  A surface acoustic wave (SAW) creates its own high-Q ultra-small volume
whispering gallery modes (WGMs), different from usual bulk acoustic WGMs, in an
optical dielectric WGM resonator. We show that it is possible to realize an
externally controllable, efficient triply-resonant opto-mechanical interaction
between two optical WGMs and the SAW WGM and to use such an interaction in
various sensor applications.
