Abstract

Optical time division switching systems require optical switches with a great bandwidth of several GHz at moderate switching voltages ( <10 V ). Unfortunately, both types of guided wave optical switches, the directional coupler switch /1/ and the X-switch /2/ require relatively high voltages for common device length of a few millimeters. The reduction of the switching voltage by increasing the length of the device is only possible at the expense of the allowable optical bandwidth. A solution, which combines the advantageous features of low voltage operation and great optical bandwidth, is the balanced bridge interferometric switch /3/. This switch has been realized in Z-cut LiNbO₃ using electrooptically tunable directional couplers as 3 dB -splitters and combiners. However, in order to utilize the excellent performance of high speed and low loss phase modulators on X-cut LiNbO₃ /4/, a simpler 3 dB coupler than a directional coupler with three electrodes would be desirable. In this paper we demonstrate the implementation of electrooptic X-switches as simple and efficient 3 dB-couplers in high speed interferometric activated switches.

© 1988 Optical Society of America