Cavity length matching and optical resonances in a Raman laser with the multimode pump source.

We report on the observation of local reduction in generation threshold and enhancement in the output energy of a nanosecond Raman laser when the round-trip time of its cavity is matched with that of a longitudinally multimode pump laser or related to the latter as a ratio of small integers. We refer both observations to the synchronous pump effect originating from the periodicity in the small-scale intensity structure of the pump pulse.

Bessel beam transformation by anisotropic crystals.

Transformation of Bessel beams by biaxial and uniaxial crystals is investigated experimentally and theoretically. Experimental observations show beam symmetry changing and formation of complex intensity patterns, depending on the orientation of the crystal. These patterns can appear as a regular system of peak intensities.

Spectral shift of Raman generation band in a Bessel pump beam.

A spectral shift in the first Stokes generation band has been observed at stimulated Raman scattering in a Bessel light beam. Under nanosecond pulse excitation in barium nitrate crystal, the Stokes emission propagating along the Bessel beam axis has been found to be frequency shifted toward the blue side by 3.7 GHz with respect to the Stokes emission propagating along the surface of a cone.

Observation of Raman conversion for 70-fs pulses in KGd(WO4)2 crystal in the regime of impulsive stimulated Raman scattering.

Raman conversion of femtosecond pulses in a solid-state medium is reported. Stimulated Raman scattering (SRS) was observed in an impulsive SRS regime when the pump pulse's duration was comparable with the period of Raman-active vibration. The generation of super broadband radiation, which is a distinguishing feature of impulsive SRS, is shown.