Widely-tunable, doubly-resonant Raman scattering on diamond in an open microcavity*

Raman lasers are a valuable resource for frequency conversion of coherent light. Diamond, in particular, is a material well-suited for Raman lasers due to the wide transparency window, high thermal conductivity and large Raman gain. Using conventional monolithic resonators, the implementation of a low-threshold Raman laser in the visible, however, has remained elusive due to material and fabrication limitations. In this work, we report a novel. In this work, we report a novel platform consisting of a diamond membrane embedded in an open-access Fabry-Perot microcavity, with quality factors exceeding 100 000. By establishing a doubly-resonant configuration, with the pump laser and the Raman transition simultaneously resonant, we demonstrate a strong enhancement of the Raman signal [1]. We further demonstrate a >THz continuous tuning range of doubly-resonant Raman scattering by exploiting the in situ tuning capability of our platform. We predict that with realistic improvements of our platform a sub-mW lasing threshold for visible wavelengths is within reach.  Our results pave the way for the creation of a universal low-power frequency shifter, a valuable addition to the nonlinear optics toolbox.

[1] S. Flagan et al, arXiv:2110.06242.