Microwave-frequency-comb generation utilizing a semiconductor laser subject to optical pulse injection from an optoelectronic feedback laser.

Microwave frequency combs are generated by optically injecting a semiconductor laser (slave) with repetitive pulses from an optoelectronic feedback laser (master). By varying the delay time, regular pulsing states with different pulsing frequencies are generated in the master laser. The pulsing output is then optically injected into the slave laser to produce desired microwave frequency combs. Microwave frequency combs with broad bandwidths and low nonharmonic spurious noise are demonstrated experimentally. To analyze their stabilities and spectral purities, single-sideband phase noise of each microwave frequency comb line is measured. Noise suppression of the microwave frequency comb relative to the injected regular pulsing state is also investigated.