Abstract

The method of cascading acousto-optic switches is shown, both theoretically and experimentally, to reduce the many interchannel crosstalk mechanisms which degrade the system performance of wavelength-routed dense wavelength multiplexed optical communication systems. Two integrated acousto-optic switches were cascaded and examined for one and two-stage switch performance, including bandpass, sidelobe levels, bar and cross-state extinctions insertion loss and imposed frequency shifts. The expanded, or dilated, version of the switch showed dramatic improvement in most figures of merit, with an expected doubling of loss. In addition, it is shown that the operating window of the switch is significantly broadened by dilation. Sidelobe suppression, achieved through apodization of the acousto-optic interaction strength, combines with dilation, is shown to reduce channel spacing as well as improve tolerance of the system to wavelength registration errors.

© 1993 Optical Society of America