Intermodulation product effects on the working of a phased-array transducer acousto-optic switch

Abstract

Acousto-optic devices play an important role in the field of optical information and communication. For a few years, we have worked on acousto-optic deflection in the Bragg regime at 1.55-µm wavelength, by controlling the rf signal applied to the piezoelectric transducer. Recently, still using the acousto-optic interaction, we have taken an interest in the 2×2 switching function. We present an acousto-optic switch architecture based on phased-array transducers. In the same crystal, we superimpose two diffraction gratings created by two rf signals. Generating a phase shift on a rf signal applied between successive elementary transducers allows us to tilt one grating so as to interconnect inputs to outputs. To predict and study some physical phenomena generated in this switch architecture, we present some characterizations made on a monotransducer cell. We point out the optical cross talk between output paths (influence of the intermodulation products due to the superimposition of two rf signals on the same transducer).