Highly Transient Stimulated Raman Scattering in SrMoO4 under Ultrafast Double-Pulse Laser Pumping

A highly transient stimulated Raman scattering in a SrMoO₄ crystal with not only the long (888cm^–1), but also the short (327cm^–1) Raman shift under ultrafast double-pulse pumping with a controllable chirp by the orthogonally polarized pump pulses at 1030 nm with a different delay between them was investigated. In the scheme with the 5.7-ps delay of the ordinary-wave pump pulse relative to the extraordinary-wave pump pulse, at the pump pulses stretched from 0.25 ps up to 6 ps by negative chirping, the highest Raman conversion efficiency of up to 44% into the long-shifted Stokes component at 1134 nm was achieved, that is 1.57 times higher than for the single-pulse pumping scheme with the same input pump energy (40 μJ). In the scheme without the delay between the input ordinary- and extraordinary-wave pump pulses, efficient and simultaneous Raman generation with both the short and long Raman shifts at the wavelengths of 1066 and 1134 nm was achieved in a wide range of the chirped pump pulse durations. In particular, the short-shifted Raman conversion into 1066 nm was efficient (10.5%) even for the pump pulse durations shorter than 1 ps corresponding to strong nonlinear phase modulation suppressing Raman conversion in the single-pulse pumping scheme.