Picosecond acoustic pulse reflection from a metal-metal interface

Picosecond duration laser pulses are used to generate ultrashort acoustic pulses in a bilayer metal film. Time-resolved transient piezoreflectance measurements permit the observation of acoustic reflections from a metal-metal interface within the film, as well as reflections from the film-substrate interface. We show that our measurements are well described by an abrupt interface model of acoustic mismatch.