Tunable stimulated Raman scattering by pumping with Bessel beams.

We report on a novel pumping scheme for stimulated Raman scattering (SRS) that uses a Bessel beam. We have used this scheme for SRS from molecular vibrations in acetone and from a polariton mode in a LiIO(3) crystal. A nearly diffraction-limited Stokes beam was observed along the cone axis of the Bessel beam. The generation mechanism of the Stokes beam is identified as being due to noncollinear scattering of the component plane waves that constitute the Bessel beam. Frequency tuning of SRS from polaritons in LiIO(3) by variation of the Bessel beam cone angle is demonstrated.