Generation of an optical frequency comb based on two cascaded dual-parallel polarization modulators.

Generation of an optical frequency comb (OFC) based on two cascaded dual-parallel polarization modulators (DPPolMs) is proposed for the first time, to the best of our knowledge. The proposed method offers superior spectral flatness and improved side-comb suppression ratio (SCSR), and requires low radio frequency drive voltage compared to two cascaded polarization modulators based on OFC generation found elsewhere in the literature. Detailed investigation is carried out through theory and simulation for 25, 49, 81, and 121 comb lines generated with the proposed two-stage OFC generator. Theoretically obtained parameters are used in the simulation to obtain the desired results. In particular, for 49 lines of OFC generation, 1 dB power fluctuation in amplitude and 16.5 dB SCSR are obtained at a comb frequency spacing of 3.5 GHz, which outperforms any polarization modulator-based OFC generator.