Raman lasers using low birefringence synthetic diamond: Material characterisation, device design, and an initial demonstration

Abstract

Intracavity Raman lasers are a simple means to shift the frequency of solid-state lasers. However, the Raman scattering process is inelastic and hence heat is dumped into the nonlinear medium - thus, the output power is often limited by thermal lensing. The current Raman crystals of choice, e.g. KGW and Ba(NO 3 ) 2 , have thermal conductivities of a few W/m.K. By contrast, diamond has a thermal conductivity of 2000W/m.K and a large Raman gain coefficient. To date, only pulsed diamond Raman lasers have been demonstrated [1, 2]. Two hurdles exist to efficient diamond Raman lasers: the short lengths of diamond available and the spatially varying birefringence of most diamond samples. Mildren et al. reported on an external cavity Raman laser where the performance was limited by diamond birefringence [1]. We will report on the use of new low birefringence diamond to address this issue in conventional lasers and its subsequent use in a CW Raman laser.