Ultra-Flat and Broadband Optical Frequency Comb Generator via a Single Mach–Zehnder Modulator

An ultra-flat and broadband optical frequency comb (OFC) generator is proposed and experimentally demonstrated by directly modulating a dual-driven Mach-Zehnder Modulator (MZM) with only one RF signal. The proposed scheme can generate two forms of OFCs by simply adjusting the bias voltages of the MZM and the power of the RF signal. One form is a 20-line OFC with a frequency spacing equals the frequency of the RF signal, the other form is a 16-line OFC with a frequency spacing of two times the frequency of the RF signal. The generated OFCs have low power variation and broad bandwidth. The proposed scheme is verified by an experiment. A 20-line OFC with a frequency spacing of 10 GHz and flatness of 0.7 dB, and a 16-line OFC with a frequency spacing of 20 GHz and flatness of 0.3 dB are experimentally demonstrated.