Fig. 1: Schematic of the hybrid electro-optic comb.
a The EO comb is generated by coupling a continuous-wave (cw) pump laser into a LN resonator under microwave modulation. b Spectrum of the EO comb when the pump laser is above the Raman lasing threshold. The EO combs spread around the pump laser and Raman laser share the same frep but have different fceo (unlocked state). With the help of four-wave mixing (FWM), these two combs expand their bandwidths and overlap. The beating frequency of the two combs in the overlapped modes is transferred to the Raman laser mode and finally locks the Raman lasing frequency being integer multiples of the microwave frequency from the pump frequency (locked state).
