Correlations between the intensities of pump, depleted pump and Stokes waves in superbroadband stimulated Raman scattering

Abstract

The pair correlations between the intensities of input pump laser radiation with spectral bandwidth of 250 cm −1, which has femtosecond and picosecond noise structures, output depleted pump radiation and Stokes light generated through stimulated Raman scattering (SRS) in compressed hydrogen have been studied experimentally under weak and strong pump depletion. The third order correlation functions were measured by means of time-delayed four-wave mixing in a Kerr-shutter scheme with two noise light beams under investigation. The data obtained show that the Stokes wave is well correlated with the input pump wave up to an energy conversion efficiency of about 30%. The measured functions display the considerable suppression of the femtosecond amplitude fluctuations in the depleted pump beam upon increasing the efficiency of SRS and pump depletion. Such a result shows a possible way for preparing superbroadband light with smooth temporal envelope and predominant phase fluctuations using SRS. The picosecond part of the correlations between the depleted pump and Stokes waves is characterized by the asymmetrical shape that is probably caused by the fact that picosecond peaks in the noise structure of the depleted pump and Stokes waves have opposite temporal profiles.