Low-noise optical injection locking of a resonant tunneling diode to a stable optical frequency comb

Abstract

Optical injection locking of a resonant tunneling diode (RTD) oscillator has been demonstrated using ultrashort pulses from a mode-locked Ti:sapphire laser operating at a 1GHz pulse rate. The source of the optical signal is a mode-locked femtosecond laser whose optical frequency comb is phase locked to a H-maser stabilized frequency synthesizer. An exceptionally large capture range of more than 5MHz is observed. The system produces stable microwave signals with low phase noise, which at 1GHz is less than −74dBc∕Hz for a 10Hz offset. The noise of the microwave injection-locked RTD signal matches that of the input optical pulses.