bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of array Nd : glass slab lasers operating at high repetition rate
Authors: Yoshida K. , Ochi K. , Kotera T. , Namikawa N. , Kaku S.
Published: February 2023

A high average power solid-state laser operating at high efficiency is desired, especially for application to material processing. As is well known, it is very difficult to produce a large Nd:YAG crystal with high optical homogeneity. On the contrary, laser glasses of large size with optical homogeneity of ±1 × 10-6 can be easily obtained. High frequency operation of laser glass is very difficult due to low thermal conductivity of glass. However it is expected that we can obtain high average power using this high-quality Nd:glass by the solution of thermal effect problems due to pumping light.
Spatial mode structure of laser arrays and phase domains
Authors: Mercier J. , McCall M. W.
Published: February 2023

Considerable effort has been directed at determining the spatial and temporal characteristics of semiconductor laser arrays. Apart from its technological significance, this interest can partly be ascribed to the fact that in regarding the system as a set of coupled oscillators, the laser array exhibits interesting nonlinear behaviour that is not as complex as the continuum spatio-temporal investigations centred around transverse effects in, for example, lasers operating at high Fresnel number.
Controlled self-pulsation and coherence length reduction up to high power levels using tandem-electrode quantum well lasers
Authors: Knop Werner , Harder Christoph , Bächtold Werner
Published: February 2023

Self-pulsating lasers are used for optical storage and have been proposed for subcarrier networks.1 In single-section lasers the pulsation frequency can only be controlled by the injection current and is restricted by absorber bleaching. Furthermore, the pulsation frequency is not well defined owing to tolerances in the fabrication process. Multisection lasers offer the possibility of independent control of gain and absorption due to the separate bias.
GalnAsSb injection lasers operating near 2.1µm up to 130°C
Authors: Baranov A. , Fouillant C. , Boissier G. , Grech P. , Gaillard S. , Alibert C. , Joullié A.
Published: February 2023

Laser diodes operating at wavelengths around 2µm are useful for applications such as molecular spectroscopy, "eye safe" communication sources, and pumps for the Ho-YAG solid-state laser system. Lasers with structures containing a GalnAsSb active region and AlGaAsSb confining layers have shown good performance in the 1.8–2.5µm wavelength domain.1-3 In this communication we present double heterostructure (DH) lasers operating at temperatures up to Tmax = 130°C, which is the highest maximum temperature reported to date for conventional DH lasers emitting at more than 2 µm.
All-optical absolute frequency stabilization of a laser diode through polarization spectroscopy
Authors: Liu Z. , Loe-Mie R. , Bloch D. , Ducloy M.
Published: February 2023

Although laser diodes have an intrinsically broad emission linewidth with very quick frequency fluctuations, it is quite tempting to extend their broad range of applications to the design of compact optical clocks with absolute frequency stability. Indeed it is known1 that the high sensitivity of laser diode emission frequency to any backreflection can be used to implement nearly all-optical schemes of frequency stabilization on an optical resonance. To reach absolute frequency stability, a major task is to resonantly generate a high-contrast retroreflected beam from a spectroscopic experiment.
Retrieving the laser beam intensity distribution from the temperature field of the heated target surface
Authors: Aksenov V. , Isaev Yu. , Zakharova E.
Published: February 2023

In the study of a powerful laser beam one faces a problem of measuring its intensity distribution over the laser beam cross section. A possible approach to the solution of this problem is to retrieve the intensity distribution I(ρ, t) from measurements of the temperature field T (ρ, t) upon heating a target surface by the laser radiation. The advent of devices designed for remote sensing of the surface temperature fields, in particular, thermal imaging systems providing for high spatial and temporal resolution of measurements, makes it possible to solve this problem. The theory of solving the inverse heat transfer problem for a uniform target irradiated with a nonuniform laser beam was reported.1 This paper contains new theoretical and numerical results that could be applied when using a powerful large-diameter laser as a heater. The algorithms have been developed to retrieve the spatial and temporal intensity distribution based on the theory of generalized function.2 The accuracy of algorithmic characteristics was estimated for the typical energy distribution.
Optimal external cavity phase filter for side lobe suppression in phase coupled CO2 waveguide laser array
Authors: Lescroart G. , Muller R. , Bourdet G. L.
Published: February 2023

Phase coupling of laser array is capable to supply high coherent power with diffraction limited beams. Generally the far field pattern of such phase coupled arrays are made of several intensity peaks, the number and intensity of which depend on the geometrical design of the array. We could define the ratio (R) as the energy in the central lobe on the total energy emitted by the array.
Investigation of the transverse-mode properties of laser cavities equipped with interferometric frequency filtering elements
Authors: Nichelatti E. , Palombini M. , Salvetti G.
Published: February 2023

Many diffraction calculations have been carried out up to now, both numerical and analytical, to determine the transversemode properties of laser resonators. Generally these calculations have been based on simplifying assumptions to reduce the problem complexity and, consequently, have been limited to only a few configurations, while more extensive analyses have considered only the eigenmodes of conventional, empty resonators. In particular, little attention has been paid to investigate the transverse-mode properties of optical cavities equipped with interferometric frequency filtering elements (IFFEs), such as etalons, or multipass interferometric reflectors, which are utilized for achieving single-longitudinalmode operation, narrow-band frequency tuning, and shot-to-shot output frequency stabilization. One can expect that the presence of these optical elements modifies both the spatial and spectral features of the oscillating modes, since it has been demonstrated that their insertion in an optical cavity induces nonlinear variations of the phase of the cavity's electric field that is equivalent to an actual change of the cavity length.1
A Ti:sapphire tube laser pumped with dense plasma emission and internal spectrum conversion
Authors: Han K. S. , Lee J. H. , Seo J. T.
Published: February 2023

A Ti:sapphire hollow-tube laser has been pumped with annular plasma emission from a hypocycloidal pinch-plasma (HCP).1 The plasma color temperature was approximately 1 eV. The hollow of the Ti:sapphire tube was filled with dye solution for spectrum conversion2 from the near-uv to 490-nm pump band of Ti laser. These new ideas for improving the laser pumping efficiency were experimentally demonstrated. The operating conditions of the HCP were the following: The input electrical energy to HCP was 3.57 kJ, argon fill gas pressure 90 Torr, and Coumarin 503 dye as the spectrum converter. The pump pulse had a halfwidth of 13µs and a rise time of 2µs. The dimensions of the laser cavity were cavity length 295 mm, gain length 150 mm. Ti:sapphire crystal was in a hollow tube 150 mm long, its outer diameter 10 mm with a wall thickness of 3 mm, leaving a 4-mm diameter hole inside (Fig. 1). The untuned laser output was ≈ 45 mJ at λc =841 ± 4 nm and its temporal halfwidth was 0.35µs. Figure 2 compares the laser output with an without the internal spectrum converter solution as a function of the reflectance of the output coupler.
New data on induced-emission cross section in solid-state laser materials
Authors: Balashov I. F. , Berezin B. G. , Ivanov V. N.
Published: February 2023

The values for induced-emission cross section of laser glasses and crystals determined from standard absorption and emission measurements and Judd-Offelt calculations are not sufficient to describe the generation properties of laser materials. A more successful way to determine effective values for laser material cross section is based on mathematical approximation of output to input energy characteristics realized in lasers with known resonator parameters.
Modelling of blue lasing in Pr:YAG waveguide lasers
Authors: Szczepanski Paweł , Tyszka-Zawadzka Anna , Malinowski Michał , Lukasiewicz Tadeusz , Łuczynski Zygmunt , Frukacz Zygmunt
Published: February 2023

The impact that an efficient, inexpensive, and reliable visible laser source would have on data storage, display technology, undersea communications, and optical processing has provided the stimulus for much recent work on solid state visible lasers. For many applications it is of essential importance to be able to design the laser for a given oscillation wavelength providing maximal power efficiency. Unless additional selective elements are included in the laser cavity, the oscillation wavelength will for a given cavity loss be chosen by the spectral shape of the emission and absorption cross sections. In general, because the spectral properties are dependent on hosts and index-raising dopants,1 time consuming numerical analyses will normally be required to predict laser operation.
Site-selective measurements of nonradiative relaxation rates of 4G5/2+2G7/2 multiplet of Nd3+ ion in SrF2:Nd3+ and SrF 2 x : LaF 3 ( 1 − x ) : N d 3 + laser crystals
Authors: Orlovskii Yu. V. , Basiev T. T. , Vorob'ev I. N. , Alimov O. K. , Papashvili A. G. , Osiko V. V.
Published: February 2023

Here we present the results of investigation of the nonradiative relaxation (NR) rates dependence of the strongly quenched (A ≪ WNR) high-lying 4G5/2 + 2G7/2- multiplet of the Nd30+-ion from the excitation wavelength in the multicenter (SrF2) and disordered

(

SrF

2
x

:

LaF

3

(

1
−
x

)

)

laser crystals.
Investigations on a Ne-H2 Penning plasma laser operating in a hollow cathode discharge
Authors: Petrov G. M. , Pramatarov P. M. , Stefanova M. S.
Published: February 2023

Penning plasma laser is a laser whose upper laser level is populated through recombination processes and the lower laser level is intensively depopulated through Penning reactions with buffer gas atoms or molecules.1 In the Ne-H2 Penning plasma laser the hydrogen gas plays the role of the Penning component.
Emittance and current measurements of electron beams induced by excimer lasers on Zn targets
Authors: Beloglazov A. , Castellano M. , Causo M. S. , Nassisi V. , Patteri P.
Published: February 2023

High brightness electron beam (e-beam) injectors are necessary for seeding the new accelerators. The RF photocathode guns have confirmed the possibility of getting emittances much lower than those provide by thermionic source.1 In particular, metal photocathodes seem to be very promising for their capability to work in degraded vacuum and to work with excimer lasers. They seem also very promising in getting emittances much lower than those provide by thermionic source.2
Multiquantum well infrared detectors
Authors: Rosencher E. , Bois P. , Duboz J. Y. , Vinter B. , Nagle J.
Published: February 2023

Carrier confinement in ultrathin semiconductor heterostructures leads to energy quantization. These artificial energy levels can be tailored to match any optical transition in the 3–20-µm-photon wavelength range by adjusting the quantum well width and the barrier composition. Optical transitions between bound and extended levels of these quantum wells give rise to a photocurrent, which is exploited for photon detection in Quantum Well Infrared Photoconductors (QWIPs). In this communication, we summarize the present understanding of the physics of QWIP detection: photoexcited carrier emission and capture probability, contact injection, and noise mechanisms. We also present the current status of the QWIP technology for infrared staring arrays and illustrate the major advantages of this new technology:

• Standard III-V substrates and technology, thermal stability, uniformity, large areas, low development costs, radiation hardness

• Adjustability from 3 to 20 µm

• New functions: multispectrality, spectrophotometry, band switching, optical reading.
Infrared detector research and development in the United Kingdom
Authors: Elliott C. T. , Baker I. M.
Published: February 2023

The current trends in infrared detectors are principally towards larger electronically addressed arrays and towards reduced cryogenic cooling requirements. In the UK the research activities have been mainly on hybrids of CdxHg1–xTe (CMT) and of ferroelectric materials on silicon. Large two-dimensional arrays and long linear arrays of CMT are presently fabricated in LPE material by the “loophole" interconnect technology. Results are presented for linear formats up to 1024 elements and for two-dimensional arrays of 128 × 128 elements. It is anticipated that loophole technology will be supplemented at some time in the future by a technology using MOVPE-grown heterostructures, so that the operating temperature of photon detectors can be increased by means of optical concentration or non-equilibrium operation. The former is described in terms of an individual field lens concentrator and the latter is illustrated by recent results on CMT and InSb/In1–x AlxSb heterostructures. The heterostructure devices, as well as producing significantly improved RoA, exhibit strong negative resistance effects at temperatures from 190 K upwards. Recent results of 128 × 256 arrays of uncooled ferroelectric hybrids fabricated by solder-bump bonding show very promising performance.
The physical origin of excess noise
Authors: New G. H. C. , Rippin M. A.
Published: February 2023

In an important 1979 paper,1 Petermann pointed out that, in certain laser resonator geometries, a typical mode may exhibit more noise than expected on the basis of the standard quantum mechanical "one photon per mode" prescription. It was subsequently shown by other authors2 that this arises because the self-producing field patterns that are commonly referred to as laser "modes" are not true modes of the radiation field. Rather than obeying the familiar condition of power-orthogonality, these satisfy the more general condition of biorthogonality with respect to a set of adjoint modes that correspond to the self-reproducing patterns travelling in the opposite direction.3
Analysis and design of resonators with Kerr media for femtosecond lasers
Authors: Magni V. , Cerullo G. , De Silvestri S. , Monguzzi A. , Svelto O.
Published: February 2023

Kerr Lens mode-locking (KLM) is a powerful technique for ultrashort pulse generation with a variety of solid-state lasers. This technique is based on the self-focusing effect in a resonator containing a Kerr medium, which modifies the transverse mode and results in power dependent losses or gain. Therefore the ultrashort pulse formation and stability crucially depend on the resonator configuration. Due to the complexity of these nonlinear resonators, their implementation is mostly based on empirical rules, in spite of a number of available theoretical works.1–3 Moreover, it is generally accepted that KLM cannot start without a suitable initiating device due to low nonlinear loss modulation.
Thermal annealing of the Si/SiO2 interface probed by surface nonlinear optical techniques
Authors: Meyer C. , Wolter F. , Lüpke G. , Emmerichs U. , Kurz H. , Yasuda T. , Lucovsky G. , Bjorkman C. H.
Published: February 2023

Optical second-harmonic (SH) and sum-frequency (SF) measurements on vicinal Si(111)-interfaces provide some quantitative details on the microscopic structure of the interface of thermally grown oxide films subjected to a post oxidation annealing. A change of the azimuthal SF-anisotropy upon rapid thermal annealing (RTA) is attributed to a relaxation of atomic bondings at the interface consistent with a decrease of the interfacial trap density.1
Conditions for optimum grating coupling efficiency in silicon-based waveguide technologies
Authors: Tikhomirov A. V. , Usievich B. A. , Sychugo V. A. , Parriaux O.
Published: February 2023

Silicon-based integrated optic technology has been the subject of a growing interest over the last ten years. As with other waveguide technologies, and in spite of its numerous intrinsic merits, not much can practically be made before the problem of the access to/from the waveguide has received a viable solution. Grating coupling is conceptually the most attractive solution since it fully planarizes the access function. One of the limitations of grating coupling is the weakness of the coupling efficiency unless smart but difficult solutions are used such as groove blazing1 or corrugation phase shifting.2 An inherent and remarkable advantage of Si-based technology is the very existence of the highly reflective silicon substrate which may allow a significant enhancement of the coupling efficiency without resorting to any additional technological step. It is easier to understand this by considering a waveguide grating coupler in its outcoupling regime. Let us imagine, as illustrated in Fig. 1, a step index slab waveguide of thickness h, index n2 on top of a silica buffer of thickness b, index n3. The substrate has a complex index n4 with large real part. The cover is generally air but can have the index n1. The zigzagging guided beam undergoes diffraction in both the cover and substrate at the grating of sinusoidal amplitude σ. The beam diffracted downwards experiences a strong partial reflection at the high index silicon surface; it will thus superpose with the wave diffracted upwards. Depending on the relative phase shift between these two waves, the net diffracted power will flow preferably into the air (a situation which is desired in an optical antenna application) or into the substrate (which is desired for waveguide power detection purpose).
Construction of partially coherent laser beams by eigenvalue methods
Authors: Gase R.
Published: February 2023

There are three reasons that relate partially coherent light to statistical quantum mechanics. First, it is shown that in the waist of a light beam the wave equation takes on the form of the time-independent Schrodinger equation.1 For a subclass of laser beams (for instance rotationally symmetrical beams), one waist with a plane wavefront exists. For these beams the wave equation has the form of a two-dimensional Schrodinger equation. Otherwise (for instance, astigmatic beams), we consider two one-dimensional Schrödinger equations in x and y directions, respectively.
High-power widely tunable solid-state lithium triborate optical parametric oscillator
Authors: Butterworth S. D. , McCarthy M. J. , Hanna D. C.
Published: February 2023

Optical parametric oscillators (OPOs) have seen a resurgence of interest with the availability of new materials and high-quality crystal manufacture. Synchronously pumped OPOs are potentially the ideal source for the many applications requiring widely tunable ultrashort pulses. For stability in both amplitude and frequency it is highly desirable to have only one of the two generated waves being resonated in a singly resonant oscillator (SRO). It has been shown previously1 that the average powers required to achieve threshold can be in the tens of milliwatts range, and are thus ideally suited for pumping by frequency-doubled diode-pumped mode-locked lasers. The OPO described here is based on a Brewster angled lithium triborate crystal. The advantages of using this crystal are Type I temperature-tuned noncritical phase-matching, which allows tight focusing and high intensities to be maintained over a very broad range of signal and idler wavelengths. Using an optional diode-pumped single pass Nd: YLF amplifier for the 1.047 μm light we have shown improvements in the average power of 60% without any degradation in the time-bandwidth product of the pulses. Average powers of the second harmonic have been improved to 480 mW in pulses of 1.9 psec at 105 MHz, giving a peak power of 2.4 kW. The LBO OPO has a threshold of 170 mW with pump depletions of 75% at 2.5 times threshold. Tuning is achieved over the ranges 0.65 to 1.0 μm (signal) and 1.1 to 2.65 μm (idler) using three mirror sets for the signal wave. A maximum output power of 110 mW with slope efficiency of 40% has been achieved at ~800 nm. Power output for the various configurations and mirror sets is shown in Figs. 1 and 2. Pulse durations of 1.5 psec are observed with time-bandwidth products of ~0.9. Further improvements to the power performance of the OPO are discussed as well as more detailed characterisation of the OPO. Preliminary attempts to control the spectral content as well as long term stabilisation of the absolute wavelength of the OPO pulse train is reported.
Experimental study on self-injection-locking oscillator
Authors: Ohzu A. , Kato M. , Arisawa T.
Published: February 2023

A new method to reduce divergence of copper vapor laser beam was developed successfully using double discharge. Divergence as small as a conventional injection locking oscillator system was obtained with the single bore unit.
Cr4+:YSGG-crystal as a Q-switch for single­frequency Nd laser
Authors: Tsvetkov V. B. , Klimov I. V. , Shcherbakov I. A. , Leininger L. , Phillipps G.
Published: February 2023

Recently Cr4+:YSGG-crystal was demonstrated to be very stable and reliable Q-switch for different Nd-type lasers.1 In the present paper the results of experimental study of the spectral and thermooptical characteristics of Nd:YAG laser with Cr4+:YSGG Q-switch as well as thermooptical properties and residual absorption of the Cr4+:crystal are presented.
The Cr3+:Yb3+:Ln3+:YSGG crystals as solid- state laser materials
Authors: Zavartsev Yu. D. , Osiko V. V. , Studenikin P. A. , Umyskov A. F.
Published: February 2023

The concentration of Ln3+ ions in gallium garnets doped by Cr3+ ions must be high enough to efficiently transfer energy Cr3+ →Ln3+. Low concentration of Ln3+ ions in some cases presents interest because it allows to avoid the concentrational quenching of some Ln3+ ion levels and to decrease the lasing threshold of three-level lasers.
Ultrafast phenomena in solid-state laser materials
Authors: Mikhailov V. P. , Kuleshov N. V.
Published: February 2023

The study of excited state dynamics in transition-metal-ion doped crystals are required for the development of tunable solid-state lasers and for the creation of new laser materials.
Electro-optic side-chain polyimide and its application to waveguide devices
Authors: Sotoyama Wataru , Tatsuura Satoshi , Yoshimura Tetsuzo
Published: February 2023

For electro-optic (EO) device applications, EO polymers must have a large EO coefficient and good thermal stability after poling. We developed an EO polyimide with nonlinear optical (NLO) chromophores as side chains, which is expected to have a high EO efficiency because of its high-density NLO chromophores and a good thermal stability because of its polyimide backbone. The side-chain polyimide we developed showed a large EO coefficient and longterm thermal stability at 120°C. Using the EO polyimide, we fabricated waveguide devices.
The lidar system in Physics Instrumentation Center for the stratospheric and tropospheric ozone sounding
Authors: Bucreev V. S. , Vartapetov S. K. , Veselovskii I. A.
Published: February 2023

The description of the lidar system developed in Physics Instrumentation Center for the stratospheric and tropospheric ozone sounding is presented. In this system two receiving telescopes of 60-cm and of 40-cm aperture are used. The spectrum analyzer of the first telescope is supplied with PMT operated in photon counting mode, it is designed for the ozone measurements in 4-40 km range. The PMT in the spectrum analyzer of the second telescope is of analog type; this telescope is used for the measurements in 0.3-5 km range.
Lens assemblies for multi-spectral camera
Authors: Lepretre François
Published: February 2023

In the framework of a contract with the Indian Space Agency (ISRO), MATRA DEFENSE—DOD/UAO have developed, produced, and tested 36 types LISS 1-LISS 2 lenses and 12 LISS 3 lenses equipped with their interferential filters. These lenses are intended to form the optical systems of multispectral cameras aboard Indian earth observation satellites 1RS 1A, 1B, 1C, and 1D. It should be noted that the multispectrum cameras of the 1RS 1A-1B satellite have been in operational orbit for two years and have given very satisfactory results.
Irradiation of human dental tissues using five laser wavelengths
Authors: Jelínková H. , Hamal K. , Kubeček V. , Dostálová T. , Krejsa O. , Kubelka J. , Kvapil Ji. , Procházka S.
Published: February 2023

This study investigates the efficiency of the Er, Ho, Nd:YAG, and Nd:YAP laser radiation influence on the hard and the soft dental tissues. The penetration depth of the radiation in tissue depends on its absorption in water, which is the function of the laser wavelength. From this point of view the ablation and the cutting effects of the five various wavelengths (1.06 µm, 1.34 µm, 1.44 µm, 2.1 µm, and 2.9 µm) were analyzed.
Electrooptic intensity modulation for Er: YAG lasers in medicine
Authors: Ozolinsh Maris , Viesturs Ansis , Livins Maris
Published: February 2023

Er:YAG lasers, due to their radiation strong interaction with human tissue, are going to find application in medicine, particularly in dentistry.1 The present work reports on the setup for computercontrolled modulation of Er:YAG laser beam. The control of the beam intensity by means of conventional electrooptic (EO) modulators meets essential difficulties due to the great wavelength of the Er:YAG laser and absorption of EO materials. We use as the electrooptic media PLZT transparent ceramics—a material with high values of EO coefficients and well transparent up to 5 microns.
Micro-optical structures realized by LIGA technology
Authors: Gemer M. , Schift H. , Bauer H.-D. , Ehrfeld W.
Published: February 2023

In the field of micro-optics LIGA has been successfully used to fabricate cylindrical lenses with aspherical contours. The surface quality of both the developed resist structures and the embossed structures have been measured using a laser profiler. Both results show an optical surface quality with a RA roughness below 50 nm.
Asymmetric two-step GaAlAs quantum well for cascaded second-order processes
Authors: Kelaidis C. , Hutchings D. C. , Arnold J. M.
Published: February 2023

Recently there has been increasing interest in obtaining large nonlinear phase shifts by an effective intensity dependent refractive index n2 based on second-order nonlinearities. These phase shifts arise as down-conversion of the second harmonic, away from perfect phase-matching, to the fundamental, which in general is out of phase with the fundamental source field. This process has been termed cascaded,1,2 as it involves the consecutive application of second-order nonlinearities χ(2)(ω,ω):χ(2)(—ω,2ω).
Growth and characterisation of NYAB crystals for compact laser systems
Authors: Leonyuk N. I.
Published: February 2023

Nonlinear optical properties for crystals RAl3(BO3)4 (R = Y and lanthanides) with huntite structure (sp. gr. R32) have been discovered first by authors1 among numerous in composition and structure anhydrous borates. In this group of borates the NdxY1_xAl3(BO3)4 (NYAB) is a new self-frequency-doubling laser crystal.2
Transient degenerate four-wave mixing in the saturable absorption of Cr4+:GSGG at 1.06 μm
Authors: Brignon A. , Huignard J.-P.
Published: February 2023

Degenerate four-wave mixing (DFWM) interaction in saturable media has received considerable attention because of its potential for application to optical phase conjugation and correction of phase distortions through aberrating media. For this purpose, saturable solid-state materials, operating at the classical wavelength of neodymium lasers near λ0 = 1.06 μm, are of great interest. Here, we present DFWM in a tetravalent chromium-doped gadolinium-scandium-gallium-garnet (Cr4+:GSGG) crystal. Indeed, tetravalent chromium (Cr4+) doped crystals were recently shown to be effective solid-state saturable absorbers for neodymium lasers.1,2 Furthermore, in comparison with traditional saturable absorbers such as dyes in solution, polymeric films, and color-center materials, these crystals exhibit chemical stability, high optical damage threshold, compactness, and would enable operation at high repetition rates.
Competition and coexistence of multiple mutually pumped oscillations in the visible and infrared
Authors: Kaczmarek M. , Ross G. W. , Eason R. W. , Solymar L.
Published: February 2023

In recent years the idea of coupling between incoherent beams has attracted a great deal of attention. A number of photorefractive conjugators and oscillators have been proposed1,2 with the doublephase-conjugate mirror (DPCM)3 and its modified version, the double-colour-pumped-oscillator (DCPO)4, as one of the most popular ones. In both of these configurations, two new beams are simultaneously self-generated due to the interaction of the two mutually incoherent input beams.
Stimulated Raman scattering in barium nitrate crystal in the external optical cavity
Authors: Zverev P. G. , Basiev T. T. , Prokhorov A. M.
Published: February 2023

Raman lasers can be used to shift laser radiation frequencies to different spectral regions. Barium nitrate crystal is one of the promising Raman materials that possess strong symmetrical vibration with 1047 cm-1 frequency and that have been successfully used for stimulated Raman scattering. Barium nitrate Raman gain was measured to be 47 cm/GW at 532 nm1 and about 11 cm/GW at 1.06 μm.2
Proposal for a novel quantum electronic device: the spectroscopic bridge
Authors: Popescu F. F.
Published: February 2023

The purpose of the present work is to show that by combining the double resonance techniques1 within a modified hydrogen maser scheme,2 the spectroscopic bridge3 could become a complex quantum electronic device.
4D pulse propagation and 4D solitons in graded-index materials
Authors: Yu S.-S. , Lai Y. , Chien C.-H.
Published: February 2023

Optical Kerr nonlinearity can give rise to interesting soliton phenomena. Spatially, the combined effects of Kerr nonlinearity with diffraction produces spatial solitons. Temporally, the combined effects of Kerr nonlinearity with group velocity dispersion produces temporal solitons. When a 4D optical pulse propagates through a nonlinear Kerr medium, all these effects show up and are coupled together. In the literature, to the best of our knowledge, there is still no satisfactory theoretical model that can accurately describe the interplay of all these effects that does not require computation power beyond today's computer technology. One of the objectives of our work is to bridge this gap.
The study of the nonlinear absorption in KTiOPO4 crystals
Authors: Maslov V. A. , Mikhailov V. A. , Shaunin O. P. , Shcherbakov I. A.
Published: February 2023

The colour centres responsible for the additional laser-induced absorption (“gray tracking") appear in KTP crystals under the action of the blue-green laser radiation. This effect significantly limits the application of KTP frequency doublers. The value of the nonlinear absorption depends on the incident radiation intensity, exposure (number of shots), and mutual orientation of the plane of polarization of the laser radiation E and the polar axis Z of the KTP crystal.1
Nonlinear optical properties of Na adsorbates on dielectrics
Authors: Rubahn H.-G.
Published: February 2023

If atoms are held at distances of a few ten Angstroms apart from a metal surface they radiate in a "confined" space, similar to atoms radiating inside a very narrow cavity. Implementing a two-photon laser-induced fluorescence (TPLIF) method the behaviour of such atoms has been investigated recently in terms of changed optical as well as surface properties (sticking and diffusion).1
Low-temperature annealing of ion-implanted KNbO3 waveguides for second harmonic generation
Authors: Pliska T. , Jundt D. H. , Fluck D. , Günter P. , Fleuster M. , Buchal C.
Published: February 2023

KNbO3 is a very attractive material for frequency conversion from the near-infrared into the blue.1,2 Results on second harmonic generation (SHG) experiments in KNbO3 waveguides formed by ion implantation were reported in Ref. 3. Implantation of MeV He+ ions into KNbO3 leads to the formation of a barrier layer with decreased refractive index a few microns below the surface defining a barrier waveguide. The incident ions loose energy by inelastic scattering with electrons and ions of the target. Ionic collisions are assumed to lead to permanent lattice damage, e.g., vacancies and interstitials. According to TRIM calculations the density of vacancies due to collision events in the waveguiding region is expected to be on the order of 2 X 1020 cm-3 (2600 ppm). Thus the creation of absorption centers (point defects, e.g., vacancies) in the waveguide is inherently related to the formation of the barrier waveguide itself.
Blue light generation by frequency doubling of diode laser radiation in KNbO3 waveguide
Authors: Fluck D. , Günter P. , Fleuster M. , Buchal Ch.
Published: February 2023

As a compact solid-state source for coherent blue and green light, laser diode-based second harmonic generation (SHG) in waveguide devices is very promising for the use in certain low-power applications such as optical storage and laser printing. Efficient blue light generation has been demonstrated in quasi-phase-matched waveguides in LiNbO3,1 LiTaO2,2 KTP,3 and in phase-matched and Cerenkov-type waveguides in KNbO3.4,5
Nonlinear integrated optical modulator with modified polyimide side chain polymers
Authors: Söchtig J. , Appassito C. , Pedersen J. , Zysset B. , Ahlheim M. , Stähelin M. , Lehr F.
Published: February 2023

A new class of nonlinear optical side chain polymers based on modified polyimide backbones1 has been developed for the use as electro-optic modulator devices. The nonlinear optical polymers with functionalised azo-dye chromophores show high glass transition temperatures in the range of 137°C to 172°C, resulting in excellent long-term stability of the electro-optic effect.2 Coefficients of r33 = 20 pm/V have been measured at 1313 nm and first prototype electro-optic modulators could be demonstrated.
Mode behaviour of a carbon monoxide slab waveguide laser
Authors: Villarreal F. , Colley A. D. , Baker H. J. , Hall D. R.
Published: February 2023

The carbon monoxide laser exhibits characteristics which make it competitive with the lasers that currently dominate industrial and medical applications, mainly carbon dioxide and Nd:YAG lasers. Properties include the potential for high efficiency (theoretically up to 60%), a wavelength which gives good absorption for metals, ceramics, and organic tissue; a high power output; the availability of suitable resonators providing good beam quality; and the possibilty of fibre optic delivery. These make the CO laser a contender for development into an industrially relevant laser source.
Noninvasive glucose monitoring using nearinfrared photoacoustic spectroscopy
Authors: Quan K. M. , Johnston E. M. , MacKenzie H. A.
Published: February 2023

Devising a noninvasive system for the determination of blood glucose concentrations is of particular interest due to the prevalence of diabetes. A pulsed photoacoustic technique has been proposed and shown to be promising for development in this area1,2 We report our recent experimental work and progress in photoacoustic spectral data analysis.
Carrier heating and fundamental limits for linearity of cable TV lasers
Authors: Gorfinkel Vera B. , Luryi Serge
Published: February 2023

Sub-carrier multiplexed (SCM) optical transmission systems, such as cable television (CATV) networks, require low-distortion distributed feedback (DFB) lasers. The amplitude modulation (AM) frequency division multiplexing (FDM) scheme, preferred in CATV networks, presents severe requirements to the linearity of the transmission. Typically, the composite second-order (CSO) distortion must not exceed –60 dBc.
A multilayered semiconductor second-harmonic generator based on a new scheme of phase-matching in a cavity
Authors: Takahashi H. , Ohashi M. , Kondo T. , Ogasawara N. , Shiraki Y. , Ito R.
Published: February 2023

Our second-harmonic generation (SHG) device based on a new phase-matching scheme is illustrated in Fig. 1. Alternating layers of half-the-harmonic-wavelength (λ2
w
/2n2
w
) thick (111)-oriented GaP and AlP are inserted in a cavity. Because of the difference in the magnitude of second-order nonlinear optical coefficient d between GaP and AlP, the nonlinearity is modulated along the longitudinal axis of the cavity as shown by the square wave (n) in the lower part of Fig. 3.
Amplification on uranium lines in a discharge in contact with an electrolytic solution
Authors: Cristescu C. P. , Popescu I. M. , Preda A. M.
Published: February 2023

The work presents results of spectroscopic measurements which are indicative of amplification at the wavelength of 2.6 μm in a gaseous medium containing uranium ions.
Ultralong-distance soliton transmission
Authors: Mollenauer L.
Published: February 2023

Summary not available.
Laser Manipulation of Atoms
Authors: Aspect Alain
Published: February 2023

Momentum exchange between atoms and photons allow laser physicists to control atomic motion. It is possible to decelerate and/or focus an atomic beam, to stop it. The average velocity of the almost stopped atoms can be decreased to very small values close to or even below the one photon recoil velocity V
R
= ħk
L
/M, corresponding to temperatures in the microkelvin range or below. Laser manipulation of atoms is also essential for the recently developing field of atom optics.
Femtosecond lasers and applications
Authors: Krausz Ferenc
Published: February 2023

The last few years have brought about significant advances in ultrashort-pulse laser physics and its widespread applications in science and technology. The state of the art of optical pulse generation is now at the point where extremely large optical bandwidths are available. The recent appearance of novel ultrabroad-band solid-state laser materials motivated the development of new ultrafast optical modulation techniques that are capable of shaping optical pulses down to a few femtoseconds in duration. The discovery of "self-mode-locking, " and the exploitation of a "solitonlike" interplay between self-phase modulation and anomalous dispersion have been the major steps towards a powerful new femtosecond laser technology based on solid-state gain materials and their nonresonant nonlinear index of refraction. Intensive theoretical and experimental research has resulted in a good understanding of the principal effects limiting pulse shortening and stability, leading to the construction of extremely compact solid-state sources of stable and reproducible optical pulses down to the 10-fs regime.
Laser spallation test for assessment of thin film adhesion
Authors: Cruz F. , Boquillon J. P. , Oltra R. , Sartori C.
Published: February 2023

The fracture energy of a metal-ceramic interface points out a critical parameter in many applications when an interface decohesion is either necessary or not desirable.
High-dynamic-range characterization of ultrashort pulses
Authors: Jung I. D. , Kärtner F. X. , Zhang G. , Keller U.
Published: February 2023

We measured high-dynamic-range (HDR) autocorrelations of pulses between 12 fs - 33 fs produced by a Ti:sapphire laser modelocked by a thin saturable absorber [1] and by Kerr-lens modelocking (KLM). We demonstrate lower pulse pedestal with soliton modelocking [2] using broadband semiconductor saturable absorbers than with Kerr lens modelocking. Initial experimental and numerical investigations indicate that third order dispersion and overdriven self-phase modulation (SPM) are the reason for the pedestals.
Carrier heating effects as a means for ultrahigh speed operation of a laser diode
Authors: de Boer A.P. , Christianen P.C.M , Rasing Th. , van der Roer Th.G. , Tolstikhin V.I.
Published: February 2023

The modulation of laser diodes emitting at 1.55 μm has become very important for high bit rate lightwave communications. Both carrier density and carrier temperature determine the optical performance of the diode. Since thermalization of hot carriers takes place on a pico second timescale, exploring carrier heating for achieving giga Hertz modulation of the optical output has a very high potential. Recently this idea has been established in some numerical simulations [1].
Laser Doppler Perfusion Imaging
Authors: Nilsson Gert
Published: February 2023

Laser Doppler Perfusion Imaging (LDPI) creates two-dimensional flow-maps of the tissue perfusion. A laser beam scans the tissue surface step-wise by means of a computer controlled stepper motor system that forms an integral part of a camera-like device positioned above the tissue surface. At each measurement site in the flow-map, the beam is arrested for about 50 msec. During this time period the backscattered light, partly Doppler shifted by the moving blood cells in the superficial microvascular network, is recorded by a photo-detector, positioned next to the stepper motors in the scanner head. At the surface of the photo-detector, frequency-shifted and non-frequency-shifted beams are mixed to form a photocurrent which is composed of a fluctuating portion superimposed on a stationary base level. The frequency content of the fluctuating portion is related to the average speed of the blood cells, while its magnitude is related to their concentration within the scattering volume. The average sampling depth in skin tissue is in the order of 0.2 mm. By using a step-wise scanning procedure, the beam is kept still in relation to the tissue when recording the backscattered Doppler signals and the movement artifact noise generated by a continuously moving beam is avoided. By making the laser beam slightly divergent, the solid angle under which the laser spot is seen on the tissue surface from the photo detector is virtually constant. This implies that the degree of coherent detection can be kept constant thereby making the perfusion signal recorded independent of the distance between the scanner head and the tissue. After signal processing, an output signal is generated that scales linearly with tissue perfusion defined as the product of the blood cell speed and concentration. This signal is stored in the computer memory and the beam is moved to the next measurement site. When all measurement sites (at maximum 4096 points) have been sampled, the stored values are displayed in the form of a colour coded image on a computer monitor. This image can be further analyzed by use of the integrated analyses software LDI-soft or exported to other software packages for further analysis. LDPI has been used with success in a number of applications including axon reflex studies in diabetics, mapping of skin blood flow in association with microdialysis and investigation of the hyperperfusion in psoriatic skin.
Noninvasive Photoacoustic Determination of Blood Glucose Using Modulated Diode Lasers
Authors: Spanner G. , Nießner R.
Published: February 2023

The noninvasive determination of blood and tissue parameters is a promising application of photoacoustic laser spectroscopy. Optical absorption spectra of human whole blood in the visible and near infrared spectral region were measured using the photoacoustic response produced by modulated diode lasers. As glucose is one of the most important blood parameters, the aim of our investigations is the development of a sensor system which is suitable for continuously noninvasive monitoring of blood glucose concentrations in diabetic patients.
First laser operation of an epitaxially grown Tm:Y2SiO5 waveguide
Authors: Rameix A. , Borel C. , Ferrand B. , Wyon C. , Shepherd D.P. , Warburton T.J. , Tropper A.C. , Hanna D.C.
Published: February 2023

Liquid Phase Epitaxy (LPE) is a promising technique for producing planar waveguide lasers. This method has already achieved good results with Y3A15O12 (YAG) [1,2]. In this paper we report the growth and laser operation of layers of a new material: Y2SiO5 (YSO) which is a promising laser host especially doped with Tm for 2μm laser operation [3].
All laser-assisted heteroepitaxial growth of Si0.8Ge0.2 on Si(100)
Authors: Serna R. , Afonso C.N. , Solis J. , Ballesteros C. , Rodríguez T.
Published: February 2023

Over the last years silicon-germanium alloys have become a subject of considerable work. High quality SiGe single crystalline alloys can be formed over the entire composition range. The tunability of the physical, optical and electronic properties with the film stoichiometry and the compatibility with existing silicon-based technology has led to numerous application of these materials in optical fiber communications (light modulators), infrared detectors, solar cells, and band gap engineering of Si based microelectronic devices. Up to date research on Si1-xGex alloys growth has been mainly focused on the use of molecular beam epitaxy, and chemical vapor deposition. While these techniques have demonstrated growth of device quality material, the optoelectronic technology has an increasing demand for higher integration. The reduction of the substrate temperatures, or of the processing times, are desirable in order to minimize impurity diffusion and to avoid junction destruction. In this context, laser annealing of Si1-xGex alloys was early proposed to promote epitaxial regrowth of e-beam amorphous deposited films.
Raman Scattering in Silicon Implanted by High Dose of Krypton
Authors: Galjautdinov M.F. , Kurbatova N.V. , Moiseev S. A. , Shtyrkov E.I.
Published: February 2023

The aim of this work is to study microstructure of a porous Si, which was formed as a result of implantation and laser annealing, by Raman spectroscopy. Possibility of formation of stable defects with noble gase atoms was also investigated after a monocrystal Si (111) doped by Kr+ (40 kev, 6·10l4-2,4·1017 ion/cm2) at room temperature. Laser annealing was performed with a ruby laser at 0,69 mkm, 50 ns, 0,3-1,6 J/cm2. Spectra of Raman scattering were taken by a DFS-52 spectrometer with a pumping irradiation at a wave length of 510,6 nm and a repetition rate of 10 kHz.
De-electric-field-enhanced second-harmonic generation in Si-SiO2 multiple quantum wells
Authors: Fedyanin A.A. , Aklsipetrov O.A. , van Hassell C.W , Rasing Th.
Published: February 2023

Contrary to crystalline quantum structures, amorphous multiple quantum wells (MQW) like Si-SiO2 heterostrustures do not require lattice matching because of their nonperiodical structure. Thus strong electron confinement can be expected in such quantum structures. Here we have studied the second-order nonlinear optical properties of amorphous Si-SiO2 MQW using Optical Second-Harmonic Generation (SHG). The anisotropic characteristics of the quadratic response as well as the influence of the applied de electric field on the SHG intensity are investigated for this type of MQW.
Nonlinear Optical Properties of Thin-Film Quasi-Zero-Dimensional Media Depending on the Matrix Materials
Authors: Goncharova Olga V. , Tikhomirov Sergey A.
Published: February 2023

Three-dimensional confinement of excitons or electrons motion in nanometer-sized microcrystallites (nanocrystals – NCs) is an important phenomenon in physics, and is expected to bring a significant improvement to ultrafast functional devices. In the past ten years, several types of quasi-zero-dimensional (QZD) media such as dielectric matrices containing dispersed semiconductor or metal NCs have been realized by using various techniques. Recently, we have succeeded in the preparation of thin-film QZD media [1]. Such media are very suitable for investigating the effect of the microstructure (including the average size, the concentration, the arranging types of NCs and the matrix material) on the quantum confinement of the electron-hole motion.