Generation of solitons in transient stimulated Raman scattering by optical phase shifts

Abstract

At the present time several groups are studying the use of optical phase shifts to initiate soliton formation in transient stimulated Raman scattering.1 Our experiments use a generator-amplifier Raman laser which is pumped by a frequency-doubled Nd:YAG laser at 532 nm. The Raman medium is hydrogen at 1-100 atm. We are studying the use of an electrooptic crystal to place a π phase shift in the Stokes beam between the generator and the amplifier. This shift momentarily causes energy transfer from the Stokes to the pump beam. Surprisingly, numerical calculations indicate that in one configuration the speed of the electrooptical switch need not be faster than the coherence time of the medium to generate a soliton pulse considerably shorter than the coherence time. Thus it appears that this technique can be used to generate pulses considerably shorter than those produced using standard electro-optical switching techniques. Numerical calculations and experimental results are presented.