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.