Generation of Nyquist pulse sequences using dual parallel Mach-Zehnder modulator and phase modulator

We propose a novel approach to generate Nyquist pulse sequences utilizing a dual parallel Mach-Zehnder modulator (DPMZM) and a phase modulator (PM). The DPMZM, driven by a single RF signal of 10 GHz, produces flat-topped optical pulses. Leveraging the time-lensing effect, the PM is employed to map these optical pulses into the frequency domain, resulting in a flat optical frequency comb (OFC) with 21 comb teeth and a frequency interval of 10 GHz. After chirp compensation and spectral shaping, Nyquist pulse sequences are obtained with a duty cycle of 0.0422.