Imaging gigahertz surface acoustic waves through the photoelastic effect

This paper presents experiments and in-depth analysis of the imaging of surface acoustic waves by means of the photoelastic effect. Gigahertz surface acoustic waves, generated by optical pump pulses in a thin gold film on a glass substrate, are imaged in the time domain by monitoring ultrafast changes in optical reflectivity. We demonstrate how images of the in-plane acoustic shear strain component can be obtained by measurements with two different optical probe pulse polarizations incident from the substrate side.