Fig. 1. Schematic diagram of the proposed OPT frequency divider. MLL, mode-locked laser; MZM, Mach–Zehnder modulator; OC, optical coupler; TODL, tunable optical delay line; PD, photodetector; BPF, bandpass filter; EA, electrical amplifier; EC, electrical coupler; PS, phase shifter.

Fig. 2. Transfer function of the MZM, and the OPT before and after the frequency division with (a) 75-MHz driving signal, (b) 50-MHz driving signal, and (c) 100-MHz driving signal.

Fig. 3. Spectra of the interharmonics generated by OEO. (a) 8.082 GHz, (b) 8.065 GHz, (c) 8.098 GHz.

Fig. 4. (a) Waveform and (b) spectra of the OPT when q equals 1/2; (c) waveform and (d) spectra of the OPT when q equals 1/3; (e) waveform and (f) spectra of the OPT when q equals 2/3.

Fig. 5. Phase noise of the OPT before and after frequency division. (a) Frequency-divided by 2, (b) frequency-divided by 3, (c) frequency-divided by 3.