Abstract

Stimulated Raman Scattering (SRS) is a well-established nonlinear optical technique for extending spectral coverage of solid-state lasers [1]. Raman crystals provide a very simple, compact and efficient means of frequency conversion. Among the practically available solid-state materials, Ba(NO₃)₂ exhibits the highest steady-state Raman gain. However, its narrow Raman bandwidth limits the steady-state regime to nanosecond pump pulse durations, since for pump pulse widths approaching the dephasing time of optical phonons, the SRS regime becomes time-dependent and the generation threshold increases [2]. For an efficient Raman conversion of picosecond pulses, crystals exhibiting sufficiently large Raman gain bandwidth are required. In this regard, tungstate crystals such as KGd(WO₄)₂, BaWO₄ and SrWO₄ offer a favorable combination of good thermo-mechanical properties, a still reasonably high steady-state Raman gain and a sufficiently wide Raman gain bandwidth to be pumped with sub-nanosecond pulses [3]. In this work we present an extremely simple and efficient travelling-wave Raman converter based on a SrWO₄ crystal pumped with intense picosecond pulses.

© 2015 IEEE