Fig. 1. Simplified block diagram of injection locking

Fig. 2. Spectra in injection locking. (a) Output spectrum of ML after modulation; (b) output spectrum of SL after injection locking

Fig. 3. Structural diagram of directly modulated laser

Fig. 4. Schematic of automatic locking of directly modulated laser

Fig. 5. Experimental setup for generation of frequency doubling signals based on injection locking of direct modulated laser

Fig. 6. Results of 10 GHz frequency doubling signal. (a) Electrical spectrum, RSPAN=40 GHz; (b) electrical spectrum, RSPAN=100 MHz; (c) phase noise; (d) spectrum after automatic locking

Fig. 7. Comparison of microwave signal power changes by automatic locking and manual locking

Fig. 8. Comparison of phase noise results. (a) Microwave signals by automatic locking and manual locking; (b) microwave signals by automatic locking and manual locking after 10 min

Fig. 9. Results of 12 GHz frequency doubling signal. (a) Electrical spectrum, RSPAN=1 MHz; (b) phase noise; (c) spectrum after injection locking