Abstract

The sensitivity for enhanced detection of surface acoustic waves (SAW) using a traveling Bragg regime grating was found to be similar to that obtained using stationary reference gratings operating in the Raman-Nath diffraction regimes.¹ An acousto-optic modulator (AOM) with a nominal frequency of 40 MHz was used to detect traveling gratings produced by SAW on a LiNbO₃ substrate. The center frequency of the SAW was 34.88 MHz corresponding to a wavelength, Λ_S, of 100 µm. With the AOM tuned to 38.5 MHz, the wavelength of the bulk acoustic wave, Λ_B, in the flint glass modulator was also about 100 µm. The AOM was operating in the Bragg diffraction regime (Q'≈11) and the SAW in these experiments was a weakly modulated traveling grating, either cw or pulsed, operating in the Raman-Nath diffraction regime.²

© 1992 Optical Society of America