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In this report we present the concept of a planar array of cold-electron bolometers, which may potentially absorb 50 to 80 percent of the incident terahertz power with linear polarization in the frequency range 50-800 GHz. The array consists of a periodically arranged unit cells each containing a ring with the four bolometers. The performance of the array unit cell is simulated numerically. The experimentally measured frequency response of the bolometric array with 10×10 unit cells in the frequency range 230-370 GHz is presented. (Abstract)

Single-frequency 20 mW microchip 1064 nm Nd:YAG laser with long-term wavelength stability 0.3 pm and tunability of ±0.1nm was developed. 1 W laser diode with 50 μm emitter size and 808 nm wavelength was used for pumping. CW and quasi-CW regimes were investigated.

Beam quality M2=1.05 and high temporal stability were obtained in end-pumped MOPA Nd:YAG Q-switched laser. Injection seeding in Master Oscillator was applied in order to obtain smooth pulse shape and reduce build-up time instability. High small-signal gain in end-pumped amplifier provided extraction efficiency ~50% in single-pass scheme. Equalization of absorbed pumping along the laser rods provided decreasing of thermal distortions.

The study was to develop high-power stable Nd:YAG master oscillator for MOPA laser system. Output power of 4.5 W was achieved with 30 W of pump power for wide range of Q-switched lasing repetition rate. 15mJ@300Hz lasing of 10 ns pulses was achieved after optimization.

End pumped CW Nd:YAG amplifier for low power stable single-frequency laser was built and investigated. High extraction efficiency ∼30% in double-pass amplifier is achieved due to high small-signal gain provided with longitudinal pumping. Pumping of amplifier is near uniformly distributed along 2 laser rods with low concentration using two-lens relay between them in order to decrease end overheating.

End pumped MOPA Nd:YAG pulsed laser was built and investigated. High extraction efficiency ∼50% in single-pass amplifier is achieved due to high small-signal gain provided with longitudinal pumping. Pumping of amplifier is near uniformly distributed along 2 laser rods with low concentration using two-lens relay between them in order to decrease end overheating.

Formation of the given laser beam intensity and phase is an important practical and scientific problem. Bimorph flexible mirror is one of the most widely used devices for this purpose. We present a new approach of multilayer bimorph mirrors and a numerical model to simulate them, based on the finite elements method. The multilayer mirror consists of a substrate and a number of PZT layers.

Iterative Gerchberg-Saxton algorithm is applied for the formation of a given intensity distribution in the far-field zone by means of bimorph flexible mirror. Results of supergaussian beam formation from initial gaussian and ring-like intensity distribution are presented. Transformation of a gaussian intensity profile into ring-like one is shown as well. Results of numerical and experimental formation are in good agreement.

We implement a new technique of intracavity bimorph flexible mirror control that allows to manipulate laser beam parameters (increase power, decrease divergence) and to form a given intensity profile at any distance including far-field. Intracavity mirror surface profile is controlled by number of voltages calculated by means of genetic algorithm combined with hill-climbing one. Then the traditional Fox-Li approach is applied. It is numerically shown the possibility of successful formation of Bessel Gauss beam shape in near field and experimental extracavity M2-factor reduction almost in 4 times.