Four-wave-mixing generation of SRS components in BaWO4 and SrWO4 crystals under picosecond excitation

Four-wave-mixing stimulated Raman scattering (SRS) generation of Stokes and anti-Stokes components in BaWO₄ and SrWO₄ crystals excited by a 1064-nm pulsed laser with a pulse duration of 18 ps has been investigated. It is shown that, due to the four-wave mixings of SRS components in short (~1 cm) crystals, the generation thresholds of the second and third Stokes components are much lower than the values determined by the cascade SRS mechanism. If the crystal length is increased by a factor of more than four, the mechanism of multiwave SRS becomes similar to the cascade mechanism (without four-wave mixings). Rotation of BaWO₄ crystal makes it possible to control the competition of the processes of four-wave-mixing SRS generation of anti-Stokes and second Stokes components.