Fig. 1. Schematic diagram of experimental setup

Fig. 2. Spectrograms and time-domain waveforms of Nyquist pulse

Fig. 3. Schematic diagram of experimental setup for measuring spectra of OFC by heterodyne method

Fig. 4. Experimental results with V_PP fixed at 1 V. (a) SMSR and flatness of OFC with different numbers of comb teeth;

Fig. 5. Experimental results of OFC with different V_PP values. (a) SMSR; (b) flatness; (c1)‒(e1) spectrograms of Nyquist pulse when V_PP is optimal; (c2)‒(e2) time-domain waveforms of Nyquist pulse when V_PP is optimal

Fig. 6. Spectrograms, time-domain waveforms, and flatness of EFC when the frequency intervals are 6, 7, and 10 MHz, respectively. (a1)‒(c1) Spectrograms; (a2)‒(c2) time-domain waveforms; (d) flatness of EFC versus frequency interval

Fig. 7. Spectrograms, time-domain waveforms, and flatness of Nyquist pulse when the frequency intervals are 6, 7, and 10 MHz, respectively. (a1)‒(c1) Spectrograms; (a2)‒(c2) time-domain waveforms; (d) flatness and SMSR of OFC versus frequency interval

Fig. 8. Phase noise of electrical signal and Nyquist pulse. (a) Electrical signal; (b) Nyquist pulse