Fig. 1. Principle diagram of heterodyne OPLL

Fig. 2. (a) OPLL structure of single section DFB semiconductor laser; (b) function circuit of lead phase shift

Fig. 3. Frequency modulation amplitude/phase response curve of single section DFB semiconductor laser

Fig. 4. (a) Beating signals of master and slave lasers under free-running and phase-locked states; (b) beating signal of master and slave lasers under phase-locked state in 100 kHz view bandwidth span

Fig. 5. Line width measurement results of slave laser before and after phase locking. (a) Free-running state; (b) phase-locked state

Fig. 6. Frequency noise power spectrum density curves of master laser and slave laser in free-running and frequency/phase-locked state with different phase shift parameters

Fig. 7. Influence of different gain coefficients on frequency noise power spectrum density of slave laser in feedback loop of OPLL