We investigate the generation of acoustic phonons from electrostriction of optical waves in
small core waveguides. We specifically consider simple step-index strip waveguides
composed of silica or silicon in air, with sub-micron lateral dimensions. Such
waveguidessupport one or a few optical modes, but a rich spectrum of acoustic phonons that
becomes densely populated as the phonon frequency increases. We evaluate rigorously the
phonon energy density that results from the electrostriction of two frequency detuned guided …