Generation of hyperparametric oscillations in silica microbubbles

Cavity resonant enhanced Stimulated Raman Scattering, Four Wave Mixing and broadband hyper-parametric oscillation in silica microbubble whispering gallery mode resonators 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 multi mode spaced. The nonlinear process is phase matched due to the interaction of different mode families of the resonator