Experimental studies of the statistical properties of radiation flows involved in superbroad-band stimulated Raman scattering

摘要

Abstract: The pair correlations between the instantaneous intensities of input pump superbroadband (250 cm$+$MIN@1$/) laser radiation with femtosecond and picosecond noise structures, output depleted pump radiation and Stokes one generated through stimulated Raman scattering in compressed hydrogen have been experimentally studied under the weak and strong pump depletion by means of time-delayed four-wave mixing in Kerr-shutter configuration. Experimental results show that the Stokes radiation is well correlated with the input pump one up to the energy conversion efficiency of about 30%. Considerable suppression of the femtosecond amplitude fluctuations in the depleted pump beam has been observed upon increasing the pump depletion that indicates the possible way for preparing superbroadband light with predominant phase fluctuations using SRS. The picosecond part of cross-correlation function between the depleted pump and Stokes radiation flows has very asymmetric shape that is probably caused by the transiency in the scattering of picosecond noise spikes and by the fact that these spikes in Stokes and depleted pump radiation flows have opposite temporal shapes. !13