirror to phase modulate the pump signal.

Cr:ZnSe laser pumped with Tm:YAP microchip laser

NASA Astrophysics Data System (ADS)

Koranda, Petr; Sulc, Jan; Doroshenko, Maxim; Jelinková, Helena; Basiev, Tasoltan T.; Osiko, Vjatcheslav; Badikov, V. V.; Badikov, D.

2010-02-01

Cr:ZnSe laser coherently longitudinally pumped with Tm:YAP microchip laser was realised. The pumping laser consisted of Tm:YAP crystal (3x3 mm) with resonator mirrors deposited directly on its faces (on rear face the dielectric layer with high reflectance for 1998 nm wavelength and high transmittance for 790 nm pumping radiation wavelength; on output face the dielectric layer with reflectance 97% at 1998 nm wavelength). The maximal output power was 5.5 W and the generated radiation wavelength was 1998 nm. The main advantage of this pumping was stable and still output without relaxation spikes (non-spiking). The Tm:YAP laser radiation was collimated and focused by the set of two CaF2 lenses. The pumping beam spot diameter inside the Cr:ZnSe crystal was 300 μm. The Cr:ZnSe laser resonator consisted of flat rear mirror (HT at 1998 nm and HR at 2100 - 2900 nm) and curved output coupler (r = -150 mm, R = 95% at 2100 - 2700 nm). The maximal output energy of stable radiation was 4 mJ (pulse duration 10 ms, repetition rate 10 Hz). For wavelength tuning the Lyott filter (quartz plate under Brewster angle) was placed between the Cr:ZnSe crystal and output coupler. The generated radiation wavelength was continuously tunable from 2246 - 2650 nm.

Motion detection, novelty filtering, and target tracking using an interferometric technique with GaAs phase conjugate mirror

NASA Technical Reports Server (NTRS)

Cheng, Li-Jen (Inventor); Liu, Tsuen-Hsi (Inventor)

1991-01-01

A method and apparatus for detecting and tracking moving objects in a noise environment cluttered with fast- and slow-moving objects and other time-varying background. A pair of phase conjugate light beams carrying the same spatial information commonly cancel each other out through an image subtraction process in a phase conjugate interferometer, wherein gratings are formed in a fast photorefractive phase conjugate mirror material. In the steady state, there is no output. When the optical path of one of the two phase conjugate beams is suddenly changed, the return beam loses its phase conjugate nature and the interferometer is out of balance, resulting in an observable output. The observable output lasts until the phase conjugate nature of the beam has recovered. The observable time of the output signal is roughly equal to the formation time of the grating. If the optical path changing time is slower than the formation time, the change of optical path becomes unobservable, because the index grating can follow the change. Thus, objects traveling at speeds which result in a path changing time which is slower than the formation time are not observable and do not clutter the output image view.

Mirroring and beyond: coupled dynamics as a generalized framework for modelling social interactions

PubMed Central

Hasson, Uri; Frith, Chris D.

2016-01-01

When people observe one another, behavioural alignment can be detected at many levels, from the physical to the mental. Likewise, when people process the same highly complex stimulus sequences, such as films and stories, alignment is detected in the elicited brain activity. In early sensory areas, shared neural patterns are coupled to the low-level properties of the stimulus (shape, motion, volume, etc.), while in high-order brain areas, shared neural patterns are coupled to high-levels aspects of the stimulus, such as meaning. Successful social interactions require such alignments (both behavioural and neural), as communication cannot occur without shared understanding. However, we need to go beyond simple, symmetric (mirror) alignment once we start interacting. Interactions are dynamic processes, which involve continuous mutual adaptation, development of complementary behaviour and division of labour such as leader–follower roles. Here, we argue that interacting individuals are dynamically coupled rather than simply aligned. This broader framework for understanding interactions can encompass both processes by which behaviour and brain activity mirror each other (neural alignment), and situations in which behaviour and brain activity in one participant are coupled (but not mirrored) to the dynamics in the other participant. To apply these more sophisticated accounts of social interactions to the study of the underlying neural processes we need to develop new experimental paradigms and novel methods of data analysis PMID:27069044

Laser-diode pumped dysprosium-doped lead thiogallate laser output wavelength temporal evolution and tuning possibilities at 4.3-4.7 um

NASA Astrophysics Data System (ADS)

Jelínková, Helena; Doroshenko, Maxim E.; Šulc, Jan; Němec, Michal; Jelínek, Michal; Osiko, Vjatcheslav V.; Badikov, Valerii V.; Badikov, Dmitri V.

2016-03-01

On the basis of our previous Dy3+:PbGa2S4 laser study, laser output wavelength temporal evolution as well as tuning possibilities in the range 4.3-4.7 μm were investigated. Active crystal was pumped by a fiber-coupled Brightlase Ultra- 50 diode laser (1.7 μm, max. power 7.5 W). Laser resonator was formed by flat dichroic pumping mirror (T = 70%@1.7 μm, R~100% @ 3.5 - 5 μm) and a concave (r = 200 mm) output coupler with R~99% @ 3.5 - 5 μm. The laser output wavelength dependence on the pump pulse duration and its evolution during the pulse was investigated first without any spectrally-selective element in the cavity. At pump pulse duration of 1 ms, generation just near Dy3+ fluorescence maximum of 4.35 μm has been observed. Prolongation of the pulse up to 5 ms led to similar lasing at 4.35 μm in the first millisecond, followed by simultaneous generation at 4.35 and 4.38 μm in the next millisecond, and further lasing at 4.6 μm till the end of the pump pulse. Increase of pump pulse duration up to 10 ms led to similar oscillation pulse development followed by generation at 4.6 μm only. Furthermore, output wavelength tuning using MgF2 birefringent filter as a cavity spectral selective element was investigated under 10 ms pumping. Almost continuous tuning without any significant dip has been observed within spectral range from 4.3 up to 4.7 μm. Due to practically closed cavity mean output power in the maximum of tuning curve was in the order of 400 μW.

Pulse compression and prepulse suppression apparatus

DOEpatents

Dane, Clifford B.; Hackel, Lloyd A.; George, Edward V.; Miller, John L.; Krupke, William F.

1993-01-01

A pulse compression and prepulse suppression apparatus (10) for time compressing the output of a laser (14). A pump pulse (46) is separated from a seed pulse (48) by a first polarized beam splitter (20) according to the orientation of a half wave plate (18). The seed pulse (48) is directed into an SBS oscillator (44) by two plane mirrors (22, 26) and a corner mirror (24), the corner mirror (24) being movable to adjust timing. The pump pulse (46) is directed into an SBS amplifier 34 wherein SBS occurs. The seed pulse (48), having been propagated from the SBS oscillator (44), is then directed through the SBS amplifier (34) wherein it sweeps the energy of the pump pulse (46) out of the SBS amplifier (34) and is simultaneously compressed, and the time compressed pump pulse (46) is emitted as a pulse output (52). A second polarized beam splitter (38) directs any undepleted pump pulse 58 away from the SBS oscillator (44).

Pulse compression and prepulse suppression apparatus

DOEpatents

Dane, C.B.; Hackel, L.A.; George, E.V.; Miller, J.L.; Krupke, W.F.

1993-11-09

A pulse compression and prepulse suppression apparatus (10) for time compressing the output of a laser (14). A pump pulse (46) is separated from a seed pulse (48) by a first polarized beam splitter (20) according to the orientation of a half wave plate (18). The seed pulse (48) is directed into an SBS oscillator (44) by two plane mirrors (22, 26) and a corner mirror (24), the corner mirror (24) being movable to adjust timing. The pump pulse (46) is directed into an SBS amplifier 34 wherein SBS occurs. The seed pulse (48), having been propagated from the SBS oscillator (44), is then directed through the SBS amplifier (34) wherein it sweeps the energy of the pump pulse (46) out of the SBS amplifier (34) and is simultaneously compressed, and the time compressed pump pulse (46) is emitted as a pulse output (52). A second polarized beam splitter (38) directs any undepleted pump pulse 58 away from the SBS oscillator (44).

Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements

NASA Technical Reports Server (NTRS)

Bair, Clayton H.; Brockman, Philip; Hess, Robert V.; Modlin, Edward A.

1988-01-01

Theoretical and experimental frequency narrowing studies of a Ti:sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported.

Nano-stepper-driven optical shutter for applications in free-space micro-optics

NASA Astrophysics Data System (ADS)

Zawadzka, Justyna; Li, Lijie; Unamuno, Anartz; Uttamchandani, Deepak G.

2002-09-01

In this paper we report a simple design of a micro-optical shutter/attenuator. The standard MUMPS process was used to fabricate the device. A vertically erected, gold-coated, 200x300 mm side length micro-mirror was precisely placed between the end faces of two closely spaced optical fibers. The position of the micro-mirror with respect to the optical fiber end face was controlled by a nano-stepping motor array. Optical and mechanical tests were performed on the device. A 1.55 mm laser beam was sent along the optical fiber. When the micro-mirror was removed from the front of the fiber, the coupling efficiency between two fibers was -10 dBm. Once the micro-mirror was placed in the optical path the coupling efficiency dropped to -51.5 dBm. The best attenuation was obtained when the micro-mirror blocked the whole cross-section of the laser beam diameter. It is evident that the device can operate as a high precision fiber optic attenuator or shutter.

Alignment reference device

DOEpatents

Patton, Gail Y.; Torgerson, Darrel D.

1987-01-01

An alignment reference device provides a collimated laser beam that minimizes angular deviations therein. A laser beam source outputs the beam into a single mode optical fiber. The output end of the optical fiber acts as a source of radiant energy and is positioned at the focal point of a lens system where the focal point is positioned within the lens. The output beam reflects off a mirror back to the lens that produces a collimated beam.

Method and apparatus for varying accelerator beam output energy

DOEpatents

Young, Lloyd M.

1998-01-01

A coupled cavity accelerator (CCA) accelerates a charged particle beam with rf energy from a rf source. An input accelerating cavity receives the charged particle beam and an output accelerating cavity outputs the charged particle beam at an increased energy. Intermediate accelerating cavities connect the input and the output accelerating cavities to accelerate the charged particle beam. A plurality of tunable coupling cavities are arranged so that each one of the tunable coupling cavities respectively connect an adjacent pair of the input, output, and intermediate accelerating cavities to transfer the rf energy along the accelerating cavities. An output tunable coupling cavity can be detuned to variably change the phase of the rf energy reflected from the output coupling cavity so that regions of the accelerator can be selectively turned off when one of the intermediate tunable coupling cavities is also detuned.

A technique for the optical analysis of deformed telescope mirrors

NASA Technical Reports Server (NTRS)

Bolton, John F.

1986-01-01

The NASTRAN-ACCOS V programs' interface merges structural and optical analysis capabilities in order to characterize the performance of the NASA Goddard Space Flight Center's Solar Optical Telescope primary mirror, which has a large diameter/thickness ratio. The first step in the optical analysis is to use NASTRAN's FEM to model the primary mirror, simulating any distortions due to gravitation, thermal gradients, and coefficient of thermal expansion nonuniformities. NASTRAN outputs are then converted into an ACCOS V-acceptable form; ACCOS V generates the deformed optical surface on the basis of these inputs, and imaging qualities can be determined.

Device for frequency modulation of a laser output spectrum

DOEpatents

Beene, James R.; Bemis, Jr., Curtis E.

1986-01-01

A device is provided for fast frequency modulating the output spectrum of multimode lasers and single frequency lasers that are not actively stabilized. A piezoelectric transducer attached to a laser cavity mirror is driven in an unconventional manner to excite resonance vibration of the transducer to rapidly, cyclicly change the laser cavity length. The result is a cyclic sweeping of the output wavelength sufficient to fill the gaps in the laser output frequency spectrum. When such a laser is used to excite atoms or molecules, complete absorption line coverage is made possible.

Device for frequency modulation of a laser output spectrum

DOEpatents

Beene, J.R.; Bemis, C.E. Jr.

1984-07-17

A device is provided for fast frequency modulating the output spectrum of multimode lasers and single frequency lasers that are not actively stabilized. A piezoelectric transducer attached to a laser cavity mirror is driven in an unconventional manner to excite resonance vibration of the tranducer to rapidly, cyclicly change the laser cavity length. The result is a cyclic sweeping of the output wavelength sufficient to fill the gaps in the laser output frequency spectrum. When a laser is used to excite atoms or molecules, complete absorption line coverage is made possible.

Modified nonlinear amplifying loop mirror for mode-locked fibre oscillators with record-high energy and high-average-power pulsed output

NASA Astrophysics Data System (ADS)

Kobtsev, Sergey; Ivanenko, Alexey; Smirnov, Sergey; Kokhanovsky, Alexey

2018-02-01

The present work proposes and studies approaches for development of new modified non-linear amplifying loop mirror (NALM) allowing flexible and dynamic control of their non-linear properties within a relatively broad range of radiation powers. Using two independently pumped active media in the loop reflector constitutes one of the most promising approaches to development of better NALM with nonlinear properties controllable independently of the intra-cavity radiation power. This work reports on experimental and theoretical studies of the proposed redesigned NALM allowing both a higher level of energy parameters of output generated by mode-locked fibre oscillators and new possibilities of switching among different mode-locked regimes.

Fiber facet gratings for high power fiber lasers

NASA Astrophysics Data System (ADS)

Vanek, Martin; Vanis, Jan; Baravets, Yauhen; Todorov, Filip; Ctyroky, Jiri; Honzatko, Pavel

2017-12-01

We numerically investigated the properties of diffraction gratings designated for fabrication on the facet of an optical fiber. The gratings are intended to be used in high-power fiber lasers as mirrors either with a low or high reflectivity. The modal reflectance of low reflectivity polarizing grating has a value close to 3% for TE mode while it is significantly suppressed for TM mode. Such a grating can be fabricated on laser output fiber facet. The polarizing grating with high modal reflectance is designed as a leaky-mode resonant diffraction grating. The grating can be etched in a thin layer of high index dielectric which is sputtered on fiber facet. We used refractive index of Ta2O5 for such a layer. We found that modal reflectance can be close to 0.95 for TE polarization and polarization extinction ratio achieves 18 dB. Rigorous coupled wave analysis was used for fast optimization of grating parameters while aperiodic rigorous coupled wave analysis, Fourier modal method and finite difference time domain method were compared and used to compute modal reflectance of designed gratings.

Scanned Laser Illuminator/Receiver

DTIC Science & Technology

1976-11-01

0.21/cm | | Optical Power 20 Watts i input I Optical Power 100 Watts | output ! Input Power 10 kW The oscillator ...8217.rectional due to the oscillating mirror. Again, con- siderable optical magnification is provided between object space and the scan mirror to minimize the...for a 100W (14) R. A. McClatchey, et al, " Optical Properties of the Atmosphere (Third Edition)," Air Force Cambridge Research Laboratories, Tech

Mode/Medium Instability in CO2 Laser

NASA Technical Reports Server (NTRS)

Webster, K. L.; Sung, C. C.

1992-01-01

Report discribes theoretical study of model/medium instability (MMI) in CO2 laser. Purposes of study to extend, to small Fresnel numbers, previous study of MMI restricted to large Fresnel numbers and to study methods of previous studies, to suppress MMI. Method of primary interest involves replacement of hard edge output mirror in laser resonator with mirror, local reflectivity of which decreases with radial distance from optical axis according to Gaussian profile.

Deployable telescope having a thin-film mirror and metering structure

DOEpatents

Krumel, Leslie J [Cedar Crest, NM; Martin, Jeffrey W [Albuquerque, NM

2010-08-24

A deployable thin-film mirror telescope comprises a base structure and a metering structure. The base structure houses a thin-film mirror, which can be rolled for stowage and unrolled for deployment. The metering structure is coupled to the base structure and can be folded for stowage and unfolded for deployment. In the deployed state, the unrolled thin-film mirror forms a primary minor for the telescope and the unfolded metering structure positions a secondary minor for the telescope.

Excitation of ultrasharp trapped-mode resonances in mirror-symmetric metamaterials

NASA Astrophysics Data System (ADS)

Yang, Shengyan; Liu, Zhe; Xia, Xiaoxiang; E, Yiwen; Tang, Chengchun; Wang, Yujin; Li, Junjie; Wang, Li; Gu, Changzhi

2016-06-01

We experimentally demonstrate a metamaterial structure composed of two mirror-symmetric joint split ring resonators (JSRRs) that support extremely sharp trapped-mode resonance with a large modulation depth in the terahertz region. Contrary to the regular mirror-arranged SRR arrays in which both the subradiant inductive-capacitive (LC) resonance and quadrupole-mode resonance can be excited, our designed structure features a metallic microstrip bridging the adjacent SRRs, which leads to the emergence of an otherwise inaccessible ultrahigh-quality-factor resonance. The ultrasharp resonance occurs near the Wood-Rayleigh anomaly frequency, and the underlying mechanism can be attributed to the strong coupling between the in-plane propagating collective lattice surface mode originating from the array periodicity and localized surface plasmon resonance in mirror-symmetric coupled JSRRs, which dramatically reduces radiative damping. The ultrasharp resonance shows great potential for multifunctional applications such as plasmonic switching, low-power nonlinear processing, and chemical and biological sensing.

Motion detection, novelty filtering, and target tracking using an interferometric technique with a GaAs phase conjugate mirror

NASA Technical Reports Server (NTRS)

Cheng, Li-Jen (Inventor); Liu, Tsuen-Hsi (Inventor)

1990-01-01

A method and apparatus is disclosed for detecting and tracking moving objects in a noise environment cluttered with fast-and slow-moving objects and other time-varying background. A pair of phase conjugate light beams carrying the same spatial information commonly cancel each other out through an image subtraction process in a phase conjugate interferometer, wherein gratings are formed in a fast photo-refractive phase conjugate mirror material. In the steady state, there is no output. When the optical path of one of the two phase conjugate beams is suddenly changed, the return beam loses its phase conjugate nature and the inter-ferometer is out of balance, resulting in an observable output. The observable output lasts until the phase conjugate nature of the beam has recovered. The observable time of the output signal is roughly equal to the formation time of the grating. If the optical path changing time is slower than the formation time, the change of optical path becomes unobservable, because the index grating can follow the change. Thus, objects traveling at speeds which result in a path changing time which is slower than the formation time are not observable and do not clutter the output image view.

Design of Off-Axis PIAACMC Mirrors

NASA Technical Reports Server (NTRS)

Pluzhnik, Eugene; Guyon, Olivier; Belikov, Ruslan; Kern, Brian; Bendek, Eduardo

2015-01-01

The Phase-Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC) provides an efficient way to control diffraction propagation effects caused by the central obstruction/segmented mirrors of the telescope. PIAACMC can be optimized in a way that takes into account both chromatic diffraction effects caused by the telescope obstructed aperture and tip/tilt sensitivity of the coronagraph. As a result, unlike classic PIAA, the PIAACMC mirror shapes are often slightly asymmetric even for an on-axis configuration and require more care in calculating off-axis shapes when an off-axis configuration is preferred. A method to design off-axis PIAA mirror shapes given an on-axis mirror design is presented. The algorithm is based on geometrical ray tracing and is able to calculate off-axis PIAA mirror shapes for an arbitrary geometry of the input and output beams. The method is demonstrated using the third generation PIAACMC design for WFIRST-AFTA (Wide Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets) telescope. Geometrical optics design issues related to the off-axis diffraction propagation effects are also discussed.

Dispersion measurement on chirped mirrors at arbitrary incidence angle and polarization state (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kovacs, Mate; Somoskoi, Tamas; Seres, Imre; Borzsonyi, Adam; Sipos, Aron; Osvay, Károly

2017-05-01

The optical elements of femtosecond high peak power lasers have to fulfill more and more strict requirements in order to support pulses with high intensity and broad spectrum. In most cases chirped pulse amplification scheme is used to generate high peak power ultrashort laser pulses, where a very precise control of spectral intensity and spectral phase is required in reaching transform-limited temporal shape at the output. In the case of few cycle regime, the conventional bulk glass, prism-, grating- and their combination based compressors are not sufficient anymore, due to undesirable nonlinear effects in their material and proneness to optical damages. The chirped mirrors are also commonly used to complete the compression after a beam transport system just before the target. Moreover, the manufacturing technology requires quality checks right after production and over the lifetime of the mirror as well, since undesired deposition on the surface can lead alteration from the designed value over a large part of the aperture. For the high harmonic generation, polarization gating technology is used to generate single attosecond pulses [1]. In this case the pulse to be compressed has various polarization state falling to the chirped mirrors. For this reason, it is crucial to measure the dispersion of the mirrors for the different polarization states. In this presentation we demonstrate a simple technique to measure the dispersion of arbitrary mirror at angles of incidence from 0 to 55 degree, even for a 12" optics. A large aperture 4" mirror has been scanned over with micrometer accuracy and the dispersion property through the surface has been investigated with a stable interference fringes in that robust geometry. We used Spectrally Resolved Interferometry, which is based on a Michaelson interferometer and a combined visible and infrared spectrometer. Tungsten halogen lamp with 10 mW coupled optical power was used as a white-light source so with the selected spectrometer we could investigate over the 500-1300 nm spectral range. We also measured the mirrors with broadband oscillator pulses, and we found that the dispersion was the same for both light source. Group Delay Dispersion was obtained with a ±2 fs^2 accuracy from the Fourier Transform method of the interference fringes. Using an adjunct mirror, we made possible to change continuously the angle of incidence at the chirped mirror within 3 and 55°. On the input part of the interferometer we placed a wire-grid polarizer, and sensitivity of the chirp mirrors to the polarization state have been measured at different incidence angles. To present the flexibility of the device we scanned two different compressor mirrors with +100 fs^2 and -500 fs^2 at the 800 nm central wavelength. We separately developed an optical arrangement to detect Group Delay shift between s and p polarization reflections of large aperture chirped compressor mirrors and we found that it's below the detection limit, so further investigation will be necessary. 1. M. Ivanov, P. B. Corkum, T. Zuo, and A. Bandrauk, Routes to Control of Intense-Field Atomic Polarizability, Phys. Rev. Lett. 74, 1995

Fault-tolerant drive electronics for a Xinetics deformable mirror at GeMS DM0

NASA Astrophysics Data System (ADS)

Barberio, Michael J.

2016-07-01

Gemini South is replacing one of the (3) CILAS DMs with a 349-actuator Xinetics DM in its GeMS MCAO system. Xinetics mirrors operate over a 40-100V dynamic range and require that inter-actuator stroke differences are limited to half-scale; each actuator must be within 30V of its neighbor to prevent mechanical stress and possible face sheet separation. A robust way to implement this protection is to use high power transient voltage suppressors (TVSs) as a 2D-mesh between the amplifiers and mirror, but this has system implications. A sustained clamp condition dissipates significant power in the devices, and if an actuator fails as short (which occurred once with the DM in a thermal chamber), the system is subject to a cascade failure event as multiple outputs drive the shorted actuator through the TVS network. This latter risk is readily resolved by using series fuses to the DM. In this third-generation driver, current sensing and logic inhibit amplifier outputs after a sustained TVS clamp condition or shorted output, and LED indicators show the location. Redundant thermal sensing is used on modular TVS row and column boards. A second 2D-mesh of high impedance resistors after the fuses will hold an unpowered channel to the average voltage of its neighbors, with a negligible influence function. A Failure Modes and Effects Analysis shows significant fault tolerance.

New receiving line for the remote-steering antenna of the 140 GHz CTS diagnostics in the FTU Tokamak

NASA Astrophysics Data System (ADS)

D'Arcangelo, O.; Bin, W.; Bruschi, A.; Cappelli, M.; Fanale, F.; Gittini, G.; Pallotta, F.; Rocchi, G.; Tudisco, O.; Garavaglia, S.; Granucci, G.; Moro, A.; Tuccillo, A. A.

2018-01-01

A new receiving antenna for collecting signals of the Collective Thomson Scattering (CTS) diagnostics in FTU Tokamak has been recently installed. The squared corrugated section and the precisely defined length make it possible to receive from different directions by remotely steering the receiving mirrors. This type of Remote-Steering (RS) antennas, being studied on FTU for the DEMO Electron Cyclotron Heating (ECH) system launch, is already installed on the W7- X stellarator and will be tested in the next campaign. The transmission of the signal from the antenna in the tokamak hall to the CTS diagnostics hall will be mainly realized by means of oversized circular corrugated waveguides carrying the hybrid HE11 (quasi-gaussian) waveguide mode, with inclusion of a special smooth-waveguide section and a short run of reduced-size square-corrugated waveguide through the tokamak bio-shield. The coupling between different waveguide types is made with ellipsoidal focusing mirrors, using quasi-optical matching formulas between the gaussian-shaped beams in input and output to the waveguides. In this work, after a complete study of feasibility of the overall line, a design for the receiving line will be proposed, in order to realize an executive layout to be used as a guideline for the commissioning phase.

Tailoring the transverse mode of a high-finesse optical resonator with stepped mirrors

NASA Astrophysics Data System (ADS)

Högner, M.; Saule, T.; Lilienfein, N.; Pervak, V.; Pupeza, I.

2018-02-01

Enhancement cavities (ECs) seeded with femtosecond pulses have developed into the most powerful technique for high-order harmonic generation (HHG) at repetition rates in the tens of MHz. Here, we demonstrate the feasibility of controlling the phase front of the excited transverse eigenmode of a ring EC by using mirrors with stepped surface profiles, while maintaining the high finesse required to reach the peak intensities necessary for HHG. The two lobes of a {{TEM}}01 mode of a 3.93 m long EC, seeded with a single-frequency laser, are delayed by 15.6 fs with respect to each other before a tight focus, and the delay is reversed after the focus. The tailored transverse mode exhibits an on-axis intensity maximum in the focus. Furthermore, the geometry is designed to generate a rotating wavefront in the focus when few-cycle pulses circulate in the EC. This paves the way to gating isolated attosecond pulses (IAPs) in a transverse manner (similarly to the attosecond lighthouse), heralding IAPs at repetition rates well into the multi-10 MHz range. In addition, these results promise high-efficiency harmonic output coupling from ECs in general, with an unparalleled power scalability. These prospects are expected to tremendously benefit photoelectron spectroscopy and extreme-ultraviolet frequency comb spectroscopy.

Oscillator-field model of moving mirrors in quantum optomechanics

NASA Astrophysics Data System (ADS)

Galley, Chad R.; Behunin, Ryan O.; Hu, B. L.

2013-04-01

We present a microphysics model for the kinematics and dynamics of optomechanics describing the coupling between an optical field, modeled here by a massless scalar field, and the internal and mechanical degrees of freedom of a movable mirror. Instead of implementing boundary conditions on the field, we introduce an internal degree of freedom and its dynamics to describe the mirror's reflectivity. Depending on parameter values, the internal degrees of freedom of the mirror in this model capture a range of its optical activities, from those exhibiting broadband reflective properties to those reflecting only in a narrow band. After establishing the model we show how appropriate parameter choices lead to other well-known optomechanical models, including those of Barton and Calogeracos [Ann. Phys. (NY)0003-491610.1006/aphy.1995.1021 238, 227 (1995)], Calogeracos and Barton, Ann. Phys. (NY)10.1006/aphy.1995.1022 238, 268 (1995), Law [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.51.2537 51, 2537 (1995)], and Golestanian and Kardar [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.78.3421 78, 3421 (1997); Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.58.1713 58, 1713 (1998)]. As a simple illustrative application we derive classical radiation pressure cooling from this model. We then connect our microphysics model to the common descriptions of a moving mirror coupled to radiation pressure (e.g., with Nx coupling, where N is the photon number and x is the mirror displacement), making explicit the underlying assumptions made in these phenomenological models. Our model is also applicable to the lesser explored case of small N, which existing models based on sideband approximations [Kimble , Phys. Rev. DPRVDAQ1550-799810.1103/PhysRevD.65.022002 65, 022002 (2001)] have not addressed. Interestingly, we also find that slow-moving mirrors in our model can be described by the ubiquitous Brownian motion model of quantum open systems. The scope of applications of this model ranges from a full quantum-mechanical treatment of radiation pressure cooling and quantum entanglement between macroscopic mirrors to the back reaction of Hawking radiation on black-hole evaporation in a moving mirror analog.

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

Double passing the Kitt Peak 1-m Fourier transform spectrometer

NASA Technical Reports Server (NTRS)

Jennings, D. E.; Hubbard, R.; Brault, J. W.

1985-01-01

Attention is given to a simple technique for performing the conversion of the Kitt Peak 1-m Fourier transform spectrometer's dual input/output optical configuration to a double pass configuration that improves spectral resolution by a factor of 2. The modification is made by placing a flat mirror in the output beam from each cat's eye, retroreflecting the beams back through the cat's eyes to the first beam splitter. A single detector is placed at the second input port, which then becomes the instrument's output.

Dynamical simulation of E-ELT segmented primary mirror

NASA Astrophysics Data System (ADS)

Sedghi, B.; Muller, M.; Bauvir, B.

2011-09-01

The dynamical behavior of the primary mirror (M1) has an important impact on the control of the segments and the performance of the telescope. Control of large segmented mirrors with a large number of actuators and sensors and multiple control loops in real life is a challenging problem. In virtual life, modeling, simulation and analysis of the M1 bears similar difficulties and challenges. In order to capture the dynamics of the segment subunits (high frequency modes) and the telescope back structure (low frequency modes), high order dynamical models with a very large number of inputs and outputs need to be simulated. In this paper, different approaches for dynamical modeling and simulation of the M1 segmented mirror subject to various perturbations, e.g. sensor noise, wind load, vibrations, earthquake are presented.

Output Power Limitations and Improvements in Passively Mode Locked GaAs/AlGaAs Quantum Well Lasers.

PubMed

Tandoi, Giuseppe; Ironside, Charles N; Marsh, John H; Bryce, A Catrina

2012-03-01

We report a novel approach for increasing the output power in passively mode locked semiconductor lasers. Our approach uses epitaxial structures with an optical trap in the bottom cladding that enlarges the vertical mode size to scale the pulse saturation energy. With this approach we demonstrate a very high peak power of 9.8 W per facet, at a repetition rate of 6.8 GHz and with pulse duration of 0.71 ps. In particular, we compare two GaAs/AlGaAs epilayer designs, a double quantum well design operating at 830 nm and a single quantum well design operating at 795 nm, with vertical mode sizes of 0.5 and 0.75 μm, respectively. We show that a larger mode size not only shifts the mode locking regime of operation towards higher powers, but also produces other improvements in respect of two main failure mechanisms that limit the output power: the catastrophic optical mirror damage and the catastrophic optical saturable absorber damage. For the 830 nm material structure, we also investigate the effect of non-absorbing mirrors on output power and mode locked operation of colliding pulse mode locked lasers.

Output Power Limitations and Improvements in Passively Mode Locked GaAs/AlGaAs Quantum Well Lasers

PubMed Central

Tandoi, Giuseppe; Ironside, Charles N.; Marsh, John H.; Bryce, A. Catrina

2013-01-01

We report a novel approach for increasing the output power in passively mode locked semiconductor lasers. Our approach uses epitaxial structures with an optical trap in the bottom cladding that enlarges the vertical mode size to scale the pulse saturation energy. With this approach we demonstrate a very high peak power of 9.8 W per facet, at a repetition rate of 6.8 GHz and with pulse duration of 0.71 ps. In particular, we compare two GaAs/AlGaAs epilayer designs, a double quantum well design operating at 830 nm and a single quantum well design operating at 795 nm, with vertical mode sizes of 0.5 and 0.75 μm, respectively. We show that a larger mode size not only shifts the mode locking regime of operation towards higher powers, but also produces other improvements in respect of two main failure mechanisms that limit the output power: the catastrophic optical mirror damage and the catastrophic optical saturable absorber damage. For the 830 nm material structure, we also investigate the effect of non-absorbing mirrors on output power and mode locked operation of colliding pulse mode locked lasers. PMID:23843678

AGARD Flight Test Instrumentation Series. Volume 15. Gyroscopic Instruments and Their Application to Flight Testing

DTIC Science & Technology

1982-09-01

center of gravity, Eq. (J.Z.,5)r [in radius of light been, Eq. (3.5.1) r aplitude of baCkscattere•d light with respect to incident light of a mirror , Eq...output, see Eq. (3.5.9)). High quality sensors are being4 built using three or more mirrors within a linear dimension of 10 co. At the present time...Fig. 3.5.1, showed an effect. The SRI shown in fjt.ýj consists of a light source (LS). a beam splitter (8S). three fully re- flecting; mirrors ,. M1I.iF

Support optimization of the ring primary mirror of a 2m solar telescope

NASA Astrophysics Data System (ADS)

Yang, Dehua; Jin, Zhenyu; Liu, Zhong

2016-08-01

A special 2-m Ring Solar Telescope (2-m RST) is to be built by YNAO-Yunnan Astronomical Observatory, Kunming, China. Its distinct primary mirror is distinctively shaped in a ring with an outer diameter of 2.02 m and a ring width of 0.35 m. Careful calculation and optimization of the mirror support pattern have been carried out first of all to define optimum blank parameters in view of performance balance of support design, fabrication and cost. This paper is to review the special consideration and optimization of the support design for the unique ring mirror. Schott zerodur is the prevailing candidate for the primary mirror blank. Diverse support patterns with various blank thicknesses have been discussed by extensive calculation of axial support pattern of the mirror. We reached an optimum design of 36 axial supports for a blank thickness of 0.15 m with surface error of 5 nm RMS. Afterwards, lateral support scheme was figured out for the mirror with settled parameters. A classical push-and-pull scheme was used. Seeing the relative flexibility of the ring mirror, special consideration was taken to unusually set the acting direction of the support forces not in the mirror gravity plane, but along the gravity of the local virtual slices of the mirror blank. Nine couples of the lateral push-pull force are considered. When pointing to horizon, the mirror surface exhibits RMS error of 5 nm with three additional small force couples used to compensate for the predominant astigmatism introduced by lateral supports. Finally, error estimation has been performed to evaluate the surface degradation with introduced errors in support force and support position, respectively, for both axial and lateral supports. Monte Carlo approach was applied using unit seeds for amplitude and position of support forces. The comprehensive optimization and calculation suggests the support systems design meet the technic requirements of the ring mirror of the 2-m RST.

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

Sokollik, T.; Leemans, W. P.; University of California, Berkeley, California 94720

We present experimental results on a tape-drive based plasma mirror which could be used for a compact coupling of a laser beam into a staged laser driven electron accelerator. This novel kind of plasma mirror is suitable for high repetition rates and for high number of laser shots.

High speed preamplifier circuit, detection electronics, and radiation detection systems therefrom

DOEpatents

Riedel, Richard A [Knoxville, TN; Wintenberg, Alan L [Knoxville, TN; Clonts, Lloyd G [Knoxville, TN; Cooper, Ronald G [Oak Ridge, TN

2010-09-21

A preamplifier circuit for processing a signal provided by a radiation detector includes a transimpedance amplifier coupled to receive a current signal from a detector and generate a voltage signal at its output. A second amplification stage has an input coupled to an output of the transimpedance amplifier for providing an amplified voltage signal. Detector electronics include a preamplifier circuit having a first and second transimpedance amplifier coupled to receive a current signal from a first and second location on a detector, respectively, and generate a first and second voltage signal at respective outputs. A second amplification stage has an input coupled to an output of the transimpedance amplifiers for amplifying the first and said second voltage signals to provide first and second amplified voltage signals. A differential output stage is coupled to the second amplification stage for receiving the first and second amplified voltage signals and providing a pair of outputs from each of the first and second amplified voltage signals. Read out circuitry has an input coupled to receive both of the pair of outputs, the read out circuitry having structure for processing each of the pair of outputs, and providing a single digital output having a time-stamp therefrom.

Radiation detection system

DOEpatents

Riedel, Richard A [Knoxville, TN; Wintenberg, Alan L [Knoxville, TN; Clonts, Lloyd G [Knoxville, TN; Cooper, Ronald G [Oak Ridge, TN

2012-02-14

A preamplifier circuit for processing a signal provided by a radiation detector includes a transimpedance amplifier coupled to receive a current signal from a detector and generate a voltage signal at its output. A second amplification stage has an input coupled to an output of the transimpedance amplifier for providing an amplified voltage signal. Detector electronics include a preamplifier circuit having a first and second transimpedance amplifier coupled to receive a current signal from a first and second location on a detector, respectively, and generate a first and second voltage signal at respective outputs. A second amplification stage has an input coupled to an output of the transimpedance amplifiers for amplifying the first and said second voltage signals to provide first and second amplified voltage signals. A differential output stage is coupled to the second amplification stage for receiving the first and second amplified voltage signals and providing a pair of outputs from each of the first and second amplified voltage signals. Read out circuitry has an input coupled to receive both of the pair of outputs, the read out circuitry having structure for processing each of the pair of outputs, and providing a single digital output having a time-stamp therefrom.

High power blue laser diodes on semipolar (202¯1¯) GaN substrates

NASA Astrophysics Data System (ADS)

Pourhashemi, Seyed Arash

High power blue laser didoes (LDs), among other applications, show the promise of realizing efficient and reliable solid state lighting systems. Since first GaN optoelectronic devices were demonstrated in early 1990s, GaN LDs were traditionally fabricated on polar c-plane. However in recent years there has been a growing interest in nonpolar and semipolar planes. Nonpolar and semipolar devices offer the prospect of achieving higher efficiencies though elimination or reduction of polarization-related electric fields. In this project I investigated semipolar (202 ¯1 ¯) plane of GaN for blue LDs fabrication. Results include blue LD (Lambda=450 nm) with highest output power, differential quantum efficiency (?d) and external quantum efficiency (EQE) reported for a GaN LD on a semipolar plane to date. Output power of 2.52 W, etad=50% and EQE=39% were achieved in pulsed mode and output power of 1.71 W was achieved in true CW mode. Moreover, use of indium tin oxide (ITO) as cladding layer in order to reduce the thickness of Mg-doped p-GaN layer was investigated. Blue LDs with ITO cladding were demonstrated in this work with highest output power, etad and EQE reported for a GaN LD with transparent conducting oxide (TCO) cladding layer to date. The lack of any natural cleavage plane orthogonal to the in-plane projection of the c-axis on semipolar planes has made Cl2-based dry etch processes the most common way to form mirror facets for semipolar LDs. However, mirror facets fabricated by dry etching can be inclined or rough. For this work, mechanical polishing was used to form LD mirror facets. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high power CW semipolar LDs.

NASA Tech Briefs, January 2003

NASA Technical Reports Server (NTRS)

2003-01-01

Topics covered include: Optoelectronic Tool Adds Scale Marks to Photographic Images; Compact Interconnection Networks Based on Quantum Dots; Laterally Coupled Quantum-Dot Distributed-Feedback Lasers; Bit-Serial Adder Based on Quantum Dots; Stabilized Fiber-Optic Distribution of Reference Frequency; Delay/Doppler-Mapping GPS-Reflection Remote-Sensing System; Ladar System Identifies Obstacles Partly Hidden by Grass; Survivable Failure Data Recorders for Spacecraft; Fiber-Optic Ammonia Sensors; Silicon Membrane Mirrors with Electrostatic Shape Actuators; Nanoscale Hot-Wire Probes for Boundary-Layer Flows; Theodolite with CCD Camera for Safe Measurement of Laser-Beam Pointing; Efficient Coupling of Lasers to Telescopes with Obscuration; Aligning Three Off-Axis Mirrors with Help of a DOE; Calibrating Laser Gas Measurements by Use of Natural CO2; Laser Ranging Simulation Program; Micro-Ball-Lens Optical Switch Driven by SMA Actuator; Evaluation of Charge Storage and Decay in Spacecraft Insulators; Alkaline Capacitors Based on Nitride Nanoparticles; Low-EC-Content Electrolytes for Low-Temperature Li-Ion Cells; Software for a GPS-Reflection Remote-Sensing System; Software for Building Models of 3D Objects via the Internet; "Virtual Cockpit Window" for a Windowless Aerospacecraft; CLARAty Functional-Layer Software; Java Library for Input and Output of Image Data and Metadata; Software for Estimating Costs of Testing Rocket Engines; Energy-Absorbing, Lightweight Wheels; Viscoelastic Vibration Dampers for Turbomachine Blades; Soft Landing of Spacecraft on Energy-Absorbing Self-Deployable Cushions; Pneumatically Actuated Miniature Peristaltic Vacuum Pumps; Miniature Gas-Turbine Power Generator; Pressure-Sensor Assembly Technique; Wafer-Level Membrane-Transfer Process for Fabricating MEMS; A Reactive-Ion Etch for Patterning Piezoelectric Thin Film; Wavelet-Based Real-Time Diagnosis of Complex Systems; Quantum Search in Hilbert Space; Analytic Method for Computing Instrument Pointing Jitter; and Semiselective Optoelectronic Sensors for Monitoring Microbes.

The Effects of Three Methods of Observation on Couples in Interactional Research.

ERIC Educational Resources Information Center

Carpenter, Linda J.; Merkel, William T.

1988-01-01

Assessed the effects of three different methods of observation of couples (one-way mirror, audio recording, and video recording) on 30 volunteer, nonclinical married couples. Results suggest that types of observation do not produce significantly different effects on nonclinical couples. (Author/ABL)

Internal stray radiation measurement for cryogenic infrared imaging systems using a spherical mirror.

PubMed

Tian, Qijie; Chang, Songtao; He, Fengyun; Li, Zhou; Qiao, Yanfeng

2017-06-10

Internal stray radiation is a key factor that influences infrared imaging systems, and its suppression level is an important criterion to evaluate system performance, especially for cryogenic infrared imaging systems, which are highly sensitive to thermal sources. In order to achieve accurate measurement for internal stray radiation, an approach is proposed, which is based on radiometric calibration using a spherical mirror. First of all, the theory of spherical mirror design is introduced. Then, the calibration formula considering the integration time is presented. Following this, the details regarding the measurement method are presented. By placing a spherical mirror in front of the infrared detector, the influence of internal factors of the detector on system output can be obtained. According to the calibration results of the infrared imaging system, the output caused by internal stray radiation can be acquired. Finally, several experiments are performed in a chamber with controllable inside temperatures to validate the theory proposed in this paper. Experimental results show that the measurement results are in good accordance with the theoretical analysis, and demonstrate that the proposed theories are valid and can be employed in practical applications. The proposed method can achieve accurate measurement for internal stray radiation at arbitrary integration time and ambient temperatures. The measurement result can be used to evaluate whether the suppression level meets the system requirement.

Novel utilisation of a circular multi-reflection cell applied to materials ageing experiments

NASA Astrophysics Data System (ADS)

Knox, D. A.; King, A. K.; McNaghten, E. D.; Brooks, S. J.; Martin, P. A.; Pimblott, S. M.

2015-04-01

We report on the novel utilisation of a circular multi-reflection (CMR) cell applied to materials ageing experiments. This enabled trace gas detection within a narrow interfacial region located between two sample materials and remotely interrogated with near-infrared sources combined with fibre-optic coupling. Tunable diode laser absorption spectroscopy was used to detect water vapour and carbon dioxide at wavelengths near 1,358 and 2,004 nm, respectively, with corresponding detection limits of 7 and 1,139 ppm m Hz-0.5. The minimum detectable absorption was estimated to be 2.82 × 10-3 over a 1-s average. In addition, broadband absorption spectroscopy was carried out for the detection of acetic acid, using a super-luminescent light emitting diode centred around 1,430 nm. The 69 cm measurement pathlength was limited by poor manufacturing tolerances of the spherical CMR mirrors and the consequent difficulty of collecting all the cell output light.

Optimization of passively mode-locked quasi-continuously diode-pumped Nd:GdVO4 laser in bounce geometry

NASA Astrophysics Data System (ADS)

Frank, Milan; Jelínek, Michal; Kubeček, Václav

2015-01-01

In this paper the operation of pulsed diode-pumped Nd:GdVO4 laser oscillator in bounce geometry passively modelocked using semiconductor saturable absorber mirror (SAM), generating microjoule level picosecond pulses at wavelength of 1063 nm, is reported. Optimization of the output coupling for generation either Q-switched mode locked pulse trains or cavity dumped single pulses with maximum energy was performed, which resulted in extraction of single pulses as short as 10 ps and energy of 20 uJ. In comparison with the previous results obtained with this Nd:GdVO4 oscillator and saturable absorber in transmission mode, the achieved pulse duration is five times shorter. Using different absorbers and parameters of single pulse extraction enables generation of the pulses with duration up to 100 ps with the energy in the range from 10 to 20 μJ.

Maximizing output power of a low-gain laser system.

PubMed

Carroll, D L; Sentman, L H

1993-07-20

Rigrod theory was used to model outcoupled power from a low-gain laser with good accuracy. For a low-gain overtone cw HF chemical laser, Rigrod theory shows that a higher medium saturation yields a higher overall overtone efficiency, but does not necessarily yield a higher measurable power (power in the bucket). For low-absorption-scattering loss overtone mirrors and a 5% penalty in outcoupled power, the intracavity flux and hence the mirror loading may be reduced by more than a factor of 2 when the gain length is long enough to saturate the medium well. For the University of Illinois at Urbana-Champaign overtone laser that has an extensive database with well-characterized mirrors for which the Rigrod parameters g(0) and I(sat) were firmly established, the accuracy to which the reflectivities of high-reflectivity overtone mirrors can be deduced by using measured mirror transmissivities, measured outcoupled power, and Rigrod theory is approximatly ±0.07%. This method of accurately deducing mirror reflectivities may be applicable to other low-gain laser systems that use high-reflectivity mirrors at different wavelengths. The maximum overtone efficiency is estimated to be approximately 80%-100%.

High power continuous-wave titanium:sapphire laser

DOEpatents

Erbert, G.V.; Bass, I.L.; Hackel, R.P.; Jenkins, S.L.; Kanz, V.K.; Paisner, J.A.

1993-09-21

A high-power continuous-wave laser resonator is provided, wherein first, second, third, fourth, fifth and sixth mirrors form a double-Z optical cavity. A first Ti:sapphire rod is disposed between the second and third mirrors and at the mid-point of the length of the optical cavity, and a second Ti:sapphire rod is disposed between the fourth and fifth mirrors at a quarter-length point in the optical cavity. Each Ti:sapphire rod is pumped by two counter-propagating pump beams from a pair of argon-ion lasers. For narrow band operation, a 3-plate birefringent filter and an etalon are disposed in the optical cavity so that the spectral output of the laser consists of 5 adjacent cavity modes. For increased power, seventy and eighth mirrors are disposed between the first and second mirrors to form a triple-Z optical cavity. A third Ti:sapphire rod is disposed between the seventh and eighth mirrors at the other quarter-length point in the optical cavity, and is pumped by two counter-propagating pump beams from a third pair of argon-ion lasers. 5 figures.

Multiple-image oscilloscope camera

DOEpatents

Yasillo, Nicholas J.

1978-01-01

An optical device for placing automatically a plurality of images at selected locations on one film comprises a stepping motor coupled to a rotating mirror and lens. A mechanical connection from the mirror controls an electronic logical system to allow rotation of the mirror to place a focused image at the desired preselected location. The device is of especial utility when used to place four images on a single film to record oscilloscope views obtained in gamma radiography.

The mirror neuron system and the strange case of Broca's area.

PubMed

Cerri, Gabriella; Cabinio, Monia; Blasi, Valeria; Borroni, Paola; Iadanza, Antonella; Fava, Enrica; Fornia, Luca; Ferpozzi, Valentina; Riva, Marco; Casarotti, Alessandra; Martinelli Boneschi, Filippo; Falini, Andrea; Bello, Lorenzo

2015-03-01

Mirror neurons, originally described in the monkey premotor area F5, are embedded in a frontoparietal network for action execution and observation. A similar Mirror Neuron System (MNS) exists in humans, including precentral gyrus, inferior parietal lobule, and superior temporal sulcus. Controversial is the inclusion of Broca's area, as homologous to F5, a relevant issue in light of the mirror hypothesis of language evolution, which postulates a key role of Broca's area in action/speech perception/production. We assess "mirror" properties of this area by combining neuroimaging and intraoperative neurophysiological techniques. Our results show that Broca's area is minimally involved in action observation and has no motor output on hand or phonoarticulatory muscles, challenging its inclusion in the MNS. The presence of these functions in premotor BA6 makes this area the likely homologue of F5 suggesting that the MNS may be involved in the representation of articulatory rather than semantic components of speech. © 2014 Wiley Periodicals, Inc.

Numerical study of low-current steady arcs

NASA Technical Reports Server (NTRS)

Kim, S. C.; Nagamatsu, H. T.

1992-01-01

The development of a high-efficiency CW YLF laser doped with Er,Tm,Ho: and featuring a strongly focusing resonator that collects a high density of pump power on the active crystal is described. The emission is investigated at 2.06 microns and a tuning range both at liquid-nitrogen (77 K) and at dry-ice (210 K) temperature. The noise characteristics and the long-term power stability of the laser is studied with an eye to employing this source for high-resolution spectroscopy in the 2-micron wavelength region. The detection of several absorption lines of NH3 at low pressure is described. The output power of the laser as a function of the power impinging on the crystal for different transmission of the output mirror is illustrated. The best result obtained is 1.46 W output for 3.2 W of argon pump. The minimum threshold achieved is 3.5 mW with a 1-percent transmission mirror. It is concluded that it is possible to develop a highly efficient Ho:YLF laser featuring low noise and sufficient tunability for high-resolution spectroscopy in the 2-micron region.

Quantum synchronization of chaotic oscillator behaviors among coupled BEC-optomechanical systems

NASA Astrophysics Data System (ADS)

Li, Wenlin; Li, Chong; Song, Heshan

2017-03-01

We consider and theoretically analyze a Bose-Einstein condensate (BEC) trapped inside an optomechanical system consisting of single-mode optical cavity with a moving end mirror. The BEC is formally analogous to a mirror driven by radiation pressure with strong nonlinear coupling. Such a nonlinear enhancement can make the oscillator display chaotic behavior. By establishing proper oscillator couplings, we find that this chaotic motion can be synchronized with other oscillators, even an oscillator network. We also discuss the scheme feasibility by analyzing recent experiment parameters. Our results provide a promising platform for the quantum signal transmission and quantum logic control, and they are of potential applications in quantum information processing and quantum networks.

Fast-axial turbulent flow CO2 laser output characteristics and scaling parameters

NASA Astrophysics Data System (ADS)

Dembovetsky, V. V.; Zavalova, Valentina Y.; Zavalov, Yuri N.

1996-04-01

The paper presents the experimental results of evaluating the output characteristics of TLA- 600 carbon-dioxide laser with axial turbulent gas flow, as well as the results of numerical modeling. The output characteristic and spatial distribution of laser beam were measured with regard to specific energy input, working mixture pressure, active media length and output mirror reflection. The paper presents the results of experimental and theoretical study and design decisions on a succession of similar type industrial carbon-dioxide lasers with fast-axial gas-flow and dc discharge excitation of active medium developed at NICTL RAN. As an illustration, characteristics of the TLA-600 laser are cited.

Compact Fiber-Parametric Devices for Biophotonics Applications

DTIC Science & Technology

2012-03-01

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

Experimental Investigation and Computer Modeling of Optical Switching in Distributed Bragg Reflector and Vertical Cavity Surface Emitting Laser Structures.

DTIC Science & Technology

1995-12-01

of a Molecular Beam Epitaxy (MBE) system prior to growing a Vertical Cavity Surface Emitting Laser ( VCSEL ). VCSEL bistability is discussed later in...addition, optical bistability 1 in the reflectivity of a DBR, as well as in the lasing power, wavelength, and beam divergence of a lasing VCSEL are...Spectral Reflectivity of AlGaAs/AlAs VCSEL Top DBR Mirror Cavity Bottom DBR Mirror Substrate Output Beam Resonance Pump Minimum Stop Band Figure 2. VCSEL

Cavity optomechanical coupling assisted by an atomic gas

NASA Astrophysics Data System (ADS)

Ian, H.; Gong, Z. R.; Liu, Yu-Xi; Sun, C. P.; Nori, Franco

2008-07-01

We theoretically study a cavity filled with atoms, which provides the optical-mechanical interaction between the modified cavity photonic field and a oscillating mirror at one end. We show that the cavity field “dresses” these atoms, producing two types of polaritons, effectively enhancing the radiation pressure of the cavity field upon the oscillating mirror, as well as establishing an additional squeezing mode of the oscillating mirror. This squeezing produces an adiabatic entanglement, which is absent in usual vacuum cavities, between the oscillating mirror and the rest of the system. We analyze the entanglement and quantify it using the Loschmidt echo and fidelity.

Molecular spectroscopy from 5-12 μm using an OP-GaP OPO

NASA Astrophysics Data System (ADS)

Maidment, Luke; Schunemann, Peter G.; Reid, Derryck T.

2017-02-01

We report a femtosecond optical parametric oscillator (OPO) based on the new semiconductor gain material orientation patterned gallium phosphide (OP-GaP) and being the first example of a broadband OPO operating across the molecular fingerprint region. OP-GaP crystals with lengths of 1 mm and several patterning periods were diced, polished, and antireflection (AR) coated for near- to mid-infrared wavelengths. We configured a synchronously pumped OP-GaP OPO in a 101.2-MHz resonator with high reflectivity from 1.15-1.35 μm, pumped with 150-fs pulses from a 1040-nm femtosecond laser (Chromacity Spark). The coating of one spherical mirror was optimized for transmission at the pump wavelength of 1040 nm and for high reflectivity at the resonant signal wavelength in a range from 1.15-1.35 μm, while the other spherical mirror collimated the idler beam emerging from the OP-GaP crystal and was silver coated to provide high reflectivity for all idler wavelengths. This collimated idler beam was output-coupled from the cavity by transmission through a plane mirror coated with high transmission for the idler wavelengths (5-12 μm) and high reflectivity for the signal wavelengths (1.15-1.35 μm) on an infrared-transparent ZnSe substrate. Idler spectra centered from 5.4-11.8 μm and extending to 12.5 μm were collected. The maximum average power was 55 mW at 5.4 μm with 7.5 mW being recorded at 11.8 μm. Details of Fourier transform spectroscopy using water vapor and a polystyrene reference standard are presented.

Non-imaging Optics of multi-LED light source for hyperspectral imaging

NASA Astrophysics Data System (ADS)

Islam, Kashif; Gosnell, Martin E.; Ploschner, Martin; Anwer, Ayad G.; Goldys, Ewa M.

2016-12-01

The main objective of our work was to design a light source which should be capable to collect and illuminate light of LEDs at the smaller aperture of cone (9mm) which could be either coupled with secondary optics of a microscope or utilized independently for hyperspectral studies. Optimized performance of cone was assessed for different substrates (diffused glass silica, Alumina, Zerodur glass, acrylic plastic) and coating surfaces (white diffused, flat white paint, standard mirror) using a simulation software. The parameters optimized for truncated cone include slanting length and Top Major R (Larger diameter of cone) which were also varied from 10 to 350 mm and 10 to 80 mm respectively. In order to see affect of LED positions on cone efficiency, the positions of LED were varied from central axis to off-axis. Similarly, interLED distance was varied from 2 mm to 6 mm to reckon its effect on the performance of cone. The optimized Slant length (80 mm) and Top Major R (50 mm) were determined for substrates (glass zerodur or acrylic plastic) and coating surface (standard mirror). The output profile of truncated source was found non uniform, which is a typical presentation of non imaging optics problem. The maximum efficiency of cone has been found for LED at the centre and it was found decreasing as LED moves away from the central axis. Moreover, shorter the interLED distance, better is the performance of cone. The primary optics of cone shaped light source is capable to lit visible and UV LEDs in practical design. The optimum parameters obtained through simulations could be implemented in the fabrication procedure if the reflectance of source would have been maintained upto finish level of a standard mirror.

Solar photovoltaic flat panel applications experiment at the Oklahoma Center for Science and Arts. Final report, September 30, 1978-May 31, 1979

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

Not Available

Science Applications, Inc., has designed a photovoltaic power system for the Oklahoma Center for Science and Arts in Oklahoma City. The system, with a basic rating of 250 kW, is enhanced to a summer peak output of 350 kW through the use of augmentation glass mirror reflectors which are arranged to maximize summer output and to match the summer output to the summer load. The baseline system consists of 3780 photovoltaic collector modules, utilizing polycrystalline silicon cells, and companion mirror reflectors arranged in modular fashion on the roof of the Center. Total system output is more than 450 MWh, ofmore » which over 420 MWh is used on-site to displace about 65 percent of the current on site load, or about 43 percent of the projected (1981) load. Another 30 MWh is returned to the utility under a buyback agreement. The total amount of energy displaced per year is approximately 850 barrels of oil, or Btu equivalent. The entire system is fully automatic, and is designed for safety and ease in maintenance and repair. It is equipped with the appropriate controls, a power monitoring system, a weather station, and other sensors for acquisition of experimental data.« less

Diode-side-pumped 131 W, 1319 nm single-wavelength cw Nd:YAG laser.

PubMed

Haiyong, Zhu; Ge, Zhang; Chenghui, Huang; Yong, Wei; Lingxiong, Huang; Jing, Chen; Weidong, Chen; Zhenqiang, Chen

2007-01-20

A diode-side-pumped high-power 1319 nm single-wavelength Nd:YAG continuous wave (cw) laser is described. Through reasonable coating design of the cavity mirrors, the 1064 nm strongest line as well as the 1338 nm one have been successfully suppressed. The laser output powers corresponding to four groups of different output couplers operating at 1319 nm single wavelength have been compared. The output coupler with the transmission T=5.3% has the highest output power, and a 131 W cw output power was achieved at the pumping power of 555 W. The optical-optical conversion efficiency is 23.6%, and the slope efficiency is 46%. The output power is higher than the total output power of the dual-wavelength laser operating at 1319 nm and 1338 nm in the experiment.

Integrated fiber-mirror ion trap for strong ion-cavity coupling

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

Brandstätter, B., E-mail: birgit.brandstaetter@uibk.ac.at; Schüppert, K.; Casabone, B.

2013-12-15

We present and characterize fiber mirrors and a miniaturized ion-trap design developed to integrate a fiber-based Fabry-Perot cavity (FFPC) with a linear Paul trap for use in cavity-QED experiments with trapped ions. Our fiber-mirror fabrication process not only enables the construction of FFPCs with small mode volumes, but also allows us to minimize the influence of the dielectric fiber mirrors on the trapped-ion pseudopotential. We discuss the effect of clipping losses for long FFPCs and the effect of angular and lateral displacements on the coupling efficiencies between cavity and fiber. Optical profilometry allows us to determine the radii of curvaturemore » and ellipticities of the fiber mirrors. From finesse measurements, we infer a single-atom cooperativity of up to 12 for FFPCs longer than 200 μm in length; comparison to cavities constructed with reference substrate mirrors produced in the same coating run indicates that our FFPCs have similar scattering losses. We characterize the birefringence of our fiber mirrors, finding that careful fiber-mirror selection enables us to construct FFPCs with degenerate polarization modes. As FFPCs are novel devices, we describe procedures developed for handling, aligning, and cleaning them. We discuss experiments to anneal fiber mirrors and explore the influence of the atmosphere under which annealing occurs on coating losses, finding that annealing under vacuum increases the losses for our reference substrate mirrors. X-ray photoelectron spectroscopy measurements indicate that these losses may be attributable to oxygen depletion in the mirror coating. Special design considerations enable us to introduce a FFPC into a trapped ion setup. Our unique linear Paul trap design provides clearance for such a cavity and is miniaturized to shield trapped ions from the dielectric fiber mirrors. We numerically calculate the trap potential in the absence of fibers. In the experiment additional electrodes can be used to compensate distortions of the potential due to the fibers. Home-built fiber feedthroughs connect the FFPC to external optics, and an integrated nanopositioning system affords the possibility of retracting or realigning the cavity without breaking vacuum.« less

A Proposal to Develop and Test a Fibre-Optic Coupled Solar Thermal Propulsion System for Microsatellites

DTIC Science & Technology

2006-03-01

high numerical aperture fibre optics. Applying fibre optics to STP allows the solar concentrator mirror to be mechanically decoupled from the solar...Applying fibre optics to STP allows the solar concentrator mirror to be mechanically decoupled from the solar heat exchanger as well as granting...concentration is achieved via an optical concentrating system, such as a series of lenses or mirrors . This concentrated sunlight impinges on a blackbody

Micromachined mirrors for raster-scanning displays and optical fiber switches

NASA Astrophysics Data System (ADS)

Hagelin, Paul Merritt

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

Design and optimization of the CFRP mirror components

NASA Astrophysics Data System (ADS)

Wei, Lei; Zhang, Lei; Gong, Xiaoxue

2017-09-01

As carbon fiber reinforced polymer (CFRP) material has been developed and demonstrated as an effective material in lightweight telescope reflector manufacturing recently, the authors of this article have extended to apply this material on the lightweight space camera mirror design and fabrication. By CFRP composite laminate design and optimization using finite element method (FEM) analysis, a spherical mirror with φ316 mm diameter whose core cell reinforcement is an isogrid configuration is fabricated. Compared with traditional ways of applying ultra-low-expansion glass (ULE) on the CFRP mirror surface, the method of nickel electroplating on the surface effectively reduces the processing cost and difficulty of the CFRP mirror. Through the FEM analysis, the first order resonance frequency of the CFRP mirror components reaches up to 652.3 Hz. Under gravity affection coupling with +5°C temperature rising, the mirror surface shape root-mean-square values (RMS) at the optical axis horizontal state is 5.74 nm, which meets mechanical and optical requirements of the mirror components on space camera.

Hybrid Electrostatic/Flextensional Mirror for Lightweight, Large-Aperture, and Cryogenic Space Telescopes

NASA Technical Reports Server (NTRS)

Patrick, Brian; Moore, James; Hackenberger, Wesley; Jiang, Xiaoning

2013-01-01

A lightweight, cryogenically capable, scalable, deformable mirror has been developed for space telescopes. This innovation makes use of polymer-based membrane mirror technology to enable large-aperture mirrors that can be easily launched and deployed. The key component of this innovation is a lightweight, large-stroke, cryogenic actuator array that combines the high degree of mirror figure control needed with a large actuator influence function. The latter aspect of the innovation allows membrane mirror figure correction with a relatively low actuator density, preserving the lightweight attributes of the system. The principal components of this technology are lightweight, low-profile, high-stroke, cryogenic-capable piezoelectric actuators based on PMN-PT (piezoelectric lead magnesium niobate-lead titanate) single-crystal configured in a flextensional actuator format; high-quality, low-thermal-expansion polymer membrane mirror materials developed by NeXolve; and electrostatic coupling between the membrane mirror and the piezoelectric actuator assembly to minimize problems such as actuator print-through.

Spontaneous mirror left-right symmetry breaking for leptogenesis parametrized by Majorana neutrino mass matrix

NASA Astrophysics Data System (ADS)

Gu, Pei-Hong

2017-10-01

We introduce a mirror copy of the ordinary fermions and Higgs scalars for embedding the SU(2) L × U(1) Y electroweak gauge symmetry into an SU(2) L × SU(2) R × U(1) B-L left-right gauge symmetry. We then show the spontaneous left-right symmetry breaking can automatically break the parity symmetry motivated by solving the strong CP problem. Through the SU(2) R gauge interactions, a mirror Majorana neutrino can decay into a mirror charged lepton and two mirror quarks. Consequently we can obtain a lepton asymmetry stored in the mirror charged leptons. The Yukawa couplings of the mirror and ordinary charged fermions to a dark matter scalar then can transfer the mirror lepton asymmetry to an ordinary lepton asymmetry which provides a solution to the cosmic baryon asymmetry in association with the SU(2) L sphaleron processes. In this scenario, the baryon asymmetry can be well described by the neutrino mass matrix up to an overall factor.

Negative coupled inductors for polyphase choppers

NASA Technical Reports Server (NTRS)

Jamieson, Robert S. (Inventor)

1984-01-01

A technique for negatively coupling the outputs of polyphase choppers is disclosed, wherein the output inductance of each phase is divided into two windings, and each winding is negatively coupled to a corresponding winding of a neighboring phase. In a preferred embodiment for a three-phase chopper circuit, the output inductance of phase A is divided into windings 100 and 102, the output inductance of phase B is divided into windings 110 and 112, and the output inductance of phase C is divided into windings 120 and 122. Pairs of windings 100 and 110, 112 and 120, and 102 and 122 are respectively disposed in transformers arranged for negatively coupling the windings of each pair.

Fiber-linked interferometric pressure sensor

NASA Technical Reports Server (NTRS)

Beheim, G.; Fritsch, K.; Poorman, R. N.

1987-01-01

A fiber-optic pressure sensor is described which uses a diaphragm to modulate the mirror separation of a Fabry-Perot cavity (the sensing cavity). A multimode optical fiber delivers broadband light to the sensing cavity and returns the spectrally modulated light which the cavity reflects. The sensor's output spectrum is analyzed using a tunable Fabry-Perot cavity (the reference cavity) to determine the mismatch in the mirror separations of the two cavities. An electronic servo control uses this result to cause the mirror separation of the reference cavity to equal that of the sensing cavity. The displacement of the pressure-sensing diaphragm is then obtained by measuring the capacitance of the reference cavity's metal-coated mirrors. Relative to other fiber-optic sensors, an important advantage of this instrument is its high immunity to the effects of variations in both the transmissivity of the fiber link and the wavelength of the optical source.

Mode-medium instability and its correction with a Gaussian-reflectivity mirror

NASA Technical Reports Server (NTRS)

Webster, K. L.; Sung, C. C.

1992-01-01

A high-power CO2 laser beam is known to deteriorate after a few microseconds due to a mode-medium instability (MMI) which results from an intensity-dependent heating rate related to the vibrational-to-translational decay of the upper and lower CO2 lasing levels. An iterative numerical technique is developed to model the time evolution of the beam as it is affected by the MMI. The technique is used to study the MMI in an unstable CO2 resonator with a hard-edge output mirror for different parameters like the Fresnel number and the gas density. The results show that the mode of the hard edge unstable resonator deteriorates because of the diffraction ripples in the mode. A Gaussian-reflectivity mirror was used to correct the MMI. This mirror produces a smoother intensity profile which significantly reduces the effects of the MMI. Quantitative results on peak density variation and beam quality are presented.

Mode-medium instability and its correction with a Gaussian reflectivity mirror

NASA Technical Reports Server (NTRS)

Webster, K. L.; Sung, C. C.

1990-01-01

A high power CO2 laser beam is known to deteriorate after a few microseconds due to a mode-medium instability (MMI) which results from an intensity dependent heating rate related to the vibrational-to-translational decay of the upper and lower CO2 lasing levels. An iterative numerical technique is developed to model the time evolution of the beam as it is affected by the MMI. The technique is used to study the MMI in an unstable CO2 resonator with a hard-edge output mirror for different parameters like the Fresnel number and the gas density. The results show that the mode of the hard edge unstable resonator deteriorates because of the diffraction ripples in the mode. A Gaussian-reflectivity mirror was used to correct the MMI. This mirror produces a smoother intensity profile which significantly reduces the effects of the MMI. Quantitative results on peak density variation and beam quality are presented.

Controllable optical bistability in a three-mode optomechanical system with atom-cavity-mirror couplings

NASA Astrophysics Data System (ADS)

Chen, Bin; Wang, Xiao-Fang; Yan, Jia-Kai; Zhu, Xiao-Fei; Jiang, Cheng

2018-01-01

We theoretically investigate the optical bistable behavior in a three-mode optomechanical system with atom-cavity-mirror couplings. The effects of the cavity-pump detuning and the pump power on the bistable behavior are discussed detailedly, the impacts of the atom-pump detuning and the atom-cavity coupling strength on the bistability of the system are also explored, and the influences of the cavity-resonator coupling strength and the cavity decay rate are also taken into consideration. The numerical results demonstrate that by tuning these parameters the bistable behavior of the system can be freely switched on or off, and the threshold of the pump power for the bistability as well as the bistable region width can also be effectively controlled. These results can find potential applications in optical bistable switch in the quantum information processing.

[The study of CO2 cavity enhanced absorption and highly sensitive absorption spectroscopy].

PubMed

Pei, Shi-Xin; Gao, Xiao-Ming; Cui, Fen-Ping; Huang, Wei; Shao, Jie; Fan, Hong; Zhang, Wei-Jun

2005-12-01

Cavity enhanced absorption spectroscopy (CEAS) is a new spectral technology that is based on the cavity ring down absorption spectroscopy. In the present paper, a DFB encapsulation narrow line width tunable diode laser (TDL) was used as the light source. At the center output, the TDL radiation wavelength was 1.573 microm, and an optical cavity, which consisted of two high reflectivity mirrors (near 1.573 microm, the mirror reflectivity was about 0.994%), was used as a sample cell. A wavemeter was used to record the accurate frequency of the laser radiation. In the experiment, the method of scanning the optical cavity to change the cavity mode was used, when the laser frequency was coincident with one of the cavity mode; the laser radiation was coupled into the optical cavity and the detector could receive the light signals that escaped the optical cavity. As a result, the absorption spectrum of carbon dioxide weak absorption at low pressure was obtained with an absorption intensity of 1.816 x 10(-23) cm(-1) x (molecule x cm(-2)(-1) in a sample cell with a length of only 33.5 cm. An absorption sensitivity of about 3.62 x 10(-7) cm(-1) has been achieved. The experiment result indicated that the cavity enhanced absorption spectroscopy has the advantage of high sensivity, simple experimental setup, and easy operation.

MAGNETIC DENSITOMETER

DOEpatents

McCann, J.A.; Jones, R.H.

1961-08-15

A magnetic densitometer for locating defects and metallic inclusions in materials is described. The apparatus consists of two primary coils connected in series opposition and adapted te be placed in inductive relation to the material under test, a source of constant frequency alternating current coupled across the primary coil combination, a pick-up coil disposed in symmetrical inductive relationship with said primary coils, a phase-shifter coupled to the output of the energizing source. The output of the phase-shifter is coupled in series with the pick-up coil. An amplifier is provided selective to the third harmonic of the energizing source frequency. The series combination of the pick-up coil and the phase-shifter output are connected across the input of the amplifier, and an amplitude comparitor is coupled to the output of the amplifier and the energizing source for comparing the instantaneous amplitude of the amplifier output and the instantaneous output of the energizing source and producing an output proportional to the difference in amplitude. A recorder is coupled to the output of the amplitude comparison means to give an indication of the amplitude difference, thereby providing a permanent presentation of the character of the changes in characteristics exhibited by the material under test. (AEC)

Second-harmonic generation from a positive-negative index material heterostructure.

PubMed

Mattiucci, Nadia; D'Aguanno, Giuseppe; Bloemer, Mark J; Scalora, Michael

2005-12-01

Resonant cavities have been widely used in the past to enhance material, nonlinear response. Traditional mirrors include metallic films and distributed Bragg reflectors. In this paper we propose negative index material mirrors as a third alternative. With the help of a rigorous Green function approach, we investigate second harmonic generation from single and coupled cavities, and theoretically prove that negative index material mirrors can raise the nonlinear conversion efficiency of a bulk material by at least four orders of magnitude compared to a bulk medium.

Polarization/Spatial Combining of Laser-Diode Pump Beams

NASA Technical Reports Server (NTRS)

Gelsinger, Paul; Liu, Duncan

2008-01-01

A breadboard version of an optical beam combiner is depicted which make it possible to use the outputs of any or all of four multimode laser diodes to pump a non-planar ring oscillator (NPRO) laser. The output of each laser diode has a single-mode profile in the meridional plane containing an axis denoted the 'fast' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis. One of the purposes served by the beam-combining optics is to reduce the fast-axis numerical aperture (NA) of the laser-diode output to match the NA of the optical fiber. Along the slow axis, the unmodified laser-diode NA is already well matched to the fiber optic NA, so no further slow-axis beam shaping is needed. In this beam combiner, the laser-diode outputs are collimated by aspherical lenses, then half-wave plates and polarizing beam splitters are used to combine the four collimated beams into two beams. Spatial combination of the two beams and coupling into the optical fiber is effected by use of anamorphic prisms, mirrors, and a focusing lens. The anamorphic prisms are critical elements in the NA-matching scheme, in that they reduce the fast-axis beam width to 1/6 of its original values. Inasmuch as no slow-axis beam shaping is needed, the collimating and focusing lenses are matched for 1:1 iumaging. Because these lenses are well corrected for infinite conjugates the combiner offers diffraction-limited performance along both the fast and slow axes.

Robust optical signal-to-noise ratio monitoring scheme using a phase-modulator-embedded fiber loop mirror.

PubMed

Ku, Yuen-Ching; Chan, Chun-Kit; Chen, Lian-Kuan

2007-06-15

We propose and experimentally demonstrate a novel in-band optical signal-to-noise ratio (OSNR) monitoring technique using a phase-modulator-embedded fiber loop mirror. This technique measures the in-band OSNR accurately by observing the output power of a fiber loop mirror filter, where the transmittance is adjusted by an embedded phase modulator driven by a low-frequency periodic signal. The measurement errors are less than 0.5 dB for an OSNR between 0 and 40 dB in a 10 Gbit/s non-return-to-zero system. This technique was also shown experimentally to have high robustness against various system impairments and high feasibility to be deployed in practical implementation.

Hyperbola-parabola primary mirror in Cassegrain optical antenna to improve transmission efficiency.

PubMed

Zhang, Li; Chen, Lu; Yang, HuaJun; Jiang, Ping; Mao, Shengqian; Caiyang, Weinan

2015-08-20

An optical model with a hyperbola-parabola primary mirror added in the Cassegrain optical antenna, which can effectively improve the transmission efficiency, is proposed in this paper. The optimum parameters of a hyperbola-parabola primary mirror and a secondary mirror for the optical antenna system have been designed and analyzed in detail. The parabola-hyperbola primary structure optical antenna is obtained to improve the transmission efficiency of 10.60% in theory, and the simulation efficiency changed 9.359%. For different deflection angles to the receiving antenna with the emit antenna, the coupling efficiency curve of the optical antenna has been obtained.

V-shaped resonators for addition of broad-area laser diode arrays

DOEpatents

Liu, Bo; Liu, Yun; Braiman, Yehuda Y.

2012-12-25

A system and method for addition of broad-area semiconductor laser diode arrays are described. The system can include an array of laser diodes, a V-shaped external cavity, and grating systems to provide feedback for phase-locking of the laser diode array. A V-shaped mirror used to couple the laser diode emissions along two optical paths can be a V-shaped prism mirror, a V-shaped stepped mirror or include multiple V-shaped micro-mirrors. The V-shaped external cavity can be a ring cavity. The system can include an external injection laser to further improve coherence and phase-locking.

Gain measurements and spatial coherence in neon-like x-ray lasers

NASA Astrophysics Data System (ADS)

Krishnan, J.; Cairns, C.; Dwivedi, L.; Holden, M.; Key, M. H.; Lewis, C. L. S.; MacPhee, A.; Neely, D.; Norreys, P. A.; Pert, G. J.; Ramsden, S. A.; Smith, C. G.; Tallents, G. J.; Zhang, J.

1995-05-01

Many of the applications with x-ray lasers require high quality output radiation with properties such as short wavelength and a high degree of coherence (longitudinal and spatial). Ne-like Yttrium (Z=39) is potentially a bright and monochromatic XUV lasing medium. The output at 15.5 nm is monochromatic due to the overlap of the J=2-1 and J=0-1 lines. A gain coefficient of 3±1 was obtained at 15.5 nm by irradiating 100 μm wide yttrium stripes at 6×1013 W/cm2 with 1.06 μm, 650 ps pulses from the Rutherford Appleton Laboratory VULCAN laser. We have investigated improving x-ray laser spatial coherence utilizing a series of amplifiers instead of the standard double target configuration. An ``injector-amplifier'' scheme was successfully demonstrated with the Ne-like Ge x-ray laser. A spatially small and coherent part of the 23 nm beam from the standard double target geometry has been relayed using a W/Si multilayer mirror onto a single or double target configuration situated at a distance of ˜1.5 m from the mirror and pumped by two 150 mm diameter beams of VULCAN laser. A beam ``foot-print monitor'' was employed with a flat mirror to relay 23 nm output onto a film pack to record the spatial variation of the x-ray laser beam. Analyzing the fringes obtained through a cross-wire placed in front of the beam shows that an increase in spatial coherence was achieved by adding amplifiers to the x-ray laser beam line.

Programmable high-output-impedance, large-voltage compliance, microstimulator for low-voltage biomedical applications.

PubMed

Farahmand, Sina; Maghami, Mohammad Hossein; Sodagar, Amir M

2012-01-01

This paper reports on the design of a programmable, high output impedance, large voltage compliance microstimulator for low-voltage biomedical applications. A 6-bit binary-weighted digital to analog converter (DAC) is used to generate biphasic stimulus current pulses. A compact current mirror with large output voltage compliance and high output resistance conveys the current pulses to the target tissue. Designed and simulated in a standard 0.18µm CMOS process, the microstimulator circuit is capable of delivering a maximum stimulation current of 160µA to a 10-kΩ resistive load. Operated at a 1.8-V supply voltage, the output stage exhibits a voltage compliance of 1.69V and output resistance of 160MΩ at full scale stimulus current. Layout of the core microelectrode circuit measures 25.5µm×31.5µm.

Manifestation of Nonuniversality of Lepton Interactions in Spontaneously Violated Mirror Symmetry

NASA Astrophysics Data System (ADS)

Dyatlov, I. T.

2018-03-01

Data from the LHCb experiments are indicative of a substantial distinction between the B → K (or K*) + e + e - and B → K (or K*) + μ + μ - branching ratios (April 2017). The branching ratio for the e+e- channel is substantially greater than that for the μ + μ - channel, whereas Standard Model (SM) calculations require that they be equal to each other. The above distinction may suggest the existence of a new interaction changing generations and discriminating between leptons that has couplings that are much greater than and are inverse in strength to the SM fermion couplings to the Higgs boson. Under conditions of spontaneously violated mirror symmetry, the coupling of SM particles to the second Higgs scalar that is inevitably present there and which is in principle heavy possesses precisely these properties. An inverse character of this coupling and its strength are not an additional hypothesis but a necessary condition for qualitatively reproducing, in addition, the observed charged-lepton mass hierarchy and the structure of weak lepton mixing—the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix. Within the mirror model being considered, all properties of the new interaction, including its inverse character, are due to the hierarchical character of the quark and charged-lepton mass spectrum.

Constraints on mirror models of dark matter from observable neutron-mirror neutron oscillation

NASA Astrophysics Data System (ADS)

Mohapatra, Rabindra N.; Nussinov, Shmuel

2018-01-01

The process of neutron-mirror neutron oscillation, motivated by symmetric mirror dark matter models, is governed by two parameters: n -n‧ mixing parameter δ and n -n‧ mass splitting Δ. For neutron mirror neutron oscillation to be observable, the splitting between their masses Δ must be small and current experiments lead to δ ≤ 2 ×10-27 GeV and Δ ≤10-24 GeV. We show that in mirror universe models where this process is observable, this small mass splitting constrains the way that one must implement asymmetric inflation to satisfy the limits of Big Bang Nucleosynthesis on the number of effective light degrees of freedom. In particular we find that if asymmetric inflation is implemented by inflaton decay to color or electroweak charged particles, the oscillation is unobservable. Also if one uses SM singlet fields for this purpose, they must be weakly coupled to the SM fields.

Scattering-free optical levitation of a cavity mirror.

PubMed

Guccione, G; Hosseini, M; Adlong, S; Johnsson, M T; Hope, J; Buchler, B C; Lam, P K

2013-11-01

We demonstrate the feasibility of levitating a small mirror using only radiation pressure. In our scheme, the mirror is supported by a tripod where each leg of the tripod is a Fabry-Perot cavity. The macroscopic state of the mirror is coherently coupled to the supporting cavity modes allowing coherent interrogation and manipulation of the mirror motion. The proposed scheme is an extreme example of the optical spring, where a mechanical oscillator is isolated from the environment and its mechanical frequency and macroscopic state can be manipulated solely through optical fields. We model the stability of the system and find a three-dimensional lattice of trapping points where cavity resonances allow for buildup of optical field sufficient to support the weight of the mirror. Our scheme offers a unique platform for studying quantum and classical optomechanics and can potentially be used for precision gravitational field sensing and quantum state generation.

Advanced figure sensor operations and maintenance manual

NASA Technical Reports Server (NTRS)

Robertson, H. J.

1972-01-01

This manual contains procedures for installing, operating, and maintaining the optical figure sensor and its associated electronic controls. The optical figure sensor, a system of integrated components, comprises: (1) a phase measuring modified interferometer employing a single frequency 6328 A laser, and a Vidissector; (2) a two-axis automatic thermal compensation control mount; (3) a five degree of freedom manual adjustment stand; and (4) a control console. This instrument provides real time output data of optical figure errors for spherical mirrors, and is also capable of measuring aspherical mirrors if a null corrector is added.

Modeling of dynamic effects of a low power laser beam

NASA Technical Reports Server (NTRS)

Lawrence, George N.; Scholl, Marija S.; Khatib, AL

1988-01-01

Methods of modeling some of the dynamic effects involved in laser beam propagation through the atmosphere are addressed with emphasis on the development of simple but accurate models which are readily implemented in a physical optics code. A space relay system with a ground based laser facility is considered as an example. The modeling of such characteristic phenomena as laser output distribution, flat and curved mirrors, diffraction propagation, atmospheric effects (aberration and wind shear), adaptive mirrors, jitter, and time integration of power on target, is discussed.

InP/InGaP quantum-dot SESAM mode-locked Alexandrite laser

NASA Astrophysics Data System (ADS)

Ghanbari, Shirin; Fedorova, Ksenia A.; Krysa, Andrey B.; Rafailov, Edik U.; Major, Arkady

2018-02-01

A semiconductor saturable absorber mirror (SESAM) passively mode-locked Alexandrite laser was demonstrated. Using an InP/InGaP quantum-dot saturable absorber mirror, pulse duration of 420 fs at 774 nm was obtained. The laser was pumped at 532 nm and generated 325 mW of average output power in mode-locked regime with a pump power of 7.12 W. To the best of our knowledge, this is the first report of a passively mode-locked Alexandrite laser using SESAM in general and quantum-dot SESAM in particular.

Stable multi-wavelength fiber lasers for temperature measurements using an optical loop mirror.

PubMed

Diaz, Silvia; Socorro, Abian Bentor; Martínez Manuel, Rodolfo; Fernandez, Ruben; Monasterio, Ioseba

2016-10-10

In this work, two novel stable multi-wavelength fiber laser configurations are proposed and demonstrated by using a spool of a single-mode fiber as an optical loop mirror and one or two fiber ring cavities, respectively. The lasers are comprised of fiber Bragg grating reflectors as the oscillation wavelength selecting filters. The influence of the length of the spool of fiber on the laser stability both in terms of wavelength and laser output power was investigated. An application for temperature measurement is also shown.

Position sensor for a fuel injection element in an internal combustion engine

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

Fulkerson, D.E.; Geske, M.L.

1987-08-18

This patent describes an electronic circuit for dynamically sensing and processing signals representative of changes in a magnet field, the circuit comprising: means for sensing a change in a magnetic field external to the circuit and providing an output representative of the change; circuit means electronically coupled with the output of the sensing means for providing an output indicating the presence of the magnetic field change; and a nulling circuit coupled with the output of the sensing means and across the indicating circuit means for nulling the electronic circuit responsive to the sensing means output, to thereby avoid ambient magneticmore » fields temperature and process variations, and wherein the nulling circuit comprises a capacitor coupled to the output of the nulling circuit, means for charging and discharging the capacitor responsive to any imbalance in the input to the nulling circuit, and circuit means coupling the capacitor with the output of the sensing means for nulling any imbalance during the charging or discharging of the capacitor.« less

Bessel-Gauss resonator with spherical output mirror: geometrical- and wave-optics analysis.

PubMed

Gutiérrez-Vega, Julio C; Rodríguez-Masegosa, Rodolfo; Chávez-Cerda, Sabino

2003-11-01

A detailed study of the axicon-based Bessel-Gauss resonator with concave output coupler is presented. We employ a technique to convert the Huygens-Fresnel integral self-consistency equation into a matrix equation and then find the eigenvalues and the eigenfields of the resonator at one time. A paraxial ray analysis is performed to find the self-consistency condition to have stable periodic ray trajectories after one or two round trips. The fast-Fourier-transform-based Fox and Li algorithm is applied to describe the three-dimensional intracavity field distribution. Special attention was directed to the dependence of the output transverse profiles, the losses, and the modal-frequency changes on the curvature of the output coupler and the cavity length. The propagation of the output beam is discussed.

New leptogenesis scenario parametrized by Dirac neutrino mass matrix

NASA Astrophysics Data System (ADS)

Gu, Pei-Hong

2017-10-01

In an S U (3 )c×S U (2 )L×S U (2 )R×U (1 )B -L left-right symmetric framework, we present a new leptogenesis scenario parametrized by the Dirac neutrino mass matrix. Benefiting from the parity symmetry motivated to solve the strong C P problem, the dimensionless couplings of the mirror fields are identified with those of the ordinary fields. In particular, the mirror Dirac neutrinos have a heavy mass matrix proportional to the light mass matrix of the ordinary Dirac neutrinos. Through the S U (2 )R gauge interactions, the mirror neutrinos can decay to generate a lepton asymmetry in the mirror muons and an opposite lepton asymmetry in the mirror electrons. Before the S U (2 )L sphaleron processes stop working, the mirror muons can efficiently decay into the ordinary right-handed leptons with a dark matter scalar, and hence the mirror muon asymmetry can be partially converted to a desired baryon asymmetry.

Optical waveguide circuit board with a surface-mounted optical receiver array

NASA Astrophysics Data System (ADS)

Thomson, J. E.; Levesque, Harold; Savov, Emil; Horwitz, Fred; Booth, Bruce L.; Marchegiano, Joseph E.

1994-03-01

A photonic circuit board is fabricated for potential application to interchip and interboard parallel optical links. The board comprises photolithographically patterned polymer optical waveguides on a conventional glass-epoxy electrical circuit board and a surface-mounted integrated circuit (IC) package that optically and electrically couples to an optoelectronic IC. The waveguide circuits include eight-channel arrays of straights, cross-throughs, curves, self- aligning interconnects to multi-fiber ribbon, and out-of-plane turning mirrors. A coherent, fused bundle of optical fibers couples light between 45-deg waveguide mirrors and a GaAs receiver array in the IC package. The fiber bundle is easily aligned to the mirrors and the receivers and is amenable to surface mounting and hermetic sealing. The waveguide-receiver- array board achieved error-free data rates up to 1.25 Gbits/s per channel, and modal noise was shown to be negligible.

Distributed meandering waveguides (DMWs) for novel photonic circuits (Conference Presentation)

NASA Astrophysics Data System (ADS)

Dag, Ceren B.; Anil, Mehmet Ali; Serpengüzel, Ali

2017-05-01

Meandering waveguide distributed feedback structures are novel integrated photonic lightwave and microwave circuit elements. Meandering waveguide distributed feedback structures with a variety of spectral responses can be designed for a variety of lightwave and microwave circuit element functions. Distributed meandering waveguide (DMW) structures [1] show a variety of spectral behaviors with respect to the number of meandering loop mirrors (MLMs) [2] used in their composition as well as their internal coupling constants (Cs). DMW spectral behaviors include Fano resonances, coupled resonator induced transparency (CRIT), notch, add-drop, comb, and hitless filters. What makes the DMW special is the self-coupling property intrinsic to the DMW's nature. The basic example of DMW's nature is motivated through the analogy between the so-called symmetric meandering resonator (SMR), which consists of two coupled MLMs, and the resonator enhanced Mach-Zehnder interferometer (REMZI) [3]. A SMR shows the same spectral characteristics of Fano resonances with its self-coupling property, similar to the single, distributed and binary self coupled optical waveguide (SCOW) resonators [4]. So far DMWs have been studied for their electric field intensity, phase [5] and phasor responses [6]. The spectral analysis is performed using the coupled electric field analysis and the generalization of single meandering loop mirrors to multiple meandering distributed feedback structures is performed with the transfer matrix method. The building block of the meandering waveguide structures, the meandering loop mirror (MLM), is the integrated analogue of the fiber optic loop mirrors. The meandering resonator (MR) is composed of two uncoupled MLM's. The meandering distributed feedback (MDFB) structure is the DFB of the MLM. The symmetric MR (SMR) is composed of two coupled MLM's, and has the characteristics of a Fano resonator in the general case, and tunable power divider or tunable hitless filter in special cases. The antisymmetric MR (AMR) is composed of two coupled MLM's. The AMR has the characteristics of an add-drop filter in the general case, and coupled resonator induced transparency (CRIT) filter in a special case. The symmetric MDFB (SMDFB) is composed of multiple coupled MLM's. The antisymmetric MDFB (AMDFB) is composed of multiple coupled MLM's. The SMDFB and AMDFB can be utilized as band-pass, Fano, or Lorentzian filters, or Rabi splitters. Distributed meandering waveguide elements with extremely rich spectral and phase responses can be designed with creative combinations of distributed meandering waveguides structures for various novel photonic circuits. References [1 ] C. B. Dağ, M. A. Anıl, and A. Serpengüzel, "Meandering Waveguide Distributed Feedback Lightwave Circuits," J. Lightwave Technol, vol. 33, no. 9, pp. 1691-1702, May 2015. [2] N. J. Doran and D. Wood, "Nonlinear-optical loop mirror," Opt. Lett. vol. 13, no. 1, pp. 56-58, Jan. 1988. [3] L. Zhou and A. W. Poon, "Fano resonance-based electrically reconfigurable add-drop filters in silicon microring resonator-coupled Mach-Zehnder interferometers," Opt. Lett. vol. 32, no. 7, pp. 781-783, Apr. 2007. [4] Z. Zou, L. Zhou, X. Sun, J. Xie, H. Zhu, L. Lu, X. Li, and J. Chen, "Tunable two-stage self-coupled optical waveguide resonators," Opt. Lett. vol. 38, no. 8, pp. 1215-1217, Apr. 2013. [5] C. B. Dağ, M. A. Anıl, and A. Serpengüzel, "Novel distributed feedback lightwave circuit elements," in Proc. SPIE, San Francisco, 2015, vol. 9366, p. 93660A. [6] C. B. Dağ, M. A. Anıl, and A. Serpengüzel, "Meandering Waveguide Distributed Feedback Lightwave Elements: Phasor Diagram Analysis," in Proc. PIERS, Prague, 1986-1990 (2015).

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

Sokollik, Thomas; Shiraishi, Satomi; Osterhoff, Jens

We present experimental results on a tape-drive based plasma mirror which could be used for a compact coupling of a laser beam into a staged laser driven electron accelerator. This novel kind of plasma mirror is suitable for high repetition rates and for high number of laser shots. In order to design a compact, staged laser plasma based accelerator or collider [1], the coupling of the laser beam into the different stages represents one of the key issues. To limit the spatial foot print and thus to realize a high overall acceleration gradient, a concept has to be found whichmore » realizes this in-coupling within a few centimeters (cf. Fig 1). The fluence of the laser pulse several centimeters away from the acceleration stage (focus) exceeds the damage threshold of any available mirror coating. Therefore, in reference [2] a plasma mirror was suggested for this purpose. We present experiments on a tape-drive based plasma mirror which could be used to reflect the focused laser beam into the acceleration stage. Plasma mirrors composed of antireflection coated glass substrates are usually used to improve the temporal laser contrast of laser pulses by several orders of magnitudes [3,4]. This is particularly important for laser interaction with solid matter, such as ion acceleration [5,6] and high harmonic generation on surfaces [7]. Therefore, the laser pulse is weekly focused onto a substrate. The main pulse generates a plasma and is reflected at the critical surface, whereas the low intensity pre-pulse (mainly the Amplified Spontaneous Emission pedestal) will be transmitted through the substrate before the mirror has been triggered. Several publications [3,4] demonstrate a conservation of the spatial beam quality and a reflectivity of about 70 %. The drawback of this technique is the limited repetition rate since for every shot a fresh surface has to be provided. In the past years several novel approaches for high repetition rate plasma mirrors have been developed [2, 8]. Nevertheless, for the staged accelerator scheme a second important requirement has to be considered. Since the electron beam has to propagate through the mirror, the thickness of the substrate has to be as thin as possible to reduce the distortion of the electron beam. A tape of only several micrometer thickness can overcome these disadvantages. It can be used with a sufficient repetition rate while it allows the electron beam to propagate through with a minimum of scattering.« less

Comparative study of high power Tm:YLF and Tm:LLF slab lasers in continuous wave regime.

PubMed

Berrou, Antoine; Collett, Oliver J P; Morris, Daniel; Esser, M J Daniel

2018-04-16

We report on Tm:YLF and Tm:LLF slab lasers (1.5 x 11 x 20 mm 3 ) end pumped from one end with a high-brightness 792 nm laser diode stack. These two lasers are compared under identical pump conditions in continuous-wave regime. A stronger negative thermal lens in Tm:LLF than in Tm:YLF is highlighted, making it more difficult to operate the Tm:LLF laser under stable lasing conditions. In a configuration where the high reflectivity cavity mirror has a radius of curvature of r = 150 mm, the Tm:YLF (Tm:LLF) laser produces a maximum output power of 150 W (143 W) for 428 W of incident pump power (respectively). For a second cavity configuration where the high reflectivity cavity mirror has a radius of curvature of r = 500 mm, the Tm:YLF laser produces a maximum output power of 164 W for 412 W of incident pump power and a 57% slope efficiency with respect to the absorbed pump power. The emitted wavelength of these two lasers are measured as a function of the output coupler reflectivity and it shows that Tm:LLF laser emits at a longer wavelength than Tm:YLF.

Wavelength-Agile External-Cavity Diode Laser for DWDM

NASA Technical Reports Server (NTRS)

Pilgrim, Jeffrey S.; Bomse, David S.

2006-01-01

A prototype external-cavity diode laser (ECDL) has been developed for communication systems utilizing dense wavelength- division multiplexing (DWDM). This ECDL is an updated version of the ECDL reported in Wavelength-Agile External- Cavity Diode Laser (LEW-17090), NASA Tech Briefs, Vol. 25, No. 11 (November 2001), page 14a. To recapitulate: The wavelength-agile ECDL combines the stability of an external-cavity laser with the wavelength agility of a diode laser. Wavelength is modulated by modulating the injection current of the diode-laser gain element. The external cavity is a Littman-Metcalf resonator, in which the zeroth-order output from a diffraction grating is used as the laser output and the first-order-diffracted light is retro-reflected by a cavity feedback mirror, which establishes one end of the resonator. The other end of the resonator is the output surface of a Fabry-Perot resonator that constitutes the diode-laser gain element. Wavelength is selected by choosing the angle of the diffracted return beam, as determined by position of the feedback mirror. The present wavelength-agile ECDL is distinguished by design details that enable coverage of all 60 channels, separated by 100-GHz frequency intervals, that are specified in DWDM standards.

Laser cleaning of ITER's diagnostic mirrors

NASA Astrophysics Data System (ADS)

Skinner, C. H.; Gentile, C. A.; Doerner, R.

2012-10-01

Practical methods to clean ITER's diagnostic mirrors and restore reflectivity will be critical to ITER's plasma operations. We report on laser cleaning of single crystal molybdenum mirrors coated with either carbon or beryllium films 150 - 420 nm thick. A 1.06 μm Nd laser system provided 220 ns pulses at 8 kHz with typical power densities of 1-2 J/cm^2. The laser beam was fiber optically coupled to a scanner suitable for tokamak applications. The efficacy of mirror cleaning was assessed with a new technique that combines microscopic imaging and reflectivity measurements [1]. The method is suitable for hazardous materials such as beryllium as the mirrors remain sealed in a vacuum chamber. Excellent restoration of reflectivity for the carbon coated Mo mirrors was observed after laser scanning under vacuum conditions. For the beryllium coated mirrors restoration of reflectivity has so far been incomplete and modeling indicates that a shorter duration laser pulse is needed. No damage of the molybdenum mirror substrates was observed.[4pt][1] C.H. Skinner et al., Rev. Sci. Instrum. at press.

Characteristics of digital micromirror projection for 3D shape measurement at extreme speed

NASA Astrophysics Data System (ADS)

Höfling, Roland; Aswendt, Petra; Leischnig, Frank; Förster, Matthias

2015-03-01

3D shape measurement is one of the growing industrial applications of the Texas Instruments DLP® micro-mirror device. This paper presents investigations on precision and repeatability of that spatial light modulators output when it is driven up to its high-speed limit. The study concerns the basic switching behavior of the individual micro-mirror at different frame rates ranging over three orders of magnitude. The 3D shape measuring methodologies are focused on phase encoded triangulation, i.e. the projection of sinusoidal patterns. The DLP chip is a bi-stable device providing an on/off pattern at each certain moment in time, i.e. it has a native binary output. Sinusoidal patterns are the result of either a temporal integration of multiple on/off patterns or a spatial integration within one on/off pattern. Both approaches are studied experimentally with respect to precision and stability of the pattern output. The STAR-07 industrial projection unit, based upon the 0.7" DLP Discovery™4100 chipset, has been used for this work and the pattern frame rates cover the range from 225 frames per second (fps) to 50,000 fps. The STAR-07 output is detected by a photodiode, amplified, and analyzed in a Yokogawa digital storage oscilloscope. All results prove the very high precision and repeatability of the STAR-07 pattern projection, up to the extreme speed of 50,000 fps.

Deflecting light into resonant cavities for spectroscopy

DOEpatents

Zare, R.N.; Martin, J.; Paldus, B.A.

1998-09-29

Light is coupled into a cavity ring down spectroscopy (CRDS) resonant cavity using an acousto-optic modulator. The AOM allows in-coupling efficiencies in excess of 40%, which is two to three orders of magnitude higher than in conventional systems using a cavity mirror for in-coupling. The AOM shutoff time is shorter than the roundtrip time of the cavity. The higher light intensities lead to a reduction in shot noise, and allow the use of relatively insensitive but fast-responding detectors such as photovoltaic detectors. Other deflection devices such as electro-optic modulators or elements used in conventional Q-switching may be used instead of the AOM. The method is particularly useful in the mid-infrared, far-infrared, and ultraviolet wavelength ranges, for which moderately reflecting input mirrors are not widely available. 5 figs.

Deflecting light into resonant cavities for spectroscopy

DOEpatents

Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.

1998-01-01

Light is coupled into a cavity ring down spectroscopy (CRDS) resonant cavity using an acousto-optic modulator. The AOM allows in-coupling efficiencies in excess of 40%, which is two to three orders of magnitude higher than in conventional systems using a cavity mirror for in-coupling. The AOM shutoff time is shorter than the roundtrip time of the cavity. The higher light intensities lead to a reduction in shot noise, and allow the use of relatively insensitive but fast-responding detectors such as photovoltaic detectors. Other deflection devices such as electro-optic modulators or elements used in conventional Q-switching may be used instead of the AOM. The method is particularly useful in the mid-infrared, far-infrared, and ultraviolet wavelength ranges, for which moderately reflecting input mirrors are not widely available.

Raman-Suppressing Coupling for Optical Parametric Oscillator

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Maleki, Lute; Matsko, Andrey; Rubiola, Enrico

2007-01-01

A Raman-scattering-suppressing input/ output coupling scheme has been devised for a whispering-gallery-mode optical resonator that is used as a four-wave-mixing device to effect an all-optical parametric oscillator. Raman scattering is undesired in such a device because (1) it is a nonlinear process that competes with the desired nonlinear four-wave conversion process involved in optical parametric oscillation and (2) as such, it reduces the power of the desired oscillation and contributes to output noise. The essence of the present input/output coupling scheme is to reduce output loading of the desired resonator modes while increasing output loading of the undesired ones.

Micro ring cavity resonator incorporating total internal reflection mirrors

NASA Astrophysics Data System (ADS)

Kim, Doo Gun; Choi, Woon Kyung; Choi, Young Wan; Yi, Jong Chang; Chung, Youngchul; Dagli, Nadir

2007-02-01

We investigate the properties of a multimode-interference (MMI) coupled micro ring cavity resonator with total-internal-reflection (TIR) mirrors and a semiconductor optical amplifier (SOA). The TIR mirrors were fabricated by the self-aligned process with a loss of 0.7 dB per mirror. The length and width of an MMI are 142 μm and 10 μm, respectively. The resulting free spectral range (FSR) of the resonator was approximately 1.698 nm near 1571 nm and the extinction ratio was about 17 dB. These devices might be useful as optical switching and add-drop filters in a photonic integrated circuit or as small and fast resonator devices.

Efficient Switching Arrangement for (N + 1)/N Redundancy

NASA Technical Reports Server (NTRS)

Lux, James; McMaster, Robert

2007-01-01

An efficient arrangement of four switches has been conceived for coupling, to four output ports, the output powers of any subset of four devices that are members of a redundant set of five devices. In normal operation, the output power of each of four of the devices would be coupled to one of the four output ports. The remaining device would be kept as a spare: normally, its output power would be coupled to a load, wherein that power would be dissipated. In the event of failure of one of the four normally used devices, that device would be disconnected from its output port and connected to the load, and the spare device would be connected to the output from which the failed device was disconnected. Alternatively or in addition, the outputs of one or more devices could be sent to ports other than the ones originally assigned to them.

Design of hybrid laser structures with QD-RSOA and silicon photonic mirrors

NASA Astrophysics Data System (ADS)

Gioannini, Mariangela; Benedetti, Alessio; Bardella, Paolo; Bovington, Jock; Traverso, Matt; Siriani, Dominic; Gothoskar, Prakash

2018-02-01

We compare the design of three different single mode laser structures consisting in a Reflective Semiconductor Optical Amplifier coupled to a silicon photonic external cavity mirror. The three designs differ for the mirror structure and are compared in terms of SOA power consumption and side mode suppression ratio (SMSR). Assuming then a Quantum Dot active material, we simulate the best laser design using a numerical model that includes the peculiar physical characteristics of the QD gain medium. The simulated QD laser CW characteristics are shown and discussed.

Direct Measurement of Scattered Light Effect on the Sensitivity in TAMA300

NASA Astrophysics Data System (ADS)

Takahashi, R.; Arai, Koji; Kawamaru, Seiji; Smith, Michael R.

2003-07-01

Laser interferometer gravitational wave detectors need vacuum tubes through which the laser beams pass. The light scattered from the arm cavity mirrors will make multiple reflections from the inside wall of the polished tube back onto the mirrors causing phase noise on the interferometer output beam. The TAMA300 has two 300-m length arms enclosed by vacuum tubes. By vibrating one of the tubes of the TAMA300, we directly observed the effect of scattered light on the displacement sensitivity. It was found that a tube vibration amplitude of 5.6 µm at 776.5 Hz increased the mirror displacement noise to 1.2 × 10-17 m. This noise level is consistent with the calculated noise due to the scattered light effect.

93% pump depletion, 3.5-W continuous-wave, singly resonant optical parametric oscillator.

PubMed

Bosenberg, W R; Drobshoff, A; Alexander, J I; Myers, L E; Byer, R L

1996-09-01

We report two cw, singly resonant optical parametric oscillator (OPO) configurations based on periodically poled lithium niobate that result in significantly higher efficiency and output power than in previous studies. Using four-mirror OPO cavities and pumping with a 1.064-microm Nd:YAG laser, we observe 93% pump depletion and obtain ~86% of the converted pump photons as useful idler output. The single-beam, in-the-bucket idler output power of 3.55 W at 3.25 microm corresponds to ~80% of quantum-limited performance. We measure and compare the amplitude noise and spectral bandwidth of the two configurations. We also demonstrate >1 W of tunable cw output over the 3.3-3.9-microm spectral range.

Naked-eye 3D imaging employing a modified MIMO micro-ring conjugate mirrors

NASA Astrophysics Data System (ADS)

Youplao, P.; Pornsuwancharoen, N.; Amiri, I. S.; Thieu, V. N.; Yupapin, P.

2018-03-01

In this work, the use of a micro-conjugate mirror that can produce the 3D image incident probe and display is proposed. By using the proposed system together with the concept of naked-eye 3D imaging, a pixel and a large volume pixel of a 3D image can be created and displayed as naked-eye perception, which is valuable for the large volume naked-eye 3D imaging applications. In operation, a naked-eye 3D image that has a large pixel volume will be constructed by using the MIMO micro-ring conjugate mirror system. Thereafter, these 3D images, formed by the first micro-ring conjugate mirror system, can be transmitted through an optical link to a short distance away and reconstructed via the recovery conjugate mirror at the other end of the transmission. The image transmission is performed by the Fourier integral in MATLAB and compares to the Opti-wave program results. The Fourier convolution is also included for the large volume image transmission. The simulation is used for the manipulation, where the array of a micro-conjugate mirror system is designed and simulated for the MIMO system. The naked-eye 3D imaging is confirmed by the concept of the conjugate mirror in both the input and output images, in terms of the four-wave mixing (FWM), which is discussed and interpreted.

Support system design of the sub-mirror cell of the LAMOST Schmidt plate

NASA Astrophysics Data System (ADS)

Yang, Dehua; Jiang, Fanghua

2006-06-01

The reflecting Schmidt plate of the Large sky Area Multi-Object Spectroscopic Telescope (LAMOST) is composed of 24 hexagonal segments, each of which is 1100 mm from corner to corner and 25 mm in thickness. Both segmented mirror active optics and deformable mirror active optics are involved in the Schmidt plate so as to compensate for optical aberration and structural deformation. A prototype of the segment support system with dummy aluminum mirror had been setup and tested during 2003 to 2004, afterwards, based on the evaluation of test, the whole support system was updated to a backlash-free and light-weighted design. For the segmented mirror active optics, the segment mirror support system is to fulfill motions of tip, tilt and piston with three linear positioning actuators. Instead of self-alignment bearing adopted in the early prototype, a centering diaphragm is employed to realize a backlash-free pintle. And a lever with reduction of 10:1 is introduced to each of the three positioning actuator mechanisms, respectively, to obtain greater load capacity and further finer output displacement, as hence releases requirement and cost of the actuators. For better performance, high strength steel blades are used in tension state for pivots of the levers preloaded with longitudinal springs. To gap the mirror segments with respect to each other for making proper space for edge sensors, three adjustable fixtures are implemented for each segment mirror module to do translation and pistion on three conrresponding nodes on the top layer of the gross mirror cell truss before being anchored once and forever. In addition, safety measurements as well as anti-rotation mechanism have been taken into consideration throughout the design and development process. This paper describes the mechanical design and related analysis of the segment mirror support system in detail.

Solid state laser

NASA Technical Reports Server (NTRS)

Rines, Glen A. (Inventor); Moulton, Peter F. (Inventor); Harrison, James (Inventor)

1993-01-01

A wavelength-tunable, injection-seeded, dispersion-compensated, dispersively-pumped solid state laser includes a lasing medium; a highly reflective mirror; an output coupler; at least one isosceles Brewster prism oriented to the minimum deviation angle between the medium and the mirror for directing light of different wavelengths along different paths; means for varying the angle of the highly reflective mirror relative to the light from at least one Brewster angle for selecting a predetermined laser operating wavelength; a dispersion compensation apparatus associated with the lasing medium; a laser injection seeding port disposed between the dispersion compensation apparatus and one of the mirror and coupler and including a reflective surface at an acute non-Brewster angle to the laser beam for introducing a seed input; a dispersion compensation apparatus associated with the laser medium including opposite chirality optical elements; the lasing medium including a pump surface disposed at an acute angle to the laser beam to define a discrete path for the pumping laser beam separate from the pumped laser beam.

External self-representations improve self-awareness in a child with autism.

PubMed

Root, Nicholas B; Case, Laura K; Burrus, Caley J; Ramachandran, V S

2015-01-01

We have previously suggested that the social symptoms of autism spectrum disorder (ASD) could be caused in part by a dysfunctional mirror neuron system (MNS). Since the recursive activity of a functioning MNS might enable the brain to integrate visual and motor sensations into a coherent body schema, the deficits in self-awareness often seen in ASD might be caused by the same mirror neuron dysfunction. CL is an autistic adolescent who is profoundly fascinated with his reflection, looking in mirrors at every opportunity. We demonstrate that CL's abnormal gait improves significantly when using a mirror for visual feedback. We also show that both the fascination and the happiness that CL derives from looking at a computer-generated reflection diminish when a delay is introduced between the camera input and screen output. We believe that immediate, real-time visual feedback allows CL to integrate motor sensations with external visual ones into a coherent body schema that he cannot internally generate, perhaps due to a dysfunctional MNS.

[The mirror neuron system in motor and sensory rehabilitation].

PubMed

Oouchida, Yutaka; Izumi, Shinichi

2014-06-01

The discovery of the mirror neuron system has dramatically changed the study of motor control in neuroscience. The mirror neuron system provides a conceptual framework covering the aspects of motor as well as sensory functions in motor control. Previous studies of motor control can be classified as studies of motor or sensory functions, and these two classes of studies appear to have advanced independently. In rehabilitation requiring motor learning, such as relearning movement after limb paresis, however, sensory information of feedback for motor output as well as motor command are essential. During rehabilitation from chronic pain, motor exercise is one of the most effective treatments for pain caused by dysfunction in the sensory system. In rehabilitation where total intervention unifying the motor and sensory aspects of motor control is important, learning through imitation, which is associated with the mirror neuron system can be effective and suitable. In this paper, we introduce the clinical applications of imitated movement in rehabilitation from motor impairment after brain damage and phantom limb pain after limb amputation.

Method for removing tilt control in adaptive optics systems

DOEpatents

Salmon, Joseph Thaddeus

1998-01-01

A new adaptive optics system and method of operation, whereby the method removes tilt control, and includes the steps of using a steering mirror to steer a wavefront in the desired direction, for aiming an impinging aberrated light beam in the direction of a deformable mirror. The deformable mirror has its surface deformed selectively by means of a plurality of actuators, and compensates, at least partially, for existing aberrations in the light beam. The light beam is split into an output beam and a sample beam, and the sample beam is sampled using a wavefront sensor. The sampled signals are converted into corresponding electrical signals for driving a controller, which, in turn, drives the deformable mirror in a feedback loop in response to the sampled signals, for compensating for aberrations in the wavefront. To this purpose, a displacement error (gradient) of the wavefront is measured, and adjusted by a modified gain matrix, which satisfies the following equation: G'=(I-X(X.sup.T X).sup.-1 X.sup.T)G(I-A)

Maximizing coupling-efficiency of high-power diode lasers utilizing hybrid assembly technology

NASA Astrophysics Data System (ADS)

Zontar, D.; Dogan, M.; Fulghum, S.; Müller, T.; Haag, S.; Brecher, C.

2015-03-01

In this paper, we present hybrid assembly technology to maximize coupling efficiency for spatially combined laser systems. High quality components, such as center-turned focusing units, as well as suitable assembly strategies are necessary to obtain highest possible output ratios. Alignment strategies are challenging tasks due to their complexity and sensitivity. Especially in low-volume production fully automated systems are economically at a disadvantage, as operator experience is often expensive. However reproducibility and quality of automatically assembled systems can be superior. Therefore automated and manual assembly techniques are combined to obtain high coupling efficiency while preserving maximum flexibility. The paper will describe necessary equipment and software to enable hybrid assembly processes. Micromanipulator technology with high step-resolution and six degrees of freedom provide a large number of possible evaluation points. Automated algorithms are necess ary to speed-up data gathering and alignment to efficiently utilize available granularity for manual assembly processes. Furthermore, an engineering environment is presented to enable rapid prototyping of automation tasks with simultaneous data ev aluation. Integration with simulation environments, e.g. Zemax, allows the verification of assembly strategies in advance. Data driven decision making ensures constant high quality, documents the assembly process and is a basis for further improvement. The hybrid assembly technology has been applied on several applications for efficiencies above 80% and will be discussed in this paper. High level coupling efficiency has been achieved with minimized assembly as a result of semi-automated alignment. This paper will focus on hybrid automation for optimizing and attaching turning mirrors and collimation lenses.

Device and method for redirecting electromagnetic signals

DOEpatents

Garcia, Ernest J.

1999-01-01

A device fabricated to redirect electromagnetic signals, the device including a primary driver adapted to provide a predetermined force, a linkage system coupled to the primary driver, a pusher rod rotationally coupled to the linkage system, a flexible rod element attached to the pusher rod and adapted to buckle upon the application of the predetermined force, and a mirror structure attached to the flexible rod element at one end and to the substrate at another end. When the predetermined force buckles the flexible rod element, the mirror structure and the flexible rod element both move to thereby allow a remotely-located electromagnetic signal directed towards the device to be redirected.

Influence of temperature on Yb:YAG/Cr:YAG microchip laser operation

NASA Astrophysics Data System (ADS)

Šulc, Jan; Eisenschreiber, Jan; Jelínková, Helena; Nejezchleb, Karel; Å koda, Václav

2017-02-01

The goal of this work was an investigation of the temperature influence (in range from 80 up to 320 K) on the laser properties of Yb:YAG/Cr:YAG Q-switched diode-pumped microchip laser. This laser was based on monolith crystal (diameter 3mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3mm long) and saturable absorber (Cr:YAG crystal, 1.36mm long, initial transmission 90% @ 1031 nm). The laser resonator pump mirror (HT for pump radiation, HR for generated radiation) was directly deposited on the Yb:YAG monolith part. The output coupler with reflection 55% for the generated wavelength was placed on the Cr:YAG part. The microchip laser was placed in the temperature controlled cupreous holder inside vacuum chamber of the liquid nitrogen cryostat. For Yb:YAG part longitudinal pulsed pumping (pumping pulse length 2.5 ms, rep-rate 20 Hz, power amplitude 21W) a fibre coupled (core diameter 400 μm, NA= 0:22) laser diode, operating at wavelength 933 nm, was used. The microchip laser mean output power, pulse duration, repetition rate, emission wavelength, and laser beam profile were measured in dependence on temperature. The generated pulse length was in range from 2.2 ns to 1.1 ns (FWHM) with the minimum at 230 K. The single pulse energy was peaking (0.4 mJ) at 180 K. The highest peak power (325 kW) was obtained at 220 K. The highest pulse repetition rate (38 kHz) and output mean power (370mW) was reached for temperature 80 K.

Wavelength tunability of laser based on Yb-doped YGAG ceramics

NASA Astrophysics Data System (ADS)

Šulc, Jan; Jelínková, Helena; Jambunathan, Venkatesan; Miura, Taisuke; Endo, Akira; Lucianetti, Antonio; Mocek, TomáÅ.¡

2015-02-01

The wavelength tunability of diode pumped laser based on Yb-doped mixed garnet Y3Ga2Al3O12 (Yb:YGAG) ceramics was investigated. The tested Yb:YGAG sample (10% Yb/Y) was in the form of 2mm thick plane-parallel face-polished plate (without AR coatings). A fiber (core diameter 100 μm, NA= 0.22) coupled laser diode (LIMO, LIMO35-F100-DL980-FG-E) with emission at wavelength 969 nm, was used for longitudinal Yb:YGAG pumping. The laser diode was operating in the pulsed regime (2 ms pulse length, 10 Hz repetition rate). The duty-cycle 2% ensured a low thermal load even under the maximum diode pumping power amplitude 20W (ceramics sample was only air-cooled). The 145mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (HR @ 1.01 - 1.09 μm, HT @ 0.97 μm) and curved (r = 150mm) output coupler with a reflectivity of ˜ 97% @ 1.01 - 1.09 μm. Wavelength tuning of the ytterbium laser was accomplished by using a birefringent filter (single 1.5mm thick quartz plate) placed inside the optical resonator at the Brewster angle between the output coupler and the laser active medium. The laser was continuously tunable over ˜ 58nm (from 1022nm to 1080 nm) and the tuning band was mostly limited by the free spectral range of used birefringent filter. The maximum output power amplitude 3W was obtained at wavelength 1046nm for absorbed pump power amplitude 10.6W. The laser slope efficiency was 34%.

The space-dependent model and output characteristics of intra-cavity pumped dual-wavelength lasers

NASA Astrophysics Data System (ADS)

He, Jin-Qi; Dong, Yuan; Zhang, Feng-Dong; Yu, Yong-Ji; Jin, Guang-Yong; Liu, Li-Da

2016-01-01

The intra-cavity pumping scheme which is used to simultaneously generate dual-wavelength lasers was proposed and published by us and the space-independent model of quasi-three-level and four-level intra-cavity pumped dual-wavelength lasers was constructed based on this scheme. In this paper, to make the previous study more rigorous, the space-dependent model is adopted. As an example, the output characteristics of 946 nm and 1064 nm dual-wavelength lasers under the conditions of different output mirror transmittances are numerically simulated by using the derived formula and the results are nearly identical to what was previously reported.

Solar-pumped 80 W laser irradiated by a Fresnel lens.

PubMed

Ohkubo, Tomomasa; Yabe, Takashi; Yoshida, Kunio; Uchida, Shigeaki; Funatsu, Takayuki; Bagheri, Behgol; Oishi, Takehiro; Daito, Kazuya; Ishioka, Manabu; Nakayama, Yuichirou; Yasunaga, Norihito; Kido, Kouichirou; Sato, Yuji; Baasandash, Choijil; Kato, Kiyoshi; Yanagitani, Takagimi; Okamoto, Yoshiaki

2009-01-15

A solar-pumped 100 W class laser that features high efficiency and low cost owing to the use of a Fresnel lens and a chromium codoped neodymium YAG ceramic laser medium was developed. A laser output of about 80 W was achieved with combination of a 4 m(2) Fresnel lens and a pumping cavity as a secondary power concentrator. This output corresponds to 4.3% of conversion efficiency from solar power into laser, and the maximum output from a unit area of Fresnel lens was 20 W/m(2), which is 2.8 times larger than previous results with mirror-type concentrator.

Research study on stellar X-ray imaging experiment, volume 1

NASA Technical Reports Server (NTRS)

Wilson, H. H.; Vanspeybroeck, L. P.

1972-01-01

The use of microchannel plates as focal plane readout devices and the evaluation of mirrors for X-ray telescopes applied to stellar X-ray imaging is discussed. The microchannel plate outputs were either imaged on a phosphor screen which was viewed by a low light level vidicon or on a wire array which was read out by digitally processing the output of a charge division network attached to the wires. A service life test which was conducted on two image intensifiers is described.

Octave-spanning carrier-envelope phase stabilized visible pulse with sub-3-fs pulse duration.

PubMed

Okamura, Kotaro; Kobayashi, Takayoshi

2011-01-15

The visible second harmonic of the idler output from a noncollinear optical parametric amplifier was compressed using adaptive dispersion control with a deformable mirror. The amplifier was pumped by and seeded in the signal path by a common 400 nm second-harmonic pulse from a Ti:sapphire regenerative amplifier. Thus, both the idler output and the second harmonic of the idler were passively carrier-envelope phase stabilized. The shortest pulse duration achieved was below 3 fs.

High power continuous-wave titanium:sapphire laser

DOEpatents

Erbert, Gaylen V.; Bass, Isaac L.; Hackel, Richard P.; Jenkins, Sherman L.; Kanz, Vernon K.; Paisner, Jeffrey A.

1993-01-01

A high-power continuous-wave laser resonator (10) is provided, wherein first, second, third, fourth, fifth and sixth mirrors (11-16) form a double-Z optical cavity. A first Ti:Sapphire rod (17) is disposed between the second and third mirrors (12,13) and at the mid-point of the length of the optical cavity, and a second Ti:Sapphire rod (18) is disposed between the fourth and fifth mirrors (14,15) at a quarter-length point in the optical cavity. Each Ti:Sapphire rod (17,18) is pumped by two counter-propagating pump beams from a pair of argon-ion lasers (21-22, 23-24). For narrow band operation, a 3-plate birefringent filter (36) and an etalon (37) are disposed in the optical cavity so that the spectral output of the laser consists of 5 adjacent cavity modes. For increased power, seventy and eighth mirrors (101, 192) are disposed between the first and second mirrors (11, 12) to form a triple-Z optical cavity. A third Ti:Sapphire rod (103) is disposed between the seventh and eighth mirrors (101, 102) at the other quarter-length point in the optical cavity, and is pumped by two counter-propagating pump beams from a third pair of argon-ion lasers (104, 105).

Researching the 915 nm high-power and high-brightness semiconductor laser single chip coupling module

NASA Astrophysics Data System (ADS)

Wang, Xin; Wang, Cuiluan; Wu, Xia; Zhu, Lingni; Jing, Hongqi; Ma, Xiaoyu; Liu, Suping

2017-02-01

Based on the high-speed development of the fiber laser in recent years, the development of researching 915 nm semiconductor laser as main pumping sources of the fiber laser is at a high speed. Because the beam quality of the laser diode is very poor, the 915 nm laser diode is generally based on optical fiber coupling module to output the laser. Using the beam-shaping and fiber-coupling technology to improve the quality of output beam light, we present a kind of high-power and high-brightness semiconductor laser module, which can output 13.22 W through the optical fiber. Based on 915 nm GaAs semiconductor laser diode which has output power of 13.91 W, we describe a thoroughly detailed procedure for reshaping the beam output from the semiconductor laser diode and coupling the beam into the optical fiber of which the core diameter is 105 μm and the numerical aperture is 0.18. We get 13.22 W from the output fiber of the module at 14.5 A, the coupling efficiency of the whole module is 95.03% and the brightness is 1.5 MW/cm2 -str. The output power of the single chip semiconductor laser module achieves the advanced level in the domestic use.

Silver Film Surface Modification by Ion Bombardment Decreases Surface Plasmon Resonance Absorption.

PubMed

Fryauf, David M; Diaz Leon, Juan J; Phillips, Andrew C; Kobayashi, Nobuhiko P

2017-05-10

Silver thin films covered with dielectric films serving as protective coatings are desired for telescope mirrors, but durable coatings have proved elusive. As part of an effort to develop long-lived protected-silver mirrors, silver thin films were deposited by electron beam evaporation using a physical vapor deposition system at the University of California Observatories Astronomical Coatings Lab. The silver films were later covered with a stack of dielectric films utilizing silicon nitride and titanium dioxide deposited by ion-assisted electron beam evaporation to fabricate protected mirrors. In-situ argon ion bombardment was introduced after silver deposition and prior to the deposition of dielectric films to assess its effects on the performance of the mirrors. We found that ion bombardment of the silver influenced surface morphology and reflectivity, and these effects correlated with time between silver deposition and ion bombardment. The overall reflectivity at wavelengths in the range of 350-800 nm was found to improve due to ion bombardment, which was qualitatively interpreted as a result of decreased surface plasmon resonance coupling. We suggest that the observed decrease in coupling is caused by silver grain boundary pinning due to ion bombardment suppressing silver surface diffusion, forming smoother silver-dielectric interfaces.

Traveling wave linear accelerator with RF power flow outside of accelerating cavities

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

Dolgashev, Valery A.

A high power RF traveling wave accelerator structure includes a symmetric RF feed, an input matching cell coupled to the symmetric RF feed, a sequence of regular accelerating cavities coupled to the input matching cell at an input beam pipe end of the sequence, one or more waveguides parallel to and coupled to the sequence of regular accelerating cavities, an output matching cell coupled to the sequence of regular accelerating cavities at an output beam pipe end of the sequence, and output waveguide circuit or RF loads coupled to the output matching cell. Each of the regular accelerating cavities hasmore » a nose cone that cuts off field propagating into the beam pipe and therefore all power flows in a traveling wave along the structure in the waveguide.« less

Using VISAR to assess the M-band isotropy in hohlraums

DOE PAGES

Lanier, Nicholas Edward; Kline, John L.; Morton, John

2016-09-27

In laser based radiation flow experiments, drive variability can often overwhelm the physics sensitivity that one seeks to quantify. Hohlraums can help by providing a more symmetrized, Planckian-like source. However, at higher temperatures, the hohlraum’s actual emission can deviate significantly from a truly blackbody, Lambertian source. At the National Ignition Facility (NIF), Dante provides the best quantification of hohlraum output. Unfortunately, limited diagnostic access coupled with NIF’s natural symmetry does not allow for Dante measurements at more than two angles. As part of the CEPHEUS campaign on NIF, proof-of-principle experiments to better quantify the gold M-band isotropy were conducted. Thesemore » experiments positioned beryllium/aluminum mirrors at differing angles, offset from the hohlraum. Filtering removes the thermal emission of the hohlraum and the remaining M-band radiation is preferentially absorbed in the aluminum layer. The subsequent hydrodynamic motion is measured via VISAR. Although indirect, this M-band measurement can be made at any angle.« less

Resonator Optical Designs For Free Electron Lasers

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.; Saxman, A.; Woodfin, G.

1985-11-01

The output beam from free-electron lasers tends to be a thin, pencil-like beam because of the nature of the gain volume. For moderate power devices, mirror damage considerations imply that the beam has to travel many meters before it can expand enough to allow retro-reflection from state-of-the-art mirrors. However, use of grazing incidence optics can resolve the problem of damage to the optical elements and result in a cavity of reasonable dimensions. The optical design considerations for such resonators are addressed in this paper. A few of the practical resonator designs approaching diffraction limited performance are presented.

Resonator optical designs for free electron lasers

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.; Saxman, A.; Woodfin, G.

1985-03-01

The output beam from free-electron lasers tends to be a thin, pencil-like beam because of the nature of the gain volume. For moderate power devices, mirror damage considerations imply that the beam has to travel many meters before it can expand enough to allow retro-reflection from state-of-the-art mirrors. However, use of grazing incidence optics can resolve the problem of damage to the optical elements and result in a cavity of reasonable dimensions. The optical design considerations for such resonators are discussed. A few of the practical resonator designs approaching diffraction limited performance are presented.

High reflectivity mirrors and method for making same

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

Heikman, Sten; Jacob-Mitos, Matthew; Li, Ting

2016-06-07

A composite high reflectivity mirror (CHRM) with at least one relatively smooth interior surface interface. The CHRM includes a composite portion, for example dielectric and metal layers, on a base element. At least one of the internal surfaces is polished to achieve a smooth interface. The polish can be performed on the surface of the base element, on various layers of the composite portion, or both. The resulting smooth interface(s) reflect more of the incident light in an intended direction. The CHRMs may be integrated into light emitting diode (LED) devices to increase optical output efficiency

Adjustable bipod flexures for mounting mirrors in a space telescope.

PubMed

Kihm, Hagyong; Yang, Ho-Soon; Moon, Il Kweon; Yeon, Jeong-Heum; Lee, Seung-Hoon; Lee, Yun-Woo

2012-11-10

A new mirror mounting technique applicable to the primary mirror in a space telescope is presented. This mounting technique replaces conventional bipod flexures with flexures having mechanical shims so that adjustments can be made to counter the effects of gravitational distortion of the mirror surface while being tested in the horizontal position. Astigmatic aberration due to the gravitational changes is effectively reduced by adjusting the shim thickness, and the relation between the astigmatism and the shim thickness is investigated. We tested the mirror interferometrically at the center of curvature using a null lens. Then we repeated the test after rotating the mirror about its optical axis by 180° in the horizontal setup, and searched for the minimum system error. With the proposed flexure mount, the gravitational stress at the adhesive coupling between the mirror and the mount is reduced by half that of a conventional bipod flexure for better mechanical safety under launch loads. Analytical results using finite element methods are compared with experimental results from the optical interferometer. Vibration tests verified the mechanical safety and optical stability, and qualified their use in space applications.

EAGLE: relay mirror technology development

NASA Astrophysics Data System (ADS)

Hartman, Mary; Restaino, Sergio R.; Baker, Jeffrey T.; Payne, Don M.; Bukley, Jerry W.

2002-06-01

EAGLE (Evolutionary Air & Space Global Laser Engagement) is the proposed high power weapon system with a high power laser source, a relay mirror constellation, and the necessary ground and communications links. The relay mirror itself will be a satellite composed of two optically-coupled telescopes/mirrors used to redirect laser energy from ground, air, or space based laser sources to distant points on the earth or space. The receiver telescope captures the incoming energy, relays it through an optical system that cleans up the beam, then a separate transmitter telescope/mirror redirects the laser energy at the desired target. Not only is it a key component in extending the range of DoD's current laser weapon systems, it also enables ancillary missions. Furthermore, if the vacuum of space is utilized, then the atmospheric effects on the laser beam propagation will be greatly attenuated. Finally, several critical technologies are being developed to make the EAGLE/Relay Mirror concept a reality, and the Relay Mirror Technology Development Program was set up to address them. This paper will discuss each critical technology, the current state of the work, and the future implications of this program.

Measurement of glyoxal using an incoherent broadband cavity enhanced absorption spectrometer

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Langford, A. O.; Fuchs, H.; Brown, S. S.

2008-12-01

We describe an instrument for simultaneous measurements of glyoxal (CHOCHO) and nitrogen dioxide (NO2) using cavity enhanced absorption spectroscopy with a broadband light source. The output of a Xenon arc lamp is coupled into a 1 m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge-coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N2+O2). Least-squares fitting, using published reference spectra, allow the simultaneous retrieval of CHOCHO, NO2, O4, and H2O in the 441 to 469 nm spectral range. For a 1-min sampling time, the precision (±1σ) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv, respectively. We directly compare measurements made with the incoherent broadband cavity enhanced absorption spectrometer with those from cavity ringdown instruments detecting CHOCHO and NO2 at 404 and 532 nm, respectively, and find linear agreement over a wide range of concentrations. The instrument has been tested in the laboratory with both synthetic and real air samples, and the demonstrated sensitivity and specificity suggest a strong potential for field measurements of both CHOCHO and NO2.

Non-linear dynamic compensation system

NASA Technical Reports Server (NTRS)

Lin, Yu-Hwan (Inventor); Lurie, Boris J. (Inventor)

1992-01-01

A non-linear dynamic compensation subsystem is added in the feedback loop of a high precision optical mirror positioning control system to smoothly alter the control system response bandwidth from a relatively wide response bandwidth optimized for speed of control system response to a bandwidth sufficiently narrow to reduce position errors resulting from the quantization noise inherent in the inductosyn used to measure mirror position. The non-linear dynamic compensation system includes a limiter for limiting the error signal within preselected limits, a compensator for modifying the limiter output to achieve the reduced bandwidth response, and an adder for combining the modified error signal with the difference between the limited and unlimited error signals. The adder output is applied to control system motor so that the system response is optimized for accuracy when the error signal is within the preselected limits, optimized for speed of response when the error signal is substantially beyond the preselected limits and smoothly varied therebetween as the error signal approaches the preselected limits.

ART-XC/SRG: joint calibration of mirror modules and x-ray detectors

NASA Astrophysics Data System (ADS)

Tkachenko, A.; Pavlinsky, M.; Levin, V.; Akimov, V.; Krivchenko, A.; Rotin, A.; Kuznetsova, M.; Lapshov, I.; Yaskovich, A.; Oleinikov, V.; Gubarev, M.; Ramsey, B.

2017-08-01

The Astronomical Roentgen Telescope - X-ray Concentrator (ART-XC) is a hard x-ray instrument with energy response 6-30 keV that will to be launched on board of the Spectrum Roentgen Gamma (SRG) Mission. ART-XC consists of seven co-aligned mirror modules coupled with seven focal plane CdTe double-sided strip detectors. The mirror modules had been fabricated and calibrated at the NASA Marshall Space Flight Center (MSFC). The Russian Space Research Institute (IKI) has developed and tested the X-ray detectors. The joint x-ray calibration of the mirror modules and focal plane detectors was carried out at the IKI test facility. Details of the calibration procedure and an overview of the results are presented here.

2D tilting MEMS micro mirror integrating a piezoresistive sensor position feedback

NASA Astrophysics Data System (ADS)

Lani, S.; Bayat, D.; Despont, M.

2015-02-01

An integrated position sensor for a dual-axis electromagnetic tilting mirror is presented. This tilting mirror is composed of a silicon based mirror directly assembled on a silicon membrane supported by flexible beams. The position sensors are constituted by 4 Wheatstone bridges of piezoresistors which are fabricated by doping locally the flexible beams. A permanent magnet is attached to the membrane and the scanner is mounted above planar coils deposited on a ceramic substrate to achieve electromagnetic actuation. The performances of the piezoresistive sensors are evaluated by measuring the output signal of the piezoresistors as a function of the tilt of the mirror and the temperature. White light interferometry was performed for all measurement to measure the exact tilt angle. The minimum detectable angle with such sensors was 30µrad (around 13bits) in the range of the minimum resolution of the interferometer. The tilt reproducibility was 0.0186%, obtained by measuring the tilt after repeated actuations with a coil current of 50mA during 30 min and the stability over time was 0.05% in 1h without actuation. The maximum measured tilt angle was 6° (mechanical) limited by nonlinearity of the MEMS system.

Variable curvature mirror having variable thickness: design and fabrication

NASA Astrophysics Data System (ADS)

Zhao, Hui; Xie, Xiaopeng; Xu, Liang; Ding, Jiaoteng; Shen, Le; Gong, Jie

2017-10-01

Variable curvature mirror (VCM) can change its curvature radius dynamically and is usually used to correct the defocus and spherical aberration caused by thermal lens effect to improve the output beam quality of high power solid-state laser. Recently, the probable application of VCM in realizing non-moving element optical zoom imaging in visible band has been paid much attention. The basic requirement for VCM lies in that it should provide a large enough saggitus variation and still maintains a high enough surface figure at the same time. Therefore in this manuscript, by combing the pressurization based actuation with a variable thickness mirror design, the purpose of obtaining large saggitus variation and maintaining quite good surface figure accuracy at the same time could be achieved. A prototype zoom mirror with diameter of 120mm and central thickness of 8mm is designed, fabricated and tested. Experimental results demonstrate that the zoom mirror having an initial surface figure accuracy superior to 1/80λ could provide bigger than 36um saggitus variation and after finishing the curvature variation its surface figure accuracy could still be superior to 1/40λ with the spherical aberration removed, which proves that the effectiveness of the theoretical design.

Actively Q-switched laser with novel Nd:YAG/YAG polygonal active-mirror

NASA Astrophysics Data System (ADS)

Lang, Ye; Chen, Yanzhong; Ge, Wenqi; He, Jianguo; Zhang, Hongbo; Liao, Lifen; Xin, Jianguo; Zhang, Jian; Fan, Zhongwei

2018-03-01

In this work, we demonstrate an efficient actively Q-switched laser based on a novel crystal Nd:YAG/YAG polygonal active mirror. A passively cooled crystal Nd:YAG/YAG polygonal active mirror with an end pump scheme was used as the gain medium. For the overlap between the TEM00 laser mode and large gain profile, a cavity was carefully designed with a large fundamental mode volume. With a maximum absorbed power of 3.1 W, a 685 mW average output power with a pulse repetition of 5 kHz was attained, and the corresponding optical-optical and slope efficiency were 22.1% and 27.7%, respectively. The pulse width was 133.9 ns. The beam quality (M 2) was 1.561 in the horizontal direction and 1.261 in the vertical direction.

The advancement of the high precision stress polishing

NASA Astrophysics Data System (ADS)

Li, Chaoqiang; Lei, Baiping; Han, Yu

2016-10-01

The stress polishing is a kind of large-diameter aspheric machining technology with high efficiency. This paper focuses on the principle, application in the processing of large aspheric mirror, and the domestic and foreign research status of stress polishing, aimed at the problem of insufficient precision of mirror surface deformation calculated by some traditional theories and the problem that the output precision and stability of the support device in stress polishing cannot meet the requirements. The improvement methods from these three aspects are put forward, the characterization method of mirror's elastic deformation in stress polishing, the deformation theory of influence function and the calculation of correction force, the design of actuator's mechanical structure. These improve the precision of stress polishing and provide theoretical basis for the further application of stress polishing in large-diameter aspheric machining.

Reflectometer design using nonimaging optics

NASA Astrophysics Data System (ADS)

Snail, Keith A.

1987-12-01

A new type of two-stage reflectometer is proposed for the measurement of directional hemispherical reflectance. The proposed reflectometer consists of a primary collecting mirror coupled to a secondary mirror chosen to eliminate the Fresnel variation of the detector (or source) response. The secondary mirror shape needed is an inverted nonimaging compound parabolic concentrator (CPC). For direct mode operation, the detector is placed at the larger CPC aperture. Ray tracing of a CPC/ellipsoid reflectometer indicates that the throughput is high and isotropic. Design trade-offs and two-stage reflectometers employing a hemisphere and dual paraboloid primary are also discussed.

Reflectometer design using nonimaging optics.

PubMed

Snail, K A

1987-12-15

A new type of two-stage reflectometer is proposed for the measurement of directional hemispherical reflectance. The proposed reflectometer consists of a primary collecting mirror coupled to a secondary mirror chosen to eliminate the Fresnel variation of the detector (or source) response. The secondary mirror shape needed is an inverted nonimaging compound parabolic concentrator (CPC). For direct mode operation, the detector is placed at the larger CPC aperture. Ray tracing of a CPC/ellipsoid reflectometer indicates that the throughput is high and isotropic. Design trade-offs and two-stage reflectometers employing a hemisphere and dual paraboloid primary are also discussed.

Spectrum splitting using multi-layer dielectric meta-surfaces for efficient solar energy harvesting

NASA Astrophysics Data System (ADS)

Yao, Yuhan; Liu, He; Wu, Wei

2014-06-01

We designed a high-efficiency dispersive mirror based on multi-layer dielectric meta-surfaces. By replacing the secondary mirror of a dome solar concentrator with this dispersive mirror, the solar concentrator can be converted into a spectrum-splitting photovoltaic system with higher energy harvesting efficiency and potentially lower cost. The meta-surfaces are consisted of high-index contrast gratings (HCG). The structures and parameters of the dispersive mirror (i.e. stacked HCG) are optimized based on finite-difference time-domain and rigorous coupled-wave analysis method. Our numerical study shows that the dispersive mirror can direct light with different wavelengths into different angles in the entire solar spectrum, maintaining very low energy loss. Our approach will not only improve the energy harvesting efficiency, but also lower the cost by using single junction cells instead of multi-layer tandem solar cells. Moreover, this approach has the minimal disruption to the existing solar concentrator infrastructures.

Measurement of Motion Transfer Functions for Mirror Suspensions

NASA Astrophysics Data System (ADS)

Stuver, Amber; Beilby, Mark; Glancy, Aran; Gonzalez, Gabriela

2001-04-01

Interferometric gravitational wave detectors, such as LIGO, use mirrors suspended in pendulums. The current LIGO dectors use simple pendulums, but advanced LIGO detectors will use multiple pendulums with some stages on soft vertical springs. A drawback of the a multiple pendulum design is that it is difficult to model and predict cross couplings from one vibrational mode to another due to slight unavoidable asymmetries in the real system. Of most concern are the couplings to motion along the optical axis and into angular motions, which have the most potential to contaminate data. Our research focuses on the experimental testing of the pendulum designs for cross couplings with a special dedicated shaking stage. The cross couplings in each degree of freedom, their isolation and damping are investigated in this research though the measurement of transfer functions as filtered though the suspension system. This research is supported by The Pennsylvania State University, the NSF Grant no. PHY-9870032, and the REU program at The Pennsylvania State University.

Interferometric source of multi-color, multi-beam entangled photons with mirror and mixer

DOEpatents

Dress, William B.; Kisner, Roger A.; Richards, Roger K.

2004-06-01

53 Systems and methods are described for an interferometric source of multi-color, multi-beam entangled photons. An apparatus includes: a multi-refringent device optically coupled to a source of coherent energy, the multi-refringent device providing a beam of multi-color entangled photons; a condenser device optically coupled to the multi-refringent device, the condenser device i) including a mirror and a mixer and ii) converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; a tunable phase adjuster optically coupled to the condenser device, the tunable phase adjuster changing a phase of at least a portion of the converged multi-color entangled photon beam to generate a first interferometeric multi-color entangled photon beam; and a beam splitter optically coupled to the condenser device, the beam splitter combining the first interferometeric multi-color entangled photon beam with a second interferometric multi-color entangled photon beam.

Multi-link laser interferometer architecture for a next generation GRACE

NASA Astrophysics Data System (ADS)

Francis, Samuel Peter

When GRACE Follow-On (GRACE-FO) launches, it will be the first time a laser interferometer has been used to measure displacement between spacecraft. In the future, interspacecraft laser interferometry will be used in LISA, a space-based gravitational wave detector, that requires the change in separation between three spacecraft to be measured with a resolution of 1 pm/rtHz. The sensitivity of an interspacecraft interferometer is potentially limited by spacecraft degrees-of-freedom, such as rotation, coupling into the interspacecraft displacement measurement. GRACE-FO and LISA therefore have strict requirements placed on the positioning and alignment of the interferometers during spacecraft integration. Decades of work has gone into adapting traditionally lab-based techniques for these space applications. As an example, GRACE-FO stops rotation of the two spacecraft from coupling into displacement using the triple mirror assembly. The triple mirror assembly is a precision optic, comprised of three mirrors, that function as a retroreflector. Provided the triple mirror assembly vertex coincides with the spacecraft centre of mass, any spacecraft rotation will asymmetrically lengthen and shorten the optical pathlengths of the incoming and outgoing beams, ensuring that the round trip pathlength between the spacecraft is unaffected. To achieve the required displacement sensitivity, the triple mirror assembly vertex must be positioned within 0.5 mm of the spacecraft centre of mass, making spacecraft integration challenging. In this thesis a new, all-fibre interferometer architecture is presented that aims to simplify the positioning and alignment of space-based interferometers. Using multiple interspacecraft link measurements and high-speed signal processing the interspacecraft displacement is synthesised in post-processing. The multi-link interferometry concept is similar to the triple mirror assembly's symmetric suppression of rotation, however, since the rotation-to-pathlength cancellation is performed in post-processing, the weighting of each interspacecraft link measurement can be optimised to completely cancel any rotation coupled error. Consequently, any uncertainty in the positioning of the multi-link interferometer during spacecraft integration can be corrected for in post-processing. The strict hardware integration requirements of current interferometers can therefore be relaxed, enabling a new class of simpler, cheaper missions. (Abstract shortened by ProQuest.).

Selective phonon damping in topological semimetals

NASA Astrophysics Data System (ADS)

Gordon, Jacob S.; Kee, Hae-Young

2018-05-01

Topological semimetals are characterized by their intriguing Fermi surfaces (FSs) such as Weyl and Dirac points, or nodal FS, and their associated surface states. Among them, topological crystalline semimetals, in the presence of strong spin-orbit coupling, possess a nodal FS protected by nonsymmorphic lattice symmetries. In particular, it was theoretically proposed that SrIrO3 exhibits a bulk nodal ring due to glide symmetries, as well as flat two-dimensional surface states related to chiral and mirror symmetries. However, due to the semimetallic nature of the bulk, direct observation of these surface states is difficult. Here we study the effect of flat-surface states on phonon modes for SrIrO3 side surfaces. We show that mirror odd optical surface phonon modes are damped at the zone center, as a result of coupling to the surface states with different mirror parities, while even modes are unaffected. This observation could be used to infer their existence, and experimental techniques for such measurements are also discussed.

Modeling of biaxial gimbal-less MEMS scanning mirrors

NASA Astrophysics Data System (ADS)

von Wantoch, Thomas; Gu-Stoppel, Shanshan; Senger, Frank; Mallas, Christian; Hofmann, Ulrich; Meurer, Thomas; Benecke, Wolfgang

2016-03-01

One- and two-dimensional MEMS scanning mirrors for resonant or quasi-stationary beam deflection are primarily known as tiny micromirror devices with aperture sizes up to a few Millimeters and usually address low power applications in high volume markets, e.g. laser beam scanning pico-projectors or gesture recognition systems. In contrast, recently reported vacuum packaged MEMS scanners feature mirror diameters up to 20 mm and integrated high-reflectivity dielectric coatings. These mirrors enable MEMS based scanning for applications that require large apertures due to optical constraints like 3D sensing or microscopy as well as for high power laser applications like laser phosphor displays, automotive lighting and displays, 3D printing and general laser material processing. This work presents modelling, control design and experimental characterization of gimbal-less MEMS mirrors with large aperture size. As an example a resonant biaxial Quadpod scanner with 7 mm mirror diameter and four integrated PZT (lead zirconate titanate) actuators is analyzed. The finite element method (FEM) model developed and computed in COMSOL Multiphysics is used for calculating the eigenmodes of the mirror as well as for extracting a high order (n < 10000) state space representation of the mirror dynamics with actuation voltages as system inputs and scanner displacement as system output. By applying model order reduction techniques using MATLABR a compact state space system approximation of order n = 6 is computed. Based on this reduced order model feedforward control inputs for different, properly chosen scanner displacement trajectories are derived and tested using the original FEM model as well as the micromirror.

Wind farm electrical system

DOEpatents

Erdman, William L.; Lettenmaier, Terry M.

2006-07-04

An approach to wind farm design using variable speed wind turbines with low pulse number electrical output. The output of multiple wind turbines are aggregated to create a high pulse number electrical output at a point of common coupling with a utility grid network. Power quality at each individual wind turbine falls short of utility standards, but the aggregated output at the point of common coupling is within acceptable tolerances for utility power quality. The approach for aggregating low pulse number electrical output from multiple wind turbines relies upon a pad mounted transformer at each wind turbine that performs phase multiplication on the output of each wind turbine. Phase multiplication converts a modified square wave from the wind turbine into a 6 pulse output. Phase shifting of the 6 pulse output from each wind turbine allows the aggregated output of multiple wind turbines to be a 24 pulse approximation of a sine wave. Additional filtering and VAR control is embedded within the wind farm to take advantage of the wind farm's electrical impedence characteristics to further enhance power quality at the point of common coupling.

Effects of self-coupling and asymmetric output on metastable dynamical transient firing patterns in arrays of neurons with bidirectional inhibitory coupling.

PubMed

Horikawa, Yo

2016-04-01

Metastable dynamical transient patterns in arrays of bidirectionally coupled neurons with self-coupling and asymmetric output were studied. First, an array of asymmetric sigmoidal neurons with symmetric inhibitory bidirectional coupling and self-coupling was considered and the bifurcations of its steady solutions were shown. Metastable dynamical transient spatially nonuniform states existed in the presence of a pair of spatially symmetric stable solutions as well as unstable spatially nonuniform solutions in a restricted range of the output gain of a neuron. The duration of the transients increased exponentially with the number of neurons up to the maximum number at which the spatially nonuniform steady solutions were stabilized. The range of the output gain for which they existed reduced as asymmetry in a sigmoidal output function of a neuron increased, while the existence range expanded as the strength of inhibitory self-coupling increased. Next, arrays of spiking neuron models with slow synaptic inhibitory bidirectional coupling and self-coupling were considered with computer simulation. In an array of Class 1 Hindmarsh-Rose type models, in which each neuron showed a graded firing rate, metastable dynamical transient firing patterns were observed in the presence of inhibitory self-coupling. This agreed with the condition for the existence of metastable dynamical transients in an array of sigmoidal neurons. In an array of Class 2 Bonhoeffer-van der Pol models, in which each neuron had a clear threshold between firing and resting, long-lasting transient firing patterns with bursting and irregular motion were observed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

DOEpatents

Woodruff, Steven D.; Mcintyre, Dustin L.

2016-03-29

A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

Numerical analysis of amplification of picosecond pulses in a THL-100 laser system with an increase in the pump energy of the XeF(C – A) amplifier

NASA Astrophysics Data System (ADS)

Yastremskii, A. G.; Ivanov, N. G.; Losev, V. F.

2018-03-01

Energy characteristics of laser radiation with a pulse width of 50 ps at an elevated pump energy of the XeF(C – A) amplifier of a hybrid THL-100 laser system are analysed numerically. The dynamics of the change in the energy and maximum intensity of laser radiation with an increase in the pump energy of the XeF(C – A) amplifier from 270 to 400 J is investigated. The results of studying the influence of the input beam divergence on the energy characteristics of the output beam are presented. It is shown that, for the existing system of mirrors, an increase in the pump energy to 400 J leads to an increase in the output energy from 3.2 to 5.5 J at a maximum radiation intensity of 57 GW cm-2. A system of amplifier mirrors with 27 laser beam passes and enlarged divergence angle of the amplified beam is considered. Theoretically, the proposed system of mirrors allows one to increase the laser pulse energy to 7.5 J at a maximum intensity of no more than 14.8 GW cm-2. The calculated efficiency of the conversion of the pump energy absorbed in the amplifier gas chamber into the lasing energy exceeds 3% in this regime.

Vertical-Cavity Surface-Emitting Lasers: Design, Fabrication and Characterization

NASA Astrophysics Data System (ADS)

Geels, Randall Scott

The theory, design, fabrication, and testing of vertical-cavity surface-emitting lasers (VCSELs) is explored in depth. The design of the distributed Bragg reflector (DBR) mirrors is thoroughly treated and both analytic and numerical approaches for computing the reflectivity are covered. The electrical properties of the DBR mirrors are also considered and graded interfaces are found to be critical in reducing the series voltage drop in the mirrors. Thickness variations due to growth rate uncertainties are considered and the permissible thickness inaccuracies are discussed. Layer thickness variations of several percent can be tolerated without large changes in the threshold current. The growth of VCSELs by molecular beam epitaxy (MBE) is described in detail as is the device processing technology for broad area as well as small area devices. Results from numerous devices are reported. Broad area in-plane lasers were used to characterize the material and determine the internal parameters. Broad area VCSELs were fabricated to determine the characteristics of the VCSEL cavity. Small area VCSELs were fabricated and extensively tested. Measured and derived parameters from small area devices include: threshold current (~0.7 mA), peak output power (>3 mW), maximum operation temperature (>110^ circC), output power at 100^ circC (~0.4 mW), and linewidth (85 MHz). The near field, far field, and polarization characteristics were also measured.

Red and infrared gas laser beam for therapy

NASA Astrophysics Data System (ADS)

Pascu, Mihail-Lucian; Ristici, Marin; Ristici, E.; Tivarus, Madalina-Elena

2000-06-01

For the low power laser therapy, the experiments show that better results are obtained when the laser beam is an overlapping of two radiations: one in the visible region of the spectrum and the other in IR region. Also, some experiments show that for good results in biostimulation it is important to have a high coherence length of laser beam; this is not the case of the laser diodes The He-Ne laser has the best coherence, being able to generate laser radiations in visible and IR. It has tow strong laser lines: 633 nm and 1.15 micrometers . Although their gains are about the same, the available power of the red radiation is 3-4 times higher because of its larger width, when they oscillate separately. Using special dichroic mirrors for simultaneous reflection of the both liens, the laser beam will consist of the two radiations, each of them having good coherence . A 420 mm active length, 1.8 mm inner diameter He-Ne laser tube and a special designed resonator has been developed. The mirrors reflect both radiations as follows: one reflects 99.9 percent and the other, the output mirror, reflects 98 percent. There is a competition between them because these lines have a common lower level. The output power of the laser beam as 6 mW for 633 nm and 4 mW for 1.15 micrometers , respectively.

Method and apparatus for controlling a microturbine

DOEpatents

Garces, Luis Jose; Cardinal, Mark Edward; Sinha, Gautam; Dame, Mark Edward

2005-08-02

An apparatus for controlling a microturbine, the apparatus including: a rectifier adapted for converting at least one generated voltage from the microturbine to a DC link voltage; an inverter adapted for converting the DC link voltage to at least one inverter output voltage, the at least one inverter output voltage being electrically coupled to an external power bus; a starter drive adapted for converting at least one starter input voltage to at least one starter output voltage, the at least one starter input voltage being electrically coupled to the external power bus, the at least one starter output voltage being electrically coupled to the microturbine.

Coupling induced logical stochastic resonance

NASA Astrophysics Data System (ADS)

Aravind, Manaoj; Murali, K.; Sinha, Sudeshna

2018-06-01

In this work we will demonstrate the following result: when we have two coupled bistable sub-systems, each driven separately by an external logic input signal, the coupled system yields outputs that can be mapped to specific logic gate operations in a robust manner, in an optimal window of noise. So, though the individual systems receive only one logic input each, due to the interplay of coupling, nonlinearity and noise, they cooperatively respond to give a logic output that is a function of both inputs. Thus the emergent collective response of the system, due to the inherent coupling, in the presence of a noise floor, maps consistently to that of logic outputs of the two inputs, a phenomenon we term coupling induced Logical Stochastic Resonance. Lastly, we demonstrate our idea in proof of principle circuit experiments.

Laser-diode pumped 40-W Yb:YAG ceramic laser.

PubMed

Hao, Qiang; Li, Wenxue; Pan, Haifeng; Zhang, Xiaoyi; Jiang, Benxue; Pan, Yubai; Zeng, Heping

2009-09-28

We demonstrated a high-power continuous-wave (CW) polycrystalline Yb:YAG ceramic laser pumped by fiber-pigtailed laser diode at 968 nm with 400 mum fiber core. The Yb:YAG ceramic laser performance was compared for different Yb(3+) ion concentrations in the ceramics by using a conventional end-pump laser cavity consisting of two flat mirrors with output couplers of different transmissions. A CW laser output of 40 W average power with M(2) factor of 5.8 was obtained with 5 mol% Yb concentration under 120 W incident pump power. This is to the best of our knowledge the highest output power in end-pumped bulk Yb:YAG ceramic laser.

Continuous-wave Nd:GYSGG laser at 1.1 μm

NASA Astrophysics Data System (ADS)

Lin, Hongyi; Liu, Hong; Huang, Xiaohua; Copner, Nigel; Sun, Dong

2018-02-01

We demonstrated a compact and simple continuous-wave (CW) Nd:GYSGG laser with triple-wavelength lines at 1105, 1107 and 1110 nm based on R2 → Y6, R1 → Y5 and R1 → Y6 of the 4F3/2 → 4I11/2 transition. The total output power of the triple-wavelength lines was 480 mW. Moreover, we obtained an efficient CW Nd:GYSGG laser at 1110 nm with the output power of 1560 mW at the pump power of 11.05 W. Those lines at 1058 and 1062 nm were suppressed completely by the simple output mirror of high transmission at 1.06 μm.

Multistage Force Amplification of Piezoelectric Stacks

NASA Technical Reports Server (NTRS)

Xu, Tian-Bing (Inventor); Siochi, Emilie J. (Inventor); Zuo, Lei (Inventor); Jiang, Xiaoning (Inventor); Kang, Jin Ho (Inventor)

2015-01-01

Embodiments of the disclosure include an apparatus and methods for using a piezoelectric device, that includes an outer flextensional casing, a first cell and a last cell serially coupled to each other and coupled to the outer flextensional casing such that each cell having a flextensional cell structure and each cell receives an input force and provides an output force that is amplified based on the input force. The apparatus further includes a piezoelectric stack coupled to each cell such that the piezoelectric stack of each cell provides piezoelectric energy based on the output force for each cell. Further, the last cell receives an input force that is the output force from the first cell and the last cell provides an output apparatus force In addition, the piezoelectric energy harvested is based on the output apparatus force. Moreover, the apparatus provides displacement based on the output apparatus force.

Seeing the partner: a video recall study of emotional behavior in same- and mixed-sex late adolescent romantic couples.

PubMed

Darling, Nancy; Clarke, Sara A

2009-08-01

Fifty-three college-aged same- and mixed-sex romantic couples (83% White, 63% female, mean age, 20.8) engaged in a video recall task in which they rated their own and their partners' behaviors and emotions. Females reported feeling more connected to partners and reported fewer negative behaviors than males. Females with male partners reported the highest feelings of connection and the fewest negative behaviors. Males with male partners reported the lowest connection and most negative behaviors. Behavioral mirroring and empathic accuracy did not vary by sex of the actor or of their partner. Partners' self-reported connection and negative behaviors were similar and they accurately perceived each others' average behavioral and emotional states. The data showed little evidence that partners' behaviors mirrored one another temporally across time segments, however. Results suggest that college-aged same and mixed-sex romantic couples show greater similarities than differences in functioning.

Movement decoupling control for two-axis fast steering mirror

NASA Astrophysics Data System (ADS)

Wang, Rui; Qiao, Yongming; Lv, Tao

2017-02-01

Based on flexure hinge and piezoelectric actuator of two-axis fast steering mirror is a complex system with time varying, uncertain and strong coupling. It is extremely difficult to achieve high precision decoupling control with the traditional PID control method. The feedback error learning method was established an inverse hysteresis model which was based inner product dynamic neural network nonlinear and no-smooth for piezo-ceramic. In order to improve the actuator high precision, a method was proposed, which was based piezo-ceramic inverse model of two dynamic neural network adaptive control. The experiment result indicated that, compared with two neural network adaptive movement decoupling control algorithm, static relative error is reduced from 4.44% to 0.30% and coupling degree is reduced from 12.71% to 0.60%, while dynamic relative error is reduced from 13.92% to 2.85% and coupling degree is reduced from 2.63% to 1.17%.

Scalable ion-photon quantum interface based on integrated diffractive mirrors

NASA Astrophysics Data System (ADS)

Ghadimi, Moji; Blūms, Valdis; Norton, Benjamin G.; Fisher, Paul M.; Connell, Steven C.; Amini, Jason M.; Volin, Curtis; Hayden, Harley; Pai, Chien-Shing; Kielpinski, David; Lobino, Mirko; Streed, Erik W.

2017-12-01

Quantum networking links quantum processors through remote entanglement for distributed quantum information processing and secure long-range communication. Trapped ions are a leading quantum information processing platform, having demonstrated universal small-scale processors and roadmaps for large-scale implementation. Overall rates of ion-photon entanglement generation, essential for remote trapped ion entanglement, are limited by coupling efficiency into single mode fibers and scaling to many ions. Here, we show a microfabricated trap with integrated diffractive mirrors that couples 4.1(6)% of the fluorescence from a 174Yb+ ion into a single mode fiber, nearly triple the demonstrated bulk optics efficiency. The integrated optic collects 5.8(8)% of the π transition fluorescence, images the ion with sub-wavelength resolution, and couples 71(5)% of the collected light into the fiber. Our technology is suitable for entangling multiple ions in parallel and overcomes mode quality limitations of existing integrated optical interconnects.

High Power OPO Laser and wavelength-controlled system for 1.6μm CO2-DIAL

NASA Astrophysics Data System (ADS)

Abo, M.; Nagasawa, C.; Shibata, Y.

2009-12-01

Unlike the existing 2.0μm CO2-DIAL, a high-energy pulse laser operating in the 1.6μm absorption band of CO2 has not been realized. Quasi phase matching (QPM) devices have high conversion efficiency and high beam quality due to their higher nonlinear optical coefficient. We adapt the PPMgLT crystal as the QPM device. The PPMgLT crystal had 3mm × 3mm apertures, and the periodically poled period was 30.9 μm, with the duty ratio close to the ideal value of 0.5. The beam quality of the pumping laser was exceed M2 ≥1.2. The repetition rate was 400 Hz and the energy was 35 mJ. The pumping laser pulse was injection-seeded by the continuous-wave (CW) fiber laser, which had a narrow spectrum. The pulse pumped the PPMgLT crystal in the ring cavity with a single pass through the dielectric mirror. The PPMgLT crystal was mounted on a copper holder, and the temperature was maintained at 40 °C using a Peltier module. The holder’s temperature was stabilized to within 0.01 °C when the copper holder was covered with a plastic case. The OPO ring cavity was a singly resonant oscillator optimized for the signal wave. Single-frequency oscillation of the PPMgLT OPO was achieved by injection seeding, as described in the following. The injection seeder was a DFB laser having a power of 30mW with a 1MHz oscillation spectrum. Their oscillation wavelength was coarse tuned by temperature and fine tuned by adjusting injection currents. The partial power of the online wavelength was split in the wavelength control unit. We locked the DFB laser as an injection seeder of the online wavelength onto the line center by referencing the fiber coupled multipath gas cell (path length 800mm) containing pure CO2 at a pressure of 700 Torr. Stabilization was estimated to within 1.8MHz rms of the line center of the CO2 absorption line by monitoring the feedback signal of a wavelength-controlled unit. Injection seeding of the PPMgLT OPO was performed by matching the cavity length to the seeder wavelength for each oscillation pulse. The on-line and off-line wavelengths were injected into the OPO cavity through its output mirror. The injection seeder could be automatically switched by applying the TTL trigger to an optical fiber switch. A typical power of 8mW was injected into the cavity. The OPO cavity length was controlled as follows. A slope voltage was applied to the piezoelectric element mounted on the cavity mirror. If the longitudinal mode of the cavity was closed at the wavelength of the injection seeder, the electrical signal monitored by the photodiode would be maximized. The CW laser beam was injected from the output coupler to control the oscillation wavelength. The maximum output energy of 12mJ at 400 Hz was observed at 35mJ of pumping laser energy. The slope efficiency was 43.7%. This output energy and this repetition rate were the highest achieved so far. No damage was observed even after 1 h of operation. Therefore higher-energy operations can be expected with this device if the beam quality of the pumping laser is improved. This work was financially supported by the System Development Program for Advanced Measurement and Analysis by the JST.

Culture, the Crack'd Mirror, and the Neuroethics of Disease.

PubMed

Gillett, Grant

2016-10-01

Human beings are sensorimotor coupled to the actual world and also attuned to the symbolic world of culture and the techniques of adaptation that culture provides. The self-image and self-shaping mediated by that mirror directly affects the neurocognitive structures that integrate human neural activity and reshape its processing capacities through top-down or autopoietic effects. Thus a crack'd mirror, which disrupts the processes of enactive self-configuration, can be disabling for an individual. That is exactly what happens in postcolonial or immigration contexts in which individuals' cultural adaptations are marginalized and disconnected in diverse and often painful and disorienting ways. The crack'd mirror is therefore a powerful trope for neuroethics and helps us understand the social and moral pathologies of many indigenous and immigrant communities.

A technology demonstrator for development of ultra-lightweight, large aperture, deployable telescope for space applications

NASA Astrophysics Data System (ADS)

Zuccaro Marchi, Alessandro; Gambicorti, Lisa; Simonetti, Francesca; Salinari, Piero; Lisi, Franco; Bursi, Alessandro; Olivier, Massimiliano; Gallieni, Daniele

2017-11-01

This work presents the latest results of new technological concepts for large aperture, lightweight telescopes using thin deployable active mirrors. The study is originally addressed to a spaceborne DIAL (Differential Absorption Lidar) at 935.5 nm for the measurement of water vapour profile in atmosphere, as an output of an ESA contract (whose preliminary results were presented at ICSO 2006). The high versatility of these concepts allows to exploit the presented technology for any project willing to consider large aperture, segmented lightweight telescopes. A possible scientific application is for Ultra High Energy Cosmic Rays detection through the fluorescence traces in atmosphere and diffused Cerenkov signals observation via a Schmidt-like spaceborne LEO telescope with large aperture, wide Field of View (FOV) and low f/#. A technology demonstrator has been manufactured and tested in order to investigate two project critical areas identified during the preliminary design: the performances of the long-stroke actuators used to implement the mirror active control and the mirror survivability to launch. In particular, this breadboard demonstrates at first that the mirror actuators are able to control with the adequate accuracy the surface shape and to recover a deployment error with their long stroke; secondly, the mirror survivability has been demonstrated using an electrostatic locking between mirror and backplane able to withstand without failure a vibration test representative of the launch environment.

Tunable Bistability in Hybrid Bose-Einstein Condensate Optomechanics

PubMed Central

Yasir, Kashif Ammar; Liu, Wu-Ming

2015-01-01

Cavity-optomechanics, a rapidly developing area of research, has made a remarkable progress. A stunning manifestation of optomechanical phenomena is in exploiting the mechanical effects of light to couple the optical degree of freedom with mechanical degree of freedom. In this report, we investigate the controlled bistable dynamics of such hybrid optomechanical system composed of cigar-shaped Bose-Einstein condensate (BEC) trapped inside high-finesse optical cavity with one moving-end mirror and is driven by a single mode optical field. The numerical results provide evidence for controlled optical bistability in optomechanics using transverse optical field which directly interacts with atoms causing the coupling of transverse field with momentum side modes, exited by intra-cavity field. This technique of transverse field coupling is also used to control bistable dynamics of both moving-end mirror and BEC. The report provides an understanding of temporal dynamics of moving-end mirror and BEC with respect to transverse field. Moreover, dependence of effective potential of the system on transverse field has also been discussed. To observe this phenomena in laboratory, we have suggested a certain set of experimental parameters. These findings provide a platform to investigate the tunable behavior of novel phenomenon like electromagnetically induced transparency and entanglement in hybrid systems. PMID:26035206

Current status of Kumgang laser system

NASA Astrophysics Data System (ADS)

Kong, Hong Jin; Park, Sangwoo; Ahn, HeeKyung; Lee, Hwihyeong; Oh, Jungsuk; Kim, Jom Sool

2015-02-01

In KAIST, Kumgang laser is being developed for demonstration of the kW level coherent beam combination using stimulated Brillouin scattering phase conjugation mirrors. It will combine 4 modules of DPSSL rod amplifier which produces 1 kW output power. It is composed of the single frequency front-end, pre-amplifier module, and main amplifier. The output powers of the pre-amp and main amplifier module are 200 W (20 mJ @ 10 kHz / 10 ns) and 1.07kW (107 mJ @ 10 kHz / 10 ns), respectively.

A wavelength scannable XeCl oscillator-ring amplifier laser system

NASA Technical Reports Server (NTRS)

Pacala, T. J.; Mcdermid, I. S.; Laudenslager, J. B.

1982-01-01

A holographic grating at grazing angle of incidence was used to achieve tunable, narrow bandwidth (0.005 nm) operation of a XeCl oscillator for injection locking of a ring amplifier. The amplifier's narrow bandwidth output energy was constant and equal to the untuned, broadband output (approximately 15 mJ) in regions where injection locking was achieved. Scanning was provided by use of a stepping motor-driven differential micrometer on the tuning mirror. This system was used to produce a laser excitation spectrum of hydroxyl radicals (OH) in a flame.

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

Schearer, L.D.; Leduc, M.

Over 250 mW of CW laser emission at 1084 nm is obtained from Nd:LiNbO{sub 3} when the rod is end-pumped along the crystalline {open quote}{ital y}{close quote} axis by 1 W from a Kr{sup +} laser at 752 nm. The laser can be tuned over 3 nm at the 1084 nm peak with a thin, uncoated etalon in the cavity. Thresholds of 30 mW of absorbed pump power were obtained with a weak output coupler, rising to 220 mW with a 35% transmitting output mirror. No pump-induced photorefractive effects were observed.

Computer simulations of neural mechanisms explaining upper and lower limb excitatory neural coupling

PubMed Central

2010-01-01

Background When humans perform rhythmic upper and lower limb locomotor-like movements, there is an excitatory effect of upper limb exertion on lower limb muscle recruitment. To investigate potential neural mechanisms for this behavioral observation, we developed computer simulations modeling interlimb neural pathways among central pattern generators. We hypothesized that enhancement of muscle recruitment from interlimb spinal mechanisms was not sufficient to explain muscle enhancement levels observed in experimental data. Methods We used Matsuoka oscillators for the central pattern generators (CPG) and determined parameters that enhanced amplitudes of rhythmic steady state bursts. Potential mechanisms for output enhancement were excitatory and inhibitory sensory feedback gains, excitatory and inhibitory interlimb coupling gains, and coupling geometry. We first simulated the simplest case, a single CPG, and then expanded the model to have two CPGs and lastly four CPGs. In the two and four CPG models, the lower limb CPGs did not receive supraspinal input such that the only mechanisms available for enhancing output were interlimb coupling gains and sensory feedback gains. Results In a two-CPG model with inhibitory sensory feedback gains, only excitatory gains of ipsilateral flexor-extensor/extensor-flexor coupling produced reciprocal upper-lower limb bursts and enhanced output up to 26%. In a two-CPG model with excitatory sensory feedback gains, excitatory gains of contralateral flexor-flexor/extensor-extensor coupling produced reciprocal upper-lower limb bursts and enhanced output up to 100%. However, within a given excitatory sensory feedback gain, enhancement due to excitatory interlimb gains could only reach levels up to 20%. Interconnecting four CPGs to have ipsilateral flexor-extensor/extensor-flexor coupling, contralateral flexor-flexor/extensor-extensor coupling, and bilateral flexor-extensor/extensor-flexor coupling could enhance motor output up to 32%. Enhancement observed in experimental data exceeded 32%. Enhancement within this symmetrical four-CPG neural architecture was more sensitive to relatively small interlimb coupling gains. Excitatory sensory feedback gains could produce greater output amplitudes, but larger gains were required for entrainment compared to inhibitory sensory feedback gains. Conclusions Based on these simulations, symmetrical interlimb coupling can account for much, but not all of the excitatory neural coupling between upper and lower limbs during rhythmic locomotor-like movements. PMID:21143960

Thin disk laser with unstable resonator and reduced output coupler

NASA Astrophysics Data System (ADS)

Gavili, Anwar; Shayganmanesh, Mahdi

2018-05-01

In this paper, feasibility of using unstable resonator with reduced output coupling in a thin disk laser is studied theoretically. Unstable resonator is modeled by wave-optics using Collins integral and iterative method. An Yb:YAG crystal with 250 micron thickness is considered as a quasi-three level active medium and modeled by solving rate equations of energy levels populations. The amplification of laser beam in the active medium is calculated based on the Beer-Lambert law and Rigrod method. Using generalized beam parameters method, laser beam parameters like, width, divergence, M2 factor, output power as well as near and far-field beam profiles are calculated for unstable resonator. It is demonstrated that for thin disk laser (with single disk) in spite of the low thickness of the disk which leads to low gain factor, it is possible to use unstable resonator (with reduced output coupling) and achieve good output power with appropriate beam quality. Also, the behavior of output power and beam quality versus equivalent Fresnel number is investigated and optimized value of output coupling for maximum output power is achieved.

Input-output theory for spin-photon coupling in Si double quantum dots

NASA Astrophysics Data System (ADS)

Benito, M.; Mi, X.; Taylor, J. M.; Petta, J. R.; Burkard, Guido

2017-12-01

The interaction of qubits via microwave frequency photons enables long-distance qubit-qubit coupling and facilitates the realization of a large-scale quantum processor. However, qubits based on electron spins in semiconductor quantum dots have proven challenging to couple to microwave photons. In this theoretical work we show that a sizable coupling for a single electron spin is possible via spin-charge hybridization using a magnetic field gradient in a silicon double quantum dot. Based on parameters already shown in recent experiments, we predict optimal working points to achieve a coherent spin-photon coupling, an essential ingredient for the generation of long-range entanglement. Furthermore, we employ input-output theory to identify observable signatures of spin-photon coupling in the cavity output field, which may provide guidance to the experimental search for strong coupling in such spin-photon systems and opens the way to cavity-based readout of the spin qubit.

Silicon photonics thermal phase shifter with reduced temperature range

DOEpatents

Lentine, Anthony L; Kekatpure, Rohan D; DeRose, Christopher; Davids, Paul; Watts, Michael R

2013-12-17

Optical devices, phased array systems and methods of phase-shifting an input signal are provided. An optical device includes a microresonator and a waveguide for receiving an input optical signal. The waveguide includes a segment coupled to the microresonator with a coupling coefficient such that the waveguide is overcoupled to the microresonator. The microresonator received the input optical signal via the waveguide and phase-shifts the input optical signal to form an output optical signal. The output optical signal is coupled into the waveguide via the microresonator and transmitted by the waveguide. At an operating point of the optical device, the coupling coefficient is selected to reduce a change in an amplitude of the output optical signal and to increase a change in a phase of the output optical signal, relative to the input optical signal.

Radial/axial power divider/combiner

NASA Technical Reports Server (NTRS)

Vaddiparty, Yerriah P. (Inventor)

1987-01-01

An electromagnetic power divider/combiner comprises N radial outputs (31) having equal powers and preferably equal phases, and a single axial output (20). A divider structure (1) and a preferably identical combiner structure (2) are broadside coupled across a dielectric substrate (30) containing on one side the network of N radial outputs (31) and on its other side a set of N equispaced stubs (42) which are capacitively coupled through the dielectric substrate (30) to the N radial outputs (31). The divider structure (1) and the combiner structure (2) each comprise a dielectric disk (12, 22, respectively) on which is mounted a set of N radial impedance transformers (14, 24, respectively). Gross axial coupling is determined by the thickness of the dielectric layer (30). Rotating the disks (12, 22) with respect to each other effectuates fine adjustment in the degree of axial coupling.

Method for removing tilt control in adaptive optics systems

DOEpatents

Salmon, J.T.

1998-04-28

A new adaptive optics system and method of operation are disclosed, whereby the method removes tilt control, and includes the steps of using a steering mirror to steer a wavefront in the desired direction, for aiming an impinging aberrated light beam in the direction of a deformable mirror. The deformable mirror has its surface deformed selectively by means of a plurality of actuators, and compensates, at least partially, for existing aberrations in the light beam. The light beam is split into an output beam and a sample beam, and the sample beam is sampled using a wavefront sensor. The sampled signals are converted into corresponding electrical signals for driving a controller, which, in turn, drives the deformable mirror in a feedback loop in response to the sampled signals, for compensating for aberrations in the wavefront. To this purpose, a displacement error (gradient) of the wavefront is measured, and adjusted by a modified gain matrix, which satisfies the following equation: G{prime} = (I{minus}X(X{sup T} X){sup {minus}1}X{sup T})G(I{minus}A). 3 figs.

BOLDMirror: a global mirror system of DNA barcode data.

PubMed

Liu, D; Liu, L; Guo, G; Wang, W; Sun, Q; Parani, M; Ma, J

2013-11-01

DNA barcoding is a novel concept for taxonomic identification using short, specific genetic markers and has been applied to study a large number of eukaryotes. The huge amount of data output generated by DNA barcoding requires well-organized information systems. Besides the Barcode of Life Data system (BOLD) established in Canada, the mirror system is also important for the international barcode of life project (iBOL). For this purpose, we developed the BOLDMirror, a global mirror system of DNA barcode data. It is open-sourced and can run on the LAMP (Linux + Apache + MySQL + PHP) environment. BOLDMirror has data synchronization, data representation and statistics modules, and also provides spaces to store user operation history. BOLDMirror can be accessed at http://www.boldmirror.net and several countries have used it to setup their site of DNA barcoding. © 2012 John Wiley & Sons Ltd.

Tunable multi-wavelength SOA based linear cavity dual-output port fiber laser using Lyot-Sagnac loop mirror.

PubMed

Ummy, M A; Madamopoulos, N; Joyo, A; Kouar, M; Dorsinville, R

2011-02-14

We propose and demonstrate a simple dual port tunable from the C- to the L-band multi-wavelength fiber laser based on a SOA designed for C-band operation and fiber loop mirrors. The laser incorporates a polarization maintaining fiber in one of the fiber loop mirrors and delivers multi-wavelength operation at 9 laser lines with a wavelength separation of ~2.8 nm at room temperature. We show that the number of lasing wavelengths increases with the increase of the bias current of the SOA. Wavelength tunability from the C to L-band is achieved by exploiting the gain compression of a SOA. Stable multi-wavelength operation is achieved at room temperature without temperature compensation techniques, with measured power and the wavelength stability within < ±0.5 dB and 
±0.1 nm, respectively.

Quantum nondemolition measurement of optical field fluctuations by optomechanical interaction

NASA Astrophysics Data System (ADS)

Pontin, A.; Bonaldi, M.; Borrielli, A.; Marconi, L.; Marino, F.; Pandraud, G.; Prodi, G. A.; Sarro, P. M.; Serra, E.; Marin, F.

2018-03-01

According to quantum mechanics, if we keep observing a continuous variable we generally disturb its evolution. For a class of observables, however, it is possible to implement a so-called quantum nondemolition measurement: by confining the perturbation to the conjugate variable, the observable is estimated with arbitrary accuracy, or prepared in a well-known state. For instance, when the light bounces on a movable mirror, its intensity is not perturbed (the effect is just seen on the phase of the radiation), but the radiation pressure allows one to trace back its fluctuations by observing the mirror motion. In this work, we implement a cavity optomechanical experiment based on an oscillating micromirror, and we measure correlations between the output light intensity fluctuations and the mirror motion. We demonstrate that the uncertainty of the former is reduced below the shot-noise level determined by the corpuscular nature of light.

Large energy laser pulses with high repetition rate by graphene Q-switched solid-state laser.

PubMed

Li, Xian-lei; Xu, Jin-long; Wu, Yong-zhong; He, Jing-liang; Hao, Xiao-peng

2011-05-09

We demonstrated that the graphene could be used as an effective saturable absorber for Q-switched solid-state lasers. A graphene saturable absorber mirror was fabricated with large and high-quality graphene sheets deprived from the liquid phase exfoliation. Using this mirror, 105-ns pulses and 2.3-W average output power are obtained from a passively Q-switched Nd:GdVO(4) laser. The maximum pulse energy is 3.2 μJ. The slope efficiency is as high as 37% approximating to 40% of the continue-wave laser, indicating a low intrinsic loss of the graphene. © 2011 Optical Society of America

Design and manufacturing methods for the integral field unit of the nirspec instrument on JWST

NASA Astrophysics Data System (ADS)

Lobb, Dan; Robertson, David

2017-11-01

An integral field unit, to be used with the near-IR spectrometer instrument of the James Webb Space Telescope (JWST), is currently under development by SSTL and CfAI. Special problems in design and manufacture of the optical system are outlined, and manufacturing methods for critical optical elements are discussed. The optical system is complex, requiring a total of 95 mirrors to produce 30 output channels. Emphasis is placed on the advantages of free-form machining in aluminium. These include: resistance to launch stress, insensitivity to temperature variations from ambient to cryogenic, and the possibility of relatively complex mirror surface shapes.

Receiver-Coupling Schemes Based On Optimal-Estimation Theory

NASA Technical Reports Server (NTRS)

Kumar, Rajendra

1992-01-01

Two schemes for reception of weak radio signals conveying digital data via phase modulation provide for mutual coupling of multiple receivers, and coherent combination of outputs of receivers. In both schemes, optimal mutual-coupling weights computed according to Kalman-filter theory, but differ in manner of transmission and combination of outputs of receivers.

The non-planar single-frequency ring laser with variable output coupling

NASA Astrophysics Data System (ADS)

Wu, Ke-ying; Yang, Su-hui; Wei, Guang-hui

2002-03-01

We put forward a novel non-planar single-frequency ring laser, which consists of a corner cube prism and a specially cut Porro prism made by Nd:YAG crystal. The relative angle between the corner cube and the Porro prism could be adjusted to control the output coupling of the laser resonator and the polarization-state of the output laser. A 1.06 μm single-frequency laser with 1 W output has been obtained.

Two-dimensional designed fabrication of subwavelength grating HCG mirror on silicon-on-insulator

NASA Astrophysics Data System (ADS)

Huang, Shen-Che; Hong, Kuo-Bin; Lu, Tien-Chang; He, Sailing

2016-03-01

We designed and fabricated a two dimensional high contrast subwavelength grating (HCG) mirrors. The computer-aided software was employed to verify the structural parameters including grating periods and filling factors. From the optimized simulation results, the designed HCG structure has a wide reflection stopband (reflectivity (R) >90%) of over 200 nm, which centered at telecommunication wavelength. The optimized HCG mirrors were fabricated by electron beam lithography and inductively coupled plasma process technique. The experimental result was almost consistent with calculated data. This achievement should have an impact on numerous photonic devices helpful attribution to the integrated HCG VCSELs in the future.

ART-XC/SRG: Status of the X-ray Optics Development

NASA Technical Reports Server (NTRS)

Gubarev, M.; Ramsey, B.; Zavlin, V.; Swartz, D.; Elsner, R. F.; ODell, S.; Kilaru, K.; Atkins, C.; McCracken, J.; Pavlinsky, M.;

PLZT Ceramic Driving Rotary Micro-mirror Based on Photoelectric-electrostatic Mechanism

NASA Astrophysics Data System (ADS)

Tang, Yujuan; Yang, Zhong; Chen, Yusong; Wang, Xinjie

2017-12-01

Based on the anomalous photovoltaic effect of PLZT, a rotary micro-mirror driven by hybrid photoelectric-electrostatic actuation of PLZT ceramic is proposed. Firstly, the mathematical modelling of coupled multi-physics fields of PLZT ceramic is established during illumination and light off phases. Then, the relationship between the rotation angle and the photovoltage of PLZT ceramics is established. In addition, the feasibility of rotary micro-mirror with hybrid photoelectric-electrostatic driving is verified via closed-loop control for photo-induced voltage of PLZT ceramic. The experimental results show that the photo-induced voltage of PLZT ceramics has good dynamic control precision using on-off closed-loop control method.

ART-XC/SRG: Status of the X-ray Optics Development

NASA Technical Reports Server (NTRS)

Gubarev, M.; Ramsey, B.; Elsner, R.; O'Dell, S.; Kolodziejczak, J.; McCracken, J.; Zavlin, V.; Swartz, D.; Kilaru, K.; Atkins, C.;

ART-XC/SRG: Status of the X-ray Optics Development

NASA Technical Reports Server (NTRS)

Gubarev, M.; Ramsey, B.; Elsner, R.; O'Dell, S.; Kolodziejczak, J.; McCracken, J.; Zavlin, V.; Swartz, D.; Kilaru, K.; Atkins, C.;

Advanced insulated gate bipolar transistor gate drive

DOEpatents

Short, James Evans [Monongahela, PA; West, Shawn Michael [West Mifflin, PA; Fabean, Robert J [Donora, PA

2009-08-04

A gate drive for an insulated gate bipolar transistor (IGBT) includes a control and protection module coupled to a collector terminal of the IGBT, an optical communications module coupled to the control and protection module, a power supply module coupled to the control and protection module and an output power stage module with inputs coupled to the power supply module and the control and protection module, and outputs coupled to a gate terminal and an emitter terminal of the IGBT. The optical communications module is configured to send control signals to the control and protection module. The power supply module is configured to distribute inputted power to the control and protection module. The control and protection module outputs on/off, soft turn-off and/or soft turn-on signals to the output power stage module, which, in turn, supplies a current based on the signal(s) from the control and protection module for charging or discharging an input capacitance of the IGBT.

Monolithic subwavelength high refractive-index-contrast grating VCSELs

NASA Astrophysics Data System (ADS)

Gebski, Marcin; Dems, Maciej; Lott, James A.; Czyszanowski, Tomasz

2016-03-01

In this paper we present optical design and simulation results of vertical-cavity surface-emitting lasers (VCSELs) that incorporate monolithic subwavelength high refractive-index-contrast grating (MHCG) mirrors - a new variety of HCG mirror that is composed of high index material surrounded only on one side by low index material. We show the impact of an MHCG mirror on the performance of 980 nm VCSELs designed for high bit rate and energy-efficient optical data communications. In our design, all or part of the all-semiconductor top coupling distributed Bragg reflector mirror is replaced by an undoped gallium-arsenide MHCG. We show how the optical field intensity distribution of the VCSEL's fundamental mode is controlled by the combination of the number of residual distributed Bragg reflector (DBR) mirror periods and the physical design of the topmost gallium-arsenide MHCG. Additionally, we numerically investigate the confinement factors of our VCSELs and show that this parameter for the MHCG DBR VCSELs may only be properly determined in two or three dimensions due to the periodic nature of the grating mirror.

Feedback-controlled radiation pressure cooling

NASA Astrophysics Data System (ADS)

Prior, Yehiam; Vilensky, Mark; Averbukh, Ilya Sh.

2008-03-01

We propose a new approach to laser cooling of micromechanical devices, which is based on the phenomenon of optical bistability. These devices are modeled as a Fabry-Perot resonator with one fixed and one oscillating mirror. The bistability may be induced by an external feedback loop. When excited by an external laser, the cavity field has two co-existing stable steady-states depending on the position of the moving mirror. If the latter moves slow enough, the field in the cavity adjusts itself adiabatically to the mirror's instantaneous position. The mirror experiences radiation pressure corresponding to the intensity value. A sharp transition between two values of the radiation pressure force happens twice per every period of the mirror oscillation at non-equivalent positions (hysteresis effect), which leads to a non-zero net energy loss. The cooling mechanism resembles Sisyphus cooling in which the cavity mode performs sudden transitions between two stable states. We provide a dynamical stability analysis of the coupled moving mirror -- cavity field system, and find the parameters for efficient cooling. Direct numerical simulations show that a bistable cavity provides much more efficient cooling compared to the regular one.

Modeling the Effects of Mirror Misalignment in a Ring Imaging Cherenkov Detector

NASA Astrophysics Data System (ADS)

Hitchcock, Tawanda; Harton, Austin; Garcia, Edmundo

2012-03-01

The Very High Momentum Particle Identification Detector (VHMPID) has been proposed for the ALICE experiment at the Large Hadron Collider (LHC). This detector upgrade is considered necessary to study jet-matter interaction at high energies. The VHMPID identifies charged hadrons in the 5 GeV/c to 25 GeV/c momentum range. The Cherenkov photons emitted in the VHMPID radiator are collected by spherical mirrors and focused onto a photo-detector plane forming a ring image. The radius of this ring is related to the Cherenkov angle, this information coupled with the particle momentum allows the particle identification. A major issue in the RICH detector is that environmental conditions can cause movements in mirror position. In addition, chromatic dispersion causes the refractive index to shift, altering the Cherenkov angle. We are modeling a twelve mirror RICH detector taking into account the effects of mirror misalignment and chromatic dispersion using a commercial optical software package. This will include quantifying the effects of both rotational and translational mirror misalignment for the initial assembly of the module and later on particle identification.

High-power narrow-linewidth quasi-CW diode-pumped TEM00 1064 nm Nd:YAG ring laser.

PubMed

Liu, Yuan; Wang, Bao-shan; Xie, Shi-yong; Bo, Yong; Wang, Peng-yuan; Zuo, Jun-wei; Xu, Yi-ting; Xu, Jia-lin; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

2012-04-01

We demonstrated a high average power, narrow-linewidth, quasi-CW diode-pumped Nd:YAG 1064 nm laser with near-diffraction-limited beam quality. A symmetrical three-mirror ring cavity with unidirectional operation elements and an etalon was employed to realize the narrow-linewidth laser output. Two highly efficient laser modules and a 90° quartz rotator for birefringence compensation were used for the high output power. The maximum average output power of 62.5 W with the beam quality factor M(2) of 1.15 was achieved under a pump power of 216 W at a repetition rate of 500 Hz, corresponding to the optical-to-optical conversion efficiency of 28.9%. The linewidth of the laser at the maximum output power was measured to be less than 0.2 GHz.

Laser output power stabilization for direct laser writing system by using an acousto-optic modulator.

PubMed

Kim, Dong Ik; Rhee, Hyug-Gyo; Song, Jae-Bong; Lee, Yun-Woo

2007-10-01

We present experimental results on the output power stabilization of an Ar(+) laser for a direct laser writing system (LWS). Instability of the laser output power in the LWS cause resolution fluctuations of being fabricated diffractive optical elements or computer-generated holograms. For the purpose of reducing the power fluctuations, we have constituted a feedback loop with an acousto-optic modulator, a photodetector, and a servo controller. In this system, we have achieved the stability of +/-0.20% for 12 min and the relative intensity noise level of 2.1 x 10(-7) Hz(-12) at 100 Hz. In addition, we applied our system to a 2 mW internal mirror He-Ne laser. As a consequence, we achieved the output power stability of +/-0.12% for 25 min.

Mirror-image discrimination in the literate brain: a causal role for the left occpitotemporal cortex.

PubMed

Nakamura, Kimihiro; Makuuchi, Michiru; Nakajima, Yasoichi

2014-01-01

Previous studies show that the primate and human visual system automatically generates a common and invariant representation from a visual object image and its mirror reflection. For humans, however, this mirror-image generalization seems to be partially suppressed through literacy acquisition, since literate adults have greater difficulty in recognizing mirror images of letters than those of other visual objects. At the neural level, such category-specific effect on mirror-image processing has been associated with the left occpitotemporal cortex (L-OTC), but it remains unclear whether the apparent "inhibition" on mirror letters is mediated by suppressing mirror-image representations covertly generated from normal letter stimuli. Using transcranial magnetic stimulation (TMS), we examined how transient disruption of the L-OTC affects mirror-image recognition during a same-different judgment task, while varying the semantic category (letters and non-letter objects), identity (same or different), and orientation (same or mirror-reversed) of the first and second stimuli. We found that magnetic stimulation of the L-OTC produced a significant delay in mirror-image recognition for letter-strings but not for other objects. By contrast, this category specific impact was not observed when TMS was applied to other control sites, including the right homologous area and vertex. These results thus demonstrate a causal link between the L-OTC and mirror-image discrimination in literate people. We further suggest that left-right sensitivity for letters is not achieved by a local inhibitory mechanism in the L-OTC but probably relies on the inter-regional coupling with other orientation-sensitive occipito-parietal regions.

Horizontal Fault Tolerance in a Fully Distributed Loosely Coupled Environment

DTIC Science & Technology

1990-08-01

been registered. As the broadcasts continue, FTMI and FTM2 will eventu- ally receive return messages indicating duplicate name, and de -register the name...acknowledgement ADVOKN FF Phase-2 negative acknowledgement CLOSE IF Request to De -Advertise a global name CLOSOK FI De -Advertise completed KILLN FF FTM broadcasts...only. Since disk mirroring is layered beneath the UNIX operating system it does violate the "easily transportable " concept. Disk mirroring was

The mirror neuron system is more active during complementary compared with imitative action.

PubMed

Newman-Norlund, Roger D; van Schie, Hein T; van Zuijlen, Alexander M J; Bekkering, Harold

2007-07-01

We assessed the role of the human mirror neuron system (MNS) in complementary actions using functional magnetic resonance imaging while participants prepared to execute imitative or complementary actions. The BOLD signal in the right inferior frontal gyrus and bilateral inferior parietal lobes was greater during preparation of complementary than during imitative actions, suggesting that the MNS may be essential in dynamically coupling action observation to action execution.

Novel deformable mirror design for possible wavefront correction in CO2 laser fusion system

NASA Astrophysics Data System (ADS)

Gunn, S. V.; Heinz, T. A.; Henderson, W. D.; Massie, N. A.; Viswanathan, V. K.

1980-11-01

Analysis at Los Alamos and elsewhere has resulted in the conclusion that deformable mirrors can substantially improve the optical performance of laser fusion systems, as the errors are mostly static or quasi-static with mainly low spatial frequencies across the aperture resulting in low order Seidel aberrations in the beam. A novel deformable mirror assembly (Fig. 1) has been fabricated with 19 actuators capable of surface deflection of ±20 microns. The mirror surface deflections are produced by a unique differential ball screw that acts as both a force and position actuator. The screw is driven by a stepper motor giving a surface positioning resolution of 0.025 micron. No holding voltage potential is required, and a piezoceramic element in series with each ball screw provides a ±1 micron amplitude high-frequency surface dither to aid the correction process. Mirror performance in terms of individual actuator influence function, cross-coupling, figure attainment, long-term surface stability as well as optical performance characteristics will be discussed.

Minimal mirror twin Higgs

DOE PAGES

Barbieri, Riccardo; Hall, Lawrence J.; Harigaya, Keisuke

2016-11-29

In a Mirror Twin World with a maximally symmetric Higgs sector the little hierarchy of the Standard Model can be significantly mitigated, perhaps displacing the cutoff scale above the LHC reach. We show that consistency with observations requires that the Z 2 parity exchanging the Standard Model with its mirror be broken in the Yukawa couplings. A minimal such effective field theory, with this sole Z 2 breaking, can generate the Z 2 breaking in the Higgs sector necessary for the Twin Higgs mechanism. The theory has constrained and correlated signals i n Higgs decays, direct Dark Matter Detection andmore » Dark Radiation, all within reach of foreseen experiments, over a region of parameter space where the fine-tuning for the electroweak scale is 10-50%. For dark matter, both mirror neutrons and a variety of self-interacting mirror atoms are considered. Neutrino mass signals and the effects of a possible additional Z 2 breaking from the vacuum expectation values of B-L breaking fields are also discussed.« less

Passively-coupled, low-coherence interferometric duct profiling with an astigmatism-corrected conical mirror.

PubMed

Ford, Helen D; Tatam, Ralph P

2017-04-17

Duct-profiling in test samples up to 25 mm in diameter has been demonstrated using a passive, low-coherence probe head with a depth resolution of 7.8 μm, incorporating an optical-fibre-linked conical mirror addressed by a custom-built array of single-mode fibres. Zemax modelling, and experimental assessment of instrument performance, show that degradation of focus, resulting from astigmatism introduced by the conical mirror, is mitigated by the introduction of a novel lens element. This enables a good beam focus to be achieved at distances of tens of millimetres from the cone axis, not achievable when the cone is used alone. Incorporation of the additional lens element is shown to provide a four-fold improvement in lateral imaging resolution, when compared with reflection from the conical mirror alone.

Illumination system design for a three-aspherical-mirror projection camera for extreme-ultraviolet lithography.

PubMed

Li, Y; Kinoshita, H; Watanabe, T; Irie, S; Shirayone, S; Okazaki, S

2000-07-01

A scanning critical illumination system is designed to couple a synchrotron radiation source to a three-aspherical-mirror imaging system for extreme ultraviolet lithography. A static illumination area of H x V = 8 mm x 3 mm (where H is horizontal and V is vertical) can be obtained. Uniform intensity distribution and a large ring field of H x V = 150 mm x 3 mm can be achieved by scanning of the mirror of the condenser. The coherence factor (sigma) of this illumination system is approximately 0.6, with the same beam divergence in both the horizontal and the vertical directions. We describe the performance of the imaging optics at sigma = 0.6 to confirm that the illumination optics can meet the requirements for three-aspherical-mirror imaging optics with a feature size of 0.06 microm.

Q-switched Nd:YAG/V:YAG microchip 1338 nm laser for laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

2017-12-01

Q-switched microchip laser emitting radiation at wavelength 1338nm was tested as a radiation source for laser induced breakdown spectroscopy (LIBS). This laser used sandwich crystal which combined in one piece the cooling part (undoped YAG crystal 4mm long), the active laser part (Nd:YAG crystal 12mm long), and the saturable absorber (V:YAG crystal 0.7mm long). The diameter of this crystal was 5 mm. The microchip resonator consisted of dielectric mirrors directly deposited on the monolith crystal surfaces. The pump mirror (HT @ 808 nm, HR @ 1.3 ¹m) was placed on the undoped YAG part. The output coupler (R = 90% @ 1338 nm) was placed on the V:YAG part. The fibre-coupled 808nm pumping laser diode was operating in pulsed regime (rep. rate 250 Hz, pulse width 300 ¹s, pulse energy 6 mJ). Using this pumping, stable and high reproducible Q-switched pulses were generated at wavelength 1338 nm. Pulse length was 6.2 ns (FWHM) and the mean output power was 33mW. The single pulse energy and peak power was 0.13mJ and 21kW, respectively. Laser was operating in fundamental TEM00 mode. The laser radiation was focused on a tested sample using single plano-convex lens (focal length 75 mm). The focal spot radius was 40 ¹m. The corresponding peak-power density was 0.83GW/cm2. The laser induced break-down was successfully reached and corresponding laser-induced plasma spectra were recorded for set of metallic elements (Cu, Ag, Au, In, Zn, Al, Fe, Ni, Cr) and alloys (Sn-Pb solder, duralumin, stainless-steel, brass). To record the spectra, StellarNet BLACK-Comet concave grating CCD-based spectrometer was used without any special collimation optics. Thanks to used laser wavelength far from the detector sensitivity, no special filtering was needed to overcome the CCD dazzling. The constructed laser could significantly improve repletion-rate of up-to-date LIBS devices.

Roughness measurements on coupling structures for optical interconnections integrated on a printed circuit board

NASA Astrophysics Data System (ADS)

Hendrickx, Nina; Van Erps, Jürgen; Suyal, Himanshu; Taghizadeh, Mohammad; Thienpont, Hugo; Van Daele, Peter

2006-04-01

In this paper, laser ablation (at UGent), deep proton writing (at VUB) and laser direct writing (at HWU) are presented as versatile technologies that can be used for the fabrication of coupling structures for optical interconnections integrated on a printed circuit board (PCB). The optical layer, a highly cross-linked acrylate based polymer, is applied on an FR4 substrate. Both laser ablation and laser direct writing are used for the definition of arrays of multimode optical waveguides, which guide the light in the plane of the optical layer. In order to couple light vertically in/out of the plane of the optical waveguides, coupling structures have to be integrated into the optical layer. Out-of-plane turning mirrors, that deflect the light beam over 90°, are used for this purpose. The surface roughness and angle of three mirror configurations are evaluated: a laser ablated one that is integrated into the optical waveguide, a laser direct written one that is also directly written onto the waveguide and a DPW insert that is plugged into a cavity into the waveguiding layer.

Electro-Optic Diffraction Grating Tuned Laser.

DTIC Science & Technology

The patent concerns an electro - optic diffraction grating tuned laser comprising a laser medium, output mirror, retro-reflective grating and an electro - optic diffraction grating beam deflector positioned between the laser medium and the reflective diffraction grating. An optional angle multiplier may be used between the electro - optic diffraction grating and the reflective grating.

Diode-pumped Kerr-lens mode-locked Yb:CaGdAlO4 laser with tunable wavelength

NASA Astrophysics Data System (ADS)

Gao, Ziye; Zhu, Jiangfeng; Wang, Junli; Wang, Zhaohua; Wei, Zhiyi; Xu, Xiaodong; Zheng, Lihe; Su, Liangbi; Xu, Jun

2016-01-01

We experimentally demonstrated a wavelength tunable Kerr-lens mode-locked femtosecond laser based on an Yb:CaGdAlO4 (Yb:CGA) crystal. The Kerr-lens mode-locked wavelength tuning range was from 1043.5 to 1076 nm, as broad as 32.5 nm, by slightly tilting the end mirror. Pulses as short as 60 fs were generated at the central wavelength of 1043.8 nm with an average output power of 66 mW. By using an output coupler with 1.5% transmittance, the Kerr-lens mode-locked average output power reached 127 mW with a pulse duration of 81 fs at a central wavelength of 1049.5 nm.

A new low voltage level-shifted FVF current mirror with enhanced bandwidth and output resistance

NASA Astrophysics Data System (ADS)

Aggarwal, Bhawna; Gupta, Maneesha; Gupta, Anil Kumar; Sangal, Ankur

2016-10-01

This paper proposes a new high-performance level-shifted flipped voltage follower (LSFVF) based low-voltage current mirror (CM). The proposed CM utilises the low-supply voltage and low-input resistance characteristics of a flipped voltage follower (FVF) CM. In the proposed CM, level-shifting configuration is used to obtain a wide operating current range and resistive compensation technique is employed to increase the operating bandwidth. The peaking in frequency response is reduced by using an additional large MOSFET. Moreover, a very high output resistance (in GΩ range) along with low-current transfer error is achieved through super-cascode configuration for a wide current range (0-440 µA). Small signal analysis is carried out to show the improvements achieved at each step. The proposed CM is simulated by Mentor Graphics Eldospice in TSMC 0.18 µm CMOS, BSIM3 and Level 53 technology. In the proposed CM, a bandwidth of 6.1799 GHz, 1% settling time of 0.719 ns, input and output resistances of 21.43 Ω and 1.14 GΩ, respectively, are obtained with a single supply voltage of 1 V. The layout of the proposed CM has been designed and post-layout simulation results have been shown. The post-layout simulation results for Monte Carlo and temperature analysis have also been included to show the reliability of the CM against the variations in process parameters and temperature changes.

Efficient solar-pumped Nd:YAG laser by a double-stage light-guide/V-groove cavity

NASA Astrophysics Data System (ADS)

Almeida, Joana; Liang, Dawei

2011-05-01

Since the first reported Nd:YAG solar laser, researchers have been exploiting parabolic mirrors and heliostats for enhancing laser output performance. We are now investigating the production of an efficient solar-pumped laser for the reduction of magnesium from magnesium oxide, which could be an alternative solution to fossil fuel. Therefore both high conversion efficiency and excellent beam quality are imperative. By using a single fused silica light guide of rectangular cross section, highly concentrated solar radiation at the focal spot of a stationary parabolic mirror is efficiently transferred to a water-flooded V-groove pump cavity. It allows for the double-pass absorption of pump light along a 4mm diameter, 30mm length, 1.1at% Nd:YAG rod. Optimum pumping parameters and solar laser output power are found through ZEMAXTM non-sequential ray-tracing and LASCADTM laser cavity analysis. 11.0 W of multimode laser output power with excellent beam profile is numerically calculated, corresponding to 6.1W/m2 collection efficiency. To validate the proposed pumping scheme, an experimental setup of the double-stage light-guide/V-groove cavity was built. 78% of highly concentrated solar radiation was efficiently transmitted by the fused silica light guide. The proposed pumping scheme can be an effective solution for enhancing solar laser performances when compared to other side-pump configurations.

All solid-state diode pumped Nd:YAG MOPA with stimulated Brillouin phase conjugate mirror

NASA Astrophysics Data System (ADS)

Offerhaus, H. L.; Godfried, H. P.; Witteman, W. J.

1996-02-01

At the Nederlands Centrum voor Laser Research (NCLR) a 1 kHz diode-pumped Nd:YAG Master Oscillator Power Amplifier (MOPA) chain with a Stimulated Brillouin Scattering (SBS) Phase Conjugate mirror is designed and operated. A small Brewster angle Nd:YAG slab (2 by 2 by 20 mm) is side pumped with 200 μs diode pulses in a stable oscillator. The oscillator is Q-switched and injection seeded with a commercial diode pumped single frequency CW Nd:YAG laser. The output consists of single-transverse, single-longitudinal mode 25 ns FWHM-pulses at 1064 nm. The oscillator slab is imaged on a square aperture that transmits between 3 and 2 mJ (at 100 and 400 Hz, resp.) The aperture is subsequently imaged four times in the amplifier. The amplifier is a 3 by 6 by 60 mm Brewster angle zig-zag slab, pumped by an 80-bar diode stack with pulses up to 250 μs. After the second pass the light is focused in two consecutive cells containing Freon-113 for wave-front reversal in an oscillator/amplifier-setup with a reflectivity of 60%. The light then passes through the amplifier twice more to produce 20 W (at 400 Hz) of output with near diffraction limited beam quality. To increase the output to 50 W at 1 kHz thermal lensing in the oscillator will be reduced.

A USPL functional system with articulated mirror arm for in-vivo applications in dentistry

NASA Astrophysics Data System (ADS)

Schelle, Florian; Meister, Jörg; Dehn, Claudia; Oehme, Bernd; Bourauel, Christoph; Frentzen, Mathias

Ultra-short pulsed laser (USPL) systems for dental application have overcome many of their initial disadvantages. However, a problem that has not yet been addressed and solved is the beam delivery into the oral cavity. The functional system that is introduced in this study includes an articulated mirror arm, a scanning system as well as a handpiece, allowing for freehand preparations with ultra-short laser pulses. As laser source an Nd:YVO4 laser is employed, emitting pulses with a duration of tp < 10 ps at a repetition rate of up to 500 kHz. The centre wavelength is at 1064 nm and the average output power can be tuned up to 9 W. The delivery system consists of an articulated mirror arm, to which a scanning system and a custom made handpiece are connected, including a 75 mm focussing lens. The whole functional system is compact in size and moveable. General characteristics like optical losses and ablation rate are determined and compared to results employing a fixed setup on an optical table. Furthermore classical treatment procedures like cavity preparation are being demonstrated on mammoth ivory. This study indicates that freehand preparation employing an USPL system is possible but challenging, and accompanied by a variety of side-effects. The ablation rate with fixed handpiece is about 10 mm3/min. Factors like defocussing and blinding affect treatment efficiency. Laser sources with higher average output powers might be needed in order to reach sufficient preparation speeds.

Inferior olive mirrors joint dynamics to implement an inverse controller.

PubMed

Alvarez-Icaza, Rodrigo; Boahen, Kwabena

2012-10-01

To produce smooth and coordinated motion, our nervous systems need to generate precisely timed muscle activation patterns that, due to axonal conduction delay, must be generated in a predictive and feedforward manner. Kawato proposed that the cerebellum accomplishes this by acting as an inverse controller that modulates descending motor commands to predictively drive the spinal cord such that the musculoskeletal dynamics are canceled out. This and other cerebellar theories do not, however, account for the rich biophysical properties expressed by the olivocerebellar complex's various cell types, making these theories difficult to verify experimentally. Here we propose that a multizonal microcomplex's (MZMC) inferior olivary neurons use their subthreshold oscillations to mirror a musculoskeletal joint's underdamped dynamics, thereby achieving inverse control. We used control theory to map a joint's inverse model onto an MZMC's biophysics, and we used biophysical modeling to confirm that inferior olivary neurons can express the dynamics required to mirror biomechanical joints. We then combined both techniques to predict how experimentally injecting current into the inferior olive would affect overall motor output performance. We found that this experimental manipulation unmasked a joint's natural dynamics, as observed by motor output ringing at the joint's natural frequency, with amplitude proportional to the amount of current. These results support the proposal that the cerebellum-in particular an MZMC-is an inverse controller; the results also provide a biophysical implementation for this controller and allow one to make an experimentally testable prediction.

Modeling Indications of Technology in Planetary Transit Light Curves-Dark-side Illumination

NASA Astrophysics Data System (ADS)

Korpela, Eric J.; Sallmen, Shauna M.; Leystra Greene, Diana

2015-08-01

We analyze potential effects of an extraterrestrial civilization’s use of orbiting mirrors to illuminate the dark side of a synchronously rotating planet on planetary transit light curves. Previous efforts to detect civilizations based on side effects of planetary-scale engineering have focused on structures affecting the host star output (e.g., Dyson spheres). However, younger civilizations are likely to be less advanced in their engineering efforts, yet still capable of sending small spacecraft into orbit. Since M dwarfs are the most common type of star in the solar neighborhood, it seems plausible that many of the nearest habitable planets orbit dim, low-mass M stars, and will be in synchronous rotation. Logically, a civilization evolving on such a planet may be inspired to illuminate their planet’s dark side by placing a single large mirror at the L2 Lagrangian point, or launching a fleet of small thin mirrors into planetary orbit. We briefly examine the requirements and engineering challenges of such a collection of orbiting mirrors, then explore their impact on transit light curves. We incorporate stellar limb darkening and model a simplistic mirror fleet’s effects for transits of Earth-like (R = 0.5 to 2 {R}{Earth}) planets which would be synchronously rotating for orbits within the habitable zone of their host star. Although such an installation is undetectable in Kepler data, the James Webb Space Telescope will provide the sensitivity necessary to detect a fleet of mirrors orbiting Earth-like habitable planets around nearby stars.

Design and analysis of an active optics system for a 4-m telescope mirror combining hydraulic and pneumatic supports

NASA Astrophysics Data System (ADS)

Lousberg, Gregory P.; Moreau, Vincent; Schumacher, Jean-Marc; Piérard, Maxime; Somja, Aude; Gloesener, Pierre; Flebus, Carlo

2015-09-01

AMOS has developed a hybrid active optics system that combines hydraulic and pneumatic properties of actuators to support a 4-m primary mirror. The mirror is intended to be used in the Daniel K. Inouye Solar Telescope (DKIST, formerly the Advanced Technology Solar Telescope) that will be installed by the National Solar Observatory (NSO) atop the Haleakala volcano in Hawaii. The mirror support design is driven by the needs of (1) minimizing the support-induced mirror distortions under telescope operating conditions, (2) shaping the mirror surface to the desired profile, and (3) providing a high stiffness against wind loads. In order to fulfill these requirements, AMOS proposes an innovative support design that consist of 118 axial actuators and 24 lateral actuators. The axial support is based on coupled hydraulic and pneumatic actuators. The hydraulic part is a passive system whose main function is to support the mirror weight with a high stiffness. The pneumatic part is actively controlled so as to compensate for low-order wavefront aberrations that are generated by the mirror support itself or by any other elements in the telescope optical chain. The performances of the support and its adequacy with the requirements are assessed with the help of a comprehensive analysis loop involving finite-element, thermal and optical modellings.

Measurement of glyoxal using an incoherent broadband cavity enhanced absorption spectrometer

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Langford, A. O.; Fuchs, H.; Brown, S. S.

2008-08-01

We describe an instrument for simultaneous measurements of glyoxal (CHOCHO) and nitrogen dioxide (NO2) using cavity enhanced absorption spectroscopy with a broadband light source. The output of a Xenon arc lamp is coupled into a 1 m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge-coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N2+O2). Least-squares fitting, using published reference spectra, allow the simultaneous retrieval of CHOCHO, NO2, O4, and H2O in the 441 to 469 nm spectral range. For a 1-min sampling time, the minimum detectable absorption is 4×10-10 cm-1, and the precision (±1σ) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv, respectively. We directly compare the incoherent broadband cavity enhanced absorption spectrometer to 404 and 532 nm cavity ringdown instruments for CHOCHO and NO2 detection, and find linear agreement over a wide range of concentrations. The instrument has been tested in the laboratory with both synthetic and real air samples, and the demonstrated sensitivity and specificity suggest a strong potential for field measurements of both CHOCHO and NO2.

Damage imaging in a laminated composite plate using an air-coupled time reversal mirror

DOE PAGES

Le Bas, P. -Y.; Remillieux, M. C.; Pieczonka, L.; ...

2015-11-03

We demonstrate the possibility of selectively imaging the features of a barely visible impact damage in a laminated composite plate by using an air-coupled time reversal mirror. The mirror consists of a number of piezoelectric transducers affixed to wedges of power law profiles, which act as unconventional matching layers. The transducers are enclosed in a hollow reverberant cavity with an opening to allow progressive emission of the ultrasonic wave field towards the composite plate. The principle of time reversal is used to focus elastic waves at each point of a scanning grid spanning the surface of the plate, thus allowingmore » localized inspection at each of these points. The proposed device and signal processing removes the need to be in direct contact with the plate and reveals the same features as vibrothermography and more features than a C-scan. More importantly, this device can decouple the features of the defect according to their orientation, by selectively focusing vector components of motion into the object, through air. For instance, a delamination can be imaged in one experiment using out-of-plane focusing, whereas a crack can be imaged in a separate experiment using in-plane focusing. As a result, this capability, inherited from the principle of time reversal, cannot be found in conventional air-coupled transducers.« less

Picosecond pulse generation in a hybrid Q-switched laser source by using a microelectromechanical mirror.

PubMed

Couderc, Vincent; Crunteanu, Aurelian; Fabert, Marc; Doutre, Florent; El Bassri, Farid; Pagnoux, Dominique; Jalocha, Alain

2012-02-27

We present a novel Q-switched laser source using a micro-optical-electromechanical mirror (MOEM) designed for short pulse emission. It is based on a hybrid configuration including a passively Q-switched microchip laser coupled to a fiber cavity closed by a cantilever type MOEM acting as an active modulator. This specially designed mirror with a single reflecting gold membrane is switched by low bias voltage ~50 V (peak to peak). This device emits pulses at tunable repetition rates up to 1.6 kHz, with ~564 ps duration and 3.4 kW peak power, which constitutes the shortest pulse duration ever reported with MOEMs based pulsed lasers.

The (un)coupling between action execution and observation. Comment on "Grasping synergies: A motor-control approach to the mirror neuron mechanism" by D'Ausilio, Bartoli and Maffongelli

NASA Astrophysics Data System (ADS)

Cavallo, Andrea; Ansuini, Caterina; Becchio, Cristina

2015-03-01

When we observe actions performed by others, our motor system resonates along with that of the observed agent [1]. The exact features of this resonant motor response, however, are unclear. Do we mirror the goal of others' actions or rather the low-kinematic features of their movements? D'Ausilio et al. suggest that this is an ill-defined problem: the mirror system plausibly replicates the same computational mechanisms implicated by motor control. Accordingly, motor synergies may not only constitute a pervasive element of motor control, but also form the fundamental unit of action observation.

Fine Surface Control of Flexible Space Mirrors Using Adaptive Optics and Robust Control

DTIC Science & Technology

2009-03-01

an AO system not only increases complexity but also lends itself to coupling between actuators. Whereas historically, control laws treated AO...adaptive optic in large ground based AO systems is treated as a static system with no dynamics. In the case of a deformable mirror, it is assumed... astigmatism , and so on. As with any series expansion, the more terms used, the more accurate the approximation will be. For this research, 21 Zernike

Method and system for compact efficient laser architecture

DOEpatents

Bayramian, Andrew James; Erlandson, Alvin Charles; Manes, Kenneth Rene; Spaeth, Mary Louis; Caird, John Allyn; Deri, Robert J.

2015-09-15

A laser amplifier module having an enclosure includes an input window, a mirror optically coupled to the input window and disposed in a first plane, and a first amplifier head disposed along an optical amplification path adjacent a first end of the enclosure. The laser amplifier module also includes a second amplifier head disposed along the optical amplification path adjacent a second end of the enclosure and a cavity mirror disposed along the optical amplification path.

DIFFRACTION SYNCHRONIZATION OF LASERS,

DTIC Science & Technology

semiconductor lasers while suppressing parasitic generation in the plane of the mirror. The diffraction coupling coefficient of open resonators is calculated, and the stability conditions of the synchronized system is determined.

Time-dependent multi-dimensional simulation studies of the electron output scheme for high power FELs

NASA Astrophysics Data System (ADS)

Hahn, S. J.; Fawley, W. M.; Kim, K. J.; Edighoffer, J. A.

1994-12-01

The authors examine the performance of the so-called electron output scheme recently proposed by the Novosibirsk group. In this scheme, the key role of the FEL oscillator is to induce bunching, while an external undulator, called the radiator, then outcouples the bunched electron beam to optical energy via coherent emission. The level of the intracavity power in the oscillator is kept low by employing a transverse optical klystron (TOK) configuration, thus avoiding excessive thermal loading on the cavity mirrors. Time-dependent effects are important in the operation of the electron output scheme because high gain in the TOK oscillator leads to sideband instabilities and chaotic behavior. The authors have carried out an extensive simulation study by using 1D and 2D time-dependent codes and find that proper control of the oscillator cavity detuning and cavity loss results in high output bunching with a narrow spectral bandwidth. Large cavity detuning in the oscillator and tapering of the radiator undulator is necessary for the optimum output power.

An overview of the thematic mapper geometric correction system

NASA Technical Reports Server (NTRS)

Beyer, E. P.

1983-01-01

Geometric accuracy specifications for LANDSAT 4 are reviewed and the processing concepts which form the basis of NASA's thematic mapper geometric correction system are summarized for both the flight and ground segments. The flight segment includes the thematic mapper instrument, attitude measurement devices, attitude control, and ephemeris processing. For geometric correction the ground segment uses mirror scan correction data, payload correction data, and control point information to determine where TM detector samples fall on output map projection systems. Then the raw imagery is reformatted and resampled to produce image samples on a selected output projection grid system.

Femtosecond (191 fs) NaY(WO4)2 Tm,Ho-codoped laser at 2060 nm.

PubMed

Lagatsky, A A; Han, X; Serrano, M D; Cascales, C; Zaldo, C; Calvez, S; Dawson, M D; Gupta, J A; Brown, C T A; Sibbett, W

2010-09-15

We report, for the first time to our knowledge, femtosecond-pulse operation of a Tm,Ho:NaY(WO(4))(2) laser at around 2060 nm. Transform-limited 191 fs pulses are produced with an average output power of 82 mW at a 144 MHz pulse repetition frequency. Maximum output power of up to 155 mW is generated with a corresponding pulse duration of 258 fs. An ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror is used for passive mode-locking maintenance.

XeCl laser pumped iodine laser using t-C4F9I

NASA Technical Reports Server (NTRS)

Hwang, In Heon; Han, Kwang S.

1989-01-01

An iodine photodissociation laser using t-C4F9I as the active material was pumped by an XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodide pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency and low threshold pump power achieved in this experiment are attributable to the high absorption cross section at the pump laser wavelength (308 nm) of the iodide used.

Fiber bundle phase conjugate mirror

DOEpatents

Ward, Benjamin G.

2012-05-01

An improved method and apparatus for passively conjugating the phases of a distorted wavefronts resulting from optical phase mismatch between elements of a fiber laser array are disclosed. A method for passively conjugating a distorted wavefront comprises the steps of: multiplexing a plurality of probe fibers and a bundle pump fiber in a fiber bundle array; passing the multiplexed output from the fiber bundle array through a collimating lens and into one portion of a non-linear medium; passing the output from a pump collection fiber through a focusing lens and into another portion of the non-linear medium so that the output from the pump collection fiber mixes with the multiplexed output from the fiber bundle; adjusting one or more degrees of freedom of one or more of the fiber bundle array, the collimating lens, the focusing lens, the non-linear medium, or the pump collection fiber to produce a standing wave in the non-linear medium.

1.55-μm InGaAs/InGaAlAs MQW vertical-cavity surface-emitting lasers with InGaAlAs/InP distributed Bragg reflectors

NASA Astrophysics Data System (ADS)

Xia, Jinan; Hoan O, Beom; Gol Lee, Seung; Hang Lee, El

2005-03-01

High-performance InGaAs/InGaAlAs multiple-quantum-well vertical-cavity surface-emitting lasers (VCSELs) with InGaAlAs/InP distributed Bragg reflectors are proposed for operation at the wavelength of 1.55 μm. The lasers have good heat diffusion characteristic, large index contrast in DBRs, and weak temperature sensitivity. They could be fabricated either by metal-organic chemical vapor deposition (MOCVD) or by molecular beam epitaxy (MBE) growth. The laser light-current characteristics indicate that a suitable reflectivity of the DBR on the light output side in a laser makes its output power increase greatly and its lasing threshold current reduce significantly, and that a small VCSEL could output the power around its maximum for the output mirror at the reflectivity varying in a broader range than a large VCSEL does.

Compact waveguide power divider with multiple isolated outputs

DOEpatents

Moeller, Charles P.

1987-01-01

A waveguide power divider (10) for splitting electromagnetic microwave power and directionally coupling the divided power includes an input waveguide (21) and reduced height output waveguides (23) interconnected by axial slots (22) and matched loads (25) and (26) positioned at the unused ends of input and output guides (21) and (23) respectively. The axial slots are of a length such that the wave in the input waveguide (21) is directionally coupled to the output waveguides (23). The widths of input guide (21) and output guides (23) are equal and the width of axial slots (22) is one half of the width of the input guide (21).

Large-Signal Klystron Simulations Using KLSC

NASA Astrophysics Data System (ADS)

Carlsten, B. E.; Ferguson, P.

1997-05-01

We describe a new, 2-1/2 dimensional, klystron-simulation code, KLSC. This code has a sophisticated input cavity model for calculating the klystron gain with arbitrary input cavity matching and tuning, and is capable of modeling coupled output cavities. We will discuss the input and output cavity models, and present simulation results from a high-power, S-band design. We will use these results to explore tuning issues with coupled output cavities.

[Trace detection of ammonia at 1.531 microm].

PubMed

Jia, Hui; Guo, Xiao-Yong; Cai, Ting-Dong; Zhao, Wei-Xiong; Wang, Lei; Tan, Tu; Zhang, Wei-Jun; Gao, Xiao-Ming

2009-12-01

A compact instrument based on the off-axis integrated-cavity output spectroscopy (ICOS) technology was developed for sensitive measurements of gas mixing ratios (ammonia in air) at room temperature by using fiber-coupled distributed feedback (DFB) diode laser operating at 1.531 microm. The absorption line of ammonia at 6 528.764 cm(-1) was chosen for trace detection. The mirrors' effective reflectivity R2 of 0.996 9 was first calibrated by carbon dioxide under this condition, and the cavity 35.8 cm in length as an absorption cell could yield an optical path of presumably 115.46 m. As a result, a minimum detectable concentration of approximately 2.66 ppmv (S/N-3) at the total pressure of 100 torr was obtained. Then the lock-in amplifier was added in the system to acquire the second harmonic signal by combination of wavelength modulation technology, which could better suppress background noise and improve the signal-to-noise ratio, and a detection limit of 0.293 ppmv (S/N-3) was achieved eventually. This work demonstrated the potential of the system for a range of atmospheric species sensing in the future.

Surface micromachined MEMS deformable mirror based on hexagonal parallel-plate electrostatic actuator

NASA Astrophysics Data System (ADS)

Ma, Wenying; Ma, Changwei; Wang, Weimin

2018-03-01

Deformable mirrors (DM) based on microelectromechanical system (MEMS) technology are being applied in adaptive optics (AO) system for astronomical telescopes and human eyes more and more. In this paper a MEMS DM with hexagonal actuator is proposed and designed. The relationship between structural design and performance parameters, mainly actuator coupling, is analyzed carefully and calculated. The optimum value of actuator coupling is obtained. A 7-element DM prototype is fabricated using a commercial available standard three-layer polysilicon surface multi-user-MEMS-processes (PolyMUMPs). Some key performances, including surface figure and voltage-displacement curve, are measured through a 3D white light profiler. The measured performances are very consistent with the theoretical values. The proposed DM will benefit the miniaturization of AO systems and lower their cost.

Axicon based conical resonators with high power copper vapor laser.

PubMed

Singh, Bijendra; Subramaniam, V V; Daultabad, S R; Chakraborty, Ashim

2010-07-01

We report for the first time the performance of axicon based conical resonators (ABCRs) in a copper vapor laser, with novel results. The unstable conical resonator comprising of conical mirror (reflecting axicon) with axicon angle approximately pi/18, cone angle approximately 160 degrees, and a convex mirror of 60 cm radius of curvature was effective in reducing the average beam divergence to approximately 0.15 mrad (approximately 25 fold reduction compared to standard multimode plane-plane cavity) with output power of approximately 31 W. Extraction efficiency of approximately 50%-60% and beam divergence of <1 mrad was achieved in other stable ABCR configurations using flat and concave mirrors with the axicon. This is a significant improvement compared to 4-5 mrad normally observed in conventional stable resonators in copper vapor lasers. The conical resonators with copper vapor laser provide high misalignment tolerance beta approximately 4-5 mrad where beta is the tilt angle of the conical mirror from optimum position responsible for approximately 20% decline in laser power. The depth of focus d was approximately three times larger in case of conical resonator as compared to that of standard spherical unstable resonator under similar beam divergence and focusing conditions.

On determining fluxgate magnetometer spin axis offsets from mirror mode observations

NASA Astrophysics Data System (ADS)

Plaschke, Ferdinand; Narita, Yasuhito

2016-09-01

In-flight calibration of fluxgate magnetometers that are mounted on spacecraft involves finding their outputs in vanishing ambient fields, the so-called magnetometer offsets. If the spacecraft is spin-stabilized, then the spin plane components of these offsets can be relatively easily determined, as they modify the spin tone content in the de-spun magnetic field data. The spin axis offset, however, is more difficult to determine. Therefore, usually Alfvénic fluctuations in the solar wind are used. We propose a novel method to determine the spin axis offset: the mirror mode method. The method is based on the assumption that mirror mode fluctuations are nearly compressible such that the maximum variance direction is aligned to the mean magnetic field. Mirror mode fluctuations are typically found in the Earth's magnetosheath region. We introduce the method and provide a first estimate of its accuracy based on magnetosheath observations by the THEMIS-C spacecraft. We find that 20 h of magnetosheath measurements may already be sufficient to obtain high-accuracy spin axis offsets with uncertainties on the order of a few tenths of a nanotesla, if offset stability can be assumed.

Innovative opto-mechanical design of a laser head for compact thin-disk

NASA Astrophysics Data System (ADS)

Macúchová, Karolina; Smrž, Martin; Řeháková, Martina; Mocek, Tomáš

2016-11-01

We present recent progress in design of innovative versatile laser head for lasers based on thin-disk architecture which are being constructed at the HiLASE centre of the IOP in the Czech Republic. Concept of thin-disk laser technology allows construction of lasers providing excellent beam quality with high average output power and optical efficiency. Our newly designed thin-disk carrier and pump module comes from optical scheme consisting of a parabolic mirror and roof mirrors proposed in 90's. However, mechanical parts and a cooling system were in-house simplified and tailor-made to medium power lasers since no suitable setup was commercially available. Proposed opto-mechanical design is based on stable yet easily adjustable mechanics. The only water nozzle-cooled component is a room-temperature-operated thindisk mounted on a special cooling finger. Cooling of pump optics was replaced by heat conductive transfer from mirrors made of special Al alloy to a massive brass baseplate. Such mirrors are easy to manufacture and very cheap. Presented laser head was manufactured and tested in construction of Er and Yb doped disk lasers. Details of the latest design will be presented.

On the use of a chirped Bragg grating as a cavity mirror of a picosecond Nd : YAG laser

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

Zubko, A E; Shashkov, E V; Smirnov, A V

2016-02-28

The first experimental evidence is presented that the use of a chirped volume Bragg grating (CVBG) as a cavity mirror of a Q-switched picosecond Nd : YAG laser with self-mode-locking leads to significant changes in the temporal parameters of the laser output. Measurements have been performed at two positions of the CVBG: with the grating placed so that shorter wavelengths reflected from its front part lead longer wavelengths or with the grating rotated through 180°, so that longer wavelengths are reflected first. In the former case, the duration of individual pulses in a train increased from ∼35 to ∼300 ps,more » whereas the pulse train shape and duration remained the same as in the case of a conventional laser with a mirror cavity. In the latter case, the full width at half maximum of pulse trains increased from ∼70 ns (Nd : YAG laser with a mirror cavity) to ∼1 ms, and the duration of individual pulses increased from 35 ps to ∼1.2 ns, respectively, which is more typical of free-running laser operation. (laser crystals and braggg ratings)« less

Discrete wavelength-locked external cavity laser

NASA Technical Reports Server (NTRS)

Pilgrim, Jeffrey S. (Inventor); Silver, Joel A. (Inventor)

2005-01-01

An external cavity laser (and method of generating laser light) comprising: a laser light source; means for collimating light output by the laser light source; a diffraction grating receiving collimated light; a cavity feedback mirror reflecting light received from the diffraction grating back to the diffraction grating; and means for reliably tuning the external cavity laser to discrete wavelengths.

Impact of Assessment Criteria on Publication Behaviour: The Case of Communication Research in Spain

ERIC Educational Resources Information Center

Masip, Pere

2014-01-01

Introduction: This paper outlines the evolution of Spanish production in the area of communication research over the last seventeen years. It analyses whether the consolidation of the existing systems of assessment of scientific activity have been mirrored by an increase in the output of Spanish authors in journals indexed by the Social Sciences…

Joint Services Electronics Program: Electronics Research at the University of Texas at Austin

DTIC Science & Technology

1990-12-31

large area 2-dimensional phased arrays , and improved beam qualities . This device structure is expected to impact laser technology over a wide range...energy. In the following pages we report on two significant accomplishments. The first involves the influence oi mirror-quantum well optical coupling on... intensity enhancements in the normal direction to the mirror of a 24 (Research Unit SSE89-1, "Growth of Ill-V Compounds by Molecular Beam Epitaxy") factor of

Mode-locked Ti:sapphire laser oscillators pumped by wavelength-multiplexed laser diodes

NASA Astrophysics Data System (ADS)

Sugiyama, Naoto; Tanaka, Hiroki; Kannari, Fumihiko

2018-05-01

We directly pumped a Ti:sapphire laser by combining 478 and 520 nm laser diodes to prevent the effect of absorption loss induced by the pump laser of shorter wavelengths (∼450 nm). We obtain a continuous-wave output power of 660 mW at a total incident pump power of 3.15 W. We demonstrate mode locking using a semiconductor saturable absorber mirror, and 126 fs pulses were obtained at a repetition rate of 192 MHz. At the maximum pump power, the average output power is 315 mW. Shorter mode-locked pulses of 42 and 48 fs were respectively achieved by Kerr-lens mode locking with average output powers of 280 and 360 mW at a repetition rate of 117 MHz.

High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration.

PubMed

Yang, Zhen; Wang, Yuye; Xu, Degang; Xu, Wentao; Duan, Pan; Yan, Chao; Tang, Longhuang; Yao, Jianquan

2016-05-15

A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning in a wide frequency range. Through the special optical design with a galvano-optical scanner and four-mirror ring-cavity structure, the maximum THz wave output energy of 12.9 μJ/pulse is achieved at 1.359 THz under the pump energy of 172.8 mJ. The fast THz frequency tuning in the range of 0.7-2.8 THz can be accessed with the step response of 600 μs. Moreover, the maximum THz wave output energy from this configuration is 3.29 times as large as that obtained from the conventional surface-emitted THz wave parametric oscillator with the same experimental conditions.

Phase difference in modulated signals of two orthogonally polarized outputs of a Nd:YAG microchip laser with anisotropic optical feedback.

PubMed

Zhang, Peng; Tan, Yi-Dong; Liu, Ning; Wu, Yun; Zhang, Shu-Lian

2013-11-01

We present an experimental observation of the output responses of a Nd:YAG microchip laser with an anisotropic external cavity under weak optical feedback. The feedback mirror is stationary during the experiments. A pair of acousto-optic modulators is used to produce a frequency shift in the feedback light with respect to the initial light. The laser output is a beat signal with 40 kHz modulation frequency and is separated into two orthogonal directions by a Wollaston prism. Phase differences between the two intensity curves are observed as the laser works in two orthogonal modes, and vary with the external birefringence element and the pump power. Theoretical analyses are given, and the simulated results are consistent with the experimental phenomena.

Hybrid concatenated codes and iterative decoding

NASA Technical Reports Server (NTRS)

Divsalar, Dariush (Inventor); Pollara, Fabrizio (Inventor)

2000-01-01

Several improved turbo code apparatuses and methods. The invention encompasses several classes: (1) A data source is applied to two or more encoders with an interleaver between the source and each of the second and subsequent encoders. Each encoder outputs a code element which may be transmitted or stored. A parallel decoder provides the ability to decode the code elements to derive the original source information d without use of a received data signal corresponding to d. The output may be coupled to a multilevel trellis-coded modulator (TCM). (2) A data source d is applied to two or more encoders with an interleaver between the source and each of the second and subsequent encoders. Each of the encoders outputs a code element. In addition, the original data source d is output from the encoder. All of the output elements are coupled to a TCM. (3) At least two data sources are applied to two or more encoders with an interleaver between each source and each of the second and subsequent encoders. The output may be coupled to a TCM. (4) At least two data sources are applied to two or more encoders with at least two interleavers between each source and each of the second and subsequent encoders. (5) At least one data source is applied to one or more serially linked encoders through at least one interleaver. The output may be coupled to a TCM. The invention includes a novel way of terminating a turbo coder.

Output Feedback Stabilization for a Class of Multi-Variable Bilinear Stochastic Systems with Stochastic Coupling Attenuation

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

Zhang, Qichun; Zhou, Jinglin; Wang, Hong

In this paper, stochastic coupling attenuation is investigated for a class of multi-variable bilinear stochastic systems and a novel output feedback m-block backstepping controller with linear estimator is designed, where gradient descent optimization is used to tune the design parameters of the controller. It has been shown that the trajectories of the closed-loop stochastic systems are bounded in probability sense and the stochastic coupling of the system outputs can be effectively attenuated by the proposed control algorithm. Moreover, the stability of the stochastic systems is analyzed and the effectiveness of the proposed method has been demonstrated using a simulated example.

Autonomous Navigation Apparatus With Neural Network for a Mobile Vehicle

NASA Technical Reports Server (NTRS)

Quraishi, Naveed (Inventor)

1996-01-01

An autonomous navigation system for a mobile vehicle arranged to move within an environment includes a plurality of sensors arranged on the vehicle and at least one neural network including an input layer coupled to the sensors, a hidden layer coupled to the input layer, and an output layer coupled to the hidden layer. The neural network produces output signals representing respective positions of the vehicle, such as the X coordinate, the Y coordinate, and the angular orientation of the vehicle. A plurality of patch locations within the environment are used to train the neural networks to produce the correct outputs in response to the distances sensed.

Ultrastrong exciton-photon coupling in single and coupled organic microcavities

NASA Astrophysics Data System (ADS)

Liu, Bin; Bramante, Rosemary; Valle, Brent; Singer, Kenneth; Khattab, Tawfik; Williams, Jarrod; Twieg, Robert

2015-03-01

We have demonstrated ultrastrong light-matter coupling in organic planar microcavities composed of a neat glassy organic dye film between two metallic (aluminum) mirrors in a half-cavity configuration. Such cavities are characterized by Q factors around 10. Tuning the thickness of the organic layer enables the observation of the ultrastrong coupling regime. Via reflectivity measurements, we observe a very large Rabi splitting around 1.227 eV between upper and lower polariton branches at room temperature, and we detect polariton emission from the lower polariton branch via photoluminescence measurements. The large splitting is due to the large oscillator strength of the neat dye glass, and to the match of the low-Q cavity spectral width to the broad absorption width of the dye film material. We also study the interaction between excitonic states of neat glassy organic dye and cavity modes within coupled microcavity structures. The high-reflectivity mirrors are formed from distributed Bragg reflectors (DBR), which are multilayer films fabricated using the coextrusion process, containing alternating layers of high (SAN25, n =1.57) and low (Dyneon THV 220G, n =1.37) refractive index dielectric polymers. Nonlinear optical measurements will be discussed. This research was supported by the National Science Foundation Center for Layered Polymer Systems (CLiPS) under Grant Number DMR-0423914.

Heat resistive dielectric multi-layer micro-mirror array in epitaxial lateral overgrowth gallium nitride.

PubMed

Huang, Chen-Yang; Ku, Hao-Min; Liao, Wei-Tsai; Chao, Chu-Li; Tsay, Jenq-Dar; Chao, Shiuh

2009-03-30

Ta2O5 / SiO2 dielectric multi-layer micro-mirror array (MMA) with 3mm mirror size and 6mm array period was fabricated on c-plane sapphire substrate. The MMA was subjected to 1200 degrees C high temperature annealing and remained intact with high reflectance in contrast to the continuous multi-layer for which the layers have undergone severe damage by 1200 degrees C annealing. Epitaxial lateral overgrowth (ELO) of gallium nitride (GaN) was applied to the MMA that was deposited on both sapphire and sapphire with 2:56 mm GaN template. The MMA was fully embedded in the ELO GaN and remained intact. The result implies that our MMA is compatible to the high temperature growth environment of GaN and the MMA could be incorporated into the structure of the micro-LED array as a one to one micro backlight reflector, or as the patterned structure on the large area LED for controlling the output light.

2 micron femtosecond fiber laser

DOEpatents

Liu, Jian; Wan, Peng; Yang, Lihmei

2014-07-29

Methods and systems for generating femtosecond fiber laser pulses are disclose, including generating a signal laser pulse from a seed laser oscillator; using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse; using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse. Other embodiments are described and claimed.

Optical calibration and test of the VLT Deformable Secondary Mirror

NASA Astrophysics Data System (ADS)

Briguglio, Runa; Xompero, Marco; Riccardi, Armando; Andrighettoni, Mario; Pescoller, Dietrich; Biasi, Roberto; Gallieni, Daniele; Vernet, Elise; Kolb, Johann; Arsenault, Robin; Madec, Pierre-Yves

2013-12-01

The Deformable Secondary Mirror (DSM) for the VLT (ESO) represents the state-of-art of the large-format deformable mirror technology with its 1170 voice-coil actuators and its internal metrology based on actuator co-located capacitive sensors to control the shape of the 1.12m-diameter 2mm-thick convex shell. The present paper reports the results of the optical characterization of the mirror unit with the ASSIST facility located at ESO-Garching and executed in a collaborative effort by ESO, INAF-Osservatorio Astrofisico di Arcetri and the DSM manufacturing companies (Microgate s.r.l. and A.D.S. International s.r.l.). The main purposes of the tests are the optical characterization of the shell flattening residuals, the corresponding calibration of flattening commands, the optical calibration of the capacitive sensors and the optical calibration of the mirror influence functions. The results are used for the optical acceptance of the DSM and to allow the next test phase coupling the DSM with the wave-front sensor modules of the new Adaptive Optics Facility (AOF) of ESO.

Comparative study of electrical and switch-skipping mechanical switch for self-powered SSHI in medium coupled piezoelectric vibration energy harvesters

NASA Astrophysics Data System (ADS)

Asanuma, H.; Sakamoto, K.; Komatsuzaki, T.; Iwata, Y.

2018-07-01

To increase output power for piezoelectric vibration energy harvesters, considerable attention has recently been focused on a self-powered synchronized switch harvesting on inductor (SSHI) technique employing an electrical and mechanical switch. However, there are two technical issues: in a medium or highly coupled harvester, the piezoelectric coupling force, which increases as the SSHI’s voltage increases, will reduce the harvester’s displacement and the resulting output power, and there are few reports comparing the performance of electrical switch SSHI (ESS) and mechanical switch SSHI (MSS) that include consideration of the piezoelectric coupling force. We developed a simulation technique that allows us to evaluate the output power considering the piezoelectric coupling force, and investigated the performance of stopper-based MSS and ESS, both numerically and experimentally. The numerical investigation predicted the following: (1) the output power for the ESS is lower than that for the MSS at acceleration lower than 3.5 m s‑2 and (2) intriguingly, the output power for the MSS continues to increase, whereas the peak–peak displacement remains constant. The experimental results showed behaviour similar to that of the numerical predictions. The results are attributed to the different switching strategies: the MSS turns on only when the harvester’s displacement exceeds the gap distance, while the ESS turns on at every maximum/minimum displacement.

Efficient Scheme for Perfect Collective Einstein-Podolsky-Rosen Steering

PubMed Central

Wang, M.; Gong, Q. H.; Ficek, Z.; He, Q. Y.

2015-01-01

A practical scheme for the demonstration of perfect one-sided device-independent quantum secret sharing is proposed. The scheme involves a three-mode optomechanical system in which a pair of independent cavity modes is driven by short laser pulses and interact with a movable mirror. We demonstrate that by tuning the laser frequency to the blue (anti-Stokes) sideband of the average frequency of the cavity modes, the modes become mutually coherent and then may collectively steer the mirror mode to a perfect Einstein-Podolsky-Rosen state. The scheme is shown to be experimentally feasible, it is robust against the frequency difference between the modes, mechanical thermal noise and damping, and coupling strengths of the cavity modes to the mirror. PMID:26212901

Shaping ultrafast laser inscribed optical waveguides using a deformable mirror.

PubMed

Thomson, R R; Bockelt, A S; Ramsay, E; Beecher, S; Greenaway, A H; Kar, A K; Reid, D T

2008-08-18

We use a two-dimensional deformable mirror to shape the spatial profile of an ultrafast laser beam that is then used to inscribe structures in a soda-lime silica glass slide. By doing so we demonstrate that it is possible to control the asymmetry of the cross section of ultrafast laser inscribed optical waveguides via the curvature of the deformable mirror. When tested using 1.55 mum light, the optimum waveguide exhibited coupling losses of approximately 0.2 dB/facet to Corning SMF-28 single mode fiber and propagation losses of approximately 1.5 dB.cm(-1). This technique promises the possibility of combining rapid processing speeds with the ability to vary the waveguide cross section along its length.

Simulation of Aluminum Micro-mirrors for Space Applications at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Kuhn, J. L.; Dutta, S. B.; Greenhouse, M. A.; Mott, D. B.

2000-01-01

Closed form and finite element models are developed to predict the device response of aluminum electrostatic torsion micro-mirrors fabricated on silicon substrate for space applications at operating temperatures of 30K. Initially, closed form expressions for electrostatic pressure arid mechanical restoring torque are used to predict the pull-in and release voltages at room temperature. Subsequently, a detailed mechanical finite element model is developed to predict stresses and vertical beam deflection induced by the electrostatic and thermal loads. An incremental and iterative solution method is used in conjunction with the nonlinear finite element model and closed form electrostatic equations to solve. the coupled electro-thermo-mechanical problem. The simulation results are compared with experimental measurements at room temperature of fabricated micro-mirror devices.

Bendable X-ray Optics at the ALS: Design, Tuning, Performance and Applications

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

Advanced Light Source, Lawrence Berkeley National Laboratory; Yashchuk, Valeriy V.; Church, Matthew N.

2008-09-08

We review the development at the Advanced Light Source (ALS) of bendable x-ray optics widely used for focusing of beams of soft and hard x-rays. Typically, the focusing is divided in the tangential and sagittal directions into two elliptically cylindrical reflecting elements, the so-called Kirkpatrick-Baez (KB) pair [1]. Because fabrication of elliptical surfaces is complicated, the cost of directly fabricated tangential elliptical cylinders is often prohibitive. This is in contrast to flat optics, that are simpler to manufacture and easier to measure by conventional interferometry. The figure of a flat substrate can be changed by placing torques (couples) at eachmore » end. Equal couples form a tangential cylinder, and unequal couples can approximate a tangential ellipse or parabola. We review the nature of the bending, requirements and approaches to the mechanical design, and describe a technique developed at the ALS Optical Metrology Laboratory (OML) for optimal tuning of bendable mirrors before installation in the beamline [2]. The tuning technique adapts a method previously used to adjust bendable mirrors on synchrotron radiation beamlines [3]. However, in our case, optimal tuning of a bendable mirror is based on surface slope trace data obtained with a slope measuring instrument--in our case, the long trace profiler (LTP). We show that due to the near linearity of the bending problem, the minimal set of data, necessary for tuning of two benders, consists of only three slope traces measured before and after a single adjustment of each bending couple. We provide an algorithm that was used in dedicated software for finding optimal settings for the mirror benders. The algorithm is based on the method of regression analysis with experimentally found characteristic functions of the benders. The resulting approximation to the functional dependence of the desired slope shape provides nearly final settings for the benders. Moreover, the characteristic functions of the benders found in the course of tuning, can be used for retuning of the optics to a new desired shape without removing it from the beamline and re-measuring with the LTP. The result of practical use of the developed technique to precisely tune a KB mirror used at the ALS for micro-focusing is also presented. We also describe a simple ray trace using the profiler data which shows expected performance in the beamline and compare the simulation with experimental data. In summary, we also discuss the next steps in the systematic improvement of optical performance for the application of KB pairs in synchrotron beamlines at the ALS.« less

Broadband cavity enhanced spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Rudich, Y.; Brown, S. S.

2015-09-01

Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity enhanced spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99933 ± 0.00003 (670 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.49 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device (CCD) array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity enhanced spectroscopy and cavity ringdown spectroscopy agree within 2 % (slope for linear fit = 0.98 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity enhanced spectroscopy and calculated based on flow dilution are also well-correlated, with r2 = 0.9998. During constant, mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1-min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically-based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to trace gases, this approach will be appropriate for measurements of aerosol extinction in ambient air, and this spectral region is important for characterizing the strong ultraviolet absorption by brown carbon aerosol.

Evaluation of mirrored muscle activity in patients with Complex Regional Pain Syndrome.

PubMed

Bank, Paulina J M; Peper, C Lieke E; Marinus, Johan; Beek, Peter J; van Hilten, Jacobus J

2014-10-01

Motor dysfunction in Complex Regional Pain Syndrome (CRPS) has been associated with bilateral changes in central motor processing, suggesting abnormal coupling between the affected and unaffected limb. We evaluated the occurrence of involuntary muscle activity in a limb during voluntary movements of the contralateral limb (i.e., mirror activity) in unilaterally affected patients to examine disinhibition of contralateral motor activity in CRPS. Mirror activity was examined during unimanual rhythmic flexion-extension movements of the wrist through in-depth analysis of electromyography recordings from the passive arm in 20 CRPS patients and 40 controls. The number of mirror-epochs was comparable for both arms in both CRPS patients and controls. Mirror-epochs in the affected arm of patients were comparable to those in controls. Mirror-epochs in the unaffected arm were shorter and showed less resemblance (in terms of rhythm and timing) to activity of the homologous muscle in the moving arm compared to mirror-epochs in controls. No evidence for disinhibition of contralateral motor activity was found during unimanual movement. Although motor dysfunction in CRPS has been associated with bilateral changes in cortical motor processing, the present findings argue against disinhibition of interhemispheric projections to homologous muscles in the contralateral limb during unimanual movement. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Analysis for maladjustment properties of passive confocal unstable resonator by using Hartmann-Shack wavefront sensor

NASA Astrophysics Data System (ADS)

Zhang, Xiang; Xiang, Anping

2007-12-01

The effect of intracavity aberration perturbation on output mode structure properties of passive confocal unstable resonator is been experimentally researched by adopting Hartmann-Shack method on the basis of numerical simulation. The results show that intracavity tilt aberration affects the outcoupled intensity distribution, but only a small intracavity tilt perturbation will not obviously augment the high-order aberrations of beam phase properties. The tilt aberration, coma aberration and astigmatism will all be brought, and also tilt aberration is the main component when intracavity mirrors have a vertical movement along the direction of optic axis. When adaptive optical elements such as deformable mirrors are adopted for intracavity aberration correction, the correction for tilt aberration should be considered at first.

Performance of chemical vapor deposition fabricated graphene absorber mirror in Yb3+ : Sc2SiO5 mode-locked laser

NASA Astrophysics Data System (ADS)

Cai, Wei; Li, Yaqi; Zhu, Hongtong; Jiang, Shouzhen; Xu, Shicai; Liu, Jie; Zheng, Lihe; Su, Liangbi; Xu, Jun

2014-12-01

A reflective graphene saturable absorber mirror (SAM) was successfully fabricated by chemical vapor deposition technology. A stable diode-pumped passively mode-locked Yb3+:Sc2SiO5 laser using a graphene SAM as a saturable absorber was accomplished for the first time. The measured average output power amounts to 351 mW under the absorbed pump power of 12.5 W. Without prisms compensating for dispersion, the minimum pulse duration of 7 ps with a repetition rate of 97 MHz has been obtained at the central wavelength of 1063 nm. The corresponding peak power and the maximum pulse energy were 516 W and 3.6 nJ, respectively.

Aging behavior and surge endurance of 870-900 nm AlGaAs lasers with nonabsorbing mirrors

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

Kadota, Y.; Chino, K.; Namizaki, M.

1984-11-01

The reliability of 870-900 nm AlGaAs TJS lasers has been investigated. An emission wavelength longer than 870 nm is realized by utilizing the band tailing effect due to heavy Zn-diffusion in the active region. A nonabsorbing mirror structure is employed to eliminate both gradual degradation and catastrophic damage of the facets. Stable continuous operation for over 10000 hours has been confirmed at ambient temperatures higher than 50/sup 0/C and output powers more than 5 mW/ facet. MTTF longer than 10/sup 5/ hours is expected for screened devices. Surge endurance has been improved to be nearly one order of magnitude highermore » than that for a conventional structure.« less

Fusion reactor pumped laser

DOEpatents

Jassby, D.L.

1987-09-04

A nuclear pumped laser capable of producing long pulses of very high power laser radiation is provided. A toroidal fusion reactor provides energetic neutrons which are slowed down by a moderator. The moderated neutrons are converted to energetic particles capable of pumping a lasing medium. The lasing medium is housed in an annular cell surrounding the reactor. The cell includes an annular reflecting mirror at the bottom and an annular output window at the top. A neutron reflector is disposed around the cell to reflect escaping neutrons back into the cell. The laser radiation from the annular window is focused onto a beam compactor which generates a single coherent output laser beam. 10 figs.

Fusion reactor pumped laser

DOEpatents

Jassby, Daniel L.

1988-01-01

A nuclear pumped laser capable of producing long pulses of very high power laser radiation is provided. A toroidal fusion reactor provides energetic neutrons which are slowed down by a moderator. The moderated neutrons are converted to energetic particles capable of pumping a lasing medium. The lasing medium is housed in an annular cell surrounding the reactor. The cell includes an annular reflecting mirror at the bottom and an annular output window at the top. A neutron reflector is disposed around the cell to reflect escaping neutrons back into the cell. The laser radiation from the annular window is focused onto a beam compactor which generates a single coherent output laser beam.

High power far-infrared optical parametric oscillator with high beam quality

NASA Astrophysics Data System (ADS)

Qian, Chuan-Peng; Shen, Ying-Jie; Dai, Tong-Yu; Duan, Xiao-Ming; Yao, Bao-Quan

2016-11-01

A high power ZnGeP2 (ZGP) optical parametric oscillator (OPO) with good beam quality pumped by a Q-switched Ho:YAG laser was demonstrated. The maximum output power of the ZGP OPO with a four-mirror ring cavity was about 5.04 W around 8.1 μm with 83.9 W Ho incident pump power, corresponding to a slope efficiency of 9.2 %. The ZGP OPO produced 36.0 ns far-IR pulse laser in the 8.0-8.3 μm spectral regions. The beam quality was measured to be M2 1.6 at the highest output power.

Wavelength-tunable Q-switched Raman fiber laser

NASA Astrophysics Data System (ADS)

Ye, Jun; Xu, Jiangming; Zhang, Hanwei; Wu, Jian; Zhou, Pu

2018-03-01

In this presentation, a wavelength-tunable Q-switched Raman fiber laser is presented for the first time, which has a backward pumped configuration, including a section of 3 km passive fiber, a homemade tunable pump source and a highly reflective fiber loop mirror. The output wavelength of the Raman fiber laser can be tuned continuously with ~44 nm range via adjusting the pump wavelength. By inserting an acoustic-optical modulator, the Q-value of the cavity can be switched between high and low level. As a result, pulsed output with a repetition rate of 500 kHz and duration time of 60-80 ns is achieved.

An improved scan laser with a VO2 programmable mirror

NASA Astrophysics Data System (ADS)

Chivian, J. S.; Scott, M. W.; Case, W. E.; Krasutsky, N. J.

1985-04-01

A 10.6-microns scan laser has been constructed and operated with an off-axis cathode ray tube, high reflectance multilayer thin-film structures, and a tapered plasma discharge tube. Equations are given for the switching time of a high-reflectance spot on the VO2 and for the relation of scan laser output power to cavity geometry, cavity losses, and the gain of the active CO2 medium. A scan capability of 2100 easily resolvable directions was demonstrated, and sequential and randomly addressed spot rates of 100,000/sec were achieved. The equations relating output power and cavity mode size were experimentally verified using a nonscanned beam.

Passively mode-locked high power Nd:GdVO4 laser with direct in-band pumping at 912 nm

NASA Astrophysics Data System (ADS)

Nadimi, Mohammad; Waritanant, Tanant; Major, Arkady

2018-01-01

We report on the first semiconductor saturable absorber mirror mode-locked Nd:GdVO4 laser directly diode-pumped at 912 nm. The laser generated 10.14 W of averaged output power at 1063 nm with the pulse width of 16 ps at the repetition rate of 85.2 MHz. The optical-to-optical efficiency and slope efficiency in the mode-locked regime were calculated to be 49.6% and 67.4% with respect to the absorbed pump power, respectively. Due to the low quantum defect pumping the output power was limited only by the available pump power.

Diffraction limited 1064nm monolithic DBR-master oscillator power amplifier with more than 7W output power

NASA Astrophysics Data System (ADS)

Zink, Christof; Maaβdorf, André; Fricke, Jörg; Ressel, Peter; Maiwald, Martin; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

2018-02-01

High brightness diode lasers with a spectrally narrowband emission, several watts of output power with an almost diffraction limited beam quality are requested light sources for several applications. In this work, a monolithic master oscillator power amplifier will be presented. The resonator of the master oscillator is formed by a high-reflection DBR grating on the rear side and an internal DBR mirror. Its power is amplified in a ridge waveguide followed by a tapered section. The monolithic MOPA provides over 7 W at 1064 nm with a narrow spectral emission width below 20 pm and an almost diffraction limited beam.

Pulse shaping system

DOEpatents

Skeldon, Mark D.; Letzring, Samuel A.

1999-03-23

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

Pulse shaping system

DOEpatents

Skeldon, M.D.; Letzring, S.A.

1999-03-23

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

Apparatus for Controlling Low Power Voltages in Space Based Processing Systems

NASA Technical Reports Server (NTRS)

Petrick, David J. (Inventor)

2017-01-01

A low power voltage control circuit for use in space missions includes a switching device coupled between an input voltage and an output voltage. The switching device includes a control input coupled to an enable signal, wherein the control input is configured to selectively turn the output voltage on or off based at least in part on the enable signal. A current monitoring circuit is coupled to the output voltage and configured to produce a trip signal, wherein the trip signal is active when a load current flowing through the switching device is determined to exceed a predetermined threshold and is inactive otherwise. The power voltage control circuit is constructed of space qualified components.

L1 Adaptive Control Augmentation System with Application to the X-29 Lateral/Directional Dynamics: A Multi-Input Multi-Output Approach

NASA Technical Reports Server (NTRS)

Griffin, Brian Joseph; Burken, John J.; Xargay, Enric

2010-01-01

This paper presents an L(sub 1) adaptive control augmentation system design for multi-input multi-output nonlinear systems in the presence of unmatched uncertainties which may exhibit significant cross-coupling effects. A piecewise continuous adaptive law is adopted and extended for applicability to multi-input multi-output systems that explicitly compensates for dynamic cross-coupling. In addition, explicit use of high-fidelity actuator models are added to the L1 architecture to reduce uncertainties in the system. The L(sub 1) multi-input multi-output adaptive control architecture is applied to the X-29 lateral/directional dynamics and results are evaluated against a similar single-input single-output design approach.

Optical re-injection in cavity-enhanced absorption spectroscopy

PubMed Central

Leen, J. Brian; O’Keefe, Anthony

2014-01-01

Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10−10 cm−1/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\sqrt {{\\rm Hz;}}$\\end{document} Hz ; an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features. PMID:25273701

Artificial Neural Network with Hardware Training and Hardware Refresh

NASA Technical Reports Server (NTRS)

Duong, Tuan A. (Inventor)

2003-01-01

A neural network circuit is provided having a plurality of circuits capable of charge storage. Also provided is a plurality of circuits each coupled to at least one of the plurality of charge storage circuits and constructed to generate an output in accordance with a neuron transfer function. Each of a plurality of circuits is coupled to one of the plurality of neuron transfer function circuits and constructed to generate a derivative of the output. A weight update circuit updates the charge storage circuits based upon output from the plurality of transfer function circuits and output from the plurality of derivative circuits. In preferred embodiments, separate training and validation networks share the same set of charge storage circuits and may operate concurrently. The validation network has a separate transfer function circuits each being coupled to the charge storage circuits so as to replicate the training network s coupling of the plurality of charge storage to the plurality of transfer function circuits. The plurality of transfer function circuits may be constructed each having a transconductance amplifier providing differential currents combined to provide an output in accordance with a transfer function. The derivative circuits may have a circuit constructed to generate a biased differential currents combined so as to provide the derivative of the transfer function.

A compressive-sensing Fourier-transform on-chip Raman spectrometer

NASA Astrophysics Data System (ADS)

Podmore, Hugh; Scott, Alan; Lee, Regina

2018-02-01

We demonstrate a novel compressive sensing Fourier-transform spectrometer (FTS) for snapshot Raman spectroscopy in a compact format. The on-chip FTS consists of a set of planar-waveguide Mach-Zehnder interferometers (MZIs) arrayed on a photonic chip, effecting a discrete Fourier-transform of the input spectrum. Incoherence between the sampling domain (time), and the spectral domain (frequency) permits compressive sensing retrieval using undersampled interferograms for sparse spectra such as Raman emission. In our fabricated device we retain our chosen bandwidth and resolution while reducing the number of MZIs, e.g. the size of the interferogram, to 1/4th critical sampling. This architecture simultaneously reduces chip footprint and concentrates the interferogram in fewer pixels to improve the signal to noise ratio. Our device collects interferogram samples simultaneously, therefore a time-gated detector may be used to separate Raman peaks from sample fluorescence. A challenge for FTS waveguide spectrometers is to achieve multi-aperture high throughput broadband coupling to a large number of single-mode waveguides. A multi-aperture design allows one to increase the bandwidth and spectral resolution without sacrificing optical throughput. In this device, multi-aperture coupling is achieved using an array of microlenses bonded to the surface of the chip, and aligned with a grid of vertically illuminated waveguide apertures. The microlens array accepts a collimated beam with near 100% fill-factor, and the resulting spherical wavefronts are coupled into the single-mode waveguides using 45& mirrors etched into the waveguide layer via focused ion-beam (FIB). The interferogram from the waveguide outputs is imaged using a CCD, and inverted via l1-norm minimization to correctly retrieve a sparse input spectrum.

A Novel Concept for a Deformable Membrane Mirror for Correction of Large Amplitude Aberrations

NASA Technical Reports Server (NTRS)

Moore, Jim; Patrick, Brian

2006-01-01

Very large, light weight mirrors are being developed for applications in space. Due to launch mass and volume restrictions these mirrors will need to be much more flexible than traditional optics. The use of primary mirrors with these characteristics will lead to requirements for adaptive optics capable of correcting wave front errors with large amplitude relatively low spatial frequency aberrations. The use of low modulus membrane mirrors actuated with electrostatic attraction forces is a potential solution for this application. Several different electrostatic membrane mirrors are now available commercially. However, as the dynamic range requirement of the adaptive mirror is increased the separation distance between the membrane and the electrodes must increase to accommodate the required face sheet deformations. The actuation force applied to the mirror decreases inversely proportional to the square of the separation distance; thus for large dynamic ranges the voltage requirement can rapidly increase into the high voltage regime. Experimentation with mirrors operating in the KV range has shown that at the higher voltages a serious problem with electrostatic field cross coupling between actuators can occur. Voltage changes on individual actuators affect the voltage of other actuators making the system very difficult to control. A novel solution has been proposed that combines high voltage electrodes with mechanical actuation to overcome this problem. In this design an array of electrodes are mounted to a backing structure via light weight large dynamic range flextensional actuators. With this design the control input becomes the separation distance between the electrode and the mirror. The voltage on each of the actuators is set to a uniform relatively high voltage, thus the problem of cross talk between actuators is avoided and the favorable distributed load characteristic of electrostatic actuation is retained. Initial testing and modeling of this concept demonstrates that this is an attractive concept for increasing the dynamic range capability of electrostatic deformable mirrors.

DIGITAL Q METER

DOEpatents

Briscoe, W.L.

1962-02-13

A digital Q meter is described for measuring the Q of mechanical or electrical devices. The meter comprises in combination a transducer coupled to an input amplifier, and an upper and lower level discriminator coupled to the amplifier and having their outputs coupled to an anticoincidence gate. The output of the gate is connected to a scaler. The lower level discriminator is adjusted to a threshold level of 36.8 percent of the operating threshold level of the upper level discriminator. (AEC)

A coupled piezoelectric-electromagnetic energy harvesting technique for achieving increased power output through damping matching

NASA Astrophysics Data System (ADS)

Challa, Vinod R.; Prasad, M. G.; Fisher, Frank T.

2009-09-01

Vibration energy harvesting is being pursued as a means to power wireless sensors and ultra-low power autonomous devices. From a design standpoint, matching the electrical damping induced by the energy harvesting mechanism to the mechanical damping in the system is necessary for maximum efficiency. In this work two independent energy harvesting techniques are coupled to provide higher electrical damping within the system. Here the coupled energy harvesting device consists of a primary piezoelectric energy harvesting device to which an electromagnetic component is added to better match the total electrical damping to the mechanical damping in the system. The first coupled device has a resonance frequency of 21.6 Hz and generates a peak power output of ~332 µW, compared to 257 and 244 µW obtained from the optimized, stand-alone piezoelectric and electromagnetic energy harvesting devices, respectively, resulting in a 30% increase in power output. A theoretical model has been developed which closely agrees with the experimental results. A second coupled device, which utilizes the d33 piezoelectric mode, shows a 65% increase in power output in comparison to the corresponding stand-alone, single harvesting mode devices. This work illustrates the design considerations and limitations that one must consider to enhance device performance through the coupling of multiple harvesting mechanisms within a single energy harvesting device.

Synchronous motor with soft start element formed between the motor rotor and motor output shaft to successfully synchronize loads that have high inertia and/or high torque

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

Umans, Stephen D; Nisley, Donald L; Melfi, Michael J

A line-start synchronous motor has a housing, a rotor shaft, and an output shaft. A soft-start coupling portion is operatively coupled to the output shaft and the rotor shaft. The soft-start coupling portion is configurable to enable the synchronous motor to obtain synchronous operation and to drive, at least near synchronous speed during normal steady state operation of the motor, a load having characteristics sufficient to prevent obtaining normal synchronous operation of the motor when the motor is operatively connected to the load in the absence of the soft-start coupling. The synchronous motor is sufficiently rated to obtain synchronous operationmore » and to drive, at least near synchronous speed during normal steady state operation of the motor, a load having characteristics sufficient to prevent obtaining normal synchronous operation of the motor when the motor is operatively connected to the load in the absence of the soft-start coupling.« less

Learning of spatial relationships between observed and imitated actions allows invariant inverse computation in the frontal mirror neuron system.

PubMed

Oh, Hyuk; Gentili, Rodolphe J; Reggia, James A; Contreras-Vidal, José L

2011-01-01

It has been suggested that the human mirror neuron system can facilitate learning by imitation through coupling of observation and action execution. During imitation of observed actions, the functional relationship between and within the inferior frontal cortex, the posterior parietal cortex, and the superior temporal sulcus can be modeled within the internal model framework. The proposed biologically plausible mirror neuron system model extends currently available models by explicitly modeling the intraparietal sulcus and the superior parietal lobule in implementing the function of a frame of reference transformation during imitation. Moreover, the model posits the ventral premotor cortex as performing an inverse computation. The simulations reveal that: i) the transformation system can learn and represent the changes in extrinsic to intrinsic coordinates when an imitator observes a demonstrator; ii) the inverse model of the imitator's frontal mirror neuron system can be trained to provide the motor plans for the imitated actions.

Universal photonic quantum computation via time-delayed feedback

PubMed Central

Pichler, Hannes; Choi, Soonwon; Zoller, Peter; Lukin, Mikhail D.

2017-01-01

We propose and analyze a deterministic protocol to generate two-dimensional photonic cluster states using a single quantum emitter via time-delayed quantum feedback. As a physical implementation, we consider a single atom or atom-like system coupled to a 1D waveguide with a distant mirror, where guided photons represent the qubits, while the mirror allows the implementation of feedback. We identify the class of many-body quantum states that can be produced using this approach and characterize them in terms of 2D tensor network states. PMID:29073057

Coronagraph for astronomical imaging and spectrophotometry

NASA Technical Reports Server (NTRS)

Vilas, Faith; Smith, Bradford A.

1987-01-01

A coronagraph designed to minimize scattered light in astronomical observations caused by the structure of the primary mirror, secondary mirror, and secondary support structure of a Cassegrainian telescope is described. Direct (1:1) and reducing (2.7:1) imaging of astronomical fields are possible. High-quality images are produced. The coronagraph can be used with either a two-dimensional charge-coupled device or photographic film camera. The addition of transmission dispersing optics converts the coronagraph into a low-resolution spectrograph. The instrument is modular and portable for transport to different observatories.

Stroboscopic Interferometer for Measuring Mirror Vibrations

NASA Technical Reports Server (NTRS)

Stahl, H. Philip; Robers, Ted

2005-01-01

Stroboscopic interferometry is a technique for measuring the modes of vibration of mirrors that are lightweight and, therefore, unavoidably flexible. The technique was conceived especially for modal characterization of lightweight focusing mirror segments to be deployed in outer space; however, the technique can be applied to lightweight mirrors designed for use on Earth as well as the modal investigation of other optical and mechanical structures. To determine the modal structure of vibration of a mirror, it is necessary to excite the mirror by applying a force that varies periodically with time at a controllable frequency. The excitation can utilize sinusoidal, square, triangular, or even asynchronous waveforms. Because vibrational modes occur at specific resonant frequencies, it is necessary to perform synchronous measurements and sweep the frequency to locate the significant resonant modes. For a given mode it is possible to step the phase of data acquisition in order to capture the modal behavior over a single cycle of the resonant frequency. In order to measure interferometrically the vibrational response of the mirror at a given frequency, an interferometer must be suitably aligned with the mirror and adjustably phase-locked with the excitation signal. As in conventional stroboscopic photography, the basic idea in stroboscopic interferometry is to capture an image of the shape of a moving object (in this case, the vibrating mirror) at a specified instant of time in the vibration cycle. Adjusting the phase difference over a full cycle causes the interference fringes to vary over the full range of motion for the mode at the excitation frequency. The interference-fringe pattern is recorded as a function of the phase difference, and, from the resulting data, the surface shape of the mirror for the given mode is extracted. In addition to the interferometer and the mirror to be tested, the equipment needed for stroboscopic interferometry includes an arbitrary-function generator (that is, a signal generator), an oscilloscope, a trigger filter, and an advanced charge-coupled-device (CCD) camera. The optical components are positioned to form a pupil image of the mirror under test on the CCD chip, so that the interference pattern representative of the instantaneous mirror shape is imaged on the CCD chip.

Possible Quantum Absorber Effects in Cortical Synchronization

NASA Astrophysics Data System (ADS)

Kämpf, Uwe

The Wheeler-Feynman transactional "absorber" approach was proposed originally to account for anomalous resonance coupling between spatio-temporally distant measurement partners in entangled quantum states of so-called Einstein-Podolsky-Rosen paradoxes, e.g. of spatio-temporal non-locality, quantum teleportation, etc. Applied to quantum brain dynamics, however, this view provides an anticipative resonance coupling model for aspects of cortical synchronization and recurrent visual action control. It is proposed to consider the registered activation patterns of neuronal loops in so-called synfire chains not as a result of retarded brain communication processes, but rather as surface effects of a system of standing waves generated in the depth of visual processing. According to this view, they arise from a counterbalance between the actual input's delayed bottom-up data streams and top-down recurrent information-processing of advanced anticipative signals in a Wheeler-Feynman-type absorber mode. In the framework of a "time-loop" model, findings about mirror neurons in the brain cortex are suggested to be at least partially associated with temporal rather than spatial mirror functions of visual processing, similar to phase conjugate adaptive resonance-coupling in nonlinear optics.

Power scaling of diode-pumped neodymium yttrium aluminum borate laser

NASA Technical Reports Server (NTRS)

Hemmati, Hamid

1991-01-01

Preliminary results are presented of the efficient diode-pumped operation of a neodymium yttrium aluminum borate (NYAB) laser at 531.5 nm using two 1-W diode-laser arrays for the pump. With 1380 mW of CW power incident on the crystal, as much as 51 mW of 532.5-nm laser radiation was obtained with the unoptimized cavity. The corresponding optical-to-optical conversion efficiency was 3.7 percent. A plot of the output 531.5 nm vs incident 807 nm pump power is shown. The crystal output power was critically dependent on the rotational and translational adjustment of the NYAB crystal inside the cavity. It is suggested that a crystal cut at the exact phase matching angle, placed in a cavity with proper optimal reflection and transmission mirror coatings, and pumped at proper wavelength can result in higher output power. Thus, the NYAB output power approaches that of a CW intracavity frequency doubled Nd:YAG laser.

Advanced chemical oxygen iodine lasers for novel beam generation

NASA Astrophysics Data System (ADS)

Wu, Kenan; Zhao, Tianliang; Huai, Ying; Jin, Yuqi

2018-03-01

Chemical oxygen iodine laser, or COIL, is an impressive type of chemical laser that emits high power beam with good atmospheric transmissivity. Chemical oxygen iodine lasers with continuous-wave plane wave output are well-developed and are widely adopted in directed energy systems in the past several decades. Approaches of generating novel output beam based on chemical oxygen iodine lasers are explored in the current study. Since sophisticated physical processes including supersonic flowing of gaseous active media, chemical reacting of various species, optical power amplification, as well as thermal deformation and vibration of mirrors take place in the operation of COIL, a multi-disciplinary model is developed for tracing the interacting mechanisms and evaluating the performance of the proposed laser architectures. Pulsed output mode with repetition rate as high as hundreds of kHz, pulsed output mode with low repetition rate and high pulse energy, as well as novel beam with vector or vortex feature can be obtained. The results suggest potential approaches for expanding the applicability of chemical oxygen iodine lasers.

Implementation of a diode-pumped Nd:YAG laser with quick-change output couplers for high-beam quality 1064 or 532 nm wavelength generation

NASA Astrophysics Data System (ADS)

Li, Chun-Hao; Tsai, Ming-Jong

2009-06-01

A novel diode-pumped Nd:YAG laser system that employs a fixed active laser medium and a pair of quick-change output couplers on a precision linear stage for 1064 or 532 nm wavelength generation is presented. Fixed elements include a rear mirror, an acousto-optical Q-switch, and a diode-pumped solid-state laser (DPSSL). Movable elements for 1064 nm generation include an intra-cavity aperture as a mode selection element (MSE) and an output coupler. Movable elements for 532 nm generation include an intra-cavity frequency conversion with KTP, an intra-cavity aperture as a mode selection element (MSE), and an output coupler. Under stable operating conditions, the 1064 nm configuration produced a beam propagation ratio of 1.18 whereas the 532 nm configuration produced a beam propagation ratio of 1.1, both of which used an intra-cavity MSE with an aperture of 1.2 mm and a length of 5 mm.

Optical Thin Film Coating Having High Damage Resistance in Near-Stoichiometric MgO-Doped LiTaO3

NASA Astrophysics Data System (ADS)

Tateno, Ryo; Kashiwagi, Kunihiro

2008-08-01

Currently, High power and compact red, green, and blue (RGB) lasers are being considered for use in large screen laser televisions and reception-lobby projectors. Among these three laser sources, green semiconductor lasers are expensive and exhibit inferior performance in terms of the semiconductor material used, making it difficult to achieve a high output. In this study, we examined the use of our coating on MgO-doped LiTaO3, using a mirror coated with a multilayer film. Over a substrate, a Ta2O5 film was used to coat a high-refractive-index film layer, and a SiO2 film was used to coat a low-refractive-index film layer. To improve reflectivity, we designed the peak of the electric field intensity to be in the film layer with the low refractive index. As a result, the film endurance of 100 J/cm2 was obtained by one-on-one testing. With the nonlinear crystal material, the mirror without our coating exhibited a damage threshold of 33 J/cm2; however, after coating, this mirror demonstrated a higher damage threshold of 47 J/cm2. Thus, the film we fabricated using this technique is useful for improving the strength and durability of laser mirrors.

MEMS Based Acoustic Array

NASA Technical Reports Server (NTRS)

Sheplak, Mark (Inventor); Nishida, Toshikaza (Inventor); Humphreys, William M. (Inventor); Arnold, David P. (Inventor)

2006-01-01

Embodiments of the present invention described and shown in the specification aid drawings include a combination responsive to an acoustic wave that can be utilized as a dynamic pressure sensor. In one embodiment of the present invention, the combination has a substrate having a first surface and an opposite second surface, a microphone positioned on the first surface of the substrate and having an input and a first output and a second output, wherein the input receives a biased voltage, and the microphone generates an output signal responsive to the acoustic wave between the first output and the second output. The combination further has an amplifier positioned on the first surface of the substrate and having a first input and a second input and an output, wherein the first input of the amplifier is electrically coupled to the first output of the microphone and the second input of the amplifier is electrically coupled to the second output of the microphone for receiving the output sinual from the microphone. The amplifier is spaced from the microphone with a separation smaller than 0.5 mm.

PARALYZER FOR PULSE HEIGHT DISTRIBUTION ANALYZER

DOEpatents

Fairstein, E.

1960-01-19

A paralyzer circuit is described for use with a pulseheight distribution analyzer to prevent the analyzer from counting overlapping pulses where they would serve to provide a false indication. The paralyzer circuit comprises a pair of cathode-coupled amplifiers for amplifying pulses of opposite polarity. Diodes are provided having their anodes coupled to the separate outputs of the amplifiers to produce only positive signals, and a trigger circuit is coupled to the diodes ior operation by input pulses of either polarity from the amplifiers. A delay network couples the output of the trigger circuit for delaying the pulses.

Ultra-low output impedance RF power amplifier for parallel excitation.

PubMed

Chu, Xu; Yang, Xing; Liu, Yunfeng; Sabate, Juan; Zhu, Yudong

2009-04-01

Inductive coupling between coil elements of a transmit array is one of the key challenges faced by parallel RF transmission. An ultra-low output impedance RF power amplifier (PA) concept was introduced to address this challenge. In an example implementation, an output-matching network was designed to transform the drain-source impedance of the metallic oxide semiconductor field effect transistor (MOSFET) into a very low value for suppressing interelement coupling effect, and meanwhile, to match the input impedance of the coil to the optimum load of the MOSFET for maximizing the available output power. Two prototype amplifiers with 500-W output rating were developed accordingly, and were further evaluated with a transmit array in phantom experiments. Compared to the conventional 50-Omega sources, the new approach exhibited considerable effectiveness suppressing the effects of interelement coupling. The experiments further indicated that the isolation performance was comparable to that achieved by optimized overlap decoupling. The new approach, benefiting from a distinctive current-source characteristic, also exhibited a superior robustness against load variation. Feasibility of the new approach in high-field MR was demonstrated on a 3T clinical scanner.

120W, NA_0.15 fiber coupled LD module with 125-μm clad/NA 0.22 fiber by spatial coupling method

NASA Astrophysics Data System (ADS)

Ishige, Yuta; Kaji, Eisaku; Katayama, Etsuji; Ohki, Yutaka; Gajdátsy, Gábor; Cserteg, András.

2018-02-01

We have fabricated a fiber coupled semiconductor laser diode module by means of spatial beam combining of single emitter broad area semiconductor laser diode chips in the 9xx nm band. In the spatial beam multiplexing method, the numerical aperture of the output light from the optical fiber increases by increasing the number of laser diodes coupled into the fiber. To reduce it, we have tried the approach to improving assembly process technology. As a result, we could fabricate laser diode modules having a light output power of 120W or more and 95% power within NA of 0.15 or less from a single optical fiber with 125-μm cladding diameter. Furthermore, we have obtained that the laser diode module maintaining high coupling efficiency can be realized even around the fill factor of 0.95. This has been achieved by improving the optical alignment method regarding the fast axis stack pitch of the laser diodes in the laser diode module. Therefore, without using techniques such as polarization combining and wavelength combining, high output power was realized while keeping small numerical aperture. This contributes to a reduction in unit price per light output power of the pumping laser diode module.

DC coupled Doppler radar physiological monitor.

PubMed

Zhao, Xi; Song, Chenyan; Lubecke, Victor; Boric-Lubecke, Olga

2011-01-01

One of the challenges in Doppler radar systems for physiological monitoring is a large DC offset in baseband outputs. Typically, AC coupling is used to eliminate this DC offset. Since the physiological signals of interest include frequency content near DC, it is not desirable to simply use AC coupling on the radar outputs. While AC coupling effectively removes DC offset, it also introduces a large time delay and distortion. This paper presents the first DC coupled IQ demodulator printed circuit board (PCB) design and measurements. The DC coupling is achieved by using a mixer with high LO to RF port isolation, resulting in a very low radar DC offset on the order of mV. The DC coupled signals from the PCB radar system were successfully detected with significant LNA gain without saturation. Compared to the AC coupled results, the DC coupled results show great advantages of less signal distortion and more accurate rate estimation.

Spectrally Selective Mirrors with Combined Optical and Thermal Benefit for Photovoltaic Module Thermal Management

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

Slauch, Ian M.; Deceglie, Michael G.; Silverman, Timothy J.

Waste heat generated during daytime operation of a solar module will raise its temperature and reduce cell efficiency. In addition to thermalization and carrier recombination, one major source of excess heat in modules is the parasitic absorption of light with sub-bandgap energy. Parasitic absorption can be prevented if sub-bandgap radiation is reflected away from the module. We report on the design considerations and projected changes to module energy yield for photonic reflectors capable of reflecting a portion of sub-bandgap radiation while maintaining or improving transmission of light with energy greater than the semiconductor bandgap. Using a previously developed, self-consistent opto-electro-thermalmore » finite-element simulation, we calculate the total additional energy generated by a module, including various photonic reflectors, and decompose these benefits into thermal and optical effects. We show that the greatest total energy yield improvement comes from photonic mirrors designed for the outside of the glass, but that mirrors placed between the glass and the encapsulant can have significant thermal benefit. We then show that optimal photonic mirror design requires consideration of all angles of incidence, despite unequal amounts of radiation arriving at each angle. We find that optimized photonic mirrors will be omnidirectional in the sense that they have beneficial performance, regardless of the angle of incidence of radiation. By fulfilling these criteria, photonic mirrors can be used at different geographic locations or different tilt angles than their original optimization conditions with only marginal changes in performance. We show designs that improve energy output in Golden, Colorado by 3.7% over a full year. This work demonstrates the importance of considering real-world irradiance and weather conditions when designing optical structures for solar applications.« less

Spectrally Selective Mirrors with Combined Optical and Thermal Benefit for Photovoltaic Module Thermal Management

DOE PAGES

Slauch, Ian M.; Deceglie, Michael G.; Silverman, Timothy J.; ...

2018-03-02

Waste heat generated during daytime operation of a solar module will raise its temperature and reduce cell efficiency. In addition to thermalization and carrier recombination, one major source of excess heat in modules is the parasitic absorption of light with sub-bandgap energy. Parasitic absorption can be prevented if sub-bandgap radiation is reflected away from the module. We report on the design considerations and projected changes to module energy yield for photonic reflectors capable of reflecting a portion of sub-bandgap radiation while maintaining or improving transmission of light with energy greater than the semiconductor bandgap. Using a previously developed, self-consistent opto-electro-thermalmore » finite-element simulation, we calculate the total additional energy generated by a module, including various photonic reflectors, and decompose these benefits into thermal and optical effects. We show that the greatest total energy yield improvement comes from photonic mirrors designed for the outside of the glass, but that mirrors placed between the glass and the encapsulant can have significant thermal benefit. We then show that optimal photonic mirror design requires consideration of all angles of incidence, despite unequal amounts of radiation arriving at each angle. We find that optimized photonic mirrors will be omnidirectional in the sense that they have beneficial performance, regardless of the angle of incidence of radiation. By fulfilling these criteria, photonic mirrors can be used at different geographic locations or different tilt angles than their original optimization conditions with only marginal changes in performance. We show designs that improve energy output in Golden, Colorado by 3.7% over a full year. This work demonstrates the importance of considering real-world irradiance and weather conditions when designing optical structures for solar applications.« less

Dual actuation micro-mirrors

NASA Astrophysics Data System (ADS)

Alneamy, A. M.; Khater, M. E.; Al-Ghamdi, M. S.; Park, S.; Heppler, G. R.; Abdel-Rahman, E. M.

2018-07-01

This paper investigates the performance of cantilever-type micro-mirrors under electromagnetic, electrostatic and dual actuation. We developed and validated a two-DOFs model of the coupled bending-torsion motions of the mirror and used it in conjunction with experiments in air and in vacuum to compare all three actuation methods. We found that electromagnetic actuation is the most effective delivering a scanning range of  ± out of a geometrically allowable range of  ± at a current amplitude i  =  3 mA and a magnetic field of B  =  30 mT. Electrostatic actuation, whether alone or in conjunction with electromagnetic actuation, limited the stable angular range to smaller values (as small as ) due to the presence of spurious piston motions. This is an innate characteristic of micro-scale electrostatic actuation, the electrostatic force and the undesirable piston motion grow faster than the electrostatic torque and the desired angular displacement as the voltage is increased and they limit the stable angular range. Finally, we found that the dual actuation can be used to design two-DOF mirrors where electromagnetic actuation drives angular motion for optical beam steering and electrostatic actuation drives piston motion to control the mirror focus.

Technique for enhancing the power output of an electrostatic generator employing parametric resonance

DOEpatents

Post, Richard F.

2016-02-23

A circuit-based technique enhances the power output of electrostatic generators employing an array of axially oriented rods or tubes or azimuthal corrugated metal surfaces for their electrodes. During generator operation, the peak voltage across the electrodes occurs at an azimuthal position that is intermediate between the position of minimum gap and maximum gap. If this position is also close to the azimuthal angle where the rate of change of capacity is a maximum, then the highest rf power output possible for a given maximum allowable voltage at the minimum gap can be attained. This rf power output is then coupled to the generator load through a coupling condenser that prevents suppression of the dc charging potential by conduction through the load. Optimized circuit values produce phase shifts in the rf output voltage that allow higher power output to occur at the same voltage limit at the minimum gap position.

Robust decentralized controller for minimizing coupling effect in single inductor multiple output DC-DC converter operating in continuous conduction mode.

PubMed

Medeiros, Renan Landau Paiva de; Barra, Walter; Bessa, Iury Valente de; Chaves Filho, João Edgar; Ayres, Florindo Antonio de Cavalho; Neves, Cleonor Crescêncio das

2018-02-01

This paper describes a novel robust decentralized control design methodology for a single inductor multiple output (SIMO) DC-DC converter. Based on a nominal multiple input multiple output (MIMO) plant model and performance requirements, a pairing input-output analysis is performed to select the suitable input to control each output aiming to attenuate the loop coupling. Thus, the plant uncertainty limits are selected and expressed in interval form with parameter values of the plant model. A single inductor dual output (SIDO) DC-DC buck converter board is developed for experimental tests. The experimental results show that the proposed methodology can maintain a desirable performance even in the presence of parametric uncertainties. Furthermore, the performance indexes calculated from experimental data show that the proposed methodology outperforms classical MIMO control techniques. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

SERS of Individual Nanoparticles on a Mirror: Size Does Matter, but so Does Shape

PubMed Central

2016-01-01

Coupling noble metal nanoparticles by a 1 nm gap to an underlying gold mirror confines light to extremely small volumes, useful for sensing on the nanoscale. Individually measuring 10 000 of such gold nanoparticles of increasing size dramatically shows the different scaling of their optical scattering (far-field) and surface-enhanced Raman emission (SERS, near-field). Linear red-shifts of the coupled plasmon modes are seen with increasing size, matching theory. The total SERS from the few hundred molecules under each nanoparticle dramatically increases with increasing size. This scaling shows that maximum SERS emission is always produced from the largest nanoparticles, irrespective of tuning to any plasmonic resonances. Changes of particle facet with nanoparticle size result in vastly weaker scaling of the near-field SERS, without much modifying the far-field, and allows simple approaches for optimizing practical sensing. PMID:27223478

SERS of Individual Nanoparticles on a Mirror: Size Does Matter, but so Does Shape.

PubMed

Benz, Felix; Chikkaraddy, Rohit; Salmon, Andrew; Ohadi, Hamid; de Nijs, Bart; Mertens, Jan; Carnegie, Cloudy; Bowman, Richard W; Baumberg, Jeremy J

2016-06-16

Coupling noble metal nanoparticles by a 1 nm gap to an underlying gold mirror confines light to extremely small volumes, useful for sensing on the nanoscale. Individually measuring 10 000 of such gold nanoparticles of increasing size dramatically shows the different scaling of their optical scattering (far-field) and surface-enhanced Raman emission (SERS, near-field). Linear red-shifts of the coupled plasmon modes are seen with increasing size, matching theory. The total SERS from the few hundred molecules under each nanoparticle dramatically increases with increasing size. This scaling shows that maximum SERS emission is always produced from the largest nanoparticles, irrespective of tuning to any plasmonic resonances. Changes of particle facet with nanoparticle size result in vastly weaker scaling of the near-field SERS, without much modifying the far-field, and allows simple approaches for optimizing practical sensing.

The first neural probe integrated with light source (blue laser diode) for optical stimulation and electrical recording.

PubMed

Park, HyungDal; Shin, Hyun-Joon; Cho, Il-Joo; Yoon, Eui-sung; Suh, Jun-Kyo Francis; Im, Maesoon; Yoon, Euisik; Kim, Yong-Jun; Kim, Jinseok

2011-01-01

In this paper, we report a neural probe which can selectively stimulate target neurons optically through Si wet etched mirror surface and record extracellular neural signals in iridium oxide tetrodes. Consequently, the proposed approach provides to improve directional problem and achieve at least 150/m gap distance between stimulation and recording sites by wet etched mirror surface in V-groove. Also, we developed light source, blue laser diode (OSRAM Blue Laser Diode_PL 450), integration through simple jig for one-touch butt-coupling. Furthermore, optical power and impedance of iridium oxide tetrodes were measured as 200 μW on 5 mW from LD and 206.5 k Ω at 1 kHz and we demonstrated insertion test of probe in 0.5% agarose-gel successfully. We have successfully transmitted a light of 450 nm to optical fiber through the integrated LD using by butt-coupling method.

Weakly modulated silicon-dioxide-cladding gratings for silicon waveguide Fabry-Pérot cavities.

PubMed

Grote, Richard R; Driscoll, Jeffrey B; Biris, Claudiu G; Panoiu, Nicolae C; Osgood, Richard M

2011-12-19

We show by theory and experiment that silicon-dioxide-cladding gratings for Fabry-Pérot cavities on silicon-on-insulator channel ("wire") waveguides provide a low-refractive-index perturbation, which is required for several important integrated photonics components. The underlying refractive index perturbation of these gratings is significantly weaker than that of analogous silicon gratings, leading to finer control of the coupling coefficient κ. Our Fabry-Pérot cavities are designed using the transfer-matrix method (TMM) in conjunction with the finite element method (FEM) for calculating the effective index of each waveguide section. Device parameters such as coupling coefficient, κ, Bragg mirror stop band, Bragg mirror reflectivity, and quality factor Q are examined via TMM modeling. Devices are fabricated with representative values of distributed Bragg reflector lengths, cavity lengths, and propagation losses. The measured transmission spectra show excellent agreement with the FEM/TMM calculations.

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

De Geronimo, Gianluigi

Embodiments of comparator circuits are disclosed. A comparator circuit may include a differential input circuit, an output circuit, a positive feedback circuit operably coupled between the differential input circuit and the output circuit, and a hysteresis control circuit operably coupled with the positive feedback circuit. The hysteresis control circuit includes a switching device and a transistor. The comparator circuit provides sub-hysteresis discrimination and high speed discrimination.

Coupled rotor/airframe vibration analysis program manual. Volume 2: Sample input and output listings

NASA Technical Reports Server (NTRS)

Cassarino, S.; Sopher, R.

1982-01-01

Sample input and output listings obtained with the base program (SIMVIB) of the coupled rotor/airframe vibration analysis and the external programs, G400/F389 and E927 are presented. Results for five of the base program test cases are shown. They represent different applications of the SIMVIB program to study the vibration characteristics of various dynamic configurations. Input and output listings obtained for one cycle of the G400/F389 coupled program are presented. Results from the rotor aeroelastic analysis E927 also appear. A brief description of the check cases is provided. A summary of the check cases for all the external programs interacting with the SIMVIB program is illustrated.

Correction of large amplitude wavefront aberrations

NASA Astrophysics Data System (ADS)

Cornelissen, S. A.; Bierden, P. A.; Bifano, T. G.; Webb, R. H.; Burns, S.; Pappas, S.

2005-12-01

Recently, a number of research groups around the world have developed ophthalmic instruments capable of in vivo diffraction limited imaging of the human retina. Adaptive optics was used in these systems to compensate for the optical aberrations of the eye and provide high contrast, high resolution images. Such compensation uses a wavefront sensor and a wavefront corrector (usually a deformable mirror) coordinated in a closed- loop control system that continuously works to counteract aberrations. While those experiments produced promising results, the deformable mirrors have had insufficient range of motion to permit full correction of the large amplitude aberrations of the eye expected in a normal population of human subjects. Other retinal imaging systems developed to date with MEMS (micro-electromechanical systems) DMs suffer similar limitations. This paper describes the design, manufacture and testing of a 6um stroke polysilicon surface micromachined deformable mirror that, coupled with an new optical method to double the effective stroke of the MEMS-DM, will permit diffraction-limited retinal imaging through dilated pupils in at least 90% of the human population. A novel optical design using spherical mirrors provides a double pass of the wavefront over the deformable mirror such that a 6um mirror displacement results in 12um of wavefront compensation which could correct for 24um of wavefront error. Details of this design are discussed. Testing of the effective wavefront modification was performed using a commercial wavefront sensor. Results are presented demonstrating improvement in the amplitude of wavefront control using an existing high degree of freedom MEMS deformable mirror.

Bio-isolated dc operational amplifier. [for bioelectric measurements

NASA Technical Reports Server (NTRS)

Lee, R. D. (Inventor)

1974-01-01

A bio-isolated dc operational amplifier is described for use in making bioelectrical measurements of a patient while providing isolation of the patient from electrical shocks. The circuit contains a first operational amplifier coupled to the patient with its output coupled in a forward loop through a first optic coupler to a second operational amplifier. The output of the second operational amplifier is coupled to suitable monitoring circuitry via a feedback circuit including a second optic coupler to the input of the first operational amplifier.

Multi-frequency klystron designed for high efficiency

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

Jensen, Aaron

A multi-frequency klystron has an electron gun which generates a beam, a circuit of bunch-align-collect (BAC) tuned cavities that bunch the beam and amplify an RF signal, a collector where the beam is collected and dumped, and a standard output cavity and waveguide coupled to a window to output RF power at a fundamental mode to an external load. In addition, the klystron has additional bunch-align-collect (BAC) cavities tuned to a higher harmonic frequency, and a harmonic output cavity and waveguide coupled via a window to an additional external load.

Microwave Power Combiner/Switch Utilizing a Faraday Rotator

NASA Technical Reports Server (NTRS)

Perez, Raul

2008-01-01

A proposed device for combining or switching electromagnetic beams would have three ports, would not contain any moving parts, and would be switchable among three operating states: Two of the ports would be for input; the remaining port would be for output. In one operating state, the signals at both input ports would be coupled through to the output port. In each of the other two operating states, the signal at only one input port would be coupled to the output port. The input port would be selected through choice of the operating state.

Laser ablation system, and method of decontaminating surfaces

DOEpatents

Ferguson, Russell L.; Edelson, Martin C.; Pang, Ho-ming

1998-07-14

A laser ablation system comprising a laser head providing a laser output; a flexible fiber optic cable optically coupled to the laser output and transmitting laser light; an output optics assembly including a nozzle through which laser light passes; an exhaust tube in communication with the nozzle; and a blower generating a vacuum on the exhaust tube. A method of decontaminating a surface comprising the following steps: providing an acousto-optic, Q-switched Nd:YAG laser light ablation system having a fiber optically coupled output optics assembly; and operating the laser light ablation system to produce an irradiance greater than 1.times.10.sup.7 W/cm.sup.2, and a pulse width between 80 and 170 ns.

Palm-top-size, 1.5 kW peak-power, and femtosecond (160 fs) diode-pumped mode-locked Yb+3:KY(WO4)2 solid-state laser with a semiconductor saturable absorber mirror.

PubMed

Yamazoe, Shogo; Katou, Masaki; Adachi, Takashi; Kasamatsu, Tadashi

2010-03-01

We report a palm-top-size femtosecond diode-pumped mode-locked Yb(+3):KY(WO(4))(2) solid-state laser with a semiconductor saturable absorber mirror utilizing soliton mode locking for shortening the cavity to 50 mm. An average output power of 680 mW and a pulse width of 162 fs were obtained at 1045 nm with a repetition rate of 2.8 GHz, which led to a peak power of 1.5 kW. Average power fluctuations of a modularized laser source were found to be +/-10% for the free-running 3000 h operation and +/-1% for the power-controlled 2000 h operation.

Design optimization of ultra-high concentrator photovoltaic system using two-stage non-imaging solar concentrator

NASA Astrophysics Data System (ADS)

Wong, C.-W.; Yew, T.-K.; Chong, K.-K.; Tan, W.-C.; Tan, M.-H.; Lim, B.-H.

2017-11-01

This paper presents a systematic approach for optimizing the design of ultra-high concentrator photovoltaic (UHCPV) system comprised of non-imaging dish concentrator (primary optical element) and crossed compound parabolic concentrator (secondary optical element). The optimization process includes the design of primary and secondary optics by considering the focal distance, spillage losses and rim angle of the dish concentrator. The imperfection factors, i.e. mirror reflectivity of 93%, lens’ optical efficiency of 85%, circumsolar ratio of 0.2 and mirror surface slope error of 2 mrad, were considered in the simulation to avoid the overestimation of output power. The proposed UHCPV system is capable of attaining effective ultra-high solar concentration ratio of 1475 suns and DC system efficiency of 31.8%.

Sharp phase variations from the plasmon mode causing the Rabi-analogue splitting

NASA Astrophysics Data System (ADS)

Wang, Yujia; Sun, Chengwei; Gan, Fengyuan; Li, Hongyun; Gong, Qihuang; Chen, Jianjun

2017-06-01

The Rabi-analogue splitting in nanostructures resulting from the strong coupling of different resonant modes is of importance for lasing, sensing, switching, modulating, and quantum information processes. To give a clearer physical picture, the phase analysis instead of the strong coupling is provided to explain the Rabi-analogue splitting in the Fabry-Pérot (FP) cavity, of which one end mirror is a metallic nanohole array and the other is a thin metal film. The phase analysis is based on an analytic model of the FP cavity, in which the reflectance and the reflection phase of the end mirrors are dependent on the wavelength. It is found that the Rabi-analogue splitting originates from the sharp phase variation brought by the plasmon mode in the FP cavity. In the experiment, the Rabi-analogue splitting is realized in the plasmonic-photonic coupling system, and this splitting can be continually tuned by changing the length of the FP cavity. These experimental results agree well with the analytic and simulation data, strongly verifying the phase analysis based on the analytic model. The phase analysis presents a clear picture to understand the working mechanism of the Rabi-analogue splitting; thus, it may facilitate the design of the plasmonic-photonic and plasmonic-plasmonic coupling systems.

Debris- and radiation-induced damage effects on EUV nanolithography source collector mirror optics performance

NASA Astrophysics Data System (ADS)

Allain, J. P.; Nieto, M.; Hendricks, M.; Harilal, S. S.; Hassanein, A.

2007-05-01

Exposure of collector mirrors facing the hot, dense pinch plasma in plasma-based EUV light sources to debris (fast ions, neutrals, off-band radiation, droplets) remains one of the highest critical issues of source component lifetime and commercial feasibility of nanolithography at 13.5-nm. Typical radiators used at 13.5-nm include Xe and Sn. Fast particles emerging from the pinch region of the lamp are known to induce serious damage to nearby collector mirrors. Candidate collector configurations include either multi-layer mirrors (MLM) or single-layer mirrors (SLM) used at grazing incidence. Studies at Argonne have focused on understanding the underlying mechanisms that hinder collector mirror performance at 13.5-nm under fast Sn or Xe exposure. This is possible by a new state-of-the-art in-situ EUV reflectometry system that measures real time relative EUV reflectivity (15-degree incidence and 13.5-nm) variation during fast particle exposure. Intense EUV light and off-band radiation is also known to contribute to mirror damage. For example offband radiation can couple to the mirror and induce heating affecting the mirror's surface properties. In addition, intense EUV light can partially photo-ionize background gas (e.g., Ar or He) used for mitigation in the source device. This can lead to local weakly ionized plasma creating a sheath and accelerating charged gas particles to the mirror surface and inducing sputtering. In this paper we study several aspects of debris and radiation-induced damage to candidate EUVL source collector optics materials. The first study concerns the use of IMD simulations to study the effect of surface roughness on EUV reflectivity. The second studies the effect of fast particles on MLM reflectivity at 13.5-nm. And lastly the third studies the effect of multiple energetic sources with thermal Sn on 13.5-nm reflectivity. These studies focus on conditions that simulate the EUVL source environment in a controlled way.

Improved design of support for large aperture space lightweight mirror

NASA Astrophysics Data System (ADS)

Wang, Chao; Ruan, Ping; Liu, Qimin

2013-08-01

In order to design a kind of rational large aperture space mirror which can adapt to the space gravity and thermal environment, by taking the choice of material, the lightweight of the mirror and the design of support into account in detail, a double-deck structure with traditional flexible hinge was designed, then the analytical mathematical model of the mirror system was established. The design adopts six supports on back. in order to avoid the constraints, mirror is connected to three middle transition pieces through six flexible hinges, and then the three transition pieces are connected to support plate through another three flexible hinges. However, the initial structure is unable to reach the expected design target and needs to be made further adjustments. By improving and optimizing the original structure, a new type of flexible hinge in the shape of the letter A is designed finally. Compared with the traditional flexible hinge structure, the new structure is simpler and has less influence on the surface figure accuracy of mirror. By using the finite element analysis method, the static and dynamic characteristics as well as the thermal characteristics of the mirror system are analyzed. Analysis results show that the maximum PV value is 37 nm and the maximum RMS value is 10.4 nm when gravity load is applied. Furthermore, the maximum PV value is 46 nm and the maximum RMS value is 10.5 nm under the load case of gravity coupled with 4℃ uniform temperature rise. The results satisfy the index of optical design. The first order natural frequency of the mirror component is 130 Hz according to the conclusion obtained by modal analytical solution, so the mirror structure has high enough fundamental frequency. And, the structural strength can meet the demand under the overload and the random vibration environment respectively. It indicates that the mirror component structure has enough dynamic, static stiffness and thermal stability, meeting the design requirements.

Measurement technology based on laser internal/external cavity tuning

NASA Astrophysics Data System (ADS)

Zhang, Shulian

2011-08-01

For an ordinary laser with two cavity mirrors, if the length of laser cavity changes half wavelength the laser frequency changes one longitudinal mode separation. For a laser with three cavity mirrors, in which a feedback mirror is used to feed part of the laser output beam back into the laser cavity, the external cavity length changes half wavelength the laser intensity fluctuates one period. This presentation gives some research results in measurement field based on changing (tuning) the length of laser internal/external cavity, including 1) HeNe laser cavity-tuning nanometer displacement measurement instruments (laser nanometer rulers), 2) HeNe laser feedback displacement measurement, 3) Nd:YAG laser feedback nanometer displacement measurement, 4) benchmark of waveplate phase retardation measurement based on laser frequency splitting, 5) in-site waveplate phase retardation measurement instruments based on laser feedback and polarization hopping, 6) quasi-common-path microchip Nd:YAG laser feedback interferometer, 7) non-contact Nd:YAG laser feedback surface profile measurement. Some of these instruments have been put into application and display some irreplaceable advantages.

Cost-effective wavelength-tunable fiber laser using self-seeding Fabry-Perot laser diode.

PubMed

Yeh, Chien-Hung; Shih, Fu Y; Wang, Chia H; Chow, Chi W; Chi, Sien

2008-01-07

We propose and experimentally demonstrate a continuous wave (CW) tunable-wavelength fiber laser using self-seeding Fabry-Perot laser diode (FP-LD) without optical amplifier inside gain cavity. By employing a tunable bandpass filter (TBF) and a fiber reflected mirror (FRM) within a gain cavity, the fiber laser can lase a single-longitudinal wavelength due to the self-seeding operation. The proposed tunable wavelength laser has a good performance of the output power (> -15 dBm) and optical side-mode suppression ratio (> 40 dB) in the wavelength tuning range of 1533.75 to 1560.95 nm. In addition, the output stabilities of the fiber laser are also investigated.

Thermal design and test of a high power spacecraft transponder platform

NASA Technical Reports Server (NTRS)

Stipandic, E. A.; Gray, A. M.; Gedeon, L.

1975-01-01

The high power transponder subsystem on board the Communications Technology Satellite (CTS) requires some unique thermal control techniques to maintain the required temperature limits throughout all mission phases. The transponder subsystem includes redundant 20-W output travelling wave tubes and a single 200-W output TWT with highly concentrated thermal dissipations of 70 W and 143 W, respectively. A thermal control system which maintains all components within the required temperature ranges has been designed and verified in thermal balance testing. Included in the design are second surface quartz mirrors on an aluminum honeycomb platform, high thermal conductivity aluminum doubler plates, commandable thermal control heaters and a Variable Conductance Heat Pipe System (VCHPS).

Tunable vertical cavity surface emitting lasers for use in the near infrared biological window

NASA Astrophysics Data System (ADS)

Kitsmiller, Vincent J.; Dummer, Matthew; Johnson, Klein; O'Sullivan, Thomas D.

2018-02-01

We present a near-infrared tunable vertical cavity surface emitting laser (VCSEL) based upon a unique electrothermally tunable microelectromechanical systems (MEMS) topside mirror designed for tissue imaging and sensing. At room temperature, the laser is tunable from 769-782nm with single mode CW output and a peak output power of 1.3mW. We show that the tunable VCSEL is suitable for use in frequency domain diffuse optical spectroscopy by measuring the optical properties of a tissue-simulating phantom over the tunable range. These results indicate that tunable VCSELs may be an attractive choice to enable high spectral resolution optical sensing in a wearable format.

Apparatus and method for generating continuous wave 16. mu. m laser radiation using gaseous CF/sub 4/

DOEpatents

Telle, J.M.

1984-05-01

Apparatus and method for generating continuous wave 16 ..mu..m laser radiation using gaseous CF/sub 4/. Laser radiation at 16 ..mu..m has been observed in a cooled static cell containing low pressure CF/sub 4/ optically pumped by an approximately 3 W output power c-w CO/sub 2/ laser. The laser cavity employed was a multiple-pass off-axis-path two spherical mirror ring resonator. Unidirectional CF/sub 4/ laser output power at 615 cm/sup -1/ exceeded 2 mW. Computer calculations indicate that for modest pump powers of about 40 W, approximately 1 W of emitted laser radiation at 16 ..mu..m might be obtained.

Apparatus and method for generating continuous wave 16 .mu.m laser radiation using gaseous CF.sub.4

DOEpatents

Telle, John M.

1986-01-01

Apparatus and method for generating continuous wave 16 .mu.m laser radiation using gaseous CF.sub.4. Laser radiation at 16 .mu.m has been observed in a cooled static cell containing low pressure CF.sub.4 optically pumped by an approximately 3 W output power cw CO.sub.2 laser. The laser cavity employed was a multiple-pass off-axis-path two spherical mirror ring resonator. Unidirectional CF.sub.4 laser output power at 615 cm.sup.-1 exceeded 2 mW. Computer calculations indicate that for modest pump powers of about 40 W, approximately 1 W of emitted laser radiation at 16 .mu.m might be obtained.

High power infrared super-Gaussian beams: generation, propagation, and application

NASA Astrophysics Data System (ADS)

du Preez, Neil C.; Forbes, Andrew; Botha, Lourens R.

2008-10-01

In this paper we present the design of a CO2 laser resonator that produces as the stable transverse mode a super-Gaussian laser beam. The resonator makes use of an intra-cavity diffractive mirror and a flat output coupler, generating the desired intensity profile at the output coupler with a flat wavefront. We consider the modal build-up in such a resonator and show that such a resonator mode has the ability to extract more energy from the cavity that a standard cavity single mode beam (e.g., Gaussian mode cavity). We demonstrate the design experimentally on a high average power TEA CO2 laser for paint stripping applications.

Investigation of continuous wave and pulsed laser performance based on Nd3+:Gd0.6Y1.4SiO5 crystal

NASA Astrophysics Data System (ADS)

Feng, Chao; Liu, Zhaojun; Cong, Zhenhua; Shen, Hongbin; Li, Yongfu; Wang, Qingpu; Fang, Jiaxiong; Xu, Xiaodong; Xu, Jun; Zhang, Xingyu

2015-12-01

We systematically investigated a laser diode (LD) pumped Nd:GYSO (Nd3+:Gd0.6Y1.4SiO5) laser. The output power of the continuous wave laser was as high as 3.5 W with a slope efficiency of 31.8%. In the Q-switched operation; the laser exhibited dual-wavelengths output (1073.6 nm and 1074.7 nm) synchronously with a Cr4+:YAG as the saturable absorber (SA). Additionally, a passively mode-locked laser was demonstrated using a semiconductor SA mirror with a maximum average output power of 510 mW at a central wavelength of 1074 nm, while the pulse width of the laser was as short as 5 ps. Our experiment proved that the Nd:GYSO mixed crystal was a promising material for a solid-state laser.

Method to simulate and analyse induced stresses for laser crystal packaging technologies.

PubMed

Ribes-Pleguezuelo, Pol; Zhang, Site; Beckert, Erik; Eberhardt, Ramona; Wyrowski, Frank; Tünnermann, Andreas

2017-03-20

A method to simulate induced stresses for a laser crystal packaging technique and the consequent study of birefringent effects inside the laser cavities has been developed. The method has been implemented by thermo-mechanical simulations implemented with ANSYS 17.0. ANSYS results were later imported in VirtualLab Fusion software where input/output beams in terms of wavelengths and polarization were analysed. The study has been built in the context of a low-stress soldering technique implemented for glass or crystal optics packaging's called the solderjet bumping technique. The outcome of the analysis showed almost no difference between the input and output laser beams for the laser cavity constructed with an yttrium aluminum garnet active laser crystal, a second harmonic generator beta-barium borate, and the output laser mirror made of fused silica assembled by the low-stress solderjet bumping technique.

Ultra-short wavelength operation in Thulium-doped silica fiber laser with bidirectional pumping

NASA Astrophysics Data System (ADS)

Xiao, Xusheng; Guo, Haitao; Yan, Zhijun; Wang, Hushan; Xu, Yantao; Lu, Min; Wang, Yishan; Peng, Bo

2017-02-01

An ultra-short wavelength operation of Tm-doped all fiber laser based on fiber Bragg gratings (FBGs) was developed. A bi-directional pump configuration for the ultra-short wavelength operation was designed and investigated for the first time. the laser yielded 3.15W of continuous-wave output at 1706.75nm with a narrow-linewidth of 50pm and a maximum slope efficiency of 42.1%. The dependencies of the slope efficiencies and pump threshold of the laser versus the length of active fiber and reflectivity of the output mirror (FBG) were investigated in detail. An experimental comparative study between two Thulium-doped fiber lasers (TDFLs) with two different pumping configuration(forward unidirectional pumping and bidirectional pumping) was presented. It is indisputable that the development of 1.7μm silicate fiber lasers with Watt-level output power open up a number of heart-stirring and tempting application windows.

Dispersion compensated mid-infrared quantum cascade laser frequency comb with high power output

NASA Astrophysics Data System (ADS)

Lu, Q. Y.; Manna, S.; Slivken, S.; Wu, D. H.; Razeghi, M.

2017-04-01

Chromatic dispersion control plays an underlying role in optoelectronics and spectroscopy owing to its enhancement to nonlinear interactions by reducing the phase mismatching. This is particularly important to optical frequency combs based on quantum cascade lasers which require negligible dispersions for efficient mode locking of the dispersed modes into equally spaced comb modes. Here, we demonstrated a dispersion compensated mid-IR quantum cascade laser frequency comb with high power output at room temperature. A low-loss dispersive mirror has been engineered to compensate the device's dispersion residue for frequency comb generation. Narrow intermode beating linewidths of 40 Hz in the comb-working currents were identified with a high power output of 460 mW and a broad spectral coverage of 80 cm-1. This dispersion compensation technique will enable fast spectroscopy and high-resolution metrology based on QCL combs with controlled dispersion and suppressed noise.

Loose Coupling of Wearable-Based INSs with Automatic Heading Evaluation.

PubMed

Bousdar Ahmed, Dina; Munoz Diaz, Estefania

2017-11-03

Position tracking of pedestrians by means of inertial sensors is a highly explored field of research. In fact, there are already many approaches to implement inertial navigation systems (INSs). However, most of them use a single inertial measurement unit (IMU) attached to the pedestrian's body. Since wearable-devices will be given items in the future, this work explores the implementation of an INS using two wearable-based IMUs. A loosely coupled approach is proposed to combine the outputs of wearable-based INSs. The latter are based on a pocket-mounted IMU and a foot-mounted IMU. The loosely coupled fusion combines the output of the two INSs not only when these outputs are least erroneous, but also automatically favoring the best output. This approach is named smart update. The main challenge is determining the quality of the heading estimation of each INS, which changes every time. In order to address this, a novel concept to determine the quality of the heading estimation is presented. This concept is subject to a patent application. The results show that the position error rate of the loosely coupled fusion is 10 cm/s better than either the foot INS's or pocket INS's error rate in 95% of the cases.

NDIR gas sensing using high performance AlInSb mid-infrared LEDs as light source

NASA Astrophysics Data System (ADS)

Camargo, E. G.; Goda, Y.; Morohara, O.; Fujita, H.; Geka, H.; Ueno, K.; Shibata, Y.; Kuze, N.

2017-08-01

In this paper, we report the performance of room temperature operated mid-infrared light emitting diode (LED) with an InSb buffer layer and AlInSb active/barrier layers, which showed to be suitable for non-dispersive infrared (NDIR) gas sensing. Characterization of the LED was performed and we found that good carrier confinement and crystalline quality was responsible for its high performance. High efficiency light extraction was obtained by adopting backside emission architecture together with surface roughening treatment and TiO2 anti-reflection coating. The fabricated AlInSb LED showed 75% higher power conversion efficiency when compared with a commercially available device. The developed LED, together with a commercially available infrared (IR) detector equipped with band-pass optical filter (AK9710, manufactured by Asahi Kasei Microdevices) were coupled into a mirror system forming a light path length of 80 mm, which was tested for CO2 gas sensing. For a non-absorbing environment, sensor output of 8 nA was obtained by driving the LED with peak current of 100 mA and, by exposing the system at CO2 concentration of 1000 ppm signal reduction due to absorbance around 12% was obtained.

High power diode lasers emitting from 639 nm to 690 nm

NASA Astrophysics Data System (ADS)

Bao, L.; Grimshaw, M.; DeVito, M.; Kanskar, M.; Dong, W.; Guan, X.; Zhang, S.; Patterson, J.; Dickerson, P.; Kennedy, K.; Li, S.; Haden, J.; Martinsen, R.

2014-03-01

There is increasing market demand for high power reliable red lasers for display and cinema applications. Due to the fundamental material system limit at this wavelength range, red diode lasers have lower efficiency and are more temperature sensitive, compared to 790-980 nm diode lasers. In terms of reliability, red lasers are also more sensitive to catastrophic optical mirror damage (COMD) due to the higher photon energy. Thus developing higher power-reliable red lasers is very challenging. This paper will present nLIGHT's released red products from 639 nm to 690nm, with established high performance and long-term reliability. These single emitter diode lasers can work as stand-alone singleemitter units or efficiently integrate into our compact, passively-cooled Pearl™ fiber-coupled module architectures for higher output power and improved reliability. In order to further improve power and reliability, new chip optimizations have been focused on improving epitaxial design/growth, chip configuration/processing and optical facet passivation. Initial optimization has demonstrated promising results for 639 nm diode lasers to be reliably rated at 1.5 W and 690nm diode lasers to be reliably rated at 4.0 W. Accelerated life-test has started and further design optimization are underway.

Source-Coupled, N-Channel, JFET-Based Digital Logic Gate Structure Using Resistive Level Shifters

NASA Technical Reports Server (NTRS)

Krasowski, Michael J.

2011-01-01

A circuit topography is used to create usable, digital logic gates using N (negatively doped) channel junction field effect transistors (JFETs), load resistors, level shifting resistors, and supply rails whose values are based on the DC parametric distributions of these JFETs. This method has direct application to the current state-of-the-art in high-temperature (300 to 500 C and higher) silicon carbide (SiC) device production, and defines an adaptation to the logic gate described in U.S. Patent 7,688,117 in that, by removing the level shifter from the output of the gate structure described in the patent (and applying it to the input of the same gate), a source-coupled gate topography is created. This structure allows for the construction AND/OR (sum of products) arrays that use far fewer transistors and resistors than the same array as constructed from the gates described in the aforementioned patent. This plays a central role when large multiplexer constructs are necessary; for example, as in the construction of memory. This innovation moves the resistive level shifter from the output of the basic gate structure to the front as if the input is now configured as what would be the output of the preceding gate, wherein the output is the two level shifting resistors. The output of this innovation can now be realized as the lone follower transistor with its source node as the gate output. Additionally, one may leave intact the resistive level shifter on the new gate topography. A source-coupled to direct-coupled logic translator will be the result.

Technological developments for ultra-lightweight, large aperture, deployable mirror for space telescopes

NASA Astrophysics Data System (ADS)

Zuccaro Marchi, Alessandro; D'Amato, Francesco; Gallieni, Daniele; Biasi, Roberto; Molina, Marco; Duò, Fabrizio; Ruder, Nikolaus; Salinari, Piero; Lisi, Franco; Riccardi, Armando; Gambicorti, Lisa; Simonetti, Francesca; Pereira do Carmo, Joao Pedro N.

2017-11-01

The increasing interest on space telescopes for scientific applications leads to implement the manufacturing technology of the most critical element, i.e. the primary mirror: being more suitable a large aperture, it must be lightweight and deployable. The presented topic was originally addressed to a spaceborne DIAL (Differential Absorption LIDAR) mission operating at 935.5 nm for the measurement of water vapour profile in atmosphere, whose results were presented at ICSO 2006 and 2008. Aim of this paper is to present the latest developments on the main issues related to the fabrication of a breadboard, covering two project critical areas identified during the preliminary studies: the design and performances of the long-stroke actuators used to implement the mirror active control and the mirror survivability to launch via Electrostatic Locking (EL) between mirror and backplane. The described work is developed under the ESA/ESTEC contract No. 22321/09/NL/RA. The lightweight mirror is structured as a central sector surrounded by petals, all of them actively controlled to reach the specified shape after initial deployment and then maintained within specs for the entire mission duration. The presented study concerns: a) testing the Carbon Fiber Reinforced Plastic (CFRP) backplane manufacturing and EL techniques, with production of suitable specimens; b) actuator design optimisation; c) design of the deployment mechanism including a high precision latch; d) the fabrication of thin mirrors mock-ups to validate the fabrication procedure for the large shells. The current activity aims to the construction of an optical breadboard capable of demonstrating the achievement of all these coupled critical aspects: optical quality of the thin shell mirror surface, actuators performances and back-plane - EL subsystem functionality.

Diagnosable structured logic array

NASA Technical Reports Server (NTRS)

Whitaker, Sterling (Inventor); Miles, Lowell (Inventor); Gambles, Jody (Inventor); Maki, Gary K. (Inventor)

2009-01-01

A diagnosable structured logic array and associated process is provided. A base cell structure is provided comprising a logic unit comprising a plurality of input nodes, a plurality of selection nodes, and an output node, a plurality of switches coupled to the selection nodes, where the switches comprises a plurality of input lines, a selection line and an output line, a memory cell coupled to the output node, and a test address bus and a program control bus coupled to the plurality of input lines and the selection line of the plurality of switches. A state on each of the plurality of input nodes is verifiably loaded and read from the memory cell. A trusted memory block is provided. The associated process is provided for testing and verifying a plurality of truth table inputs of the logic unit.

Development of electro-optic systems for self cleaning concentrated solar reflectors

NASA Astrophysics Data System (ADS)

Stark, Jeremy W.

The current demand for energy usage in the world is increasing at a rapid pace; in China alone, the electricity usage has increased by 12% per year from 2006-2010, where more than 75% of electrical power is produced by coal burning facilities. Numerous studies have shown the effects of carbon dioxide emissions on global climate change, and even showing the permanence of high carbon dioxide levels after emissions cease. Current trends away from carbon emitting power facilities are pushing solar energy into a position for many new solar power plants to be constructed. Terrestrial solar energy at AM1.5 is generally given at 1kW/m2, which is a vast free source of energy that can be be harvested to meet the global demand for electricity. Aside from some areas receiving intermittent levels of solar insolation, one of the largest hindrances to large scale solar power production is obscuration of sunlight on solar collectors caused by dust deposition. In areas with the highest average solar insolation, dust deposition is a major problem for maintaining a constant maximum power output. The southern Negev desert in Israel receives on average 17g/m2 per month in dust deposition on solar installations, which in turn causes losses of a third of the total power output of the installation. In these areas, water is a scarce commodity, which can only be used to clean solar installations at a prohibitive cost. To resolve this problem, a cost effective solution would be the application of electrodynamic screens (EDS), which can be implemented by embedding a set of parallel electrodes into the sun facing surface of solar collectors, including concentrating mirrors or photovoltaic (PV) modules, and applying a low frequency pulsed voltage to these electrodes. Three major contributions made in the course of this research in advancing (EDS) for self-cleaning solar mirrors are: (1) development of non-contact specular reflectometer for solar mirrors that allows measurement of reflectance loss as a function of dust deposition, (2) development of a dust deposition analyzer capable of measuring size distribution of deposited dust and provides mass concentration of dust on the surface of the mirror, and (3) optimization of electrode geometry of EDS film for minimizing optical reflection losses caused by the lamination of the film on the mirror surface while maintaining high reflection efficiency with high dust removal efficiency. The non-contact specular reflectometer and the dust deposition analyzer allowed experimental investigation of reflection losses as functions of surface mass concentration of dust on mirrors for validation of the optical model presented in this study.

Multi-emitter laser multiplexer using a two-mirror beam shaper

NASA Astrophysics Data System (ADS)

Cobb, Joshua M.; Brennan, John; Bhatia, Vikram

2014-12-01

A system was designed and built to spatially multiplex four broad area laser diodes (BALD) and condense the light into a multi-mode fiber with a core diameter of 105 um and an NA of 0.15. The lasers were efficiently combined with an étendue aspect ratio scaler (EARS) optic. The EARS works under the principle of a two mirror beam shaper. We were able to successfully couple more than 87% of the optical energy into the fiber. The design of the optical system and the results of several built systems are discussed.

Electrically injected visible vertical cavity surface emitting laser diodes

DOEpatents

Schneider, Richard P.; Lott, James A.

1994-01-01

Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors.

Electrically injected visible vertical cavity surface emitting laser diodes

DOEpatents

Schneider, R.P.; Lott, J.A.

1994-09-27

Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors. 5 figs.

Radius of Curvature of Off-Axis Paraboloids

NASA Technical Reports Server (NTRS)

Robinson, Brian; Reardon, Patrick; Hadaway, James; Geary, Joseph; Russell, Kevin (Technical Monitor)

2002-01-01

We present several methods for measuring the vertex radius of curvature of off-axis paraboloidal mirrors. One is based on least-squares fitting of interferometer output, one on comparison of sagittal and tangential radii of curvature, and another on measurement of displacement of the nulled test article from the ideal reference wave. Each method defines radius of curvature differently and, as a consequence, produces its own sort of errors.

Unstable Resonator Retrofitted Handheld Laser Designator

DTIC Science & Technology

1978-06-01

retrofitted with a negative-branch unstable resona- tor laser and hybrid pump cavity in place of the conventional plane-mirror/ porro prism resonator and...directed by prism B to an expanding telescope, shared with the viewing system of the designator. The actual, unfolded resonator length is approxi...was performed based on using a plane- parallel cavity consisting of a 47% reflectivity output coupler, porro - prism reflector, and the same LiNb03

Tandem-Mirror Ion Source

NASA Technical Reports Server (NTRS)

Biddle, A.; Stone, N.; Reasoner, D.; Chisholm, W.; Reynolds, J.

1986-01-01

Improved ion source produces beam of ions at any kinetic energy from 1 to 1,000 eV, with little spread in energy or angle. Such ion beams useful in studies of surface properties of materials, surface etching, deposition, and development of plasma-diagnostic instrumentation. Tandemmirror ion source uses electrostatic and magnetic fields to keep electrons in ionization chamber and assure uniform output ion beam having low divergence in energy and angle.

FEV manoeuvre induced changes in breath VOC compositions: an unconventional view on lung function tests

NASA Astrophysics Data System (ADS)

Sukul, Pritam; Schubert, Jochen K.; Oertel, Peter; Kamysek, Svend; Taunk, Khushman; Trefz, Phillip; Miekisch, Wolfram

2016-06-01

Breath volatile organic compound (VOC) analysis can open a non-invasive window onto pathological and metabolic processes in the body. Decades of clinical breath-gas analysis have revealed that changes in exhaled VOC concentrations are important rather than disease specific biomarkers. As physiological parameters, such as respiratory rate or cardiac output, have profound effects on exhaled VOCs, here we investigated VOC exhalation under respiratory manoeuvres. Breath VOCs were monitored by means of real-time mass-spectrometry during conventional FEV manoeuvres in 50 healthy humans. Simultaneously, we measured respiratory and hemodynamic parameters noninvasively. Tidal volume and minute ventilation increased by 292 and 171% during the manoeuvre. FEV manoeuvre induced substance specific changes in VOC concentrations. pET-CO2 and alveolar isoprene increased by 6 and 21% during maximum exhalation. Then they decreased by 18 and 37% at forced expiration mirroring cardiac output. Acetone concentrations rose by 4.5% despite increasing minute ventilation. Blood-borne furan and dimethyl-sulphide mimicked isoprene profile. Exogenous acetonitrile, sulphides, and most aliphatic and aromatic VOCs changed minimally. Reliable breath tests must avoid forced breathing. As isoprene exhalations mirrored FEV performances, endogenous VOCs might assure quality of lung function tests. Analysis of exhaled VOC concentrations can provide additional information on physiology of respiration and gas exchange.

Rigrod laser-pumped-laser resonator model: II. Application to thin and optically-dilute laser media

NASA Astrophysics Data System (ADS)

Brown, D. C.

2014-08-01

In part I of this paper, and to set the foundation for this part II, we derived the resonator equations describing the normalized intensities, output power, gain, and extraction efficiency for a standard resonator incorporating two dielectric mirrors and a gain element. We then generalized the results to include an absorbing region representing a second laser crystal characterized by a small-signal transmission T0. Explicit expressions were found for the output power extracted into absorption by the second laser crystal and the extraction efficiency, and the limits to each were discussed. It was shown that efficient absorption by a thin or dilute second laser crystal can be realized in resonators in which the mirror reflectivities were high and in which the single-pass absorption was low, due to the finite photon lifetime and multi-passing of the absorbing laser element. In this paper, we apply the model derived in part I to thin or dilute laser materials, concentrating on a Yb, Er:glass intracavity pumped by a 946 nm Nd:YAG laser, a Yb, Er:glass laser-pumped intracavity by a 977 nm diode laser, and an Er:YAG laser-pumped intracavity to a 1530 nm diode laser. It is shown that efficient absorption can be obtained in all cases examined.

FEV manoeuvre induced changes in breath VOC compositions: an unconventional view on lung function tests

PubMed Central

Sukul, Pritam; Schubert, Jochen K.; Oertel, Peter; Kamysek, Svend; Taunk, Khushman; Trefz, Phillip; Miekisch, Wolfram

2016-01-01

Breath volatile organic compound (VOC) analysis can open a non-invasive window onto pathological and metabolic processes in the body. Decades of clinical breath-gas analysis have revealed that changes in exhaled VOC concentrations are important rather than disease specific biomarkers. As physiological parameters, such as respiratory rate or cardiac output, have profound effects on exhaled VOCs, here we investigated VOC exhalation under respiratory manoeuvres. Breath VOCs were monitored by means of real-time mass-spectrometry during conventional FEV manoeuvres in 50 healthy humans. Simultaneously, we measured respiratory and hemodynamic parameters noninvasively. Tidal volume and minute ventilation increased by 292 and 171% during the manoeuvre. FEV manoeuvre induced substance specific changes in VOC concentrations. pET-CO2 and alveolar isoprene increased by 6 and 21% during maximum exhalation. Then they decreased by 18 and 37% at forced expiration mirroring cardiac output. Acetone concentrations rose by 4.5% despite increasing minute ventilation. Blood-borne furan and dimethyl-sulphide mimicked isoprene profile. Exogenous acetonitrile, sulphides, and most aliphatic and aromatic VOCs changed minimally. Reliable breath tests must avoid forced breathing. As isoprene exhalations mirrored FEV performances, endogenous VOCs might assure quality of lung function tests. Analysis of exhaled VOC concentrations can provide additional information on physiology of respiration and gas exchange. PMID:27311826

Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

DOEpatents

Beach, Raymond J.; Benett, William J.; Mills, Steven T.

1997-01-01

The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a "rack and stack" configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber.

A design study of mirror modules and an assembly based on the slumped glass for an Athena-like optics

NASA Astrophysics Data System (ADS)

Basso, Stefano; Civitani, Marta; Pareschi, Giovanni; Buratti, Enrico; Eder, Josef; Friedrich, Peter; Fürmetz, Maria

2015-09-01

The Athena mission was selected for the second large-class mission, due for launch in 2028, in ESA's Cosmic Vision program. The current solution for the optics is based on the Silicon Pore Optics (SPO) technology with the goal of 2m2 effective area at 1keV (aperture about 3m diameter) with a focal length of 12m. The SPO advantages are the compactness along the axial direction and the high conductivity of the Silicon. Recent development in the fabrication of mirror shells based on the Slumped Glass Optics (SGO) makes this technology an attractive solution for the mirror modules for Athena or similar telescopes. The SGO advantages are a potential high collecting area with a limited vignetting due to the lower shadowing and the aptitude to curve the glass plates up to small radius of curvature. This study shows an alternative mirror design based on SGO technology, tailored for Athena needs. The main challenges are the optimization of the manufacturing technology with respect to the required accuracy and the thermal control of the large surface in conjunction with the low conductivity of the glass. A concept has been elaborated which considers the specific benefits of the SGO technology and provides an efficient thermal control. The output of the study is a preliminary design substantiated by analyses and technological studies. The study proposes interfaces and predicts performances and budgets. It describes also how such a mirror system could be implemented as a modular assembly for X-ray telescope with a large collecting area.

GaAs/AlOx high-contrast grating mirrors for mid-infrared VCSELs

NASA Astrophysics Data System (ADS)

Almuneau, G.; Laaroussi, Y.; Chevallier, C.; Genty, F.; Fressengeas, N. s.; Cerutti, L.; Gauthier-Lafaye, Olivier

2015-02-01

Mid-infrared Vertical cavity surface emitting lasers (MIR-VCSEL) are very attractive compact sources for spectroscopic measurements above 2μm, relevant for molecules sensing in various application domains. A long-standing issue for long wavelength VCSEL is the large structure thickness affecting the laser properties, added for the MIR to the tricky technological implementation of the antimonide alloys system. In this paper, we propose a new geometry for MIR-VCSEL including both a lateral confinement by an oxide aperture, and a high-contrast sub-wavelength grating mirror (HCG mirror) formed by the high contrast combination AIOx/GaAs in place of GaSb/A|AsSb top Bragg reflector. In addition to drastically simplifying the vertical stack, HCG mirror allows to control through its design the beam properties. The robust design of the HCG has been ensured by an original method of optimization based on particle swarm optimization algorithm combined with an anti-optimization one, thus allowing large error tolerance for the nano-fabrication. Oxide-based electro-optical confinement has been adapted to mid-infrared lasers, byusing a metamorphic approach with (Al) GaAs layer directly epitaxially grown on the GaSb-based VCSEL bottom structure. This approach combines the advantages of the will-controlled oxidation of AlAs layer and the efficient gain media of Sb-based for mid-infrared emission. We finally present the results obtained on electrically pumped mid-IR-VCSELs structures, for which we included oxide aperturing for lateral confinement and HCG as high reflectivity output mirrors, both based on AlxOy/GaAs heterostructures.

Content-addressable memory based enforcement of configurable policies

DOEpatents

Berg, Michael J

2014-05-06

A monitoring device for monitoring transactions on a bus includes content-addressable memory ("CAM") and a response policy unit. The CAM includes an input coupled to receive a bus transaction tag based on bus traffic on the bus. The CAM stores data tags associated with rules of a security policy to compare the bus transaction tag to the data tags. The CAM generates an output signal indicating whether one or more matches occurred. The response policy unit is coupled to the CAM to receive the output signal from the CAM and to execute a policy action in response to the output signal.

Optical single photons on-demand teleported from microwave cavities

NASA Astrophysics Data System (ADS)

Barzanjeh, Sh; Vitali, D.; Tombesi, P.

2013-03-01

We propose a scheme for entangling the optical and microwave output modes of the respective cavities by using a micro mechanical resonator. The micro mechanical resonator, on one side, is capacitively coupled to the microwave cavity and, on the other side, it is coupled to a high-finesses optical cavity. We then show how this continuous variable entanglement can be profitably used to teleport the non-Gaussian number state |1> and the superposition (|0\\rangle +|1\\rangle )/\\sqrt 2 from the microwave cavity output mode onto an output of the optical cavity mode with fidelity much larger than the no-cloning limit.

Time-dependent multi-dimensional simulation studies of the electron output scheme for high power FELs

NASA Astrophysics Data System (ADS)

Hahn, S. J.; Fawley, W. M.; Kim, K.-J.; Edighoffer, J. A.

1995-04-01

We examine the performance of the so-called electron output scheme recently proposed by the Novosibirsk group [G.I. Erg et al., 15th Int. Free Electron Laser Conf., The Hague, The Netherlands, 1993, Book of Abstracts p. 50; Preprint Budker INP 93-75]. In this scheme, the key role of the FEL oscillator is to induce bunching, while an external undulator, called the radiator, then outcouples the bunched electron beam to optical energy via coherent emission. The level of the intracavity power in the oscillator is kept low by employing a transverse optical klystron (TOK) configuration, thus avoiding excessive thermal loading on the cavity mirrors. Time-dependent effects are important in the operation of the electron output scheme because high gain in the TOK oscillator leads to sideband instabilities and chaotic behavior. We have carried out an extensive simulation study by using 1D and 2D time-dependent codes and find that proper control of the oscillator cavity detuning and cavity loss results in high output bunching with a narrow spectral bandwidth. Large cavity detuning in the oscillator and tapering of the radiator undulator is necessary for the optimum output power.

Current Technology Development Efforts on the International X-Ray Observatory

NASA Technical Reports Server (NTRS)

Robinson, David

2011-01-01

The International X-ray Observatory (IXO) is a collaboration between NASA, ESA, and JAXA which is under study for launch in 2021. IXO will be a large 6600 kilogram Great Observatory-class mission which will build upon the legacies of the Chandra and XMM-Newton X-ray observatories. There is an extensive ongoing effort to raise the technology readiness level of the X-ray mirror from TRL 3 to TRL 6 in the next decade. Improvements have recently been made in the area of positioning and bonding mirrors on the nanometer scale and developing metals and composites with a matching coefficient of thermal expansion to the glass X-ray mirrors. On the mission systems side, the NASA reference design has been through a preliminary coupled loads analysis and a STOP analysis of the flight mirror assembly has been initiated. An impact study was performed comparing launching IXO on an Ariane 5 or a U.S. EELV. This paper will provide a snapshot of NASA's current observatory configuration and summarize the progress of these various technology and design efforts.

Controlling X-ray deformable mirrors during inspection

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

Huang, Lei; Xue, Junpeng; Idir, Mourad

2016-10-14

The X-ray deformable mirror (XDM) is becoming widely used in the present synchrotron/free-electron laser facilities because of its flexibility in correcting wavefront errors or modification of the beam size at the sample location. Owing to coupling among the N actuators of an XDM, (N + 1) or (2N + 1) scans are required to learn the response of each actuator one by one. When the mirror has an important number of actuators (N) and the actuator response time including stabilization or the necessary metrology time is long, the learning process can be time consuming. In this paper, a fast andmore » accurate method is presented to drive an XDM to a target shape usually with only three or four measurements during inspection. The metrology data are used as feedback to calculate the curvature discrepancy between the current and the target shapes. Three different derivative estimation methods are introduced to calculate the curvature from measured data. The mirror shape is becoming close to the target through iterative compensations. Finally, the feasibility of this simple and effective approach is demonstrated by a series of experiments.« less

Technologies for the fabrication of the E-ELT mirrors within the T-REX project

NASA Astrophysics Data System (ADS)

Pareschi, G.; Aliverti, M.; Bianco, A.; Basso, S.; Citterio, O.; Civitani, M.; Ghigo, M.; Pariani, G.; Sironi, G.; Riva, M.; Vecchi, G.; Zerbi, F.

With its primary mirror with 39 m of diameter, the E-ELT will be the largest optical/near-infrared telescope in the world and will gather 13 times more light than the largest optical telescopes existing today. The different optical sub-systems of E-ELT, including the primary mirror based on hundreds of reflecting tiles assembled together, represent key components for the implementation of the telescopes. A huge amount of aspherical reflecting elements have to be produced with "state of the art" figuring and polishing technologies and measured with proper metrological equipments. In the past couple of years, in the context of the T-REX project, a specific development program was carried out at the Brera Astronomical Observatory-INAF in order to address a numbers of technology aspects related to the fabrication of the E-ELT mirrors. In this paper we give a short overview of the activities that have been carried out. Other papers in this volume report on specific activities that have pursed within such a development program. skip=8pt

Specular reflectance of soiled glass mirrors - Study on the impact of incidence angles

NASA Astrophysics Data System (ADS)

Heimsath, Anna; Lindner, Philip; Klimm, Elisabeth; Schmid, Tobias; Moreno, Karolina Ordonez; Elon, Yehonatan; Am-Shallem, Morag; Nitz, Peter

2016-05-01

The accumulation of dust and soil on the surface of solar reflectors is an important factor reducing the power output of solar power plants. Therefore the effect of accumulated dust on the specular reflectance of solar mirrors should be understood well in order to improve the site-dependent performance prediction. Furthermore, an optimization of the CSP System maintenance, in particular the cleaning cycles, can be achieved. Our measurements show a noticeable decrease of specular reflectance when the angle of incidence is increased. This effect may be explained by shading and blocking mechanisms caused by dirt particles. The main physical causes of radiation loss being absorption and scattering, the near-angle scattering leads to a further decrease of specular reflectance for smaller angles of acceptance. Within this study mirror samples were both outdoor exposed and indoor artificially soiled. For indoor soiling, the mirror samples were artificially soiled in an in-house developed dusting device using both artificial-standardized dust and real dust collected from an arid outdoor test field at the Negev desert. A model function is proposed that approximates the observed reduction of specular reflectance with the incidence angle with a sufficient accuracy and by simple means for this soil type. Hence a first step towards a new approach to improve site dependent performance prediction of solar power plants is taken.

Optimization of output power and transmission efficiency of magnetically coupled resonance wireless power transfer system

NASA Astrophysics Data System (ADS)

Yan, Rongge; Guo, Xiaoting; Cao, Shaoqing; Zhang, Changgeng

2018-05-01

Magnetically coupled resonance (MCR) wireless power transfer (WPT) system is a promising technology in electric energy transmission. But, if its system parameters are designed unreasonably, output power and transmission efficiency will be low. Therefore, optimized parameters design of MCR WPT has important research value. In the MCR WPT system with designated coil structure, the main parameters affecting output power and transmission efficiency are the distance between the coils, the resonance frequency and the resistance of the load. Based on the established mathematical model and the differential evolution algorithm, the change of output power and transmission efficiency with parameters can be simulated. From the simulation results, it can be seen that output power and transmission efficiency of the two-coil MCR WPT system and four-coil one with designated coil structure are improved. The simulation results confirm the validity of the optimization method for MCR WPT system with designated coil structure.

Theoretical modeling, simulation and experimental study of hybrid piezoelectric and electromagnetic energy harvester

NASA Astrophysics Data System (ADS)

Li, Ping; Gao, Shiqiao; Cong, Binglong

2018-03-01

In this paper, performances of vibration energy harvester combined piezoelectric (PE) and electromagnetic (EM) mechanism are studied by theoretical analysis, simulation and experimental test. For the designed harvester, electromechanical coupling modeling is established, and expressions of vibration response, output voltage, current and power are derived. Then, performances of the harvester are simulated and tested; moreover, the power charging rechargeable battery is realized through designed energy storage circuit. By the results, it's found that compared with piezoelectric-only and electromagnetic-only energy harvester, the hybrid energy harvester can enhance the output power and harvesting efficiency; furthermore, at the harmonic excitation, output power of harvester linearly increases with acceleration amplitude increasing; while it enhances with acceleration spectral density increasing at the random excitation. In addition, the bigger coupling strength, the bigger output power is, and there is the optimal load resistance to make the harvester output the maximal power.

Low threshold diode-pumped picosecond mode-locked Nd:YAG laser with a semiconductor saturable absorber mirror

NASA Astrophysics Data System (ADS)

Eshghi, M. J.; Majdabadi, A.; Koohian, A.

2017-01-01

In this paper, a low threshold diode pumped passively mode-locked Nd:YAG laser has been demonstrated by using a semiconductor saturable absorber mirror. The threshold power for continuous-wave mode-locking is relatively low, about 3.2 W. The resonator stability across the pump power has been analytically examined. Moreover, the mode overlap between the pump beam and the laser fundamental mode has been simulated by MATLAB software. Adopting Z-shaped resonator configuration and suitable design of the resonator’s arm lengths, has enabled the author to prepare mode-locking conditions, and obtain 40 ps pulses with 112 MHz pulse repetition rate. The laser output was stable without any Q switched instability. To the best of our knowledge, this is the lowest threshold for CW mode-locking operation of a Nd:YAG laser.

Modeling and analysis of the solar concentrator in photovoltaic systems

NASA Astrophysics Data System (ADS)

Mroczka, Janusz; Plachta, Kamil

2015-06-01

The paper presents the Λ-ridge and V-trough concentrator system with a low concentration ratio. Calculations and simulations have been made in the program created by the author. The results of simulation allow to choose the best parameters of photovoltaic system: the opening angle between the surface of the photovoltaic module and mirrors, resolution of the tracking system and the material for construction of the concentrator mirrors. The research shows the effect each of these parameters on the efficiency of the photovoltaic system and method of surface modeling using BRDF function. The parameters of concentrator surface (eg. surface roughness) were calculated using a new algorithm based on the BRDF function. The algorithm uses a combination of model Torrance-Sparrow and HTSG. The simulation shows the change in voltage, current and output power depending on system parameters.

The design and development of a solar tracking unit

NASA Technical Reports Server (NTRS)

Jones, I. W.; Miller, J. B.

1984-01-01

The solar tracking unit was developed to support the Laser Heterodyne Spectrometer (LHS) airborne instrument, but has application to a general class of airborne solar occultation research instruments. The unit consists of a mirror mounted on two gimbals, one of which is hollow. The mirror reflects a 7.6 cm (3.0 in.) diameter beam of sunlight through the hollow gimbal into the research instrument optical axis. A portion of the reflected sunlight is directed into a tracking telescope which uses a four quadrant silicon detector to produce the servo error signals. The colinearity of the tracker output beam and the research instrument optical axis is maintained to better than + or - 1 arc-minute. The unit is microcomputer controlled and is capable of stand alone operation, including automatic Sun acquisition or operation under the control of the research instrument.

Monolithic solid-state lasers for spaceflight

NASA Astrophysics Data System (ADS)

Krainak, Michael A.; Yu, Anthony W.; Stephen, Mark A.; Merritt, Scott; Glebov, Leonid; Glebova, Larissa; Ryasnyanskiy, Aleksandr; Smirnov, Vadim; Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth

2015-02-01

A new solution for building high power, solid state lasers for space flight is to fabricate the whole laser resonator in a single (monolithic) structure or alternatively to build a contiguous diffusion bonded or welded structure. Monolithic lasers provide numerous advantages for space flight solid-state lasers by minimizing misalignment concerns. The closed cavity is immune to contamination. The number of components is minimized thus increasing reliability. Bragg mirrors serve as the high reflector and output coupler thus minimizing optical coatings and coating damage. The Bragg mirrors also provide spectral and spatial mode selection for high fidelity. The monolithic structure allows short cavities resulting in short pulses. Passive saturable absorber Q-switches provide a soft aperture for spatial mode filtering and improved pointing stability. We will review our recent commercial and in-house developments toward fully monolithic solid-state lasers.

Hybrid zero-voltage switching (ZVS) control for power inverters

DOEpatents

Amirahmadi, Ahmadreza; Hu, Haibing; Batarseh, Issa

2016-11-01

A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM generation circuitry. The predictive control block is coupled to receive a measure of Vin and an output voltage at a grid connection point. A memory stores a current control algorithm configured for resetting a PWM period for a switching signal applied to control nodes of the first and second power switch whenever the inductor current reaches a predetermined upper limit or a predetermined lower limit.

Polarization-dependent coupling between a polarization-independent high-index-contrast subwavelength grating and waveguides

NASA Astrophysics Data System (ADS)

Katayama, Takeo; Ito, Jun; Kawaguchi, Hitoshi

2016-07-01

We investigated the optical coupling between a polarization-independent high-index-contrast subwavelength grating (HCG) and two orthogonal in-plane waveguides. We fabricated the HCG with waveguides on a silicon-on-insulator substrate and demonstrated that a waveguide with a strong output is switched by changing the polarization of light injected into the HCG. The light coupled more strongly to the waveguide in the direction perpendicular to the polarization of the incident light than to that in the parallel direction. If this waveguide-coupled HCG is incorporated into a polarization bistable vertical-cavity surface-emitting laser (VCSEL), the output waveguide can be switched by changing the lasing polarization of the VCSEL.

Statics and dynamics of electrothermal micromirrors

NASA Astrophysics Data System (ADS)

Morrison, Jessica A.

Adaptive and smart systems are growing in popularity as we shift toward personalization as a culture. With progressive demands on energy efficiency, it is increasingly important to focus on the utilization of energy in a novel way. This thesis investigates a microelectromechanical system (MEMS) mirror with the express intent to provide flexibility in solid state lighting (SSL). By coupling the micromirror to an optical source, the reflected light may be reshaped and directed so as to optimize the overall illumination profile. In addition, the light may be redirected in order to provide improved signal strength in visible light communications (VLC) with negligible impact on energy demands. With flexibility and full analog control in mind, the design of a fully integrated tip-tilt-piston micromirror with an additional variable focus degree of freedom is outlined. Electrothermal actuators are used to both steer the light and tune the focal length. A detailed discussion of the underlying physics behind composite beams and thermal actuators is addressed. This leads directly into an overview of the two main mirror components, namely the segmented mirror and the deflection actuators. An in-depth characterization of the dynamics of the mirror is discussed including the linearity of the thermal response. Frequency domain analysis of such a system provides insight into tunable mechanical properties such as the resonant frequency and quality factor. The degenerate resonant modes can be separated significantly. It is shown that the frequency response may be tuned by straining specific actuators and that it follows a predictable pattern. As a result, the system can be scanned at increasingly large angles. In other words, coupled mechanical modes allow variable damping and amplification. A means to determine the level of coupling is examined and the mode shape variations are tracked as a function of the tuning parameters. Finally, the applications of such a device are explored and tested. Such applications include reliable signal-to-noise ratio (SNR) enhancements in VLC of 30 dB and color tunable steerable lights using laser diodes. A brief discussion of the implications of dynamic illumination and tunable systems is juxtaposed with an explanation behind the integration of an electrothermal micromirror and an all digital driver.

Radially polarized passively mode-locked thin-disk laser oscillator emitting sub-picosecond pulses with an average output power exceeding the 100 W level.

PubMed

Beirow, Frieder; Eckerle, Michael; Dannecker, Benjamin; Dietrich, Tom; Ahmed, Marwan Abdou; Graf, Thomas

2018-02-19

We report on a high-power passively mode-locked radially polarized Yb:YAG thin-disk oscillator providing 125 W of average output power. To the best of our knowledge, this is the highest average power ever reported from a mode-locked radially polarized oscillator without subsequent amplification stages. Mode-locking was achieved by implementing a SESAM as the cavity end mirror and the radial polarization of the LG* 01 mode was obtained by means of a circular Grating Waveguide Output Coupler. The repetition rate was 78 MHz. A pulse duration of 0.97 ps and a spectral bandwidth of 1.4 nm (FWHM) were measured at the maximum output power. This corresponds to a pulse energy of 1.6 µJ and a pulse peak power of 1.45 MW. A high degree of radial polarization of 97.3 ± 1% and an M 2 -value of 2.16 which is close to the theoretical value for the LG* 01 doughnut mode were measured.

Compact pulsed high-energy Er:glass laser

NASA Astrophysics Data System (ADS)

Wan, Peng; Liu, Jian

2012-03-01

Bulk Erbium-doped lasers are widely used for long-distance telemetry and ranging. In some applications such as coherent Doppler radars, laser outputs with a relatively long pulse width, good beam profile and pulse shape are required. High energy Q-switched Er:glass lasers were demonstrated by use of electro-optic (E/O) Q-switching or frustrated total internal reflection (FTIR) Q-switching. However, the output pulse durations in these lasers were fixed to relatively small values and extremely hard to tune. We report here on developing a novel and compact Q-switched Er:Yb co-doped phosphate glass laser at an eye-safe wavelength of 1.5 μm. A rotating mirror was used as a Q-switch. Co-linear pump scheme was used to maintain a good output beam profile. Near-perfect Gaussian temporal shape was obtained in our experiment. By changing motor rotation speed, pulse duration was tunable and up to 240 ns was achieved. In our preliminary experiment, output pulse energies of 44 mJ and 4.5 mJ were obtained in free-running and Q-switched operation modes respectively.

Remote adjustable focus Raman spectroscopy probe

DOEpatents

Schmucker, John E.; Blasi, Raymond J.; Archer, William B.

1999-01-01

A remote adjustable focus Raman spectroscopy probe allows for analyzing Raman scattered light from a point of interest external probe. An environmental barrier including at least one window separates the probe from the point of interest. An optical tube is disposed adjacent to the environmental barrier and includes a long working length compound lens objective next to the window. A beam splitter and a mirror are at the other end. A mechanical means is used to translated the prove body in the X, Y, and Z directions resulting in a variable focus optical apparatus. Laser light is reflected by the beam splitter and directed toward the compound lens objective, then through the window and focused on the point of interest. Raman scattered light is then collected by the compound lens objective and directed through the beam splitter to a mirror. A device for analyzing the light, such as a monochrometer, is coupled to the mirror.

Do you mean me? Communicative intentions recruit the mirror and the mentalizing system

PubMed Central

Becchio, Cristina; Colle, Livia; Bara, Bruno G.; Walter, Henrik

2014-01-01

Being able to comprehend communicative intentions and to recognize whether such intentions are directed toward us or not is extremely important in social interaction. Two brain systems, the mentalizing and the mirror neuron system, have been proposed to underlie intention recognition. However, little is still known about how the systems cooperate within the process of communicative intention understanding and to what degree they respond to self-directed and other-directed stimuli. To investigate the role of the mentalizing and the mirror neuron system, we used functional magnetic resonance imaging with four types of action sequence: communicative and private intentions as well as other-directed and self-directed intentions. Categorical and functional connectivity analyses showed that both systems contribute to the encoding of communicative intentions and that both systems are significantly stronger activated and more strongly coupled in self-directed communicative actions. PMID:23620602

Intrinsic cavity QED and emergent quasinormal modes for a single photon

NASA Astrophysics Data System (ADS)

Dong, H.; Gong, Z. R.; Ian, H.; Zhou, Lan; Sun, C. P.

2009-06-01

We propose a special cavity design that is constructed by terminating a one-dimensional waveguide with a perfect mirror at one end and doping a two-level atom at the other. We show that this atom plays the intrinsic role of a semitransparent mirror for single-photon transports such that quasinormal modes emerge spontaneously in the cavity system. This atomic mirror has its reflection coefficient tunable through its level spacing and its coupling to the cavity field, for which the cavity system can be regarded as a two-end resonator with a continuously tunable leakage. The overall investigation predicts the existence of quasibound states in the waveguide continuum. Solid-state implementations based on a dc-superconducting quantum interference device circuit and a defected line resonator embedded in a photonic crystal are illustrated to show the experimental accessibility of the generic model.

Enhancing nanoparticle electrodynamics with gold nanoplate mirrors.

PubMed

Yan, Zijie; Bao, Ying; Manna, Uttam; Shah, Raman A; Scherer, Norbert F

2014-05-14

Mirrors and optical cavities can modify and enhance matter-radiation interactions. Here we report that chemically synthesized Au nanoplates can serve as micrometer-size mirrors that enhance electrodynamic interactions. Because of their plasmonic properties, the Au nanoplates enhance the brightness of scattered light from Ag nanoparticles near the nanoplate surface in dark-field microscopy. More importantly, enhanced optical trapping and optical binding of Ag nanoparticles are demonstrated in interferometric optical traps created from a single laser beam and its reflection from individual Au nanoplates. The enhancement of the interparticle force constant is ≈20-fold more than expected from the increased intensity due to standing wave interference. We show that the additional stability for optical binding arises from the restricted axial thermal motion of the nanoparticles that couples to and reduces the fluctuations in the lateral plane. This new mechanism greatly advances the photonic synthesis of ultrastable nanoparticle arrays and investigation of their properties.