Quasi-phase matching generation of blue coherent radiation at stimulated Raman scattering

We present a new, to our knowledge, method of anti-Stokes generation by stimulated Raman scattering in media with variations of third order nonlinearity ( χ (3)) along longitudinal coordinate. By numerical simulation of steady-state and transient stimulated Raman scattering we determined the quasi-phase matching condition in different media and obtained the conditions of high anti-Stokes conversion efficiency. We calculated the dependence of energy conversion from pump into anti-Stokes on the ratio of pump to Stokes input intensities. We showed instances in which the efficiency of anti-Stokes generation exceeded 35%. We determined that the conversion efficiency depends on the ratio of dephasing time to pulse duration and essentially decreases with its increasing. The results of the study can be used for the development of new effective Raman nonlinear-optical devices.