Optical Heterodyne With Lower Phase Noise

Proposed improvement enhances utility of optical-heterodyne apparatus used to generate radio signal at chosen frequency between 1 and 1,000 GHz. Two lasers injection-locked to third, mode-locked laser. Beat-frequency heterodyne output contains much less phase noise if generated from outputs of two independent lasers, and phase-coherent with reference signal. Potential applications include phased-array radar, fiber-optic communication systems, fiber-optic stabilized oscillators, and other applications involving conversions between optical and millimeter-wave signals.