Space and time structure of ultrashort pulses formed by opposed stimulated scattering of laser beams

A theoretical analysis is made of the space and time structure of optical pulses formed by opposed stimulated Brillouin scattering (STBS) of focused laser beams allowing for an inhomogeneous transverse intensity distribution. It is shown that the laser pulses obtained under conditions of maximum compression and efficient STBS reflection have a complex space and time intensity distribution. The time structure of the reflected pulses obtained in the case of a large focusing angle is due to smoothing of a quasiperiodic time substructure of the Stokes pulse because of a transverse redistribution of the intensities of the interacting beams. Calculations are made of the coefficients of reflection and STBS compression as a function of the excess of the pump intensity above the threshold and of the focusing angle. Good agreement with experiments is found.