bluuebunny/crossref_metadata_2025 huggingface dataset:
Cascading process in femtosecond regime and measurement of second order nonlinearity in nonlinear crystals
Authors: Rassoul R. Maleck , Ivanov A. , Cussal-Blanc S. , Freysz E. , Ducasse A.
Published: February 2023

Cascading phenomena are related to the back action effect of the second harmonic (SH) on the phase of the primary radiation. This has recently attracted much interest in the field of ultrafast all-optical switching applications, where the amplitude of the second order nonlinear coefficient χ(2) has to be accurately known. However, obtaining a precise measurement of χ(2) usually requires a calibration against a perfectly known nonlinear reference crystal. Moreover, the influence of cascading on the spectrum of the harmonic pulse, which has hardly been seen using pisosecond pulses, has never been explored in the femtosecond regime.
On The Scaling For Values of Electronic Nonlinear Susceptibilities In Organic Polymers
Authors: Kovalev Valeri I.
Published: February 2023

Presently much attention is given by the researchers to optically transparent polymers (OTP) as the materials for fabrication variety devices based on nonlinear optical phenomena (see for an example /1/). The value of OTP nonlinear susceptibility (NS) is the principal parameter which define the efficiency and the competitivity of such devises. That is why the search for the simple and reliable method to select materials with increased NSs is the point of the importance.
Discretized Coupled-mode Theory for Fiber Grating Analysis
Authors: Jeong Yoonchan , Lee Byoungho
Published: February 2023

Fiber gratings have invoked intense research attention in recent years. The imprinted grating structures in fiber couple a propagating fundamental core-mode to other modes for resonant wavelengths and hence produce excellent wavelength filtering properties. To enhance the properties according to applications, a lot of grating structures are imposed in fibers. For example, phase-shifted ones, apodized ones, chirped ones, and so forth are applied to the grating structures for both reflection and transmission gratings. For the grating structure analysis, conventional coupled-mode theory and fundamental matrix theory [1] have good agreements with experimental results for almost periodic grating structures. However, the theories could not resolve the grating structures into less than grating periods, since they are based on a Fourier series representation for the grating structure. Even more, in the case that the whole grating length is not long enough compared to grating period or in the case that there exists no periodicity in the grating structure, its profile should be represented by not Fourier series but Fourier integral. These problems can be overcome by the discretized coupled-mode theory proposed in this paper. This method represents the grating structure as it is by discretizations along the structure. Hence, it can analyze arbitrary grating structures and resolve them into less than grating period. For example, if the discretization number is one hundred for the 500 nm fundamental grating period, then Nyquist theorem expects that the analysis should have 10 nm resolution for the grating structure. According to the grating structure variations, the discretization can be adjusted. Therefore, a precise analysis can be obtained no matter how complex the grating structure is. In this scheme, the nonlinear property of fiber grating can be considered easily. Together with Fourier transform analysis, the grating nonlinear response [2] including fiber grating soliton problems can be analyzed with high precision.
Simple Compensated Spectrometric Optical Fibre Accelerometer for vibration monitoring
Authors: Cobo A. , Morante M.A. , Arce J.L , López-Higuera J.M.
Published: February 2023

In this Paper, a novel design of a fibre optic accelerometer is presented, with simplicity and low cost as its main characteristics. It is based on a simple optical fibre cantilever beam as the vibration-sensitive element, and a diffraction grating to produce the spectral dispersion of the light from the fibre end. This wavelength-dependent modulation allows a simple compensation of the output signal against variations of the optical power emitted by the source or losses in the optical path.
Novel Schemes of Slab Solid-State Lasers
Authors: Orlov L. , Nekrashevich J. , Zhukovsky V.
Published: February 2023

The main practical limitations in the operation of any solid-rod laser due to the thermal gradients could be solved by development of the rectangular-slab laser with a good cooling. Such construction pennits to obtain a uniform pumping of large volumes of active media with high gain and low thermal lensing. But it is very difficult to extract all energy from the whole volume in this case; even for a multipass zig-zag slab laser (designed at General Electric and other laboratories |1|) the efficiency is rather low.
All Solid-State Laser Systems Tunable Between 0.35 and 1,7 μm Based on Raman Shifters Pumped By Ti:Sapphire- and LiF:Fr - Laser
Authors: Orlovich V.A. , Kachinsky A.V. , A.V.Ermakov
Published: February 2023

In spectroscopy, photochemistry, biology and environmental applications, narrow-band pulsed laser radiation sources, tunable in the UV. VIS and IR spectrum regions, are normally required. In the recent years, optical parametric oscillators (OPO), in particular OPOs on BBO crystals, covering the 0.4 - 2.2 μm spectrum interval by tunable radiation, have been extensively used for this purpose. Such OPOs, however, require single-mode Nd:YAG lasers for pump, and if proper measures are not taken, generate radiation whose spectral width is wavelength-dependent and equals to 0.2 - 3.0 nm, thus imposing heavy restrictions on their application range. Utilization of spectral selectors and/or injection of dye-laser narrow-band radiation, will permit this disadvantage to be avoided, but at the same time will inevitably involve a very complicated OPO optical construction, narrowed tunability range and enhanced expenses. On the other hand, relatively simple narrow-band lasers on Ti:Sapphire and LiF:F2-crystals are being extensively used at present. These lasers provide a linewidth as narrow as ~ 10-1 cm-1 and do not require single-mode Nd:YAG-lasers for pump.
Comparison of FT-IR and Diode Laser Based Absorption Spectroscopy for Trace Gas Monitoring
Authors: Chen W. , Moinet D. , Tittel F.
Published: February 2023

This work describes a comparison of the performance characteristics between a conventional Fourier transform infrared (FT-IR) and new mid-infrared gas sensors based on diode laser pumped difference frequency generation (DFG) in periodically poled lithium niobate (PPLN) at wavelengths between 3 to 5 microns. Minimum detectable concentrations of trace gases in air at sub ppm levels were obtained using this type of diode laser absorption spectroscopy [1].
Thinfilm optical waveguide type ionsensor based on PVC membrane
Authors: Kim Kyungho , Minamitani Haruyuki , Matsumoto Kunihiro , Momose Itoe
Published: February 2023

In recent years, many (bio)chemical sensors for detecting important constituents of human body, such as Na+,. Ca2+, K+, and Cl−, etc., have been reported. Generally, these sensors are based on electrode has been known to have low sensitivity, which make it difficult to sense materials of very small reactivity. Meanwhile, absorption spectro-photometry and ATR (Attenuated Total Reflection) spectrometry have the high sensitivity and are suitable to sensing required high level sensitivity. However, a common problem with absorption spectro-photometry is nonlinearity of the absorbance with concentration caused by stray ray when the sample has high absorbance at the selected wavelength. It is complex and tedious for this method to be applied to the analysis of turbid biochemicals because of multiple dilutions of the sample and the need for a special setup, etc. One of the limitations of ATR spectrometry is that it shows poor sensitivity for weakly light-absorbing samples. This arises because the effective sample thickness is in the order of the penetration length of the evanescent wave into the sample, which is small. In this study, we propose a thin-film optical waveguide type ion sensor for solving the limits of conventional transmission or reflection measurements as mentioned above. The proposed sensor improves sensitivity and selectivity by taking in ionophore and chromoionophore in sensing layer. The sensing layer (refractive index;1.51 at λ=488nm) was made and deposited by spincoating of ionophore (HDOPP-Ca for Ca2+ or Valynomycin for K+), chromoionophore, PVC-PVA-PVAc copolymer and BEHP on waveguide layer. The waveguide layer was fabricated by rf sputtering of Corning 7059 glass (refractive index;1.59 at λ=488nm) on Pyrex glass (refractive index;1.48 at λ=488nm) substrate. The fabricated waveguide sensor was placed on stage, and laser light of 488nm or 633nm was coupled into the waveguide by the prism coupling method. The decoupled light was measured with an optical powermeter. To evaluate the characteristics of this sensor, CaCl2 solution and KCl solution of pH5.3 (Acetate Buffer) was used, and during the experiment its concentration was gradually increased from 10−5 to 10−2mol.
Monolithic integration of InGaAs-InAlGaAs optoelectronic devices for 1.55µm emission by quantum well intermixing
Authors: Kowalski O. P. , McDougall S. D. , Marsh J. H. , Bryce A. C. , Ironside C. N.
Published: February 2023

A novel quantum well intermixing (QWI) technique1 has been used to achieve substantial band gap shifts in the InGaAs-InAlGaAs material system enabling the first demonstration of monolithically integrated devices in this system. Wavelength tuned lasers have also been fabricated, displaying a tuning range up to 150 nm.
Sub-8-fs pulses from a visible optical parametric amplifier
Authors: Cerullo G. , Nisoli M. , De Silvestri S.
Published: February 2023

Visible light pulses shorter than 10 fs are required in several advanced ultrafast spectroscopy experiments. Optical parametric amplifiers (OPAs) pumped by the second harmonic (SH) of a Ti.Sapphire laser provide such pulses, but with durations limited by the narrow phase matching bandwidths. Gale et al. [1] discovered a peculiar property of ß-barium borate (BBO) for optical parametric amplification, when pumped at 400 nm: using noncollinear phase matching with a pump-signal angle of 3.7°, the phase matching angle becomes independent of wavelength over most of the visible. Recently, this property was exploited to build noncollinear OPAs tunable across the visible, generating sub-20 fs pulses [2, 3].
Modeling of thermal birefringence in longitudinal diode-pumped Nd:YAG laser systems
Authors: Schmid M. , Weber R. , Weber H.P.
Published: February 2023

Longitudinal diode laser pumping results in pronounced inhomogeneous heating of the laser material. This heat distribution affects the quality of a beam passing through the crystal due to thermal dispersion and thermal expansion.
Phase Conjugation Based on a Brillouin Liquid at 1.06µm and 2.09µm
Authors: Medrano C. , Biaggio I. , Montemezzani G. , Günter P. , Poberaj I.
Published: February 2023

In many lidar applications laser sources capable of producing high energy laser pulses with a diffraction imited wavefront are required. The energy of the pulses is usually increased by adding one or several optical amplifier stages. However the optical amplifiers tend to degrade the wavefront quality to several times the diffraction limit. Phase conjugate mirrors for beam aberration correction have been proposed [1].
Fermi-level Pinning in GaInP/AlGaInP Laser Diodes
Authors: Smowton P.M. , Blood P.
Published: February 2023

We have studied Fermi-level pinning in 670nm GaInP quantum well laser diodes by measuring spontaneous emission spectra as functions of injection current and heatsink temperature with the aim of understanding the processes which govern the earner distributions above threshold. We observe that the spontaneous emission from the well itself pins above threshold but that the emission from the barrier region, alongside the well, continues to increase. Various explanations have been suggested for observations of this sort including carrier thermalisation, spectral hole burning and capture bottlenecks but in this presentation we set out to show that it is possible to explain the obseived behaviour simply in terms of effects due to internal fields.
Femtosecond Micromachining
Authors: Momma C , Nolte S. , Tünnermann A.
Published: February 2023

For a variety of industrial micromachining applications, such as the production of injector nozzles, the machining of sophisticated medical implants and also direct medical applications (tissue removal), the highest achievable precision and a minimum invasion is required. In the past years it has been demonstrated that the ultrashort-pulse machining technique, applying solid-state femtosecond laser systems, can meet these requirements, even for very problematic, sensitive, and delicate materials, such as e g. metals [1,2] and organic tissues.
RF-Excited Slab Waveguide CO2 Lasers Utilising Graded Phase Mirror Resonators
Authors: Wasilewski B , Baker H J , Hall D R
Published: February 2023

RF discharge excited slab-waveguide carbon dioxide lasers have been developed as relatively inexpensive sources of good beam quality, high power, far infrared radiation (10.6µm). They commonly incorporate a hybrid resonator design which involves waveguide propagation in the transverse direction and a confocal-unstable design in the lateral (wide) dimension. Such resonators offer excellent beam quality, adequate for most applications. However, they may exhibit variations in the beam shape when mirrors are tilted, and scaling the laser to high powers requires use of wide spherical mirrors, which causes increased sensitivity to unwanted spherical curvatures (bending and twisting) overlaid on the mirror shape during manufacturing and/or mounting, To remove this unwanted behaviour, alternative resonator geometries are under consideration.
Optimization of fiber laser designs by a modal method
Authors: Pertsch Thomas , Gias Peter , Naumann Martin , Schirrmacher Andre , Boneß Reiner
Published: February 2023

Diode laser pumped fiber lasers become important as high power light sources. The design of the refractive index profile and doping distribution of high power laser fibers has to meet several requirements: 1) a large entrance area and a high numerical aperture to match the high beam parameter product of high power pump sources, i.e. diode laser arrays, 2) an effective transfer of pump power to excited states in the active material to allow for a short resonator length, 3) a high brightness by a small beam parameter product of the generated laser radiation. These requirements led to a variety of fiber designs, i.e. circular and offset double clad and M-proftle fibers (cf. Fig. 1) [1,2].
Recent Advances in Bose-Einstein Condensation
Authors: Ketterle Wolfgang
Published: February 2023

The observation of Bose-Einstein condensation (BEC) in dilute atomic gases was the realization of many long-standing goals: (1) to cool neutral atoms into the ground state of the system, thus exerting ultimate control over the motion and position of atoms limited only by Heisenberg's uncertainty relation; (2) to generate a coherent sample of atoms all occupying the same quantum state (this was subsequently used to realize an atom laser, a device which generates coherent matter waves); and (3) to create a quantum fluid with properties quite different from the quantum liquids He-3 and He-4. This provides a test-ground for many-body theories of the dilute Bose gas which were developed many decades ago, but never tested experimentally.
An Introduction to Subcentimeter Satellite Laser Ranging: Hardware and Applications
Authors: Degnan John J.
Published: February 2023

Satellite laser ranging (SLR) to an artificial satellite equipped with a passive retroreflector array was first demonstrated by the NASA Goddard Space Flight Center in 1964. Over the past three decades, the range precision has improved by roughly three orders of magnitude - from a few meters to a few millimeters - and over 50 satellites have been tracked by laser. Today, an international network of over 40 stations routinely track a constellation of over 20 artificial satellites and the Moon in support of a wide range of applications. Science applications include a a geocentric global reference frame accurate to a centimeter, the monitoring of tectonic plate motion, regional crustal deformation near plate boundaries, the static and time varying components of the Earth’s gravity field, motion of the Earth’s spin axis, variations in the Earth rotation rate (Length of Day), surface topography (oceans, land, and ice), monitoring of large mass movements within the atmosphere and oceans and providing constraints to global circulation models, lunar physics, general relativity, and the measurement of fundamental physical constants. Engineering applications include precise orbit prediction, the measurement of nonconservative forces in space, subnanosecond global time transfer between atomic clocks and the calibration and testing of groundbased microwave radars as well as new spacebased navigation systems such as the Global Positioning System (GPS).
Focusing lenses for the 20-beam fusion laser: SHIVA
Authors: O’Neal William C.
Published: February 2023

The SHIVA high energy laser facility now under construction at Lawrence Livermore Laboratory is a 20-arm, 1.06-µm Nd-glass laser system that can focus 20-30 TW of power nearly uniformly on a 300-1500-µm diam deuterium-tritium laser fusion pellet. The facility will be in operation in 1977 and should produce significant thermonuclear burn (fusion energy output = 1 % light energy input).
System for imaging through inclement weather at submillimeter wavelengths
Authors: Kruse P. W.
Published: February 2023

A concept for an active imaging system which includes a laser to scan the scene in raster fashion boresighted with a scanning receiver is under investigation. This is in effect a laser-aided forward looking infrared system which will be employed to recognize vehicular targets in inclement weather at ranges of several kilometers. The scattering properties of fog and clouds require operation at wavelengths greater than 100 µm in order that the range may not be severely limited by attenuation. The scattering properties of rain, and the need to have sufficient angular resolution consistent with a receiver diameter no greater than 1-2 m, place an upper limit to the wavelength of about 2 mm. The optical transmittance of the clear atmosphere permits operation only in a few windows between 350 µm and 1.5 mm. The range equation based upon an optical heterodyne detection system has been derived for operation in the selected windows in clear weather, fog, and rain. The properties of submillimeter lasers and detectors have been reviewed. A program is now underway at U.S. Army Missile Command to develop atmospheric attenuation and target signature information.
Analysis of the fusion-effectiveness of active and passive pulse-stackers
Authors: Harney R. C. , Schipper J. F.
Published: February 2023

Isentropic compression of thermonuclear fuel pellets in laser fusion systems requires a laser pulse with a faster-than-exponential rise in intensity. One method of producing such pulses, known as pulse-stacking, consists of generating a sequence of pulses with appropriate amplitudes and recombining them with appropriate time delays to form an approximation to the required pulse shape. Numerous active and passive pulse-stacking systems have been proposed, although adequate documentation on these is almost entirely lacking. In this report we analyze the performance characteristics of several of the better-documented systems: the Thomas-KMS fusion pulse-stacker,1 the Pockels cell pulse-stacker of Harney,2 and the Emmett-LLL pulse-stacker.3 These systems are typical of the best suggestions to date and are shown schematically in Figs. 1(a)-(c).
OMEGA-X: a high peak power glass laser users facility
Authors: Lubin M. , Soures J.
Published: February 2023

Studies in laser-pellet fusion, x-ray generation and the development of an x-ray laser, high energy density equation of state, and the fundamental interaction of intense radiation with single particles will benefit from the availability of a multikilojoule high brightness radiation source.
Laser isotope separation: a revolution in chemistry
Authors: Rhodes George
Published: February 2023

Great advances have been made in laser isotope separation schemes as applied to uranium enrichment. The metal vapor approach has been shown to enrich 235U by several scenarios and the photodissociation of cooled UF6 has shown promise. These remarkable programs have provided impetus for development of tunable lasers and new spectroscopic concepts. The logical extensions of the technology to new power reactor construction materials and reactor waste management are obvious. Recent developments in these areas will be discussed.
Eight-terminal bidirectional fiber optic data bus employing T-couplers
Authors: Altman D. E. , Taylor H. F.
Published: February 2023

The concept of the data bus (a single transmission line that serves a number of spatially distributed terminals) is becoming increasingly evident in the design of new military aircraft and ships. Fiber optics is a strong candidate to replace electrical cables in data bus systems of the future. This paper describes the component and system characteristics of a breadboard fiber optics data bus designed for time-division-multiplexed operation.
Fiber-optic directional coupler
Authors: Pan J. J.
Published: February 2023

Recent progress in the field of fiber-optic communication creates an urgent demand for fiber directional couplers for applications to optic data bus networks, switches, modulators, power dividers/ combiners, and multiplexers/demultiplexers. T, star, and active couplers have been fabricated either in bundle configuration or in single-fiber fashion; however, none of these couplers offers bidirectional directivity. Integrated optics circuit (IOC) rectangular waveguide directional couplers have been investigated extensively by numerous authors; but their use may not be realistic in a practical communications system due to the interface losses between fibers and IOCs. This paper presents a 10-dB directional coupler, as depicted in Fig. 1, fabricated from Corning multimode low-loss individual fibers, with directivity better than 21.6 dB and insertion loss of 0.6-0.8 dB.
Application of adaptive optical techniques to figure control of large telescopes
Authors: Scott R. M.
Published: February 2023

Large telescopes in space offer a great advantage to astronomers because their performance is not limited by the atmosphere. The space environment provides a further advantage in that it is free of gravity, but the thermal environment is a distinct disadvantage with respect to the performance of large optics. Weight in a large space system is always a major design problem. With these considerations in mind there has been increasing consideration of large mirrors of light weight, but this results in considerable flexibility. This paper reviews the progress toward systems in which the errors of figure of the mirror in space are measured and corrections made to perfect the figure by the application of controlled mechanical stresses. Several laboratory systems to demonstrate the principles and the design of a system for the Large Space Telescope are described. Some directions for future development are indicated.
Shared apertures in tracking turbulence-induced wavefront tilt errors
Authors: Greenwood Darryl P.
Published: February 2023

In many optical pointing and tracking systems it is not practical to beam split the incoming wavefront in order to derive a tracking signal. The tracker optics are typically placed adjacent to a larger pointing mirror or telescope. We have found that this configuration is not optimum in tracking turbulence-induced wavefront errors. Instead, the tracker should either be in the region of the pointer central obscuration or be in a thin annulus surrounding the pointer. Wherever the tracker is located, its signal should be low-pass filtered, perhaps by the servo itself. Low frequencies correspond to large-scale turbulence, and such turbulence appears the same to both the pointer and the tracker.
Modal wavefront control system
Authors: Neufeld C. , Sloan E. L. , Skolnick M. L.
Published: February 2023

A 9-channel 100-Hz closed-loop modal multidither COAT (Coherent Optical Adaptive Technique) system is described that could be used to improve propagation of a laser beam through the atmosphere and compensate for system induced optical aberrations.
Figure sensor control of a deformable mirror
Authors: Angelbeck A. W. , Wisner G. R. , Greiner A. F. , Hasselmark E. D. , Freeman R. H. , Reynolds H. C.
Published: February 2023

Figure sensor control of a deformable mirror has been developed which allows for closed-loop control of an arbitrary figure on the mirror. Figure sensing is implemented through the use of an optical heterodyne-type interferometer which monitors the optical figure (contour) of the mirror. Error signals are generated in a dedicated minicomputer by comparing the measured contour and the desired contour.
High power industrial CO2 lasers and their applications
Authors: Locke Edward B.
Published: February 2023

Over the past several years several companies have manufactured and sold multikilowatt CO2 lasers for industrial applications. The purpose of this paper is to review the technology embodied in these lasers and to present the nature and utility of the applications. Included in the laser technology section are slow flow, rapid flow, and cross flow lasers. The applications include cutting, welding, and surface heat treating. Appropriate examples of each application will be shown.
Look Sea laser illuminated underwater viewing system
Authors: Stachnik William J.
Published: February 2023

Starting in 1971 the Naval Underwater Systems Center and the Ball Brothers Research Corp, designed, built, and tested a synchronous spot-scanned underwater viewing system. Funded by the Advanced Research Projects Agency this system became known as LOOK SEA.
Recording module of the 3M laser microfilm system
Authors: Neumann Hans D.
Published: February 2023

The early work of recording computer output on microfilm was done with the cathode ray tube as the image forming device. A system capable of writing in vacuo directly on film with a focused electron beam was developed by the 3M Company for use with their Dry Silver Film, which required only heat to develop the latent image. The Electron Beam Recorder was designed to write on 16-mm film, but to produce the standard microfiche additional equipment is required to transfer the data by contact printing onto 105-mm material. Sometime saved through the dry process is lost again during this step of duplication. By extending the spectral sensitivity of Dry Silver Film into the red region, the film became suitable for exposure with the light of a low-cost He-Ne laser. The system to be designed would allow direct recording on 105-mm film. Performance criteria established with the EBR system governed the specification of the LBR. The properties of the laser and the possible method of scanning the beam dictated the design of a special optical system. The telecentric lens system forms a combined image of computer-generated alpha numeric symbols and static form data from a transparency slide on the microfilm; 48× or 25× reduction is selected by the simple movement of one optical element. Through a combination of acoustooptic and electromechanical deflection of the laser beam, characters are formed at the rate of 25,000/sec within a 5 × 7 dot matrix. To ensure reproducibility through four generations of copy the system is capable of resolving 154 lines/mm at 48× reduction on developed Dry Silver Film. Forms may be superimposed in registration with the symbolic data at the rate of 4 frames/sec. A comparison between Xe flash and incandescent illumination of the form slide leaves the tungsten halogen lamp as the preferred light source.
Electrooptical imaging in diagnostic radiology
Authors: Nudelman S. , Roehrig H. , Capp M. P.
Published: February 2023

High resolution photoelectronic imaging devices are under investigation for diagnostic radiology. Discussion will be presented of cost factors and the state of the art of components indicating the likelihood that video systems will compete effectively with photographic systems.
Laser velocimetry: current technology and applications
Authors: Stevenson Warren H.
Published: February 2023

Use of the optical Doppler shift of laser light scattered from small particles as a noninterfering means of measuring instantaneous local fluid velocities has revolutionized flow measurement technology. Early laser velocimeters were essentially modified interferometers suitable for use only under laboratory conditions. Continued improvements in optical design have led to less sensitive configurations applicable to industrial environments. Optimum optical design for a given measurement task requires recognition of several interrelated and sometimes subtle factors including the unique nature of Gaussian laser beam propagation.
Ranging laser atmospheric transmissometer
Authors: McHenry Thomas F.
Published: February 2023

As a tool in the evaluation of various electrooptical systems, it is desirable to be able to measure accurately the atmospheric transmission over long optical paths. Typically, this is accomplished by providing a calibrated radiation source at one end of the path and a calibrated radiometer at the other. The radiation measured by the receiving radiometer is compared with that which would have been received at the same distance in a vacuum, and the ratio is defined as the atmospheric transmission τ.
High-power gas lasers
Authors: Fahlen Theodore S.
Published: February 2023

This presentation will be a review of current, un-classified, high-power gas-laser technology. Here high power is defined as exceeding 1000-W average power. Because almost all industrial applications that use gas lasers use the cw electrically excited CO2 laser, this device will be emphasized. A brief discussion of other high-power gas lasers, such as CO, TEA CO2, chemical, excitation-transfer, and excimer lasers, will also be included as these lasers may be candidates for future industrial systems.
Room temperature cw GaAs and GaAIAs lasers
Authors: Gill Robert B.
Published: February 2023

During the past 8 years, compounds of Ga1−
x
Al
x
As have been the subject of intensive study for the reproducible fabrication of reliable ir emitting lasers capable of sustained cw operation at and above room temperature. Numerous types of stripe-geometry double heterojunction lasers have been proposed and demonstrated including:

(1) lasers with contact stripes isolated using an insulator such as silicon dioxide;

(2) lasers with contact stripes isolated by bounding regions of high resistivity GaAs formed by proton bombardment;

(3) lasers with contact stripes isolated by bounding p−n junction regions which are reversed biased during laser operation.
High performance laser
Authors: Seitel Steven C.
Published: February 2023

Projected Nd:YAG laser applications require greater pulse energies, higher data rates, and spatially more uniform output beams than are presently available. The High Performance Laser (HPL) oscillator–amplifier system produces 500-mJ pulses of 17-nsec width. The depolarized output is constant over the pulse repetition frequency range of 10-60 Hz. Without compensation for thermal lensing, the raw-beam divergence is 4 mR at 10 Hz, increasing to 8 mR at 60 Hz. Examination of the multimode beam profile across the output aperture shows a single broad lobe with no secondary maxima and a peak-to-average intensity ratio less than three.
Development of subpicosecond x-ray and visible streak camera
Authors: Lieber Albert J. , Sutphin H. Dean , Webb Clinton B. , Williams Arthur H.
Published: February 2023

It has been recognized for several years in the laser-plasma diagnostics development program at LASL that x-ray diagnostics yielding temporal resolution of better than 1 psec and good spatial resolution are critical to the understanding of interactions. Virtually all present ultrafast streak cameras are based upon the RCA C73435 type of shutter tube which was developed over a score of years ago. Efforts in this country and Europe have resulted in a package with 10–20-psec x-ray resolution at best. Among the tube’s weaknesses are its sector-focused electron geometry which requires operation
Infrared pyrometer for high-resolution surface temperature measurements on rotating turbine blades
Authors: Uguccini Orlando W.
Published: February 2023

A high-resolution radiation pyrometer, designed at the NASA Lewis Research Center, was tested on an operating turbine engine. This pyrometer was used to obtain temperature profiles of the viewed surface of several turbine blades at blade tip speeds up to 366 m/sec (1200 fps).
Simple optical interferometer for measuring phase changes smaller than 10−5 Å
Authors: Weber Larry F.
Published: February 2023

To measure subangstrom phase changes in the ac plasma display panel, the Jamin interferometer shown in Fig. 1 was used. The system features a double detector differential amplifier arrangement that balances out to the shot noise limit the amplitude variations from the laser. A servo system rotates a glass plate to compensate for low frequency vibrations and thermal variations. The optical flats have beam splitters that cause nearly 100% of the laser power to fall on the detectors, thus increasing SNR. A lens focuses the beam to give diffraction-limited spatial resolution in the region of the plasma cell.
Wideband 1064-nm detector evaluation
Authors: Green Samuel I.
Published: February 2023

The purpose of this program1 was to evaluate the performance of several candidate detectors for use as communications detectors in a 400-Mbps 1064-nm laser communication system. The detector types supplied by NASA were the RCA (Montreal) silicon avalanche photodiode with a reach through structure, the Varian LSE electrostatic photomultiplier, and the Rockwell International (Science Center) hybrid detector with gallium arsenide antimonide avalanche photodiode and integral transresistance preamplifier. Characterization testing included measurement of bit error rate performance in a 400-Mbps pulse gated binary modulation (PGBM) laser communication system test bed, a scan of cathode photoresponse uniformity, and a photograph of output waveform showing response time.
Two-beam CO2 laser system for laser induced fusion experiments
Authors: Parker J. V. , Nutter M. J. , Hayden J. J. , Singer S. , Liberman I.
Published: February 2023

As the only well developed laser system potentially suitable for a laser fusion power system, it is critical that the feasibility of fusion induced by CO2 laser pulses be demonstrated. For the next 2 years (until the 10-kJ 8-beam system at LASL becomes operational), the principal tool for carrying out these investigations will be the Dual Beam Laser System (DBLS). Designed primarily as a prototype for the four modules that will comprise the 10-kJ laser system, DBLS has been upgraded to an experimental target facility by the addition of a high-contrast short-pulse oscillator and the necessary target diagnostic and handling equipment. With target experiments scheduled to begin in the spring of 1976, the DBLS is currently undergoing evaluation to establish its short-pulse performance characteristics.
Prepulse elimination in high-power CO2 lasers
Authors: Liberman I. , Hayden J. J. , Singer S.
Published: February 2023

We are presently completing a CO2 laser designed to produce peak power in excess of 2 TW to study the scaling characteristics of pellets for laser induced fusion. The design goal of 2500 J in a 1 nsec pulse also includes other requirements, among them being that the energy on the target before the arrival of the main pulse be kept under 100 μJ. This requirement is needed to prevent the target from disintegrating before the TW pulse can compress it. Since the small signal gain in the dual-beam triple-pass amplifier is estimated to be about 108, the prepulse energy from the oscillator–preamplifier feeding the final amplifier must be less than 10−12 J. Since about 0.2 J is required to drive each half of the dual beam module, a prepulse rejection ratio better than 4 × 1011 must be achieved.
Soliton-sinc optical pulse propagation in the presence of high-order effects
Authors: Peng Weiliang , Zhang Xiang , Jing Liqing , Gao Yanxia , Deng Zhixiang , Fan Dianyuan , Zhang Lifu
Published: February 2023

We investigate the propagation dynamics of the soliton-sinc, a kind of novel hybrid pulse, in the presence of higher-order effects with emphasis on the third-order dispersion (TOD) and Raman effects. At variance with the fundamental sech soliton, the traits of the band-limited soliton-sinc pulse can effectively manipulate the radiation process of dispersive waves (DWs) induced by the TOD. The energy enhancement and the radiated frequency tunability strongly depend on the band-limited parameter. A modified phase-matching condition is proposed for predicting the resonant frequency of the DWs emitted by soliton-sinc pulses, which is verified by the numerically calculated results. In addition, Raman-induced frequency shift (RIFS) of the soliton sinc pulse increases exponentially with a decrease of the band-limited parameter. Finally, we further discuss the simultaneous contribution of the Raman and TOD effects to the generation of the DWs emitted from the soliton-sinc pulses. The Raman effect can then either reduce or amplify the radiated DWs depending on the sign of the TOD. These results show that soliton-sinc optical pulses should be relevant for practical applications such as broadband supercontinuum spectra generation as well as nonlinear frequency conversion.
Investigation of the cap layer for improved GeSn multiple quantum well laser performance
Authors: Abernathy Grey , Ojo Solomon , Stanchu Hryhorii , Zhou Yiyin , Olorunsola Oluwatobi , Grant Joshua , Du Wei , Jheng Yue-Tong , Chang Guo-En , Li Baohua , Yu Shui-Qing
Published: February 2023

The study of all-group-IV SiGeSn lasers has opened a new avenue to Si-based light sources. SiGeSn heterostructure and quantum well lasers have been successfully demonstrated in the past few years. It has been reported that, for multiple quantum well lasers, the optical confinement factor plays an important role in the net modal gain. In previous studies, adding a cap layer was proposed to increase the optical mode overlap with the active region and thereby improve the optical confinement factor of Fabry–Perot cavity lasers. In this work, SiGeSn/GeSn multiple quantum well (4-well) devices with various cap layer thicknesses, i.e., 0 (no cap), 190, 250, and 290 nm, are grown using a chemical vapor deposition reactor and characterized via optical pumping. While no-cap and thinner-cap devices only show spontaneous emission, the two thicker-cap devices exhibit lasing up to 77 K, with an emission peak at 2440 nm and a threshold of 214 kW/cm2 (250 nm cap device). The clear trend in device performance disclosed in this work provides guidance in device design for electrically injected SiGeSn quantum well lasers.
Optimal optical Ferris wheel solitons in a nonlocal Rydberg medium
Authors: Qiu Jia-Bin , Qin Lu , Zhao Xing-Dong , Qian Jing
Published: February 2023

We propose a scheme for the creation of stable optical Ferris wheel (OFW) solitons in a nonlocal Rydberg electromagnetically induced transparency (EIT) medium. Depending on a careful optimization of both the atomic density and the one-photon detuning, we obtain an appropriate nonlocal potential provided by the strong interatomic interaction in Rydberg states that can perfectly compensate for the diffraction of the probe OFW field. Numerical results show that the fidelity remains larger than 0.96, while the propagation distance has exceeded 160 diffraction lengths. Higher-order OFW solitons with arbitrary winding numbers are also discussed. Our study provides a straightforward route to generate spatial optical solitons in the nonlocal response region of cold Rydberg gases.
Cs microcell optical reference with frequency stability in the low 10−13 range at 1 s
Authors: Gusching Anthony , Millo Jacques , Ryger Ivan , Vicarini Remy , Abdel Hafiz Moustafa , Passilly Nicolas , Boudot Rodolphe
Published: February 2023

We describe a high-performance optical frequency reference based on dual-frequency sub-Doppler spectroscopy (DFSDS) using a Cs vapor microfabricated cell and an external-cavity diode laser at 895 nm. Measured against a reference optical signal extracted from a cavity-stabilized laser, the microcell-stabilized laser demonstrates an instability of 3 × 10−13 at 1 s, in agreement with a phase noise of +40 dBrad2/Hz at 1-Hz offset frequency, and below 5 × 10−14 at 102 s. The laser short-term stability limit is in good agreement with the intermodulation effect from the laser frequency noise. These results suggest that DFSDS is a valuable approach for the development of ultra-stable microcell-based optical standards.
Optimal deployment of automated external defibrillators in a long and narrow environment
Authors: Lin Chih-Hao , Chu Kuan-Chao , Lee Jung-Ting , Kao Chung-Yao
Published: February 2023

Aim of the study

Public access to automated external defibrillators (AEDs) plays a key role in increasing survival outcomes for patients with out-of-hospital cardiac arrest. Based on the concept of maximizing “rescue benefit” of AEDs, we aimed to propose a systematic methodology for optimizing the deployment of AEDs, and develop such strategies for long and narrow spaces.

Methods

We classified the effective coverage of an AED in hot, warm, and cold zones. The AEDs were categorized, according to their accessibility, as fixed, summonable, or patrolling types. The overall rescue benefit of the AEDs were evaluated by the weighted size of their collective hot zones. The optimal strategies for the deployment of AEDs were derived mathematically and numerically verified by computer programs.

Results

To maximize the overall rescue benefit of the AEDs, the AEDs should avoid overlapping with each other’s coverage as much as possible. Specific rules for optimally deploying one, two, or multiple AEDs, and various types of AEDs are summarized and presented.

Conclusion

A methodology for assessing the rescue benefit of deployed AEDs was proposed, and deployment strategies for maximizing the rescue benefit of AEDs along a long, narrow, corridor-like, finite space were derived. The strategies are simple and readily implementable. Our methodology can be easily generalized to search for optimal deployment of AEDs in planar areas or three-dimensional spaces.
Atherogenic dyslipidemia and associated risk factors among hypertensive patients of five health facilities in Northeast Ethiopia
Authors: Mohammed Ousman , Alemayehu Ermiyas , Ebrahim Endris , Fiseha Mesfin , Gedefie Alemu , Ali Abdurrahman , Ebrahim Hussen , Tilahun Mihret
Published: February 2023

Background

One of the major risk factors for cardiovascular disease is atherogenic dyslipidemia. There was, however, little information available in Ethiopia. Therefore, the purpose of this study was to estimate the prevalence of atherogenic dyslipidemia and related risk factors in Northeast Ethiopian hypertension patients.

Materials and methods

A systematic random sampling technique was used to perform a cross-sectional study at an institution with 384 chosen participants. A structured questionnaire was used to collect the socio-demographic, anthropometric, lifestyle, and clinical characteristics of the respondents. Student’s t-test, Mann-Whitney test, and Pearson’s Chi-square test were employed to compare groups based on the type of data. Furthermore, Bivariate and multivariable logistic regression analyses were performed to identify factors independently associated with dyslipidemia. Crude and adjusted odds ratios and their corresponding 95% Confidence Intervals (CI) were computed. In all cases, statistical significance was declared at p <0.05.

Results

The majority (93.2%; 95%CI: 90.6–95.6) of patients had at least one atherogenic dyslipidemia. The prevalence of elevated total cholesterol (TC), elevated triglyceride (TG), raised low-density lipoprotein cholesterol (LDL-c), and reduced high-density lipoprotein cholesterol (HDL-c) were 47.7%, 50.3%, 44.3%, and 59.6%, respectively. Being≥ 40 years were at higher risk for having elevated levels of TC (AOR: 3.22, 95% CI: 2.40–4.32), TG (AOR: 2.30, 95% CI: 1.61–3.79), and LDL-c (AOR: 4.68, 95% CI: 2.0–10.95) than those who were below 40years. Obese participants were more likely to have high concentrations of TC (AOR: 2.57, 95%CI: 2.10–3.22), LDL-c (AOR: 3.13, 95% CI: 1.97–5.10), HDL-c (AOR: 2.71, 95% CI: 1.77–4.58), and TG (AOR: 2.23, 95%CI: 1.79–4.16).

Conclusion

This study revealed that a high prevalence of atherogenic dyslipidemia. Thus, to prevent atherogenic dyslipidemia, it is crucial to create routine blood lipid testing programs and carry out suitable intervention programs focused on risk factor reduction.
Genetic diversity and population structure of Uganda’s yam (Dioscorea spp.) genetic resource based on DArTseq
Authors: Amponsah Adjei Emmanuel , Esuma Williams , Alicai Titus , Bhattacharjee Ranjana , Dramadri Isaac Onziga , Edema Richard , Chamba Emmanuel Boache , Odong Thomas Lapaka
Published: February 2023

Assessing the genetic diversity of yam germplasm from different geographical origins for cultivation and breeding purposes is an essential step for crop genetic resource conservation and genetic improvement, especially where the crop faces minimal attention. This study aimed to classify the population structure, and assess the extent of genetic diversity in 207 Dioscorea rotundata genotypes sourced from three different geographical origins. A total of 4,957 (16.2%) single nucleotide polymorphism markers were used to assess genetic diversity. The SNP markers were informative, with polymorphic information content ranging from 0.238 to 0.288 and a mean of 0.260 across all the genotypes. The observed and expected heterozygosity was 0.12 and 0.23, respectively while the minor allele frequency ranged from 0.093 to 0.124 with a mean of 0.109. The principal coordinate analysis, model-based structure and discriminant analysis of principal components, and the Euclidean distance matrix method grouped 207 yam genotypes into three main clusters. Genotypes from West Africa (Ghana and Nigeria) had significant similarities with those from Uganda. Analysis of molecular variance revealed that within-population variation across three different geographical origins accounted for 93% of the observed variation. This study, therefore, showed that yam improvement in Uganda is possible, and the outcome will constitute a foundation for the genetic improvement of yams in Uganda.