V. F. Seregin

Study of Thermo-Optical Distortions in a Plate Active Element with Zigzag Beam Path

Phase distortions introduced into the laser beam propagating in a plate under diode pumping of the active element (AE) and for intentionally caused temperature gradients in the AE are studied. The temperature distribution along the optical axis of the active element is measured during its end diode pumping. Phase distortions of the test beam propagating through the nonuniformly heated active element are studied. Interference patterns are obtained and optical distortions of the test beam are measured at various temperature gradients in the crystal.

Nd3+:GGG and Cr4+:GGG epitaxial films for neodymium lasers

An efficient technology was developed for growing the gadolinium gallium garnet (GGG) single-crystal films doped with Nd3+ or Cr and Ca ions. The films with thickness up to 100 µm have been grown by liquid-phase epitaxy method on undoped GGG substrates of small and big sizes (5–8 mm and up to 76 mm in diameter, respectively). The dependence of absorption, luminescence spectra and optical losses at the wavelength of 1 µm on growth temperature and melt-solution composition was studied. We demonstrated that Cr4+ centers have been implemented in epitaxial films and these films may be used as passive Q-switches for laser systems.

Terbium garnets for high average power Faraday isolators: Influence of composition, doping and high temperature annealing to the losses in the near-IR range

Terbium garnet single crystals (terbium gallium garnet, TGG, and terbium-scandium gallium garnet, TSAG) combine relatively high Verdet constant, low absorption coefficient, high thermal conductivity and high optical quality. The combination of properties leads to TGG being the most popular magneto-optic material at high-power applications for creation compact and efficient optical rotators and isolators for visible and near-IR range.

Method for measuring optical characteristics of opaque and translucent solids at temperatures to 1600°C

A setup is developed for measuring optical characteristics of opaque and translucent solids in the temperature range of 25 to 1600°C and spectral range of 0.65 to 10.6 µm. Procedures of calibration experiments and measurements of spectral and integral emissivity are described. These procedures allow spectral and integral emissivity and spectral and integral reflectances of various materials, including translucent ones, to be measured accurate to about 10% in the spectral range of 0.65 to 10,6 µm and temperature range of 25 to 1600°C. Optical characteristics of materials are measured at the atmospheric pressure in the normal oxygen atmosphere or in the atmosphere with reduced oxygen content (inert gas or carbon dioxide blowing on the frontal surface of the samples). The accuracy of the thus obtained data on temperature and spectrum dependences of optical characteristics of materials allow measurements to be performed for developing various structures capable of operating at high temperatures.

Thermooptical distortions in a Nd:YAG slab with a zigzag beam propagation

Efficient operation of diode-pumped solid-state lasers with both high average power and good beam quality is generally limited by thermal effects in the laser gain medium. The effects of these distortions can be mitigated by application different pumping and extraction architecture. Zigzag slab lasers (see, for example, [1,2]) have demonstrated near-diffraction-limited output power at above 1 kW, because zigzag propagation by means of total internal reflections (TIR) eliminates thermally induced optical path differences over the entire beam area [3]. All the best slab architecture could demonstrate only at homogeneous pump distribution over active volume. We investigate experimentally the degree of absorbed pumping inhomogeneity which could influence the beam quality.

Effect of nonuniform heating of the active disk on characteristics of the solid-state laser cavity

Generation characteristics of the neodymium laser with disk active element and diodepumped active medium were studied. It was shown that lasing occurs at a cavity length significantly exceeding the focal length of the thermal lens induced in the active element. Bending radii of the active disk surface were determined depending on the absorbed pump power. The cavity calculation performed taking into account the active disk surface bending showed that the negative lens formed by such bending of the surface and a laser mirror deposited on it efficiently compensates for the positive thermal lens, thus expanding the stability region of the disk laser cavity.

The growth and characterization of Nd:GGG and Cr/sup 4+/:GGG epitaxial films for solid-state lasers

Optically pumped solid-state lasers can benefit in a number of applications when using the waveguiding geometry in which pumping emission and lasing modes overlap well and pumping density is high. This paper presents the results of investigations of the gadolinium-gallium garnet (GGG) films grown by liquid phase epitaxy (LPE) method. We have studied spectral and lasing characteristics of the epilayers and the growing conditions influence to the film properties. Samples of epitaxial films of different composition starting from pure (undoped) GGG and then doped with Nd or Cr ions (with Mg or Ca codoping) were grown by LPE technique with 12-25 /spl mu/m thickness and 76 mm in diameter.