Optoelectronic phase-locking of microwave signals up to 18 GHz by a laser-diode-based GaAs:Cr photoconductive harmonic mixer

A GaAs:Cr photoconductive switch activated by 30-ps optical pulses from a gain-switched laser diode ( lambda =0.79 mu m) was used as a harmonic mixer to optoelectronically phase-lock microwave signals up to 18.01 GHz. The conversion loss of the harmonic mixer was 70 dB at 16.01 GHz. The phase noise degradation of the phase-locked 16.01-GHz signal at 5-kHz offset measured with respect to the 1.0-GHz synthesizer signal for driving the laser diode was 30 dB.<
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