Enhanced Diamond Brillouin Scattering Based on Cascaded Raman Conversion

Stimulated Brillouin scattering (SBS) is a wavelength-conversion effect favored by many researchers because of its low threshold, narrow linewidth and low noise intensity [1], [2]. In the past, low threshold and narrow linewidth Brillouin laser output has been obtained based on optical fiber, on-chip-waveguides and microcavities [3–5], but there are also problems such as low output power and difficult to control the cascade order. Comparatively, diamond crystal not only has a large Brillouin frequency shift (~70 GHz @1 μm) and gain coefficient (~80 cm/GW @0.5 μm) [7], [8], it has ultra-high thermal conductivity (>2000 Wm
⁻¹
K
⁻¹
) and very wide spectral transmission band (>0.23 μm). These characteristics are important and give diamond the potential to break through the current bottlenecks limiting waveguide-based Brillouin lasers.