Characteristics of pulse amplification and energy utilization efficiency of a round-trip neodymium glass amplifier with a stimulated Brillouin scattering mirror

An experimental investigation was made of the output energy, deformation of the time structure of a pulse, and precision of phase conjugation in a round-trip neodymium glass amplifier with a stimulated Brillouin scattering (STBS) mirror. The efficiency of utilization of the stored energy, reaching 90% under optimal conditions, depended on the overlap of the pulses in the active medium and this overlap in turn affected the characteristics of the STBS mirror. The Frantz–Nodvik equation was used to develop a program for the design of a round-trip amplifier allowing for the overlap of the pulses and for the nonlinearity of STBS. It was found that deterioration of the angular divergence of spatially homogeneous and speckle-inhomogeneous beams was due to the simultaneous effect of imperfections of the phase conjugation process and of gain saturation.