The optical-waveguide readout of signals in surface acoustic wave devices

The readout of radio signals at the carrier frequency in surface acoustic wave devices with the aid of an optical beam propagating along the surface in an optical waveguide is considered. The readout circuits employ either a support grating or a Mach-Zehnder interferometer. The way in which the power of the electrical output signal, the gain factor, and the signal-noise ratio at the output of the photodetector depend on the parameters of the readout circuits is analyzed. A comparison is made between optical readout circuits and a circuit for the direct readout of a signal with the aid of an interdigital transducer.