Ivan Kuznetsov

Thermal Effects in End-Pumped Yb:YAG Thin-Disk and Yb:YAG/YAG Composite Active Element

The small signal gain and phase and polarization distortions of laser radiation have been investigated theoretically and experimentally in end-pumped Yb:YAG thin-disk and Yb:YAG/YAG composite active element under nonlasing conditions. Comparison of experimental data with calculation results reveals an additional heat release whose negative influence is three times stronger than that of amplified spontaneous emission in the thin-disk active element.

Thermal conductivity measurements using phase-shifting interferometry

A new technique for measuring thermal conductivity of solids, including creation of a steady-state one-dimensional heat flow through a studied sample and measurement of temperature distribution using phase-shifting interferometry has been developed. The technique is a handy tool for studying small-size (> 1 mm) samples. The thermal conductivity of new magneto-optical materials such as Ce:TAG optical ceramics (0%, 0.05% and 0.1% doping), MgAl2O4 spinal ceramics, and Tb2O3–B2O3-GeO2 magneto-optical glass was measured.

Improvement of thermal management in the composite Yb:YAG/YAG thin-disk laser

To improve the thermal management in the composite Yb:YAG/YAG thin-disk laser a new design of laser head is developed. Thermal-induced phase distortions, small signal gain and lasing in the upgraded laser head are investigated and compared with previously published results. A substantial decrease of the thermal lens optical power and phase aberrations and increase of the laser slope efficiency are observed. A continuous-wave laser with 440 W average power and 44% slope efficiency is constructed.

Thermal effects in Yb:YAG single-crystal thin-rod amplifier.

This work presents a new design for the laser gain module based on a ytterbium-doped yttrium aluminum garnet (Yb:YAG) single-crystal thin rod. Thermal effects (temperature, phase, and polarization distortion of laser radiation) and small signal gain are investigated both experimentally and theoretically. We then analyzed the influence of thermal effects and amplified spontaneous emission on the power scaling of the laser based on the gain module. A small signal gain as high as 3.3 per pass was experimentally achieved.

Thin-tapered-rod Yb:YAG single-crystal laser amplifier

Thin-tapered-rod single-crystal active element is proposed to use in laser amplifiers. Numerical and experimental investigation of small signal gain in thin-rod and thin-tapered-rod geometries is performed and advantages of thin-tapered-rod active element are shown.

Comparison of composite and disk shaped active elements for pulsed lasers

Characteristics of active elements with different geometry have been compared theoretically. The possibility to reduce thermally the induced distortions of laser radiation and to increase the stored energy in a disk laser with a composite active element at room and cryogenic temperatures has been investigated

Comparison of thermal effects in Yb:YAG disk laser head at room and cryogenic temperature conditions

Theoretical and experimental analysis of small signal gain, phase and polarization distortion of laser radiation in end-pumped Yb:YAG thin disk and composite Yb:YAG/YAG active elements is performed at room and cryogenic temperature under non-lasing conditions.

Thin-rod and thin-tapered-rod ytterbium amplifiers for fiber lasers

Laser amplifiers based on the thin-rod (“single-crystal fiber”) and thin-tapered-rod Yb:YAG active elements are developed and tested. The ability of applying the new broadband Yb-doped materials in the thin-rod geometry is discussed and such active elements will be tested soon.

High-power laser based on amplifiers with Yb:YAG elements of advanced geometries

High average and high peak power picosecond laser composed of ytterbium fiber oscillator, Yb:YAG thin-rod preamplifiers and Yb:YAG thin-disk multipass amplifier is under development. 82 W average power at 11.5 kHz repetition rate is achieved.

Thermal distortions and heat sources in disk laser active element

Thermally induced phase distortions of disc laser active element are measured and calculated. Theoretical model shows deviation from experiment. Extra heat sources are expected to be the reason of the deviation.