Generation of hyper-parametric oscillations in silica microbubbles

Cavity resonant enhanced stimulated Raman scattering (SRS), four-wave mixing, and broadband hyper-parametric oscillation in silica microbubble whispering gallery mode resonators (WGMR) in forward and backward directions are reported in this Letter. We show that microbubbles can operate not only in a highly ideal two-photon emission regime, but also generate combs, both natively and multimode spaced. The nonlinear process is phase matched because of the interaction of different mode families of the resonator. (C) 2015 Optical Society of America