Generation of broadband optical frequency comb with rectangular envelope using cascaded intensity and dual-parallel modulators

A novel approach using two cascaded intensity modulators and one single dual-parallel modulator to generate an optical frequency comb (OFC) is proposed and experimentally demonstrated. One broadband OFC with rectangular envelope can be achieved easily by adjusting the power of the microwave signals and the direct current bias applied to the modulators. The scheme is a relatively simple and low-power consumption solution for OFC generation, where specially tailored waveforms and high-power microwave signals are not used. In the experiment, 20 comb lines within 0.6 dB spectral power variation are obtained at 10 GHz microwave frequency. The experimental results agree well with the theoretical calculation.