Self-induced destructive interference suppression of stimulated electronic Raman scattering

Abstract

The self-induced suppression (SIS) of stimulated electronic Raman scattering (SERS) is discussed. The nature of SIS is that SERS induces in gaseous media the generation of new fields by a four-wave mixing (FWM) process which destructively interferes with SERS and results in its suppression. The behaviour of Stokes radiation is investigated under SIS of SERS, both in the steady-state case and in the non-stationary regime of interaction with an ultrashort pump pulse. The effect is shown to be absent in the non-stationary case. On the basis of this result the author is able to explain in a simple manner the 'strange' dependence of the Stokes wavelength on pump pulse duration observed experimentally in barium vapours. The author also discusses the possible application of SIS of SERS for Stokes frequency switching. This can be achieved by stimulation of destructive interference between SERS and FWM if, simultaneously with the pump pulse, a signal wave at a frequency of one of the parametrically generated fields is switched on. As a result the FWM is intensified leading to strong suppression of SERS on a given transition and the Stokes radiation is now generated on the other transition with a new frequency. The method can be used to convert the laser frequency into the far-IR region and for a new spectroscopic study of gaseous media.