We report on realization of an efficient triply-resonant coupling between two long lived optical modes and a high frequency surface acoustic wave (SAW) mode of the same monolithic crystalline whispering gallery mode resonator. The coupling results in an opto-mechanical oscillation and generation of a monochromatic SAW. A strong nonlinear interaction of this mechanical mode with other equidistant SAW modes leads to mechanical hyper-parametric oscillation and generation of a SAW pulse train and associated frequency comb in the resonator. We visualized the comb observing the modulation of the modulated light escaping the resonator.
@article{arxiv.1106.1477,
title = {Surface Acoustic Wave Frequency Comb},
author = {A. A. Savchenkov and A. B. Matsko and V. S. Ilchenko and D. Seidel and L. Maleki},
journal= {arXiv preprint arXiv:1106.1477},
year = {2011}
}