Magnesium Fluoride Brillouin and Raman Microlaser

Stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) are essential light-matter interactions in materials and play a crucial role in various laser applications. In this letter, we fabricated a z-cut magnesium fluoride (MgF
$_{2}$
) crystalline whispering gallery mode (WGM) microcavity with a radius of
$180$
μm and quality factors (
$Q$
) exceeding 10
$^{8}$
at 1550 nm. SBS and SRS lasing were demonstrated using this high-
$Q$
MgF
$_{2}$
microcavity. The Brillouin frequency shift lies within the calculated broadened gain window, while the Raman frequency shift matches the A1g symmetric stretching vibration mode. By employing an excitation mapping method, we investigated the dynamics of SBS and SRS lasing together with four-wave mixing as the frequency detuning between the pump laser and the cavity resonance was varied. Our results reveal rich nonlinear frequency conversion phenomena enabled by the MgF
$_{2}$
microcavity, and highlight its potential for compact microlasers and sensors.