Generation of short light pulses under the stimulated Brillouin scatteringin fibers with an optimal feedback

The generation of short light pulses (less than or equal to 1 ns) in single mode fibers under pumping by wide laser pulses (of a microsecond duration) due to the backward stimulated Brillouin scattering (SBS) is numerically i nvestigated. The influence of the acoustic diffraction is taken into accoun t. The cases of acoustic waveguide and anti-waveguide fibers are considered . For an acoustic anti-waveguide fiber, a dependence of overlap integral S on the acoustic mode number n has a sharp peak in the region of n similar t o 100. Computer simulations have demonstrated the energy conversion of the pump wave into short pulses of the signal (Stokes) wave in the case of sync hronous pumping. The optimal length of the fiber should be approximately eq ual to the half-length of the pump pulse. The bypass time of the Stokes pul se of the optimal circuit fiber and the feedback loop must be equal to the repetition period of the pump pulse. An importance of acoustic mode structu re of the fiber for the process of forming pulse train in shown. We have fo und that the acoustic anti-waveguide fibers with a small core (a < 3 <mu>m) can be preferable for obtaining the stable train of compressed pulses.