Laser warning receivers and high data rate optical communication systems require local oscillators which can rapidly track the frequency of received radiation. Situations occur where significant uncertainty exists regarding the optical carrier frequency of the anticipated signal. Such uncertainty can result from doppler shifts in the radiation transmitted from satellites, missiles, etc., or in the case of uncooperative transmitters, transmitters tuned to differing operating frequencies. A common approach to tracking the frequency of received radiation employs a phase-locked-loop. Recent optical implementations of this widely used electronic concept, such as A. Scholtz, W. Leeb, R. Flatscher, and H. Philips, "Realization of a 10.mu.m Homodyne Receiver," Journal of Lightwave Tech., Vol. LT-5, No. 4, Apr. 1987 and S. Lowney and D. Marquis., "Frequency Acquisition and Tracking for Optical Heterodyne Communication Systems," Journal of Lightwave Tech., Vol. LT-5, No. 4, Apr. 1987., exploit an optical voltage controlled oscillator (OVCO), to provide frequency tunable laser output in a feedback control loop with various kinds of rf frequency discrimination to compare the OVCO frequency with that of the received radiation. These implementations achieve frequency lock in times on the order of hundreds of microseconds. The presently disclosed approach can acquire frequency lock at least two orders of magnitude faster with a reduced amount of hardware.