Fig. 1. Schematic diagram of optical injection locking laser system. (a) Reflection type; (b) transmission type

Fig. 2. Simulation modeling diagram of OIL system with external APS

Fig. 3. Locking characteristics of injected light amplitude variation under different frequencies. （a）（b） Frequency is 0.9 MHz；

Fig. 4. Locking characteristics of injected light amplitude variation under different frequencies

Fig. 5. Schematic diagram of simulation parameter settings. (a) Injected light waveform (triangular wave variation); (b) frequency offset varies linearly with time

Fig. 6. Characteristics of increasing the locking range of OIL by APS. (a) Enhancement of locking range; (b) detail enlarged image

Fig. 7. Relationship between output phase difference and injected optical power

Fig. 8. Fitting curves between the lowest unlocking threshold power and APS frequency. (a) Lowest unlocking threshold power (unit: mW); (b) lowest unlocking threshold power (unit: dBm)

Fig. 9. Experimental setup for transmitting 16QAM signals on 3.5 km MCF in SHCD system

Fig. 10. Offline DSP algorithm process at the receiving end

Fig. 11. Phase diagrams and constellations. (a)(b) Without polarization; (c)(d) frequency is 1 MHz; (e)(f) frequency is 10 MHz

Fig. 12. Functional relationship between BER and ROP