Light and sound waves interactions in optical fibers and silicon photonic circuits

We are accustomed to consider the propagation of light and sound waves as separate and unrelated phenomena. However, such division would be incorrect. The propagation of light in a waveguide exerts mechanical forces that can drive elastic wave oscillations. The mechanical (or acoustic) waves, in turn, can scatter and modulate light. Interactions between light and sound are being studied since the 1880's.