Galina Shevyrdyaeva

Phase-matching properties of BaGa4S7 and BaGa4Se7: Wide-bandgap nonlinear crystals for the mid-infrared

Biaxial BaGa4S7 and BaGa4Se7 crystals transparent in the mid-IR have been grown by the Bridgman–Stockbarger technique in sufficiently large sizes and with good optical quality to measure the refractive indices and analyze phase-matching properties. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Midinfrared optical parametric oscillator based on the wide-bandgap BaGa 4 S 7 nonlinear crystal

The orthorhombic biaxial crystal BaGa(4)S(7) has been employed in a 1064 nm pumped optical parametric oscillator generating <6 ns long idler pulses with energies as high as 0.5 mJ at 6.217 μm and average power of ~50 mW at 100 Hz. Notwithstanding the relatively low nonlinearity, ~3 times above threshold operation has been achieved at pump intensities more than 5 times below the crystal surface damage limit.

Optical properties of lithium indium selenide

Conditions of growth of LiInS2 and LiInSe2 crystals with high optical quality are studied. Data on the dispersion of refractive indices in red-phase LiInSe2 crystals are presented. Possible nonlinear three-frequency processes in LiInS2 and LiInSe2 crystals used for SHG and OPO are analyzed. Potentials of these crystals for application in OPO devices are shown.

Optical properties of thallium mercury iodide

We investigated the growth conditions and obtained Tl4HgI6 nonlinear crystals of red and black phases. We also measured the dispersion of the black-phase crystal refractive indices and analyzed possible nonlinear three-frequency processes.

Phase-matching and femtosecond difference-frequency generation in the quaternary semiconductor AgGaGe5Se12.

We present data on the linear (transmission, index of refraction) and nonlinear (second-order susceptibility) optical properties of the quaternary semiconductor AgGaGe5Se12 with orthorhombic symmetry--a solid solution in the AgxGaxGe1-xSe2 system with x = 0.17. The nonlinear coefficients are estimated from phase-matched second-harmonic generation near 3 microm. After numerical analysis of the phase-matching configurations for three-wave nonlinear interactions, the first experimental results on difference-frequency mixing, producing tunable (4-7.5-microm) femtosecond pulses at a 1-kHz repetition rate, are described. The pulses of only five optical cycles (FWHM = 84 fs) are generated near 5 microm with energy of 0.5 microJ. Because of its higher damage threshold, larger birefringence and bandgap, and greater variety of phase-matching schemes, AgGaGe5Se12 could become an alternative to AgGaS2 and AgGaSe2, more widely used in high-power and specific applications.

BaGa 4 S 7 : wide-bandgap phase-matchable nonlinear crystal for the mid-infrared

We report measurements of the transparency, nonlinear coefficients and damage threshold of BaGa4S7 grown by the Bridgman-Stockbarger technique. We also present calculations showing that this crystal is phase-matchable for down conversion into the mid-IR starting from a pump wavelength of 1064 nm.

Preparation and Structure of AgGa1 – xInxSe2 Single Crystals

AgGa1 – xInxSe2 single crystals grown by the Bridgman–Stockbarger method, using presynthesized charges with x = 0.27, 0.335, and 0.375 are studied by x-ray diffraction (phase analysis, determination of lattice parameters, structure refinement of powdered crystals by the Rietveld profile analysis method, and single-crystal structural analysis). The results suggest that the crystals may contain Se and Ag vacancies. The polarity of the crystals is found to depend on their composition.

PbIn 6 Te 10 : new nonlinear crystal for three-wave interactions with transmission extending from 1.7 to 25 µm

We have grown single crystals of PbIn6Te10, with clear transparency from 3 to 20 µm, and showed that this new nonlinear material possesses sufficient birefringence for phase-matching of three-wave parametric interactions and a nonlinear coefficient of 51 pm/V.

Phase-matched second-harmonic generation at 1064nm in quaternary crystals of silver thiogermanogallate

We demonstrate, for the first time to our knowledge, frequency doubling of 1064 nm radiation in sulphide crystals of Ag/sub x/Ga/sub x/Ge/sub 1-x/S/sub 2/ having engineerable birefringence and superior nonlinearity in comparison to oxide crystals.

Optical damage studies of mercury thiogallate nonlinear crystals for use in 1-μm pumped optical parametric oscillators

Abstract. We investigated optical damage (surface and bulk) in one of the most promising wide bandgap nonoxide nonlinear crystals, HgGa2S4, that can be used in ∼1-μm pumped optical parametric oscillators (OPOs) and synchronously pumped OPOs (SPOPOs) for generation of idler pulses above 4 μm without two-photon absorption losses at the pump wavelength. The optical damage has been characterized at the pump wavelength for different repetition rates using uncoated and antireflection-coated (mainly with a single layer for pump and signal wavelengths) samples. HgGa2S4 is the most successful nonlinear crystal (both in terms of output energy and average power) for such OPOs, but optical damage inside the OPO has a lower threshold and represents at present the principal limitation for the achievable output. It is related to peak pulse and not to average intensity, and bulk damage in the form of scattering centers occurs before surface damage. Such bulk damage formation is faster at higher repetition rates. Lower repetition rates increase the lifetime of the crystal but do not solve the problem. The safe pump fluence in extracavity measurements is <1  J/cm2, which corresponds to ∼100  MW/cm2 for the 8-ns pulse duration (both values peak on-axis). In the OPO, however, peak on-axis fluence should not exceed 0.3  J/cm2 limited by the formation of bulk scattering centers in orange-phase HgGa2S4. In the nanosecond OPO regime, the damage resistivity of Cd-doped HgGa2S4 is higher and that of the almost colorless CdGa2S4 is roughly two times higher, but the latter has no sufficient birefringence for phase-matching. In SPOPOs operating in the ∼100  MHz regime, the damage limitations are related both to the peak pulse and the average intensities, but here HgGa2S4 seems the best nonoxide candidate to obtain first steady-state operation with Yb-based mode-locked laser pump sources.