bluuebunny/crossref_metadata_2025 huggingface dataset:
Noise Effects in Crossed Beam C n 2 Estimation
Authors: Tyler Glenn A.
Published: February 2023

Although crossed beam

C
n
2

measurement techniques have been used in the past it has generally been known that they are quite sensitive to measurement noise.1,2 Recently a matrix formulation of this concept has been implemented to develop a least-squares estimator for the unknown

C
n
2

-profile. This newly developed estimator is applicable to scintillation measurements, wavefront gradient measurements or a combination of the two and provides the best estimate in the presence of noise.
Finite-outer-scale Zernike polynomial phase screen generator
Authors: Tyson Robert K.
Published: February 2023

A digital representation of the optical path differences of the atmosphere is useful in modeling and analysis of imaging and propagation system. Commonly called phase screens, these models must accurately represent the conditions of the atmosphere as represented by the turbulence spectra. That is, the digital realizations must have spatial statistics that follow the accepted theories of Kolmogorov and Von Karman.
Observation of Doubly Scattered Coherent Waves Through Ground Induced Turbulence
Authors: Holbert Eirik , Rafert Bruce
Published: February 2023

Building upon the work of Phillips, et al. (1990) and Eric Jakeman (1987), a simple experimental apparatus has been developed and consists of various lasers, a 60 cm beam expander/director designated T1, and a 1220 m target board outfitted with reflectors at the Malabar Test Facility, Phillips Lab OL-AG. Retroreflectors were used to ensure an exact path reversal through the intervening turbulence due solely to temperature differentials at the ground- air interface. This apparatus produces a doubly forward scattered coherent wave. Observation along the twice travelled beam path using a beam splitter and a simple refracting telescope, laser line filter, and video camera produced a basic gaussian profile with a 3db enhancement peak due to stong turbulence.
An experiment to investigate the isoplanatic angle of the atmosphere in the near infrared
Authors: Neal Daniel R. , Michie Robert B. , Drummond Jack , McCarthy Don , Christou Julian , McKechnie T. Stewart
Published: February 2023

Recently there has been considerable discussion of the properties of atmospheric turbulence. The size of the outer scale (L0), and the scaling of the isoplanatic angle with wavelength have been questioned[1]. In order to address these questions, we conducted an experiment to make correlation measurements of the intensities in widely separated binary stars (~ 30 arc sec) as a function of separation.
All-Optical Image Compensation for Atmospheric Turbulence
Authors: Kramer Mark A. , Martinez Ty , Alley Thomas G.
Published: February 2023

The development of optically addressed spatial light modulators (OASLM) has allowed real-time application of holographic imaging techniques [1,2]. The low write intensities of OASLM's make them ideal candidates for real-time holographic elements. In the all-optical system presented in this paper, the duties of the wavefront sensor, computer, and deformable mirror of a conventional adaptive optical system are all accomplished by the OASLM. A reference wavefront is sent through the atmosphere and aquires a wavefront distortion due to the atmospheric optical turbulence. This atmospheric reference is then interfered with a coherent local reference. The image that is to be corrected is then reflected off the read-side of the OASLM. The first -order diffracted image will have the phase distortion that is present on the aberrated reference removed from it.
Large-Aperture Telescope Compensation Using A Membrane Light Modulator: A Single-Pixel Demonstration
Authors: Mitchell P. V. , Gaeta C.J. , White J.O. , O'Meara T.R. , Brown W.P. , Pepper D.M. , Schiller C.M. , Horsky T.N. , Warde C.
Published: February 2023

The use of large-aperture telescopes for various ground-based and space-based applications demands high-quality imaging capabilities. In many cases, the cost and complexity of such optical systems is prohibitive. Innovative adaptive optics using a membrane light modulator (MLM) offers the potential of providing high-quality real-time compensation of large-aperture telescopes with relatively inexpensive components. A particular spatial light modulator (SLM) — the charge-transfer membrane light modulator (CTMLM) — is chosen over other devices because of its potential to function as a compact, rugged, corrector element, providing a large number of pixels with reasonable dynamic range and response time. This choice of device was motivated by our previous studies and experiments using other SLMs, including liquid crystal light valves. A typical MLM1 consists of a large array of highly reflective deformable membrane pixels formed on the surface of a charge transfer plate (CTP). The pixels can be driven electrostatically by direct hard-wire contacting, via electron-beam addressing, as well as by optical addressing. These devices1 were originally developed for display systems and optical data processing networks. We exploit the fact that the membrane can impose a phase shift onto a pixelized input beam, thereby controlling its optical wavefront.
Adaptive Optics for the ESO Very Large Telescope
Authors: Merkle Fritz , Hubin Norbert
Published: February 2023

Adaptive optics is one of the main features of the Very Large Telescope (VLT) of the European Southern Observatory (ESO). The VLT consists of an array of four 8 meter telescopes arranged in a quadrilateral configuration (see Figure 1). These four telescopes can be operated individually, in a so-called incoherent combined mode (mainly for high resolution spectroscopy), and in a coherently combined mode as a long baseline interferometer to achieve highest spatial resolution in the milliarcsecond range. In order to increase the performance and flexibility in use of the VLT in the interferometric mode, two to four mobile telescopes of the two meter class will be added to the array. Each telescope will be equipped with adaptive optics systems for real-time correction of atmospheric turbulence effects.
An Artificial Intelligence system for a smart control of an Adaptive Optics Common User Instrument
Authors: Demailly L. , Gendron E.
Published: February 2023

An upgrade of the COME-ON+ VLT adaptive optics prototype project is currently under study : an Adaptive Optics Common User Instrument for the ESO 3.6m telescope. To allow an efficient use as a common user instrument, a new human interface and control system, including an improved modal optimization of the control, is being designed and is presented.
The Come-On-Plus Project
Authors: Rousset G. , Madec P-Y. , Beuzit J-L. , Cuby J-G. , Gigan P. , Lena P. , Rigaut F. , Boyer C. , Gaffard J-P. , Richard J-C. , Vittot M. , Gendron E. , Hubin N. , Merkle F.
Published: February 2023

The Come-On-Plus system described in this paper is an upgraded version of the VLT adaptive optics1 prototype system Come-On2. It will be set up on the ESO 3.6m telescope during summer of 1992. The project is a collaboration between ONERA, Observatoire de Paris, Laserdot, LEP and ESO. The modifications will enhance the performance of the previous instrument3 • a better correction capability of the mirror: the previous 19 actuator deformable mirror will be replaced by a 52 actuator deformable mirror, • a better detectivity of the wavefront sensor (WFS) for very faint reference sources, • an additional wavefront sensor for bright reference sources, • an extended bandwidth of the servo loop: the wavefront sensor 400 Hz sampling rate will allow to extend the correction bandwidth to 30 Hz (compared to 9 Hz for the current system), • a new control algorithm applying mode selection dedicated to astronomical applications.
Results of the COME-ON experiment
Authors: Rigaut F. , Léna P. , Madec P.Y. , Rousset G. , Gendron E. , Merkle F.
Published: February 2023

The last results obtained with the adaptive optics (AO) system COME-ON are reported here. A new set-up, pushing the servo-loop bandwidth up to 25 Hz, allowed to get diffraction limited long exposure images down to 1.7 μm on a 3.6-m telescope (i.e. 96 milliarcsec). Compared with the turbulent case, gains in Strehl ratio

(
S
)

up to 13 are reported. Profile of partially corrected images are shown, which confirm partly the predicted profiles. These results are based on data collected at the ESO 3.6-m telescope, La Silla, Chile, on April 1991.
Polarization Interferometry For Segmented Mirror Phasing
Authors: Blum J. D. , Sebring T. A.
Published: February 2023

This paper documents the design, construction and testing of a polarization interferometry based device for measuring the relative axial positioning of the individual segments of a multi-segment optical system. The device was designed to operate from an off-axis position in order to leave the central portion of the focal plane free for other sensors. The device was constructed and tested and shown to provide resolution of better than 2 nanometers. The concepts embodied in the device could be applied to nearly all segmented aperture phasing tasks.
Determination of Thermally Induced Bending of Spacecraft Booms by Exploitation of Adaptive Optics Images - The HST Solar Arrays
Authors: Kissell Kenneth. E. , Lambert John V. , Atricano John
Published: February 2023

The Hubble Space Telescope uses four novel flexible roll-up solar arrays, extended and supported by an adaptation of the Dehaviland (SPAR of Canada) spring-metal boom, for electric power. The hollow booms endure large solar-induced thermal flexures due to differential solar heating which can be balanced only by conduction during eclipse. By exploiting adaptive optics images, such as from the AMOS CIS, one can resolve virtual solar images (glints) on the cylindrical booms whose positions along the boom will shift with the observer-spacecraft-sun position angles while the attitude of the boom remains fixed in inertial space when the HST is observing some celestial target.
A Two-Wavelength, Simultaneous Phase Shifting Interferometer For Phasing and Figure Control of Segmented Mirrors
Authors: Kendrick Richard L.
Published: February 2023

Lockheed has developed a two-wavelength, simultaneous phase shifting interferometer that is being used as a truth sensor in the Eastman Kodak Active Optics System Demonstration (AOSD). The AOSD test bed consists of a 2.6 meter segmented primary mirror with a static center piece and 6 active petals of which one is currently in place. The petal surface is deformable as well as adjustable in tilt and piston. The Lockheed interferometer is being used to measure tilt, piston and surface figure for comparison with other instruments in the AOSD.
Performance of a Large Reaction Compensated Fast Steering Mirror
Authors: Kaplan David L.
Published: February 2023

In this paper, the performance of a Fast Steering Mirror (FSM) is measured and compared to the predictions of a simple set of coupled differential equations. The FSM has a 24-cm diameter optical element, is capable of ±3 mrad angular motion, and uses a reaction mass to cancel torques arising from the mirror motion that would otherwise couple into an optical bench. Local position sensors provide feedback for closed-loop control. Quantities such as angular stroke versus input signal, mechanical assembly frequency response, power consumption versus frequency and effective resistance and inductance as a function of frequency are presented and compared to the theoretical predictions. Reaction attenuation characteristics are covered in some detail. In addition, control system measurements (open loop response, closed loop response, and error attenuation) are given and compared to expectations. Very good agreement between theoretical predictions and experimental results were achieved in most areas.
Active Optical System Demonstration
Authors: Crowe David A.
Published: February 2023

The need for ultra-lightweight high precision optical systems to satisfy spaceborne scenarios such as the Strategic Defense Initiative, tactical weapons, and other military-related activities has driven technology evolution to meet these new stressing requirements. The key areas of technology pursuits are Optics, Structures, Sensors, and Control Systems.
Development of an uncooled deformable mirror suitable for correction of atmospheric turbulence
Authors: Lillard Robert L. , Stopher Ronald W.
Published: February 2023

An overview of the design, construction, and performance testing of a small scale, uncooled, Deformable Mirror (DM) is presented. The design approach was to produce a DM which represents a low cost, high reliability device with small signal bandwidths of greater than 1 kHz, full power bandwidth greater than 100 Hz, and 4 pm of mirror surface motion (stroke). The mirror incorporates 21 actuators arranged in a 5 × 5 square array on 1 cm center-to-center spacings. Each actuator is individually addressable to provide 21 discrete correction subapertures. The mirror is constructed from conventional optical materials in a simple configuration designed to minimize manufacturing and assembly costs. Test data will be presented which indicates that all of the key design goals have been met or surpassed. A scaled version of this DM with similar temporal (stroke and bandwidth) and spatial (actuator spacing and number) characteristics would be suitable for correction of atmospheric turbulence on moderate aperture (2-4 meter) telescopes. Potential applications of this technology include ground based astronomy, ground-based surveillance and tracking, ground to space optical communication, and low power laser beam clean-up.
History of the AMOS 1.6m Telescope Compensated Imaging System
Authors: Albetski John P.
Published: February 2023

The AMOS Compensated Imaging System (CIS) was developed during the mid and late 1970’s by the Defense Advanced Research Projects Agency. Upon installation on the AMOS 1.6 meter telescope in March of 1982 it became the first compensated imaging system to be used on a large aperture telescope. Today the CIS continues to operate as a primary AMOS sensor system and is used to collect imagery of space objects on a nightly basis. Now that many large aperture astronomical telescopes are being equipped with adaptive optics, it is appropriate that we review the design of and experience with this system and the lessons learned from its operation over a period of more than ten years.
Atmospheric Turbulence Compensation Using Self-Referenced Binary Holographic Interferometry
Authors: Ma S. , Guthals D. , Hu P. , Campbell B.
Published: February 2023

Analysis of a technique to perform atmospheric compensation of ground-based telescopes using self-referenced interferometry with a binary holographic recording media will be presented.
High-power femtosecond Yb:YAG laser based on a power-scalable concept
Authors: Spühler G. J. , Au J. Aus der , Paschotta R. , Keller U. , Moser M. , Erhard S. , Karszewski M. , Giesen A.
Published: February 2023

We demonstrate a power-scalable concept for femtosecond lasers with very high average powers. It is based on a thin disk Yb:YAG laser [1], passively mode-locked with a semiconductor saturable absorber mirror (SESAM) [2, 3]. In a first step, we obtained 16.2 W of average power in pulses with 730 fs duration, 0.47 μJ energy, and 560 kW peak power (Fig. 1). This is to our knowledge the highest average power reported for a laser oscillator in the sub­picosecond regime, and we expect even significantly higher powers to be possible in the near future. The repetition rate is 34.6 MHz and the beam quality is close to diffraction-limited (M2 < 1.5). Such lasers are interesting for numerous applications, e.g. for synchronously pumping high-power optical parametrical oscillators in RGB laser displays.
Continuous wave and Q-switched operation of diode pumped quasi-three level Nd:YLF lasers
Authors: Spiekermann S. , Laurell F.
Published: February 2023

We present continuous wave Nd:YLF lasers operating at 908 and 903 nm as well as Q-switched operation at 908 nm.
32 fs KTP Optical Parametric Oscillator with Chirped Mirrors
Authors: Zhang X. P. , Giessen H. , Hebling J. , Rühle W.W. , Kuhl J.
Published: February 2023

We obtained 32 fs pulses at 1180 nm with a spectral FWHM of 53 nm and a repetition rate of 80 MHz from an optical parametric oscillator with chirped mirrors that was pumped by a modelocked Ti:Sapphire laser.
First OPO based on a cylindrical nonlinear optical crystal
Authors: Pacaud Olivier , Boulanger Benoît , Fève Jean-Philippe , Ménaert Bertrand
Published: February 2023

We demonstrate the first OPO based on a 21.2mm-diameter cylindrical KTP crystal. We obtain a signal wavelength tuning between 1570nm and 1647nm corresponding to an angular tuning of 20.5° with a 1064nm pump.
Simultaneous and Successive Chromatic Contrast Effects: New Findings and Elaboration of the Opponent Model
Authors: Laxar Kevin , Wooten B. R.
Published: February 2023

Most experimental results indicate that simultaneous and successive chromatic (hue) contrast produce similar effects, and most models assume generally similar underlying neural processes (e.g., Wooten, 1970/1971). Methodology has often confounded the two effects, however. The present study shows that for some conditions, simultaneous hue contrast yields different results than successive hue contrast, providing evidence of different neural processes.
The Abney, Tyndall, Guth and Moeller effects explained by B-cone input to the r-g channel
Authors: Ingling Carl R. , Grigsby Scott S. , Billock Vincent A.
Published: February 2023

Four odd effects occur when violet lights are desaturated. They turn unaccountably red (Abney effect); if the redness is assessed by an indirect method such as cancellation (which desaturates), they appear to have a latent redness some ten times greater than their apparent redness (Moeller effect); they become much brighter than can be explained by the addition of the desaturant (Guth effect); and they become more, not less, discriminable (Tyndall effect).
Influence Theory for Retinex Models
Authors: Stine Wm Wren , Sparrow John E.
Published: February 2023

The color constancy problem is one of calculating reflectance values for surfaces under differing illuminants. Retinex theory (e.g., Land, 1986) states that relative receptor responses are used to recover surface reflectance after they have been normalized with respect to the responses of neighboring receptor responses. Specifically, a number of paths to the pixel in question are randomly chosen and the logarithm of the ratio of the pixel receptor's response to the geometric mean of the receptor responses over a large number of paths is used as the lightness value for the pixel in question. Symbolically (1) where r(x,k) is the response of receptor x (to pixel x) of class k (where k is either the short wavelength, medium wavelength, or long wavelength cone), G(p,k) is the geometric mean of all of the receptor responses of class k covered by the random paths p, and l(x,k) is the resulting lightness value for receptor x (to pixel x) of class k. By normalizing the lightness value to the geometric mean of the neighboring receptor responses the change of the lightness value in response to overall spectral changes in illumination is minimized.
Spatial and Chromatic Parameters of Simultaneous Contrast
Authors: Blackwell K. Tiplitz , Buchsbaum G.
Published: February 2023

Simultaneous contrast is the change in the perceived color of a visual field caused by surrounding fields. In general, the size, location and color of the surrounding fields influence the perceived color of the center. We report results which illustrate that the effect of the surround on the center decreases exponentially as a function of distance from center to surround and increases exponentially as a function of surround size. In addition, the effect of surround color on the perception of the center suggests that simultaneous contrast may result from the visual system trying to remove that portion of the color signal which is common to both center and surround.
Linear Model Algorithms for Color Correction
Authors: Maloney Laurence T.
Published: February 2023

Human and machine visual sensing is enhanced when information about the surface properties of objects in a scene, including their intrinsic colors, can be reliably estimated despite changes in the ambient lighting conditions, and the presence of other objects in the scene.
High Resolution "Paint by Number"
Authors: Thornton Jay , Burkhardt Jim , Donovan Bill , McCann John
Published: February 2023

In working with high resolution (eg. 3000x3000 pixels) digital images, hard copy is often a difficult step. In this laboratory, we use a film recorder which writes a high resolution image raster directly onto Polaroid instant color print film. Since our digital images often represent computed responses from a psychophysical color model, we are concerned that the color in the print be controlled as precisely as possible. This concern has led to the development of a special purpose color computer which resides in the film recorder and transforms the input image pixel values into those output exposure control values necessary to attain the desired color on film. This color transformation is done on the fly without slowing down the printing of the image.
Colorimetric Calibration of a Video Digitizing System: Algorithm and Applications
Authors: Lee Raymond L.
Published: February 2023

Obtaining accurate colorimetric information about color samples may seem to be a hopeless task unless we have access to elaborate spectroradiometers and sophisticated illumination standards. However, it is possible to obtain very good estimates of chromaticity values even if we use broad-band devices such as color video cameras, provided that we have a reliable way of estimating their color and luminance biases.
Resonantly-pumped 459nm Sum-frequency Upconversion Laser
Authors: Kean P N , Dixon G J
Published: February 2023

Nonlinear frequency conversion of laser diodes and diode-pumped solid-state lasers provides potential sources of coherent laser radiation in the blue spectral region. Two efficient methods based on nonlinear frequency conversion are the direct doubling of laser diodes and intracavity doubling of the 946nm transition of Nd:YAG. Both of these methods however, require the use of Potassium Niobate. Although this crystal has a relatively large nonlinear coefficient, it is difficult to polish and depoles into multiple ferroelectric domains under slight stress or excessive temperature cycling. Reorientation of the domains lowers the effective crystal nonlinearity and produces domain walls which appear as 'cracks' within the bulk medium. These properties may well limit the application of KNbO3 in commercial devices.
Second Harmonic Generation in Quasi-Phase-Matching Waveguides
Authors: Arvidsson Gunnar
Published: February 2023

Use of integrated optical waveguides is advantageous for frequency conversion of light from low-power lasers. The light can be confined to a very small cross section area for a comparatively long distance so that high conversion efficiencies can be obtained with pump sources such as laser diodes and laser diode pumped solid state lasers.
Efficient Direct Diode Laser Frequency Doubling in Quasi-Phase Matched LiNbO3 Waveguide
Authors: Cao Xiaofan , Ramaswamy Ramu V. , Srivastava Ramakant
Published: February 2023

We report efficient (22%/W) blue light generation by direct diode laser frequency doubling in second order quasi-phase matched LiNbO3 channel waveguides.
Blue-green light generation from a neodymium fiber laser
Authors: Buritskii K.S. , Gapontsev V.P. , Dianov E.M. , Maslov V.A. , Samartsev I.E. , Chernykh V.A. , Shcherbakov E.A.
Published: February 2023

Much interest has been attracted recently to the problem of design compact blue-green light sources. Most the activity is concentrated around the frequency doubling of semiconductor lasers with the wavelengths of 0.8-0.9 μm. On the other hand rare-earth doped fiber lasers are an interesting alternative to diode lasers due to their tunability, high quality output beam etc [1]. Such lasers are compatible with channel KTP-waveguides [2] which are very promising for the nonlinear frequency conversion from the near-IR to green and blue. The phase-matched type II interaction or quasi- phase-matched type I interaction can be used depending on the fundamental wavelength [3].
Lasers in Flow Cytometry and Biotechnology
Authors: Sklar Larry A.
Published: February 2023

Lasers are used by the biomedical community in many applications. These include flow cytometry, microscope imaging, solution spectroscopy, and very recently, optical manipulation of cells and subcellular particles. This paper reviews applications of lasers involving fluorescent probes. In most applications, these technologies require ~10 mW of laser power focused to cellular dimension (except for the solution measurements). I estimate that there are several thousand flow cytometers, several hundred laser imaging systems, and several hundred laser spectroscopy instruments distributed between the biomedical, physics and chemistry communities. Optical trapping as a commercial technology is emerging rapidly at the time this paper is being written using IR diode lasers to manipulate the cells.
Visible Upconversion Fiber Lasers
Authors: Tropper A C
Published: February 2023

Over the past two years several upconversion-pumped visible laser systems based on lanthanide-doped fluorozirconate glass fibre have been reported[1-5], illustrating the great potential of this medium for efficient infrared to visible conversion. Confinement of pump radiation in a small core fiber lead to rapid multiple step pumping of high-lying metastable energy levels for fairly modest levels of pump power. Compared to silica fibers the low vibrational energies of the heavy metal fluoride glass matrix leads to a greatly reduced competition to optical pumping and emission processes from nonradiative decay. A further advantage relative to silica is the narrowness of the absorption and fluorescence bands giving higher peak cross-sections and less likelihood of unwanted excited state absorption(ESA). Fluoride fibre fabrication technology has now reached a point at which small core fibres (i.e. monomode in the visible) with scattering losses down to ~ 0.2dBm−1 can be made, so that the remarkable properties of the fluoride glass host can be embodied in efficient compact devices.
Bulk Crystal Upconversion Lasers
Authors: Krupke William F.
Published: February 2023

Recent advances in high-power, high-efficiency semiconductor laser diodes and diode arrays has revived interest in the identification and development of practical upconversion lasers (for which the output laser wavelength is shorter than the wavelength(s) of the optical pump(s)). It is hoped that upconversion lasers will compete favorably with alternative approaches, such as wavelength shifting of laser diode radiation using nonlinear processes, to perform commercial applications, such as the production of full color images using laser-based tri-stimulus sources. For upconversion laser action to occur, the energy carried by two or more pump photons must be accumulated in the upper laser level of the gain medium. In most general terms, this accumulation of pump energy occurs by the successive absorption of pump photons via intra-ion radiative transitions, by the summation of absorbed pump photon energy via ion-ion interactions, or by combinations of both. To compete favorably with nonlinear wavelength shifting devices, practical upconversion lasers will have to operate at room temperature, and with conversion efficiencies of pump energy to laser output that match or exceed those of nonlinear conversion-based devices.
Versatile Blue-Green Laser Diodes and LEDs in ZnSe-based Quantum Wells
Authors: Jeon H. , Ding J. , Nurmikko A.V. , Xie W. , Grillo D. , Kobayashi M. , Gunshor R.L.
Published: February 2023

The culmination in the development of wide bandgap II-VI compound semiconductors towards light emitting applications in the blue-green has been the recent demonstration of diode laser action by the 3M group [1] and the Brown-Purdue team [2]. In this paper we show different variations in the heterostructure design to produce high power, high efficiency laser action, which is especially clear at low temperatures. Our system is based on the (Zn,Cd)Se/ZnSe or (Zn,Cd)Se/Zn(S,Se) QWs the former of which had earlier been shown by us to show good electronic confinement [3], enhanced excitonic effects [4], and good optically pumped laser action, including cw operation at T=77K [5].
Large Second-Order Nonlinearity in Poled Fused Silica*
Authors: Myers R. A. , Mukherjee N. , Brueck S. R. J.
Published: February 2023

Fused silica is ubiquitous in modern technology, playing an essential enabling role in both optoelectronics and microelectronics. Fused silica is amorphous with a macroscopic inversion symmetry that forbids second harmonic generation (SHG). Thus the discovery by Österberg et. al. [1] of efficient SHG in glass fibers upon "training" with optical fields has generated considerable in terest.
Novel Organic Nonlinear Optical Materials for SHG Devices of Semiconductor Lasers
Authors: Itoh Yuzo , Imanishi Yasuo , Sagawa Masakazu , Kagawa Hiroyuki , Hamada Tomoyuki , Kakuta Atsushi
Published: February 2023

In order to apply organic nonlinear optical materials to the SHG devices for semiconductor lasers, cut-off wavelength of the materials should be shorter than around 400 nm since the wavelength of commonly used semiconductor lasers is about 800 nm. Unfortunately, in the case of organic materials, enlargement of nonlinearity(hyperpolarizability) and shortening of the cut-off wavelength are the tradeoff relations. To develop novel organic nonlinear optical materials both with large nonlinearity and short cut-off wavelength, we used a molecular design method and chose heteroconjugate molecules as target materials.
Two-dimensional modal analysis of blue-green lasers using ZnSe based p-n and metal-insulator-semiconductor (MIS) heterostructures
Authors: Chung C. , Jain F.
Published: February 2023

The wide energy gap II-VI compounds semiconductors, such as ZnSe, ZnS, MnSe, CdSe, and their ternary and quaternary alloys, are particularly suitable for the realization of short wavelength optoelectronic devices. These materials have been found to exhibit excellent luminescent properties as demonstrated by photoluminescent spectra [1] and the successful operation of photopumped lasers [2]. Recently, Haase et al[3] reported p-n heterojunction injection laser operating at cryogenic temperatures. Currently, several research groups are investigating p-type doping of ZnSe using MBE, MOCVD and CBE growth techniques. However, compensation at high nitrogen level (>1018 cm-3) still remains a problem[4]. While the effort in optimizing p-n heterojunctions to obtain room temperature lasers is being pursued intensely, an alternate approach is the use of MIS structures to obtain injection luminescence[5,6]. This paper discusses modal analysis of p-n double heterojunction and MIS laser heterostructures. In particular, ZnSe-ZnSSe, ZnSe-ZnCdSe structures are analyzed. Numerical computations of field intensities, confinement factors r and the threshold current densities JTH are presented. Experimental data of luminescence spectra in Au-SiO2-ZnSe MIS devices is also presented.
Quasi-phasematched waveguides periodically poled by applying an external field for efficient SHG
Authors: Yamada M. , Nada N. , Saitoh M. , Watanabe K.
Published: February 2023

The realization of a compact and low cost blue coherent light source is essential for high-density optical data storage, laser printing, and color display applications. So far laser-diode-based second-harmonic-generation (SHG) devices seems to be the most convenient way of making a violet or blue light sources. The conversion efficiency of quasi-phasematching (QPM) SHG is highest when the periodic reversal of the sign of the nonlinear coefficient d of the material occurs in the phasematching period[1]. The QPM-SHG allows the use of any component of the nonlinear susceptibility tensor, and by selecting the period of the sign inversion of the d coefficient, light with arbitrary wavelengths within the transparency range of the nonlinear materials can be generated. A high conversion efficiency QPM-SHG device has the following requirements: 1) it should be composed of materials with large nonlinear coefficients and good transparency, 2) its waveguide should have low loss with strong mode confinement, 3) a good overlap between the fundamental and the second harmonic field, and 4) the periodically inverted domain structure should be obtainable at any depth in the waveguide suitable for first order QPM. The last requirement, in particular, is most important for taking full advantage of the materials.
Phase-matched and Cerenkov-type second harmonic blue light generation in ion-implanted KnbO3 waveguides
Authors: Fluck D. , Günter P. , Fleuster M. , Buchal Ch.
Published: February 2023

Several approaches have been described for generating blue light by frequency doubling near infrared laser sources in nonlinear optical materials [1]. KnbO3 has been shown to have excellent nonlinear optical properties making it particularly attractive for nonlinear optics [2]. Thanks to its large nonlinear optical susceptibilities, its room-temperature phasematchibility between 860 nm and 980 nm by angle tuning, its transparency down to 390 nm, and its very high threshold to optical damage, KnbO3 proved to be one of the most promising materials for high-efficiency frequency doubling of near infrared laser radiation into the blue and green spectral range [3-5].
Fabrication of periodically inverted domain structures in LiTaO3 using proton exchange
Authors: Makio Satoshi , Nitanda Fumio , Ito Kohei , Sato Masayoshi
Published: February 2023

Optical storage and laser printer applications require a compact solid-state blue source to achieve greater versatility. One method to obtain this blue light is via Quasi phase matched (QPM) second harmonic generation (SHG).1,2 With QPM we are able to fabricate a high-efficiency blue light source. By inverting the spontaneous polarization with an appropriate period it is possible to phase match any arbitrary wavelength. Several methods have been used to fabricate periodic domain inversion in LiNbO3 and LiTaO3. Ti indiffusion3 or Li outdiffusion4 near the Curie temperature are well-known techniques to reverse the polarization in LiNbO3. Electron beam bombardment5,6,7 has also been employed to make "well"-shaped inverted domains. Periodically poled structures in LiTaO3 can be realized through selective proton exchange (PE) followed by heat treatment near the Curie temperature8. A few micron deep semi-circular shaped domains with a first-order period has been fabricated using proton exchange and a quick heat treatment near the Curie temperature, generating 15mW of blue light9.
Frequency Doubling of Laser Diode using Periodically Domain-inverted LiTaO3
Authors: Yamamoto K. , Mizuuchi K. , Kitaoka Y. , Kato M.
Published: February 2023

As compact, solid-state sources for blue coherent light, laser diode-based second harmonic generation (SHG) devices hold great potential for use in high-density optical disk and laser printer applications. In such applications, the primary concerns for the blue light sources are those of stability and high power generation over several milliwatts.
Cerenkov-type second harmonic generation in lossy slab waveguides
Authors: Kinoshita T. , Sasaki K. , Yokoh Y. , Ashitaka H. , Ogata N.
Published: February 2023

Poled polymer films have been extensively studied because of easy preparation and their potential for applications of nonlinear optical devices. In frequency doubling by optical waveguides Cerenkov-type phase matching is advantageous because it requires only loose specifications of film thickness and refractive indices in device designings.
GaN for short-wavelength light emitting devices: growth kinetics and techniques
Authors: Ross Jennifer , Newman Nathan , Rubin Mike
Published: February 2023

In the recent year, great steps have been achieved in the development of blue-green semiconductor diode lasers and LEDs, however material issues in the wide-bandgap semiconductors still limit practical device applications. The II-VI compounds ZnSe and ZnS and the III-V semiconductors GaN and AIN are the two material system being investigated for green to ultra- violet light emitting devices, with most research to date concentrating on the II-VI materials. Problems with electromigration, heating, and subsequent processing in early ZnSe/ZnS laser diodes has led many researchers to investigate the more robust material GaN for commercially viable short wavelength LEDs and laser diodes. GaN blue LEDs at room temperature have been demonstrated by Akasaki et al. [1], but p-type doping levels are not yet sufficiently high for laser diodes. The main obstacle in fabricating high quality GaN for device applications has been controlling background impurity and dopant concentrations during crystal growth and finding suitable substrates with closely matching lattice and thermal expansion coefficients. The dilemma in obtaining p-type conduction in GaN is hypothesized to be due to a large concentration of nitrogen vacancies[2] acting as shallow donors making compensation difficult. Aside from Akasaki's and Nakamura's work in Japan [1,13], all GaN material by any growth techniques has been n-type. Advances in the last few years, have produced undoped material with a reduced concentration using Metal Organic Chemical Vapor Deposition (MOCVD) (4x1016 cm-3) [3] and plasma/ion-assisted Molecular Beam Epitaxy (MBE) (8 x 1013 cm-3)[4].
Laser Induced Fluorescence Detection in Capillary Electrophoresis with a Blue Frequency Doubled Light Source
Authors: Laurell Fredrik , Jansson Mårten , Roeraade Johan
Published: February 2023

Capillary electrophoresis (CE) is a rapid and efficient separation technique for small volume samples, which has attracted much attention. Combined with laser induced fluorescence (LIF) detection, extraordinary sensitivity can be achieved. Lasers, emitting light in the visible as well and in the UV have been used in recent studies to detect biomolecules, e.g., amino acids, DNA1 or proteins2. Compared to classical electrophoresis, CE offers better possibilities for automated analysis where a compact and reliable detection unit is necessary. An all solid state laser for LIF would be the ideal light source. Compared to gas lasers, which have been employed, the solid state laser is more compact, stable and has a lower power consumption. Moreover, the reliability and the minimum maintenance requirement of a solid state laser would be an important advantage3. Frequency doubled diode lasers using quasi-phase matching (QPM) waveguides are interesting candidates as light sources for LIF, as the output wavelength could be chosen to match the absorption band of the fluorescing analyte. Also, sufficient power (in the order of mW) in the blue light region could be generated4.
Growth of ZnMgSSe and Fabrication of Blue Laser Diodes
Authors: Akimoto K. , Okuyama H. , Miyajima T. , Morinaga Y. , Hiei F. , Ozawa M.
Published: February 2023

For decades, wide gap II-VI semiconductors have been intensively studied for application to visible light emitting devices. Recently some research groups have fabricated laser diodes that emit blue-green light from a ZnCdSe/ZnSSe single and multi quantum well active layer.1 However, emission of genuinely blue light can not be obtained from these type of structures. When we use Zn(S)Se as an active layer material, blue light can be obtained. But there have not been candidates for a cladding layer material, that is lattice-matched to the substrate and has sufficient band-gap energy. In this paper, we firstly propose a new material, ZnMgSSe. This material meets the requirements of the cladding layer of Zn(S)Se for fabricating a blue laser diodes. Secondly, we report the successful CW operation of ZnSe/ZnMgSSe multi quantum well and double-heterostructure blue lasers at 77K for the first time.
Advances in II-VI Blue-Green Laser Diodes
Authors: Walker C.T. , DePuydt J.M. , Haase M.A. , Qiu J. , Cheng H.
Published: February 2023

Significant progress toward the development of viable blue and green II-VI laser diodes (LDs) was made since the initial demonstration of these devices in our laboratory nearly 2 years ago [1]. Lasing was obtained in the pulsed mode at room temperature [2] with threshold current densities less than 1000 A/cm2 and continuous wave devices have been operated at 80 K. It is also important to note that several other laboratories succeeded in confirming laser oscillation in related structures [4-10]. Some recent advances in II-VI laser diodes include the development of electrical contacts to p-type ZnSe with lower contact resistances, the growth of high quality lattice matched ternaries and the realization of increased efficiencies in CdXZn1−XSe quantum wells grown by atomic layer epitaxy.
An Organic Crystal 3,5-dimethyl-1-(4-nitrophenyl)pyrazole for Compact Visible Light-sources
Authors: Hyuga H. , Goto C. , Okazaki Y. , Harada A. , Mitsumoto S. , Kamiyama K. , Umegaki S.
Published: February 2023

The advent of blue-green IIVI semiconductor lasers is stimulating
the research activity in more efficient frequency-conversions of III-V
semiconductor-laser sources. In almost all cases of the conversions,
inorganic materials are being used. On the other hand, organic
materials have been developed and expected to give more efficiencies
in the conversions because of their higher figures of merit in
comparison with the inorganics.
Comparative experimental study of KTA and KTP for the SHG at 1.32 μm and 1.064 μm
Authors: Boulanger B. , Marnier G. , Fève J.P. , Ménaert B. , Cabirol X. , Bonnin C. , Villeval P.
Published: February 2023

We report the first experiment, to our knowledge, of type II phase-matching SHG at 1.32 pm in KTiOAsO4 (KTA) [1,2]. The phase-matching directions are measured in an orientated sphere of the studied crystal placed at the center of an Euler circle and illuminated by the focused beam at the fundamental wavelength [3]. The KTA and KTP crystals which we study are grown using a flux of alkali metal halide [4]. The crystals are cut in a sphere with a diameter of 2.45 mm for KTA and 5.12 mm for KTP. The spherical coordinates (θ, ϕ) of the phase-matching directions measured are given in figure 1.
Characterization for the Single-Mode-Operation of Diode-Pumped Nd:YVO4 Lasers for Intracavity Doubling
Authors: Tatsuno K. , Helmfrid S. , Andou T. , Miyai T.
Published: February 2023

Intracavity frequency doubling of diode-pumped Nd:YVO4
lasers is expected to be a promising approach for an optical source of
the future optical disk systems. In the previous paper, we have shown
ultra high storage density erasable magneto-optical recordings of HDTV
pictures played back by a stable compact green laser (CGL) consisting
of Nd:YVO4 and KTP. The conversion efficiency of the
CGL was up to 10% (50mW-diode laser to 5mW green output) due to large
emission cross section and absorption coefficient of the
Nd:YVO4 gain medium. In the CGL, single axial- and
polarization-mode operation is important to avoid fluctuations in the
green output power due to the nonlinear coupling between the
modes. To confirm a long term stability of the CGL, perturbations
in cavity parameters for the single-mode operation must be
considered.
Comparative spectroscopy of Ho3+ and Yb3+ in KYF4, BaY2F8, and YLiF4
Authors: Peale R. E. , Zhang X. X. , Bass M. , Chai B. H. T.
Published: February 2023

A recent comparison of Yb, Ho upconversion energy transfer in different fluoride crystals has been performed[1]. The purpose was to demonstrate the promise of Yb,Ho:KYF4 as a green upconversion laser as compared with similarly doped BaY2F8 (BYF) and YLiF4 (YLF). We compare here high resolution, low temperature absorption spectra for the three crystals and our determination of the energy levels.
Tunable blue light source by intracavity frequency doubling of a Cr-doped LiSAF laser
Authors: Balembois François , Georges Patrick , Salin François , Roger Gérard , Brun Alain
Published: February 2023

Compact solid state lasers emitting in the blue-green wavelength range are expected to be the key components for optical recording and underwater communications or as spectroscopic sources. To develop such lasers, several approaches are under study at numerous laboratories around the world. Possible solutions include up-conversion lasers [1,2], green or blue diode lasers [3], sum frequency mixing techniques [4] or frequency doubled near IR sources [5] that produce blue or green light at fixed wavelengths. Compact sources generating tunable blue light could be particularly useful for spectrosopic experiments. One possibility is an optical parametric oscillator pumped by the third harmonic of a YAG laser but this solution requires high peak power from the pump laser [6].
Radiative transition probabilities of trivalent rare-earth ions in LiYF4
Authors: Li C. , Guyot Y. , Linarès C. , Moncorgé R. , Joubert M. F.
Published: February 2023

Lithium yttrium fluoride (LiYR4) doped with different rare-earth ions has been the subject of several studies. Its IR laser applications are well known [1] and, as an upconversion laser, it is now the object of extensive investigations [2]. In particular, the exact knowledge of the values of the radiative probabilities of the intraconfigurational 4f transitions of the rare-earth ions in this crystal is always a matter of discussion [3, 4] and this is the reason why we try to clarify this point in this paper in the case of Nd3+, Er3+, Tm3+ and Ho3+ doped LiYF4.
Power and Spatial Characteristics of Electron-Beam-Pumped Semiconductor Laser Emitters Made by Different Technologies
Authors: Gurskii A. L. , Davydov S. V. , Lutsenko E. V. , Kulak I. I. , Mitcovets A. I. , Yablonskii G. P.
Published: February 2023

Recently [1] it was shown that the creation, by means of chemical etching [2], of certain microrelief on the anion surfaces of laser wafers instead a totally reflecting silver mirror permits increasing the output power of lasers based on CdSSe compounds by about one order of magnitude compared to the multicomponent emitters with the silver mirrors.
Fundamental Walk-Off Compensation in KTP
Authors: Nightingale J. L.
Published: February 2023

Intracavity-frequency-doubled, diode-pumped lasers are attractive sources of visible light. The best characterized materials for a diode-pumped, frequency-doubled system are Nd:YAG as the laser medium and KTP as the nonlinear medium. Since frequency doubling of a 1064 nm fundamental wavelength in KTP requires Type II phasematching, both fundamental polarization states must be excited to generate the second harmonic. Poynting vector walk-off between these fundamental polarization states can introduce resonator loss.1 By orienting the KTP at an oblique angle of incidence within the resonator and fabricating the KTP so that the phasematching condition is satisfied, this loss can be eliminated.
Second Harmonic Generation of a High Power Coherent Laser Diode
Authors: Waarts Robert , Parke Ross , Nam Derek , Welch David , Mehuys David , Hardy Amos , Lang Robert , O'Brien Steve , Scifres Don
Published: February 2023

Frequency doubling of laser diodes has been demonstrated in bulk crystals, bulk crystals in a resonant cavities as well as in periodically poled waveguides. The output power available from the frequency doubling schemes however, has been limited by the relatively low output powers available from laser diodes. Frequency doubling of laser light requires a high brightness diffraction limited input beam with single spectral mode. Coherent output power from a semiconductor laser has been limited for many years to 100-200 mW, However, recently over 1 Watt cw diffraction limited output power has been obtained from a monolithically integrated flared master oscillator power amplifier (MOPA)1.
Green laser diode pumped erbium fiber laser
Authors: Piehler David , Craven Dawn , Kwong Norman
Published: February 2023

Upconversion lasers based on rare-earth ion doped fluoride glass fibers are efficient, robust systems for converting infrared laser light into visible laser light [1].