Frequency characteristics of opto-acoustic transducers

An opto-acoustic transducer (OAT) converts a spatial distribution of optical intensity into a corresponding distribution of acoustical amplitude. In designing such a device, operating frequency and bandwidth must be considered. We have developed an equivalent circuit model for the OAT to predict the frequency dependence of the transducing characteristics. In particular, the switching ratio, i.e., the ratio of acoustical pressurein the illuminated region to that in the dark region, and the transfer function for acoustical pressure-to-voltage amplitude are explored as functions of frequency. The switching ratios found to be extremely frequency sensitive for many important cases. The effects of this sensitivity on device design and performance are discussed.