Stable multi-frequency generator based on phase-locked optical frequency combs

A photonic generation of multi-frequency source based on the heterodyne of two phase-locked optical frequency combs (OFCs) is proposed and demonstrated. By applying an optical phase-locked loop, the phase noise induced by optical links is decreased by approximately 70, 66, and 35 dB at 0.01, 0.1, and 1.0 Hz offset frequencies, respectively. The proposed scheme provides 8 radio frequency signals, the frequencies of which span from 540 to 4040 MHz, with a 500-MHz interval. The number of generated signals can be readily scaled by using OFCs with broader bands, whereas the frequencies can be scaled by tuning the repetition rates of OFCs.