Nonplanar phase-matching of stimulated anti-Stokes Raman scattering pumped by a Bessel beam

摘要

We have studied the behaviour of anti-Stokes emission of stimulated Raman scattering (SRS) in hydrogen gas pumped with a Bessel beam of variable cone angle. We demonstrate that for the generation of anti-Stokes emission via a four-photon process including pump and Stokes photons two types of phase-matching exist: the usual planar phase-matching involving two collinear pump photons and nonplanar phase-matching involving two noncollinear pump photons with wave vectors on the surface of the cone of the Bessel beam. Both types of phase-matching are distinguished experimentally by their different behaviour when a small azimuthal part of the pump wave vectors is blocked.