Time-resolved imaging of GHz acoustic vibrations at arbitrary frequencies using asynchronous periodic probe laser pulses

We present a technique for imaging gigahertz surface acoustic waves in the time domain at arbitrary frequencies, in which acoustic waves are excited asynchronously to the optical probe pulse train used to detect them. We apply this approach to the two-dimensional imaging of electrically excited single-frequency surface acoustic waves on a GaAs substrate with a deposited interdigital transducer. This technique significantly increases the possible fields of application for gigahertz acoustic wave device imaging.