Abstract

An integrated-optic tapped delay line has been designed and tested. Potential applications include electro-optic time delay networks for beam forming and beam steering in phased-array antennas. In the latter, the delay line is used to deliver an optical signal that is intensity modulated at an rf frequency. Delays of a few nanoseconds are achievable; actual time delays are selected by electronically addressing grating-based switches integrated with optical waveguides. The integrated-optic device consists of a folded-path optical waveguide that provides long path lengths in a small, compact structure. Thick phase-reflective gratings are used as the reflective elements to achieve the folded configuration. The thick phase gratings also function as electronically addressable taps to provide time-delay selection. The taps offer the additional advantage that their transmittance is controllable by a dc bias field. This ensures a switching network capable of delivering a constant optical power to the detector which is used to convert the optical signal to an rf electronic signal. The delay line described in this paper is based on LiNbO₃ waveguides.

© 1990 Optical Society of America