Alexis V. Kudryashov

High-Power Nd:Y3Al5O12 Ceramic Laser

High power CW (continuous wave) polycrystalline Nd:Y3Al5O12 (Nd:YAG) ceramic rod laser was demonstrated for the first time. The maximum output power of 31 W with a 18.8% slope efficiency was obtained at 1064 nm using 214.5 W/808 nm laser diode pumping.

Semipassive bimorph flexible mirrors for atmospheric adaptive optics applications

A semipassive bimorph mirror is considered as the most promising corrector for low-order and at the same time low-cost atmo- spheric adaptive optical systems. Theoretical and experimental results of the response functions study are presented. A simple response function histeresis compensation method is suggested. The efficiency of correct- ing the first eight Zernike polynomials with a 17-electrode bimorph mirror is given. It is shown that such a corrector can be successfully used to compensate turbulence with the Kolmogorov spectrum.

Correction of strong phase and amplitude modulations by two deformable mirrors in a multistaged Ti:sapphire laser

We describe a novel scheme consisting of two deformable bimorph mirrors that can free ultrashort laser pulses from simultaneously present strong wave-front distortions and intensity-profile modulations. This scheme is applied to the Max-Planck-Institut für Quantenoptik 10-TW Advanced Titanium-Sapphire Laser (ATLAS) facility. We demonstrate that with this scheme the focusability of the ATLAS pulses can be improved from 10(18) to 2x10(19) W/cm(2) without any penalty in recompression fidelity.

Shack-Hartmann wavefront sensor for laser beam analyses

Shack-Hartmann wave-front sensor (SHWS) was designed to measure both intensity distribution and phase distortion of optical fields in real time and high accuracy. It can be widely used not only in measuring, diagnostic, but also in adaptive optical systems to compensate for phase distortions. Various parameters such as peak-to-valley, root-mean square, Zernike coefficients, beam quality (M2) could be calculated with the help of such a sensor. The results of wavefront measurements by using our SHWS are reported in this paper.

Cw industrial rod YAG:Nd 3+ laser with an intracavity active bimorph mirror

A special type of resonator with an intracavity wide-aperture active mirror was built, and a concave spherical bimorph active corrector was investigated. An increase of laser beam quality by a factor of 2-2.5 was achieved in a multimode regime of laser generation with an intracavity-controlled mirror. It was shown that various radiation mode structures could be formed at the laser output and in the far-field zone.

Control of high power CO2 laser beam by adaptive optical elements

Abstract The spatial and temporal beam characteristics of a cw pumped CO 2 laser with active mirrors in the cavity have been investigated. The five-pass unstable cavity with magnification M = 2 was used, where one of the folding mirrors was replaced by a water cooled flexible mirror based on a bimorph piezoelement. The pulse-periodical regime of the laser generation in different frequency range of controlling signals with a 100% beam power modulation depth was realized. The maximal pulse power value exceeding three times the average power level was obtained at 3.8 kHz pulse repetition frequency. The modulation and stabilization of the output power of a CO 2 100 W laser with a Fabry-Perot interferometer was realized.

Characterization of wave-front corrected 100 TW, 10 Hz laser pulses with peak intensities greater than 1020W∕cm2

An improvement of laser-focused peak intensity has been achieved in a JAERI 100 TW Ti:sapphire chirped-pulse amplifier chain with a feedback controlled adaptive optics system operating at a 10 Hz repetition rate. The Strehl ratio was enhanced to 0.8 by means of a Bimorph deformable mirror with a Shack-Hartmann wave-front sensor. Measurements of optical parameters of the laser pulse and an experimental tunneling ionization yield of helium have practically confirmed focusing to ultrarelativistic intensities of over 1020W∕cm2 within 16% accuracy.

Active laser resonator performance: formation of a specified intensity output

We discuss the formation of a specified super-Gaussian intensity distribution of a fundamental mode by means of an intracavity controlled mirror, which is a water-cooled bimorph flexible mirror equipped with four controlling electrodes. Analysis has confirmed the possibility to form fourth-, sixth-, and eighth-order super-Gaussian intensity distributions at the output of the stable resonators of industrial cw CO(2) and YAG:Nd(3+) lasers. We present the results of the experimental formation of fourth-order and sixth-order super-Gaussian fundamental modes at the output of a cw CO(2) laser by means of an intracavity flexible mirror. We observed an increase in power up to 12% and an enlargement of the peak value of the far-field intensity by as much as 1.6 times that with a Gaussian TEM(00) mode of the cw CO(2) laser.

Doughnut-like laser beam output formation by intracavity flexible controlled mirror

The formation of the given low loss and large beamwidth doughnut-like fundamental mode of stable resonator by an intracavity flexible mirror is discussed. The mirror is a bimorph one with one round and two ring controlling electrodes. An inverse propagation method is used to determine the appropriate shape of the controlled mirror. The mirror reproduces the shape with minimal RMS error by combining weights of experimentally measured response functions of the mirror sample. The voltages applied to each mirror electrode are calculated. The calculations are carried out for industrial CW CO2 laser.

Super-Gaussian laser intensity output formation by means of adaptive optics

An optical resonator using an intracavity adaptive mirror with three concentric rings of controlling electrodes, which produc low loss and large beamwidth super-Gaussian output of order 4, 6, 8, is analyzed. An inverse propagation method is used to determine the appropriate shape of the adaptive mirror. The mirror reproduces the shape with minimal RMS error by combining weights of experimentally measured response functions of the mirror sample. The voltages applied to each mirror electrode are calculated. Practical design parameters such as construction of an adaptive mirror, Fresnel numbers, and geometric factor are discussed.