Fig. 1. Schematic of phase modulation of CML laser

Fig. 2. Phase modulation waveforms based on CML RZ-DPSK format

Fig. 3. Transmitter scheme of RZ-DPSK transmission system based on CML

Fig. 4. Modulation signals waveform. (a) Three-level drive signal; (b) RZ-DPSK signal output by CML

Fig. 5. Spectra before and after signal modulation

Fig. 6. Constellation of modulated signal

Fig. 7. Receiver scheme of RZ-DPSK transmission system based on CML

Fig. 8. Demodulated signal waveform

Fig. 9. Signal eye diagrams after demodulation of CML transmission system. (a) RZ-OOK signal eye diagram demodulated by CML laser system; (b) eye diagram after code conversion

Fig. 10. Experimental scheme of signal performance comparison of different transmission systems

Fig. 11. Performance comparison of bit error rate of DPSK signal based on CML and LiNbO₃ transmitters