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All space--time coupling effects arising in an asymmetric optical compressor consisting of two non-identical pairs of diffraction gratings are described analytically. In each pair, the gratings are identical and parallel to each other, whereas the distance between the gratings, the groove density and the angle of incidence are different in different pairs. It is shown that the compressor asymmetry does not affect the far-field fluence and on-axis focal intensity. The main distinctive feature of the asymmetric compressor is spatial noise lagging behind or overtaking the main pulse in proportion to the transverse wave vector. This results in a degraded contrast but reduces beam fluence fluctuations at the compressor output. Exact expressions are obtained for the spectrum of fluence fluctuations and fluence root mean square that depends only on one parameter characterizing compressor asymmetry. The efficiency of small-scale self-focusing suppression at subsequent pulse post-compression is estimated. [ABSTRACT FROM AUTHOR]

The eXawatt Center for Extreme Light Studies project aimed to create a large scientific infrastructure based on lasers with giant peak power. The project relies on the significant progress achieved in the last decade. The planned infrastructure will incorporate a unique light source with a pulse power of 600 PW using optical parametric chirped pulse amplification in large-aperture KD2PO4, deuterated potassium dihydrogen phosphate crystals. The interaction of such laser radiation with matter represents a completely new fundamental physics. The direct study of the space--time structure of vacuums and other unknown phenomena at the frontier of high-energy physics and the physics of superstrong fields will be challenged. Expected applications will include the development of compact particle accelerators, the generation of ultrashort pulses of hard X-ray and gamma radiation for material science enabling one to probe material samples with unprecedented spatial and temporal resolution, the development of new radiation and particle sources, etc. The paper is translation from Russian [Kvantovaya Elektronika 53, 95 (2023)]. [ABSTRACT FROM AUTHOR]

The International Symposium on Transparent Ceramics for Photonic Applications is an annual international conference since 2005. The previous LCS events were held in Poland (2005), Japan (2006), France (2007), China (2008), Spain (2009), Germany (2010), and Singapore (2011). The 8th LCS was held in Russia in the city of Nizhny Novgorod on December 4-7, 2012. The aim of the symposium was to provide a forum for material scientists, chemists and physicists, to discuss the state of the art of optical transparent ceramics, including basic aspects and promising applications, and to give an insight into future advances and research possibilities in this field. The symposium program included invited talks as well as contributed presentations. This year the main focuses of the symposium were: - Synthesis of high purity powders and transparent ceramics - Optical spectroscopy and characterization of physical properties - New materials and novel fabrication methods - Ceramic lasers and amplifiers - Composite structured laser ceramics. The International Program Committee had 24 members from 16 countries worldwide (http://www.8lcs.iapras.ru/committees.html). The OSA representative in the International Program Committee was academician S. N. Bagayev. After revision, the symposium program consisted of 42 reports, including 13 invited talks (invited speaker names can be found on the webpage: http://www.8lcs.iapras.ru/invited.html). Among the 67 participants of the LSC 2012, 44 were from Russia, 9 from P.R. China, 6 from Japan, 3 from Ukraine, 2 from South Korea, 1 from UK, 1 from Germany, and 1 from Singapore. The oral presentations were given in English. The symposium took four days and was divided into three sessions: ' Ceramics fabrication ', ' Ceramics characterization ' and ' Ceramic lasers '. As representatives of the industry, Dr. Hideki Yagi from Konoshima Chemical Co. Ltd. (Japan) gave the interesting review ' Transparent ceramics for photonic applications ' and Dr. Ken-ichi Ueda from Hamamatsu Photonics K.K. (Japan) told about important applications of laser ceramics in his lecture ' Thermal lens free ceramic laser '. The fellow of the Optical Society of America, director of the Institute of Extreme Light (France), Gerard Mourou, has visited the technical sessions and a subsequent discussion of the Laser Ceramics Symposium. The LCS has brought together leading experts from around the world, stimulated active discussions and contacts between the scholars and gave a brilliant opportunity for the participants to start further fruitful research collaborations. The four-days LCS 2012 was attended by 67 scientists and engineers from around the world. Pictures could be found in the gallery at: http://www.8lcs.iapras.ru/photoshots.html. The next, the 9th Laser Ceramics Symposium will be held in Seoul, South Korea in 2013. [ABSTRACT FROM AUTHOR]

All the basic elements of a 300 J/1 ns Nd:glass laser with high-efficiency (70%) frequency conversion are described in detail. These include a seed laser, a system shaping the spatial structure of the beam, a six-cascade amplifier based on neodymium phosphate glass rods 10-100 mm in diameter, and a second-harmonic generator on a DKDP crystal with ooe interaction. Reliable and easy operation guaranteed long-term functioning of the laser as a pump for the output cascade of a chirped pulse parametric amplifier in a petawatt laser complex. [ABSTRACT FROM AUTHOR]

Small-scale self-focusing is the main cause of power limitation in nanosecond Nd:glass lasers. We report pioneer observation in experiment of laser beam noise amplification for B-integral (nonlinear phase) order of unity, i.e., without destruction of nonlinear medium. Analytical dependences of noise amplification coefficient on the B-integral have been obtained for one nonlinear medium as well as for two nonlinear media separated by an air gap with image relay. A simple analytical dependence has been found for an optimal distance between two nonlinear media for which the maximum allowable value of B-integral increases from 2.7 to 4.3. The maximum attainable energy in neodymium-phosphate glass lasers with rod amplifiers 10 cm in diameter is 400 J with a pulse duration of 1 ns. [ABSTRACT FROM AUTHOR]

Two methods of compensation of thermal leasing in high-power terbium gallium garnet (TGG) Faraday isolators have been investigated in detail: compensation by means of an ordinary negative lens and compensation using FK51 Schott glass possessing a negative dn/dT. Key thermooptic constants for TGG crystals and FK51 glass were measured. We find that the contribution of the photoelastic effect to the total thermal lens cannot be neglected for either TGG or FK51. We define a figure of merit for compensating glass and show that for FK5I, an ordinary negative lens with an op- timal focus is more efficient, but requires physical repositioning of the lens for different laser powers. In contrast, the use of FK51 as a compensating element is passive and works at any laser power, but is less effective than simple telescopic compensation. The efficiency of adaptive compensation can be considerably enhanced by using a compensating glass with figure of merit more than 50, a crystal with natural birefringence or gel. [ABSTRACT FROM AUTHOR]

Presents a theoretical and experimental investigation of self-induced depolarization in terbium gallium garnet crystals due to the absorption of laser radiation. Dependence of depolarization induced by absorption of laser radiation on the square of the incident power and the absorption of material; Faraday effect; Photoelastic effect; Verdet constant.

Examines a two-channel repetitively pulsed ND-YAG laser. Compensation of aberration and polarization distortions in ND-YAG crystals; Summation of two channels of radiation into a single diffraction-limited beam with a pulse energy up to 5 J; Stimulated Brillouin scattering.

The spectroscopic characteristics of Er-doped lead silicate glasses were investigated with respect to the effects of glass modifiers (Li+, Na+, K+, Mg2+, Ca2+, Sr2+, and Ba2+)with various optical basicities. Using the absorption spectra of the glasses, the Judd--Ofelt parameters of the glasses were calculated and examined, with an emphasis on the glass emission intensity ratio at 1572 nm. The spectra of the samples at low temperatures were examined, and the Stark splitting of Er3+ was investigated. The McCumber method was used to determine the emission cross sections of glasses. The SPM glass exhibited high values of full width at half maximum (51.24 nm) and the emission cross section at 1572 nm (1.908 x 10-21 cm²), with potential applications for guiding component design of 1.5-μm fiber lasers and amplifiers. [ABSTRACT FROM AUTHOR]

It was shown experimentally that for a 65-fs 17-J pulse, the effect of filamentation instability, also known as small-scale self-focusing, is much weaker than that predicted by stationary and nonstationary theoretical models for high B-integral values. Although this discrepancy has been left unexplained at the moment, in practice no signs of filamentation may allow a breakthrough in nonlinear pulse post-compression at high laser energy. [ABSTRACT FROM AUTHOR]

The presented laser driver for a photoinjector of an electron linear accelerator delivers 10-ps long laser pulses with the energy of 1.85 μJ at the wavelength of 262 nm. Laser pulses irradiating with the repetition rate of 10 MHz form the rectangular 800-μ s long pulse trains with 18.5-W mean power inside them. The pulse train repetition rate is 10 Hz. Short-lived absorption centers accumulating in BBO fourth-harmonic generator crystal cause significant distortion of the pulse train envelope. The envelope remains rectangular due to precompensating of these distortions in the fiber acousto-optical modulator with fast varying transmission. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we describe adaptive compensation of thermal lens in a Faraday isolator using a DKDP crystal. Thermal lens measurements were made with a modification of the conventional Hartmann sensor – a 2D scanning Hartmann sensor. Our experiments showed that a DKDP crystal does not influence the isolation ratio of Faraday isolator and efficiently compensates for thermal lens. The negative effect produced by the thermal lens is estimated as the amount of power losses from the original beam mode (Gaussian mode in our experiments). Without compensation the losses were measured to be about 25% for 45W radiation power and were compensated to less than 0.5% by a negative thermal lens in a 5.5mm-thick DKDP crystal. Numerical extrapolation of experimental data to a higher power range has shown that for the powers up to 150W, power losses can be made less than 5%. [Copyright &y& Elsevier]

The input pulse of the laser PEARL with energy of 18 J and pulse duration of about 60 fs was compressed to 10 fs after passage through a 4-mm-thick KDP crystal and reflection at two chirped mirrors with sum dispersion of −200 fs2. The experiments were performed for the В-integral values from 5 to 19 without visible damage to the optical elements, which indicates that small-scale self-focusing is not a significant issue. It was shown that, by virtue of the low dispersion of the group velocity, the KDP crystal has some advantages over silica: a larger pulse compression coefficient, especially at a small value of the В-integral (B = 5, ..., 9), lower absolute values of chirped mirror dispersion, and also a possibility to control the magnitude of nonlinearity and dispersion by changing crystal orientation. [ABSTRACT FROM AUTHOR]

A cryogenic Faraday isolator based on terbium-gallium garnet (TGG) ceramics has been designed and studied in experiments. Its performance capabilities at the laser radiation power of 435 W are demonstrated, and our models suggest that the isolator should perform up to 2 kW. Thermal effects-thermally induced depolarization and thermal lens in the TGG ceramics in the 89-293 K temperature range are investigated. It is shown that the TGG ceramics compares well to the TGG monocrystal as a medium for Faraday isolators, including cryogenic ones. At the same time, in contrast to the TGG monocrystal, ceramics allows creating large-aperture Faraday isolators for lasers with high-average and high-peak power. [ABSTRACT FROM AUTHOR]

Faraday isolators for high average power lasers operating at room temperature are surveyed. Three devices on [001] oriented TGG crystals with the most known optical schemes are considered: traditional scheme, and schemes with compensation of thermally induced depolarization inside magnetic field and outside magnetic field. We report a unique 30-mm-aperture Faraday isolator with thermally induced depolarization compensation inside magnetic field. It provides 33.5-dB isolation ratio at 1.5-kW average laser power. [ABSTRACT FROM AUTHOR]

An original method for suppressing small-scale self-focusing in laser beams with the intensity of several TW/cm has been proposed, justified theoretically and verified in experiment. The idea underlying the method is to filter spatial perturbations during beam propagation in free space. [ABSTRACT FROM AUTHOR]

We present the design and performance of the LIGO Input Optics subsystem as implemented for the sixth science run of the LIGO interferometers. The Initial LIGO Input Optics experienced thermal side effects when operating with 7 W input power. We designed, built, and implemented improved versions of the Input Optics for Enhanced LIGO, an incremental upgrade to the Initial LIGO interferometers, designed to run with 30 W input power. At four times the power of Initial LIGO, the Enhanced LIGO Input Optics demonstrated improved performance including better optical isolation, less thermal drift, minimal thermal lensing, and higher optical efficiency. The success of the Input Optics design fosters confidence for its ability to perform well in Advanced LIGO. [ABSTRACT FROM AUTHOR]

Abstract: A Faraday isolator with one magneto-optical element providing 31dB isolation ratio for 330W average power lasers was produced and investigated in an experiment. These remarkable parameters were achieved by increasing the magnetic field and using a [001] oriented TGG crystal. [Copyright &y& Elsevier]

Faraday rotators with short magneto-optical elements are created and experimentally studied. The magneto-optical elements are made three to four times shorter either by cooling them to nitrogen temperatures or by increasing the magnetic field. These ways are shown to increase maximum average laser power passing through the Faraday isolators up to 50 kW. [ABSTRACT FROM AUTHOR]

Using two 20 mm in diameter, 1.4 mm thick, 5 at% doping Yb:YAG ceramic active elements (AEs) we reached 233 mJ at 143 Hz in the output with 70 ns, 30 mJ input pulses. According to our 3D calculations we extracted about half of the stored energy. To our knowledge, this output result is the best among all high repetition rate cryogenic pulse Yb:YAG ceramic thin disk laser systems. [ABSTRACT FROM AUTHOR]