All-solid-state, synchronously pumped, ultrafast BaWO_4 Raman laser with long and short Raman shifts generating at 1180, 1225, and 1323 nm

摘要

A lot of attention is currently focused on synchronously pumped, extra-cavity crystalline Raman lasers generating one or two Stokes Raman components in KGW or diamond Raman-active crystals, and also generating additional components of stimulated polariton scattering in lithium niobate crystal having both cubic and quadratic nonlinearities. In this contribution we report on generation of more than two Stokes components of stimulated Raman scattering with different Raman shifts in the all-solid-state, synchronously pumped, extra-cavity Raman laser based on the Raman-active a-cut BaWO_4 crystal excited by a mode-locked, 220 nJ, 36 ps, 150 MHz diode side-pumped Nd:GdVO_4 laser generating at the wavelength of 1063 nm. Excitation by the pumping radiation polarized along the BaWO_4 crystal optical axis resulted in the Raman generation with not only usual (925cm~(-1)), but also additional (332cm~(-1)) Raman shift. Besides the 1180-nm first and 1323 nm second Stokes components with the Raman shift of 925cm~(-1) from the 1063nm fundamental laser wavelength, we have achieved generation of the additional 1227nm Raman component with different Raman shift of 332cm~(-1) from the 1180nm component. At the 1227 nm component the strongest 12-times pulse shortening from 36ps down to 3ps was obtained due to shorter dephasing time of this additional Raman line (3ps for the 332-cm~(-1) line instead of 6.5ps for the 925cm~(-1) line). It has to be also noted that the 1225 nm generation is intracavity pumped by the 1179 nm first Stokes component resulting in the strongest pulse shortening close to the 332cm~(-1) line dephasing time (3ps). Slope efficiency of three Stokes components generation exceeded 20%.