S.G.Grechin, D.A.Mashkovsky, V.N.Rozhdestvin, E.A.Sharandin, O.A.Smirnova, B.L.Sozinov
"Regenerative amplification in multipass laser amplifiers with PC-SBS mirror"
VIII Conference on Laser Optics, 1995, v.2, p.251

      The results of the theoretical and experimental studies for forming the energy, temporal, polarization and spaceous radiation characteristics at the regenerative amplification in four-pass amplifier at YAG:Nd3+ with Phase Conjugation mirror have been presented. It has been shown that in this mode of gain at optimaly chosen parameters and operating modes of the elements the radiation power increase by 2-3 times under the corresponding duration decrease (the generator pulse duration is decreased by 3-4 times) has been provided. Maximum pulse duration decrease in obtained at optimaly chosen threshold of SMBS mirror (5-10 mJ). This threshold value is easily provided in the amplifiers with real inhomogeneities of the active elements.

      The range of the input signals at which a single radiation pulse is formed, has been determined. And in this case it is possible to decrease by 20-30 times the input pulse energy which provides the maximum energy removal in the active element (from 500 up to 20 uJ for the element YAG:Nd3+ d = 8x100 mm, G0 = 22). The presence of depolarization in the optical elements of the amplifier results in the generation mode of it's operation, the energy output radiation decrease and worthening the quality of the spaceous characteristics.

      In the far zone the radiation has a single kernel with a smooth distribution, but repeated reflection from PC-SMBS mirror in the regeneration mode results in worthening of the quantity of the spaseos characteristics compared with the case of the initial four-pass amplifier (the energy part at the diffraction angle is decreased from 86% up to 60-70%). The requirements for the optical quality of the active elements have been stated.