Abstract

We have recently reported on surface wave acousto-optic Bragg interactions at microwave frequencies in titanium-diffused lithium niobate (Ti:LiNbO₃) optical waveguides (1,2). Acousto-optic Bragg bandwidths up to 530 MHz using a single wideband beam steering SAW transducer with an upper frequency limit above 2 GHz have been achieved (2). However, although these devices are sufficiently useful to allow the practical implementation of a spectrum analyser function, they suffer from relatively poor efficiency at such high frequencies. This is partly due to the beam steering configuration used where adjacent elements are driven in anti-phase and stepped by an integral number of half wavelengths (3). The resulting bus bar connecting pattern introduces stray capacitance and losses. The problem is compounded when multiple tilted beam steering devices are employed whether these are separately driven via a power divider or connected together on the substrate. In this paper we propose a new transducer configuration which should allow greater efficiency together with wideband operation. We call this device a Continuous Finger Staircase Array transducer (COFSA).

© 1982 Optical Society of America