Simultaneous generation of optical frequency comb and microwave frequency comb utilizing a directly modulated laser

A simple, power-efficient, and easily adjustable scheme for OFC and MFC generation by utilizing the nonlinear modulation characteristics of DML is proposed and experimentally demonstrated. When the repetition frequency and power of RF signal are set to 6.3 GHz and 2.1 dBm, respectively, a 28-line OFC with flatness of 2.71 dB is generated. By properly controlling the repetition frequency and the power of the RF signal, the comb spacing of OFC can be tuned from 6.7 GHz to 12 GHz. Using a RF signal of 400 MHz with 11-dBm power, a 62-line MFC with flatness range of ±8 dB is obtained. Similarly, the comb spacing of generated MFC can be adjusted from 400 MHz to 3 GHz. This system exhibits the advantages of low cost and easy operation, and provides a new way for simultaneous generation of OFC and MFC.