Tunable and ultraflat optical frequency comb generator based on cascaded intensity modulators

An optical frequency comb generator based on two-cascade intensity modulators is proposed and experimentally demonstrated. By carefully adjusting direct current biases and drive amplitudes of radio frequency signals of the two intensity modulators, the combs consisting of 3, 5, 9, 15, or 25 lines with the relative amplitude flatness within 1 dB can be generated. The scheme is relatively simple and adjustable, where the frequency spacing varies with microwave frequency applied on modulators.