Generation of Seven-Line Optical Frequency Comb Based on a Single Polarization Modulator

A flat and tunable optical frequency comb generation scheme based on a single polarization modulator (PolM) is proposed and experimentally demonstrated. In the proposed scheme, the even- and odd-order optical sidebands of the polarization-modulated signal are split by a polarization beam splitter (PBS) into two paths, respectively. The signal with lower power is amplified and then combined with the other path by a polarization beam combiner. By carefully controlling the power of the radio frequency signal to the PolM, the polarization states of the signal before the PBS and the gain of the erbium doped fiber amplifier, seven flat comb lines can be generated. An experiment is performed. Seven comb lines within 1.8-dB spectral power variation are obtained.