Laser induced damage threshold of GaSe with antireflection microstructures at a wavelength of 5 µm.

Large GaSe crystals were grown and various antireflection microstructures (ARMs) were fabricated on their cleaved surfaces using optimized femtosecond laser ablation, which provided the antireflection effect in a wide wavelength range of 4-16 µm. The influence of ARMs created on the GaSe surface on the change of the laser-induced damage threshold (LIDT) of the crystal at a wavelength of 5 μm was evaluated. The 5-µm Fe:ZnMgSe laser with the pulse duration of 135 ns was used for the LIDT test in conditions close to single pulse exposure.

Antireflection microstructures fabricated on the surface of a LiGaSe nonlinear crystal.

LiGaSe is a propitious material for nonlinear parametric conversion in the mid-infrared (mid-IR) range. Its refractive index of n = 2.25 in the 2-12 µm wavelength range results in significant losses due to Fresnel reflection.

Anisotropic Thermal Expansion and Electronic Structure of LiInSe.

Optical quality cm-sized LiInSe crystals were grown using the Bridgman-Stockbarger method, starting from pure element reagents, under the conditions of a low temperature gradient of 5-6 degrees/cm and a slight melt overheating. The phase purity of the grown crystal was verified by the powder XRD analysis. The thermophysical characteristics of LiInSe were determined by the XRD measurements in the temperature range of 303-703 K and strong anisotropy of the thermal expansion coefficients was established.

Crystal Growth, Structure, and Optical Properties of LiGaGe2Se6.

Large single crystals of LiGaGe2Se6 were grown, and their structure and linear optical properties were studied. According to XRD results there is some disorder because of the Li ion fluctuation and their redistribution along two cationic sites. The shape of the fundamental absorption edge versus temperature was analyzed, and direct band gap values were estimated from the Tauc plots.

Structures and optical properties of two phases of SrMgF4.

SrMgF4 has an extremely large bandgap Eg of 12.50 eV as obtained from reflection dispersion. The symmetry of this crystal is monoclinic P21 at room temperature and transforms to the orthorhombic Cmc21 phase near 478 K as the temperature increases.