Fig. 1. Experimental setup diagram.

Fig. 2. The process of spectrum and pulse evolution of each point. (a) and (d), respectively, correspond to the spectrum and pulse of point a in Fig. 1; (b) and (e), respectively, correspond to the spectrum and pulse of point b in Fig. 1; (c) and (f), respectively, correspond to the spectrum and pulse of point c in Fig. 1.

Fig. 3. (a) Spectrum of nine-line optical frequency comb spaced at 3.2 GHz. (b) Corresponding Nyquist pulse sequence with a repetition rate of 3.2 GHz.

Fig. 4. (a) Modulation depth versus DC bias. (b) Out-of-band suppression ratio versus modulation depth.

Fig. 5. Spectra generated by two light sources of (a) 1549.6 nm and (b) 1551.4 nm. (c) Nyquist pulse train with the repetition rate of 6.4 GHz.

Fig. 6. (a) Spectrum generated when three light sources are applied. (b) Nyquist pulse train with the repetition rate of 9.6 GHz.

Fig. 7. Principle of generating (a) rectangular wave and (b) sawtooth wave.

Fig. 8. (a) Rectangular waves with a repetition rate of 3.2 GHz and duty cycle of 0.26. (b) A zoomed view of a single period.

Fig. 9. Sawtooth waveforms with a repetition rate of 3.2 GHz and duty cycles of (a) 0.52 and (b) 0.67.