Optical Frequency Comb and Nyquist Pulse Generation With Integrated Silicon Modulators

We demonstrate nine-line optical frequency comb (OFC) and sinc-shaped Nyquist pulse generation based on two cascaded silicon Mach-Zehnder modulators. The OFC has a flatness of 1.83 dB, a frequency spacing of 5 GHz, and a corresponding Nyquist pulsewidth of ~22 ps. Moreover, multi-wavelength operation and repetition rate tunability have also been demonstrated, which indicates the potential of our work to generate an on-chip high-speed pulse train demanded in optical communications and microwave photonics applications.