Integrated acousto-optic heterodyning device modules in LiNbO_3 substrate

Abstract

This paper reports the realization of integrated acousto-optic (AO) device modules that combine a wideband AO Bragg cell, an ion-milled Bragg diffraction grating, and a titanium-indiffused protonexchanged waveguide lens in a Y-cut LiNbO(3) substrate, 1 x 8 x 16 mm(3) in size, to perform optical heterodyning, and their application to rf signal processing. These integrated AO heterodyne modules have demonstrated the capabilities for channelized detection of the amplitude, the frequency, and the phase of wideband rf signals and thus the capability to perform interferometric rf spectral analysis with significantly improved performances over the conventional AO Bragg cells. The single-unit (basic) modules have provided single-tone simultaneous and two-tone third-order spurious-free dynamic ranges of 51 and 40 dB, respectively, and a bandwidth of 205 MHz centered at 350 MHz at the optical wavelength of 0.6328 microm, the optical power of 1.0 mW, and the drive power of 50 mW/rf signal input. Furthermore the dual-unit modu es that consist of a pair of identical basic heterodyne devices in the same LiNbO(3) waveguide substrate, also 1 x 8 x 16 mm(3) in size, have been constructed and used to measure the angle of arrival of the rf signals.