Stimulated Brillouin Scattering by Dual Lasers Pumping in WGM Microcavities

Stimulated Brillouin scattering (SBS) is experimental investigated in several hundred microns in diameter microspheres with a little eccentricity by melting a fiber tip in a fusing splicer. Fourth order cascaded SBS at C-band (~1540 nm) with 27 mW can be achieved with the abundant and high Q modes in the microspheres. This kind of microcavity also supports high Q modes in O-band (~1320 nm) and second order SBS has been observed. In addition, SBS is also investigated by pumping-heating method with a heating laser at O-band and a pumping laser at C-band. We achieved a tunable SBS with high flexibility on the wavelength, thus the pumping laser can be set at a specified wavelength assisted by the heating laser. This method provides us a new approach for generation of SBS without tuning the pumping laser wavelength and will benefit various applications.