Laser-generated surface acoustic waves in a ring-shaped waveguide resonator.

Surface acoustic wave (SAW) waveguide resonator is formed by a ring-shaped strip of copper 10 microm wide and approximately 130 microm in diameter embedded into a 0.8 microm thick layer of silica on a silicon wafer. SAWs are excited at one side of the copper ring by a short laser pulse focused into a spatially periodic pattern and detected via diffraction of the probe laser beam overlapped with the excitation spot. SAW wavepackets with central frequency 460 MHz travel around the ring and are detected each time they make a full circle and pass trough the probe spot. Potential applications of ring resonators for SAWs are discussed.