Tunable multi-frequency microwave signal generation in optoelectronic oscillator based on directly modulated laser

In this paper, we propose an Optoelectronic Oscillator (OEO) based on a Directly Modulated Laser (DML) to generate multi-frequency microwave signals. The proposed OEO features in a DML with no external modulator in the loop, an electrical mixer to provide the multi-frequency injection signals, and a two-channel electrical filter bank to choose the desired oscillation modes. The generated multi-frequency microwave signals have excellent performance in the Side Mode Suppression Ratio (SMSR), phase noise, tunability and coherence. In the proof-of-concept experiment, triple-frequency microwave signals are demonstrated with the frequency tunability of 8 - 12 GHz, and the SMSR and phase noise can be up to 53 dB and -120 dBc/Hz @ 10 kHz, respectively. Moreover, quintuple- and septuple-frequency microwave signals are also successfully generated.