bluuebunny/crossref_metadata_2025 huggingface dataset:
High efficient excimer ArF and KrF lasers with buffer gas He
Authors: Bagaev S.N. , Razhev A.M. , Zhupikov A.A.
Published: February 2023

One of the most interesting and perspective application of discharge-pumped excimer ArF and KrF lasers is medicine (ophthalmology, cardiosurgery, dentistry), where UV radiation is used to the ablation of submicron layers of biological tissues without their thermal damage.
Fractal resonator modes
Authors: Courtial Johannes
Published: February 2023

Physical approximations to fractal radiation patterns have been largely limited to essentially random distributions with fractal-like scaling behaviour and the generation of fractal radiation patterns using fractal arrays. Recently, a complex design for an all-optical device that generates fractal intensity patterns, based on the principle of the multiple reduction copy machine (Fig. 1 (a)) with feedback, has been introduced [1]. Within this work the resonator properties of a modified and simplified version of such a device are investigated.
Diffractive optical elements for beam-shaping tasks in solid-state laser systems
Authors: Barton Ian M. , Blair Paul , Waddie Andrew J. , Ballüeder Karsten , Taghizadeh Mohammad R. , McKinnes Hazel , Bett Tom H.
Published: February 2023

We apply diffractive optical elements (DOEs) to a number of laser beam-shaping tasks. These tasks include customisation of the modes of a laser resonator, lensless beam propagation and a free-space Gaussian to flattop beam conversion. DOEs are inherently suited for operation with high-power solid-state lasers systems due to their excellent functionality and efficiency, and the high damage threshold of fused silica.
GEO 600 - A Laser Interferometric Gravitational Wave Detector
Authors: Robertson N A
Published: February 2023

To search for gravitational waves from astrophysical sources, GEO 600 will use laser interferometry over a physical arm length of 600 m. The detector is currently being constructed in the North of Germany, near Hannover, by research groups from Hannover, Garching and Glasgow, with theoretical input from Cardiff and Potsdam. It will utilise a four pass delay line Michelson interferometer with power and signal recycling implemented to reduce the limitation to sensitivity set by photo-electron shot noise in the detector output. Illumination will be by single frequency Nd: YAG laser light at a level of 10 W, from a diode pumped slave laser, injection locked by a small monolithic diode pumped ring laser.
Q-switching and scaling of a diode-pumped Er: YLF laser at 2.8 µm
Authors: Wyss Chr. , Lüthy W. , Weber H.P.
Published: February 2023

Micro-surgical applications using 3 µm Erbium lasers demand a pulsed output of more than 1 Watt, with pulse duration between 0.1 µs and 1 µs. In our paper we demonstrate pulses with the favorable duration for the first time in a 3 µm crystal laser. Scaling of the output power is performed using a new diode-laser pump source. The M4-factor of our diode laser module is an improvement of more than a factor of two compared to the best commercially available system.
Mid IR Diodes for Spectroscopy and Trace Gas Detection
Authors: Tacke Maurus
Published: February 2023

Infrared wavelengths from some 3μm out to beyond 10 feature strong and characteristic absorption lines of most molecules, making gas analysis with high resolution spectroscopy the main application of mid infrared diode lasers. Especially if gas mixtures are analyzed under low pressures of some 10 mbar. gas components can be detected very selectively and sensitively by this technique. At such pressures, the absorption lines are not pressure broadened, and due to the narrower residual Doppler broadening the absorption lines can be scanned individually and often without interference of other gas components. This feature makes gas analysis with tunable diode lasers an important tool for atmospheric and environmental research as well as for instance for very fast spectroscopical analysis of automotive exhaust gases.
Laser Wind Sensing and Connected Laser Technology
Authors: Phillips Mark W.
Published: February 2023

CTI has developed rugged coherent lidar systems based on solid state two micron laser technology, for ground-based and airborne wind measurements, and is currently involved in plans to deploy the first coherent lidar on the Space Shuttle to measure global winds from low earth orbit [1,2]. Applications for these lidar systems include meteorology, monitoring of wind shear, microbursts, and wake vortices in the vicinity of airports, clear air turbulence, and winds above and below aircraft for efficient fuel consumption during flight. This paper discusses: (1) laser design features that have been implemented at CTI to achieve efficient injection-seeded Q-switched operation of both end-pumped and side-pumped two micron lasers for coherent lidar applications, (2) example data from field measurements, including wake vortex detection, and (3) planned features of the Shuttle-borne Doppler wind lidar, and the development path for deployment on a free-flying satellite. Figure 1 below shows an example of local wind profile data acquired with a ground-based two micron lidar, while Figure 2 shows example lidar transceiver hardware developed for airborne operation to 40,000 ft altitude.
Biological Aerosol Sensor Breadboard
Authors: DeSha Michael S.
Published: February 2023

In recent history, manmade and natural events have shown us the ever-present need for systems to monitor the troposphere for contaminates. These contaminants may take either a chemical or biological form, which determines the methods we use to monitor them. Monitoring the troposphere for biological contaminants is of particular interest to my organization. Whether manmade or natural, contaminants of a biological origin share a similar constitution: typically the aromatic amino acids tryptophan, phenylalanine, and tyrosine in varying amounts. All of these proteinaceous compounds have the capability to autofluoresce when exposed to ultraviolet radiation. This establishes the basis of the laser induced fluorescence (LIF) technique we use to detect biological contaminants. This technique can be employed in either point or remote detection schemes and is a valuable tool for discriminating proteinaceous from non-proteinaceous aerosols. For this particular presentation I am going to describe a breadboard point sensor I designed and fabricated to detect proteinaceous aerosols.
High-Speed Multi-Frame Fabry-Perot Doppler Interferometer for Instantaneous Velocity Field Measurements
Authors: Mak A.A. , Serebryakov V. A. , Rusov V.A. , Ustyugov V.I. , Orlov O.A. , Khaleev M.M. , Komev A.F. , Pokrovsky V.P. , Stupnikov V.K. , Gryasnov G.M. , Xianxiang Tan , Yanping Wang , Koronkevich S. V. , Smirnova E.A. , Paduch M. , Tomachevsky K.
Published: February 2023

The high-speed laser Fabry-Perot Doppler shift interferometer facility with image recording by means of 8-frame electro-optical camera was elaborated for measuring of the deformation dynamics of the fast moving objects.
Generation of intense diffraction-limited white light and 4-fs pulses
Authors: Cheng Z. , Tempea G. , Brabec T. , Ferencz K. , Spielmann Ch. , Krausz F.
Published: February 2023

Ever since its discovery spectral continuum generation by ultrashort laser pulses has attracted much interest owing to its significance for ultrafast spectroscopy. In this paper we report, for what is to our knowledge the first time, the generation of nearly diffraction-limited truly white-light femtosecond continuum exhibiting comparable spectral intensities all over the range of 400-1100 nm. This performance could be obtained by propagating very short (≈ 25 fs) pulses through a capillary (or hollow waveguide) filled with some noble gas as a nonlinear medium. The key advantage of waveguiding lies in the fact that energy transfer into higher-order transverse modes and hence associated accumulation of spatial effects (e.g. self focusing/defocusing, filamentation) is confined to a relatively short propagation length over which higher-order modes dephase with respect to the fundamental one. Spatially uniform self-phase modulation (SPM) of the fundamental mode, however, can accumulate over much longer distances limited merely by propagation losses and possible pulse broadening effects. As a result, hollow waveguides offer the potential for a much stronger nonlinear phase accumulation without degradation of beam quality as compared to bulk media.
Polymer Light Emitting Diodes for Segmented and Matrix Displays
Authors: Visser Robert Jan
Published: February 2023

Polymer Light Emitting Diodes (Polymer LEDs) is an interesting technology for flat and thin displays. The high brightness at low voltage, relatively low power consumption, high contrast and low viewing angle dependence combined with a low thickness makes this an extremely attractive option for flat and thin displays. Basic technology and application in segmented and matrix displays will be discussed.
Laser Ablation of Carbon with High-Pulse-Rate Nanosecond and Picosecond Lasers
Authors: Rode Andrei V. , Luther-Davies Barry , Gamaly Eugene G.
Published: February 2023

We discuss and demonstrate a novel technique for the deposition of high quality thin films via pulsed laser deposition (PLD) using high repetition rate (up to several tens of MHz) picosecond or nanosecond laser pulses. Differences between this method and conventional PLD arise because the pulse energy is markedly reduced compared with the conventional high-energy low repetition rate lasers used for PLD and this significantly improves the quality of the films due to the large decrease (up to nine orders of magnitude) in the number of particles evaporated during a single laser pulse. This effectively eliminates the major disadvantage of PLD which is the formation of particulates in the film.
Crystallographic, Optical and Waveguiding Properties of Nd:YAG and Nd:YAP layers Created by Pulsed Laser Deposition.
Authors: Jelínek M. , Lančok J. , Šonský J , Grivas C. , Vanois N. , Flory F
Published: February 2023

The thin films of YAG (Y3Al5O12) and YAP (YAlO3) doped with Nd were prepared by pulsed laser deposition on sapphire (0001) and (1102) substrates and YAP (001) substrate from crystalline YAG target of 0.8 at% of Nd, and crystalline YAP targets of 0.74 at% of Nd, 0.80 at% of Nd and 0.90 at% of Nd concetrations. The substrate temperature Ts varied from 860°C to 1100°C and oxygen pressure po in the range from 8.5 × 10–3 Pa to 5.5 Pa. Energy density of KrF excimer laser beam was 3 - 4 J/cm2. Film thickness on sapphire substrates was between 6 µm and 11 µm and on YAP round 20 µm.
Continuous-Wave Optical Parametric Oscillator Based On Periodically-Poled KTiOPO4
Authors: Garashi A. , Arie A. , Rosenman G. , Skliar A.
Published: February 2023

Owing to its high effective nonlinear coefficient (≈ 9.5 pm/V), high photorefractive damage threshold, low susceptibility to thermal lensing as well as the wide commercial availability of the KTiOPO4 substrate, periodically-poled KTiOPP4 (PP-KTP) is a very attractive material for nonlinear frequency conversion applications. In particular, when used in an optical parametric oscillator (OPO), these advantages enable pumping by a CW visible source, operation near room temperature and a low threshold. All these features were demonstrated by the OPO device reported here. To the best of our knowledge, this is the first report of continuous-wave operation of an OPO employing a PP-KTP crystal.
Progress in Chemical Oxygen-Iodine Lasers
Authors: Truesdell K.
Published: February 2023

Summary not available.
A 100 Watt Copper Bromide Laser for Materials Processing
Authors: Sabotinov N V , Mizeraczyk J , Kostadinov I K , Livingstone E S , Little C E
Published: February 2023

The copper bromide vapour laser (CuBrVL) is a low-temperature version of the most powerful and high-efficiency visible laser, the copper vapour laser (CVL). For the first time a high power 100 W CuBrVL developed for practical applications is reported.
"Implemention of a Harriot-Cell in a 6 kW CO2 - Industrial Laser":
Authors: Basalka H. , Fuchsgruber R. , Bohrer M.
Published: February 2023

Concerning the very strong demand of the industry on high power lasers with excellent beam quality, a new concept of a compact 6 kW CO2-laser with coaxial discharge has been combined with the idea of the Herriot - Cell. Both advantages, the compactness and the simple concept of the 6 kW laser, having a toroidal resonator with a ringshaped beam contour, and the very high beam quality of the Herriot - Cell could giude to new HQM-laser concept. The possibility to use both resonator types on the same machine, industrial performance in high quality laser welding with 6 kW and laser cutting with a beam power up to 4 kW could be established.
All-Electrode Bounded Bore, RF Excited CO2 Laser
Authors: Vitruk Peter , Broderick Jeff
Published: February 2023

All metal, non-free space, square-bore, RF-excited CO2 lasers [1] have 10-15% electro-optical efficiency and power extraction of up to 0.5 W/cm, which potentially could be further optimized In this presentation we describe an improved RF-excitation geometry, referred to as all-electrode bounded laser bore, schematically shown in Figure 1. This new electrode geometry helps to increase both the power extraction and efficiency of the diffusion-cooled RF excited CO2 laser.
Laser Ablation of Polymers: Non-Stationary Model of Thermal Destruction Within the Bulk
Authors: Arnold N. , Bityurin N. , Luk'yanchuk B.
Published: February 2023

The models of UV-laser ablation of polymers can be subdivided into two groups. The first ones assume direct photon-assisted bond breaking. In this case the fluence and the absorption coefficient of the polymer directly determine ablation threshold and rate. This yields simple expressions for the ablated depth vs. fluence, which can be corrected for the screening of incoming radiation, changes in the absorption coefficient, etc.
Nanocrystalline Growth of Hard Coatings by Pulsed Laser Deposition
Authors: Zergioti I. , Fotakis C. , Haidemenopoulos G. N.
Published: February 2023

The main objective of this research work was the growth of Titanium Carbide and Titanium Diboride hard coatings on tool steels with Pulsed Laser Deposition (PLD) in order to improve their surface mechanical properties. A pulsed KrF excimer laser was used with the deposition chamber at a base pressure of 10−6 mbar. The morphology and the microstructure of the coatings were examined using Scanning Electron Microscopy, X Ray Diffraction and Transmission Electron Microscopy.
Study of Surface Modifications on Metals and Ceramics Induced by Excimer Lasers
Authors: Ocaña JX. , Nicolás G. , Autric M. , García-Beltrán A. , Molpeceres C. , Morales M. , Yáñez A. , Ramil A. , Alvarez J.C. , Saavedra E.
Published: February 2023

The use of high energy pulses delivered by excimer lasers induces several interesting surface modifications on metals and ceramics. These transformations, mainly of mechanical and chemical nature, are located in the near surface region and depend on the irradiation conditions applied.
A Neodymium doped hollow optical fiber laser for applications in sensing and laser guided atoms
Authors: Glas P. , Naumann M. , Schirrmacher A. , Pertsch Th.
Published: February 2023

An attractive candidate for performing atom guidance is the evanescent field at the border of a dielectric light guide since providing a short range (repulsive) potential. In contrast to passive hollow capillaries, we have realised a lasing one made up from highly doped phosphate glass. Compared to its passive counterpart, the laser capillary has the big advantage that the in-coupled light being spectrally removed from the atomic transition of the atoms to be manipulated is used for pumping the laser. The capillary had a diameter of 70 μm possessing a protection coating. The bore diameter was 11 pm. The doping concentration amounted to 2·1020 cm-3 Nd3+. The capillary length was 1.6 cm (7 cm), butt coupled mirrors form the resonator. The capillary could be illuminated side-on or end-on with pump radiation for the active ions delivered by a diode laser at λ=805 nm. The output mirror had a transmission of < 1% to realise a high intracavity power being desirable to create a strong optical potential necessary in evanescent waveguiding of atoms. The near field distribution is shown in Fig.1. To proof the reaction of the evanescent field on an absorptive disturbance we have filled the capillary with an ir-dye (concentration ~0.07 g/1) finding a strongly modulated (mode locked) output when pulsing the diode laser, Fig.2. (The transverse damping distance in the dye solution is only ~0.3 μm). For an empty capillary the emission gets stationary after some typical relaxation oscillations. To estimate the optical potential we have made a numerical analysis of the laser field distribution in the hollow waveguide. Fig.3 shows the mode field at λ=780 nm in the capillary. We have calculated the optical potential U(r) to guide 85Rb atoms with an intra fiber power of 2 W. The frequency detuning from the atomic resonance is 10 GHz, the saturation intensity of the atomic transition is 1.8 mW/cm The optical barrier as a function of distance from the inner surface in terms of temperature is shown in Fig.1c (inset). The realisation of active atomic waveguides may stimulate interesting studies in atom optics, near field optics and cavity QED.
Refractive corneal surgery with a Q-switched Er:YAG laser
Authors: Lubatschowski H. , Ziolek C. , Heisterkamp A. , Welling H. , Hetzel U. , Drommer W. , Kermani O. , Ertmer W.
Published: February 2023

Recently erbium lasers have been proposed as an alternative to ArF-excimer lasers for photoablative tissue processing, in particular for refractive corneal surgery. ArF-excimer lasers emitting at 193 nm are well known for their excellent quality in tissue processing. On the other hand, the excimer laser suffers from the disadvantages of high prime and operating costs, expensive beam delivery systems, handling with hazardous gas and its bulky dimensions.
The Modelling of Diode Laser Transscleral Cyclophotocoagulation of Ocular Biotissues
Authors: Pustovalov V.K. , Kotelevets S.V. , Smetannikov A.S. , Jean B.
Published: February 2023

The computer modelling of optical and thermal processes of diode laser transscleral cyclophotocoagulation of ocular biotissues for the purposes of medical treatment of glaucoma is performed. A mathematical model of optical and thermal processes is elaborated and the results of computer simulation are presented. In this case the computer simulation allow one to accomplish a detailed treatment of process characteristics, the influence of radiation parameters on the results of laser radiation action on ocular biotissues and to provide the possibility for optimization of laser treatment regimes.
Stresses and Damages Generated on Different Materials by Laser Induced Vapor Bubble
Authors: Isselin Jean-Christophe , Alloncle Patricia , Autric Michel
Published: February 2023

Focusing a high power laser beam in a transparent liquid is a convenient technique to generate and to study the dynamics of an isolated vapor bubble. Beyond a certain threshold of power density the dielectric breakdown of the medium occurs. This phenomenon is characterized by the formation of a luminous plasma and the emission of a strong spherical shock wave. The plasma is quickly replaced by a vapor bubble, which expands to a maximum volume and then collapses. At the end of the collapse phase, the pressure inside the bubble rapidly increases and a second shock wave is generated. Then, the cavity can follow several oscillations.
A New Configuration of Unstable Resonator for Low Gain Active Medium
Authors: Pokhsrarian K.
Published: February 2023

New resonator configuration developments to obtain almost complete extraction of the stored energy from a large-volume active medium, to produce a diffraction-limited laser beam continues to be of interest Unstable resonators are used to generate a nearly diffraction-limited output beam from a large-diameter active medium. However, an unstable resonator may be used for a gain medium that has a reasonably high round-trip gain.
A water passively Q-switched Cr:Yb:Ho:YSGG laser
Authors: Zagumennyi A. I. , Zavartsev Yu. D. , Umyskov A.F. , Osiko V.V. , Shcherbakov I. A. , Studenikin P. A , Zerrouk A.F.
Published: February 2023

The potential of many application in laser medicine has inspired extensive studies in recent years related to development of 3 pm solid state lasers, based on Er3+-doped crystals (YAG, YSGG, YLF, YAlO3, CaF2) and Ho-doped crystals. New Cr,Yb,Ho: YSGG crystal is very suitable active medium for solid-state laser, it combines a high lasing efficiency with high gain coefficient, and it makes possible to tune continuously the output radiation wavelength in the range 2.84 - 3.05 µm. The Er3+ and Ho3+ crystal have the essential different of upper laser level population mechanisms.
InGaAs/GaAs piezoelectric lasers
Authors: Khoo E. A. , Woodhead J. , David J. P. R. , Pabla A. S. , Grey R. , Rees G. J.
Published: February 2023

Strained InGaAs quantum wells grown on (111) GaAs are known to be piezoelectric owing to the polar nature of the zinc blende crystal. The resulting built-in electric field can modify the electronic band structure and its optical properties, leading to interesting device applications in electro-optics and non-linear optics.
Effects of P-Doping on the Hot-Electron Cooling in Semiconductor Lasers: Phonon Bath Sharing and Electron-Hole Starring
Authors: Tsai Chin-Yi , Chen Chih-Hsiung , Sung Tien-Li , Tsai Chin-Yao
Published: February 2023

Cooling of hot carriers and phonon dynamics are two major physical processes in the hot-carrier regime of semiconductors and semiconductor nanostructures where the carrier temperature is different from the lattice temperature [1][2]. Since the optical susceptibility (thus, gain and refractive index) is a function of the carrier temperature, carrier heating relating to these two processes is expected to play an important role on the performance of semiconductor lasers, such as modulation bandwidth, frequency chirping, nonlinear distortion, linewidth rebroadening, and power-independent linewidth. It was also experimentally demonstrated that a subpicosecond switch-off and switch-on of semiconductor lasers can be realized by such a transient hot-carrier effect.
A highly integrated system for fast, flexible and comprehensive characterisation of semiconductor lasers.
Authors: Larkins E C , Dods S R A , Andrianov A V , Morgan J , Harrison I , Benson T M , Orton J W
Published: February 2023

The field of high power semiconductor lasers has become one of the most competitive and fastest growing areas in optoelectronics, with commercial applications ranging from materials processing to medicine. As a result, it has become critical for manufacturers to improve the performance and reliability of their laser bars, while simultaneously reducing their cost and time to market.
Passive Q-switching and nonlinear spectroscopy of Cr4+: (Ca,Sr)Gd4(SiO4)3O crystals
Authors: Mikhailov V.P. , Yumashev K.V. , Posnov N.N. , Denisov I.A. , Moncorge R.
Published: February 2023

Cr4+-doped crystals are known as lasing media for tunable solid state lasers in the near infrared spectral range as well as useful passive Q-switches for several solid-state lasers. These applications motivate an active search for new crystal hosts doped with the Cr4+ ion. Recently, room temperature laser action have been demonstrated for Cr4+-doped SrGd4(SiO4)3O (Cr4+:SrGdSOAP) and CaGd4(SiO4)3O (Cr4+:CaGdSOAP) crystals at 1.44 µm and 1.37 µm, respectively.
Investigation of Spectropolarization Characteristics of Leaf Reflected Radiation for Some Potato Sorts
Authors: Belyaev B. I. , Belyaev Yu. V. , Chumakov A. V. , Nekrasov V. P. , Shuplyak V. I.
Published: February 2023

The polarization characteristics of radiation reflected by the plant leaves are most sensitive to the changes of plant structure as compared with the other factors. Studies of the spectropolarization characteristics angular dependencies of radiation reflected by the plant leaves allow to investigate the mechanisms of reflected radiation flux formation: the specular reflection on the leaf surface, the singly and multiply scattering within leaf, the leaf pigment absorption, and the cuticle refraction of radiation going out from the leaf.
Excited-state dynamics and energy transfer processes involved in the 1.5 and 2.3µm laser transitions in Yb:Tm doped LiYF4 and KY3F10 single crystals
Authors: Braud A. , Girard S. , Doualan J.L. , Moncorgé R. , Diaf M. , Thuau M.
Published: February 2023

Tm doped fluoride crystals sensitized with Yb ions were early recognized as very efficient upconversion laser materials for visible room temperature operation under infrared excitation. Recently, the advantage of ytterbium as codopant was pointed out to enhance the 1.5µm emission 3H4→3F4 and to avoid the bottlenecking effect on this laser transition[1]. In order to determine several energy-transfer parameters involved in the excitation processes of Yb-Tm doped laser materials, samples of Tm:Yb:LiYF4 and Tm:Yb:KY3F10 with different dopant concentrations were grown by Czochralski technique, oriented and cut. Energy transfer processes and upconversion effects in Tm:Yb codoped fluoride crystals were quantitatively studied with classical energy transfer models (direct dipole-dipole interaction - Förster-Dexter model extended by Inokuti-Hirayama and migration assisted energy transfer - Yokota-Tanimoto or Burshtein models), using absorption, emission and excited-state absorption cross sections experimental data as input parameters. The results were systematically compared, in the case of fast energy migration, with those deduced from the adjustement between the rate equation model and the measured kinetics of the excited state levels of the Yb (2F5/2) and Tm (3F4,3H4, 1G4 and 1D2) ions. Both decay times after short pulse excitation and rise times after square-pulse shape excitation on the Yb ions were investigated to obtain a complete description of the excitation scheme for the Tm upper energy levels.
Microdisks with circular photonic bandgap boundaries exhibiting high-quality low-order modes
Authors: Labilloy D. , Benisty H. , Weisbuch C. , Krauss T.F. , Smith C.J.M. , Houdré R. , Oesterle U.
Published: February 2023

Novel microcavities are fabricated that consist of GaAs microdisks (~3 μm diameter) sandwiched between AlAs cladding, bounded by a circular grating of deeply etched air trenches. An emitting layer of InAs quantum dots is inserted in GaAs. The grating acts as a 4th-order Bragg reflector for the in-plane cavity, so that some 2nd-order diffraction towards air can occur. This allows to observe upwards the horizontal resonances through the mode leakage. Microdisks modes usually require high azimuthal number l to be confined through total internal reflection, while drum-like modes with low-azimuthal number l only see the poorer normal reflection at the semiconductor-air interface (30%). In our cavity, the circular Bragg mirror is highy reflective for these low-l modes. Peaks with Q’s up to 650 are observed, and modes are tentatively identified up to l=6. The cavity finesse peaks at 50, corresponding to a reflectivity in excess of 85%.
Solid State Materials for Raman Lasers
Authors: Basiev Tasoltan T. , Zverev Petr G. , Sobol Alexander A. , Powell R. C.
Published: February 2023

Stimulated Raman Scattering (SRS) in solid state materials is a new extensively growing area in laser physics. SRS allows to change laser radiation frequency with the certain energy shift that is determined by the crystal structure of Raman material. The advantage of solid state Raman material is their high concentration of Raman active centers and their favorable thermal and mechanical properties. There is a limited number of solids that have been identified to possess the narrow, isolated and intense Raman active vibronic modes which are necessary for efficient SRS scattering. Intense modes in solids can be attributed to internal symmetrical vibrations within molecular ionic complexes, such as [CO3], [NO3], [SO4], [WO4] and similar. In spite of a large number of solids which exhibit SRS properties, nitrates of alkaline and alkali-halide metals attract attention as the most promising class of Raman laser media.
Photosensitive lead germanate glass waveguides grown by Pulsed Laser Deposition
Authors: Mailis Sakellaris , Riziotis Christos , Wang Ji , Taylor Beth , Anderson Andrew , Barrington Steven , Eason Robert W , Grivas Christos , Vainos Nikolaos
Published: February 2023

Photosensitivity in (predominantly) germanium doped fibres and planar waveguide structures is the subject of intense current interest. Permanent refractive index gratings, written using UV light from either pulsed or c.w. laser sources, can be produced by interferometric exposure, yielding Δn values ranging from 10-5 to 10-3. Additional techniques such as hydrogen loading, or flame brushing, can further increase this value to ~10-2. In this paper, we report our studies of planar waveguides of lead germanate glass, grown by Pulsed Laser Deposition. The films are grown under various partial pressures of oxygen, and show distinct and systematic differences in colour, waveguide loss and photosensitivity. We interpret our results in the context of induced oxygen vacancies produced during the growth.
Longitudinally Pumped By Several Laser Diode Bars 1-khz Q-switched ND:YAG Laser with Nonlinear Frequency Conversion
Authors: Mak A.A. , Oriov O.A. , Novikov G.E. , Ustyugov V.I. , Ivanov V.B. , Kriganovsky V.I. , Papernyi S.B.
Published: February 2023

The usage of compact diode-pumped nanosecond pulse length, mJ energy and kHz repetition frequency range QCW lasers seems to be very prospective for such applications as micromachinery, spectroscopy, photolithography, color laser displays, etc. Application areas could be sufficiently extended if the near IR laser output could be efficiently converted into the visible and UV spectral ranges1 (see also Lambda Physik product data: StarLine laser) Assuming the typical Q-switched Nd:YAG laser optical conversion efficiency (at 1064 nm) of about 20 - 30% (with respect to absorbed pump power at 808 nm) one can estimate the required peak pump power incident to the gam crystal (at 300-μs pulses) being in the range of from tens to hundreds of Watt. The corresponding average pump power should be of the order of tens of Watt (at duty cycle of about 20 - 30%). Meaning thermal loading, this level is permissible for end pump layout, which is preferable from a view point of laser conversion efficiency and beam quality. The required pump power for such a laser can be provided by several high power laser diode bars (LDBs), but there is a problem of a proper beam shaping to provide circular symmetrical and tight focusing of a pump light into laser crystal. One of the ways of laser diode bar combining and shaping was reported earlier2. In this paper we describe a QCW Nd.YAG laser of the IR, visible and UV ranges, using the modification of mentioned pump technique. It should be also noted that this technique is especially valuable for lasing at quasi 3-level 946-nm neodymium transition.
Optical Neural Network Training on a Reconfigurable Processor
Authors: Naughton T. J. , Keating J. G. , Rott J. , Klíma M.
Published: February 2023

We present the initial experiments of a project to train large-scale artificial neural networks (ANNs) using a reconfigurable optical processing system. The system is built around a Calomel (mercurous chloride) acousto-optic (AO) matrix-vector multiplier[1]. The matrix of weights are displayed on a two-dimensional LCD (liquid crystal display) panel and the input vector is encoded in the acoustic wave of the AO unit. This system has been investigated in order to determine the processing limits due to (i) the combination of individual components and to (ii) the fundamental limits imposed by the nature of this optical processing technique.
A High-Speed 12-Layer Two-Dimensional Bar-Code Detection System with Balanced Raster Scanner
Authors: Wakatmi Hiroo , Ajiki Hiroshi
Published: February 2023

Two-dimensional (2D) bar-code detection systems (BCDSs) have great possibilities for use in high-speed process automation systems because they permit direct access to management information data. The conventional 2D BCDSs used to detect 2D bar codes such as Code16K and Code49, mainly use a raster scanner with a tilted axis. This scanner, however, is not sufficient for high-speed applications (such as goods management in production lines), since its speed is limited to nearly 500 scan/s at most due to low stability and low durability. This is because the center of gravity greately deviates from its central axis and the ball-bearings around it are easily worn especially in high-speed rotation.
Sunlight Holography: the First Holograms and Holographic Interferograms Produced Under Direct Sunny Illumination
Authors: Petrov Valery
Published: February 2023

The first holograms and holographic interferograms are obtained under direct sunny illuaination. They are rapidly produced on ultra high resolution silver halide media utilizing momental monobath technique1. High quality holographic reconstructions were obtained in spite of tremendous white light exposures.
Femtosecond dynamics in semiconductor lasers: ‘dark pulse’ formation
Authors: Kauer M. , Heberle A. P. , Cleaver J. R. A. , Baumberg J. J.
Published: February 2023

The dynamic behavior of semiconductor lasers (LDs) and amplifiers (SOAs) reveals fundamental information about the electron and photon systems and their interplay on a wide range of timescales. Subpicosecond optical pulses probe these interactions well, as their propagation is very sensitive to the underlying electron and photon dynamics.
ISO Standards for Measurement of Laser Beam Parameters
Authors: Giesen Adolf
Published: February 2023

The characterization of laser beams and laser optical components generates much interest among laser users and manufacturers. It is the subject of discussion by national and international standardization committees and the focus of an important European project (Eureka project EU-1269: CHaracterization of Optical Components and Laser Beams, also known as CHOCLAB).
SBS Mirrors for High Power Lasers
Authors: Anonymous
Published: February 2023

This paper is an overview of results obtained in investigations of SBS-based phase-conjugated devises: new possibilities and results achieved at the Institute of Experimental Physics of the Russian Federal Nuclear Center on development of SBS mirrors for a wide range of lasers (gas and solid-state). Special attention has been paid to questions of preparation and inlet of the SBS-mirror gas media. We give the SBS cell parameters and characteristics of various gas mixtures in a wide range of pressures and densities also including characteristics near the critical point and of liquefied gases as well. We give experimental results from investigations of processes competing with SBS at pulse lengths from 2ns to tens of microseconds when irradiated by single pulse or repetitively pulsed radiation with the pulse rate up to hundreds of kHz. The possibility of self-compensation of thermal and striction distortions in the SBS medium has been demonstrated experimentally. We have formulated criteria for selection of mixtures for SBS mirror operation under various conditions taking into account radiation self-action.
Waveguide Resonators
Authors: Baker H J , Cao Q , Chesworth A , Hall D R
Published: February 2023

Laser resonators which incorporate planar waveguide propagation are now perhaps the most common type, through their use in semiconductor diode lasers. Here, waveguiding is essential for good mode overlap with the sub-micron thickness of the gain region. However, the narrow guides in edge emitting diode lasers produce the well known problems of facet damage and large fast-axis beam divergence, whilst non-linear focusing effects limit the width scaling of power for broad junction diode laser. Only recently has the alternative of vertical cavity, surface emitting laser diodes started to change this picture.
Intracavity phase conjugation in active medium of frequency selective pulsed CO laser
Authors: Ionin A.A. , Kotkov A.A. , Kurnosov A.K. , Napartovich A.P. , Seleznev L.V.
Published: February 2023

Energetic, temporal and spectral characteristics of the phase conjugation (PC) process at intracavity degenerate four wave mixing (DFWM) of frequency selective pulsed ebeam controlled discharge (EBCD) CO laser radiation are studied both experimentally and theoretically. Laser gas mixture CO:N2:He=1:4:5, gas density 0.3 Amagat, gas temperature 120-140 K, interaction angle ~10 mrad at DFWM without optical delay between probe wave E3 and co-propagating pumping one E1, active medium length 1.2 m, laser resonator length 17.7 m. PC reflectivity (PCR) on energy was ~1%, being independent of specific input energy. The dependencies of PCR on pressure had quite different behavior for different selected spectral lines. An influence of the neighboring vibrational band lasing on PCR for the spectral line under the investigation is demonstrated (Tab.l), PCR decreasing at switching on neighboring line lasing.
Laser startup for magnetic fusion
Authors: Frank Alan M.
Published: February 2023

Using a laser to create a hot plasma appears to be a viable technique for starting up a magnetic mirror machine. Hitting a solid pellet with a focused high-power laser produces a plasma rapidly enough to overcome the buildup instabilities of other techniques.
Design, construction, and initial performance of ARGUS: a two-beam laser irradiation facility
Authors: Simmons W. W. , Allen G. A. , Neef W. S. , Wallerstein E. P.
Published: February 2023

The ARGUS laser system is presently performing irradiation experiments leading toward laser fusion at the Lawrence Livermore Laboratory. The laser is a two-arm system with 20-cm final amplifier apertures and is capable of delivering more than 3 TW of focusable power to laser fusion targets. This capability is planned to be upgraded in the near future. In this paper we describe the physical characteristics of the laser and associated facility and some important components incorporated therein, and we shall summarize system performance to date.
Design techniques and measured performance for a uniformly pumped 4-cm diam rod amplifier
Authors: Linford G. J. , Yarema S. M.
Published: February 2023

Laser amplifiers designed for use in laser fusion systems must necessarily meet stringent gain uniformity requirements in order to avoid impairing the laser beam apodization. Since the intensity profile of the laser beam directly affects the illumination uniformity (and hence the implosion symmetries) of laser fusion targets, it is essential that the individual laser amplifiers in each amplifier chain have high gain and highly uniform gain distributions. For large aperture glass laser rod amplifiers, this is difficult to achieve since the pumping radiation from the flashlamps must pass through the outer portions of the laser rod before the axis can be pumped.
Thermal imaging systems principles
Authors: Lloyd M.
Published: February 2023

Infrared cameras, which image natural 10-µm thermal emissions, have become the preferred means for seeing at night. Fifteen years of intensive thermal imaging development have resulted in mature devices that perform near the theoretical limits.
Special purpose applications of the Philips MCA videodisk system
Authors: Kenney George C.
Published: February 2023

A description of special purpose applications of the standard videodisk player including computer interfaced digital rom, x-ray, and high resolution picture/document archival storage, and talking encyclopedia will also be given.
Mastering and replicating of optical videodisks
Authors: Winslow John
Published: February 2023

Optical videodisk mastering and replicating can be summarized as follows: first, enough small marks are made on a 12-in. diam disk to define 30 min of good video. Then the marks are duplicated cheaply and accurately enough to give the consumer good TV on a disk he can afford.
Lasercutting: current and future applications
Authors: Salyer Robert
Published: February 2023

In 1968, Hughes Aircraft Company began investigating techniques for cutting single layers of apparel fabrics at a speed, accuracy, and cost required for economic application in the apparel industry. Forty-two methods were studied, and lasercutting was selected as the most promising. In 1969, Hughes began developing a lasercutting system.
Point-of-sale scanner: designed for production
Authors: Hebert Raymond T.
Published: February 2023

There have been many implementations of label reading systems over the years to handle a wide range of individual applications. Many potential users have been discouraged by the customizing costs, economic uncertainties, and lack of credible long-term service plans for such equipment. But a careful consideration of the economic justifications and the establishment of a powerful encoding standard by an organization of the end users themselves have created a strong and committed market. Specifically, the Uniform Grocery Product Code Council has established the Universal Product Code (UPC) for application to food products to permit automated checkout and inventory control in the nation’s 40,000 plus supermarkets.
Development of a high-speed dual-lag photon processor
Authors: Mayo W. T.
Published: February 2023

In some of the more difficult applications of laser Doppler velocimetry such as in combustion research, transonic flow, transverse wind, and others, the optical signals are too small for classical detection methods. This paper summarizes the theory, experimental prototype hardware, and test results for a new type of high-speed photon-correlation signal processor which is being developed for weak laser velocimeter signals and other photon-resolved signals. The new system may also be considered to be a statistical digital frequency discriminator. It uses full multiplication with 10-nsec delay time and has the potential for extension to the measurement of the velocity correlations and spectra.
Damage resistant optical components for 2-5-μm laser systems
Authors: Leung K. M. , Tang C. C. , Bass M. , Soileau M. J.
Published: February 2023

In recent years, alkaline-earth fluoride materials have been developed for use as high performance optical components in lasers operating in the spectral range from 2 μm to 5 μm (for example, HF and DF lasers). However, as in the cases of high power Nd glass and CO2 lasers, damage to optical components due to extremely high optical fluxes has proved a severe system limitation. Suitable 2–5-μm optical materials for damage resistant optics have not yet been evaluated systematically using a well-controlled laser source in this spectral region. In this paper we will discuss the properties of candidate optical materials for high-power 2–5-μm laser systems and present experimental data on damage resistance for the best obtainable samples. This information describing the laser–light-material interaction will provide electrooptical system engineers with data essential to the design of reliable high-power 2–5-μm lasers.
Recent developments in injection lasers
Authors: O’Brien J. T. , Limm A. C. , Hughes F. R.
Published: February 2023

A status report summarizes the improved performance characteristics resulting from the application of restricted area contacts to single and double heterojunction laser structures. A geometric description of the process known as the stripe geometry contact is given as it relates to both GaAs and AIGaAs injection lasers. Application of the striped contacts to the fabrication of both pulsed and cw lasers has resulted in significant improvements in both performance and reliability of these devices. Data are presented that establish the superior device performance and reliability of both high peak power pulsed devices and room temperature cw lasers. The data include extended operating life tests for both pulsed and cw devices, comparisons of catastrophic damage limits, power output efficiency, as well as output and threshold current as a function of temperature. Radiation patterns, risetime, and polarization characteristics are also described. The paper also summarizes characteristics of cw injection lasers which can be supplied in a variety of packaging configurations. These devices have demonstrated analog modulation bandwidths well in excess of 100 MHz and appear well suited to use with available fiber optics materials having transmission windows in the 820-nm range.
Instrumentation for pulsed laser spectroscopy
Authors: Klauminzer Gary K.
Published: February 2023

Pulsed laser instrumentation will be discussed, emphasizing advantages and limitations of engineering designs and techniques toward achieving optimum signal-to-noise with low cost, ease of operation, and reliability in a normal laboratory environment.
Assessing Contact Lens Edge geometry and base curve radius using a clinical OCT: an in-vitro study
Authors: Ares Jorge , Tolón Nerea , Otin Sofia , Gargallo- Diana
Published: February 2023

The purpose of this study was to evaluate the potential use of a clinical spectral domain Optical Coherence Tomography (OCT) to characterize the contour of Contact Lens (CL) edges and measure the Base Curve Radius (BCR) of Rigid Gas-Permeable Contact Lenses (RGP CL) in vitro. An optomechanical adapter was designed and 3-D printed to facilitate imaging of the CLs with a commercial OCT (3D OCT-1000). Image processing algorithms and a simple calibration method were developed to obtain accurate BCR estimates from the OCT B-scan images. The results showed that the 3D OCT-1000 combined with the adapter could acquire images with enough quality to discriminate different edge geometries of contact lenses. Additionally, the statistical analysis of the BCR measurements demonstrated that the OCT measurements were accurate and repeatable, nearly meeting the standards of accuracy and repeatability proposed by ISO 18369-2:2018-3.
A comparative evaluation of intranasal α2-adrenoceptor agonists and intranasal midazolam as premedication in pediatric sedation: A meta-analysis of randomized controlled trials
Authors: Fu Yuzhi , Zhang Qianqian , Jiang Yongxian , Lang Bingchen
Published: February 2023

Background

Midazolam and α2-adrenoceptor agonists have been widely used off-label as intranasal sedatives for children. The present meta-analysis aimed to evaluate the effects of two interventions in pediatric sedation.

Methods

PubMed, Embase, and Cochrane Library were searched from inception to April 2022. All randomized controlled trials used intranasal α2-adrenoceptor agonists and midazolam as sedatives in children were enrolled. Parental separation, anesthesia induction or facemask acceptance, sedation level, different hemodynamic parameters and adverse events were considered as outcomes.

Results

Totally 21 studies with 1,495 patients were included. Only one study reported comparison between midazolam and clonidine met the inclusion criteria, and patients in clonidine group had significantly better mask acceptance compared to midazolam group. Compared with midazolam, using of dexmedetomidine was associated with higher rate of satisfactory parental separation (52.88% vs 75.18%, RR = 0.70, with 95%CI [0.55, 0.90]), anesthesia induction or facemask acceptance (60.92% vs 81.47%, RR = 0.76, 95% CI [0.68, 0.84]) and less incidence of postoperative pain and nasal irritation.

Conclusion

Compared with midazolam, dexmedetomidine should be considered as the preferred intranasal sedative option for pediatric patients, since it provides more satisfactory sedative level with less incidence of several side effects. But insufficient evidences about effects of intranasal clonidine and overall low and moderate quality evidences evaluated by GRADE system indicate that superiority of intranasal α2-adrenoceptor agonists in pediatric sedation needs to be validated by more studies with high quality and large sample size in future.