Optical probing of nonlinear SAW waveform

A new type of laser probe of surface acoustic waves (SAW) is reported. The probe operation is based on knife-edge technique, while a pulsed laser is employed in order to sample the waveform of SAW. The spatial resolution of the probe is 1.3 /spl mu/m and its bandwidth is greater than 1 GHz. Nonlinear SAW on single crystal LiNbO/sub 3/ plates has been studied at the input frequency 200 MHz with the new method. It is shown that the initially sinusoidal wave breaks into a train of pulses, up to four per period. The observed spectrum of the wave included as many as 10 harmonics.