Optical frequency comb generation via an intensity modulator in a Sagnac loop

Abstract

We propose a simple optical frequency comb generator with a Nyquist temporal waveform that uses an intensity modulator in a Sagnac loop. By properly adjusting the polarization of the output from the Sagnac loop, a quasi-rectangular-shaped five-tone optical frequency comb with a Nyquist temporal waveform is theoretically and experimentally demonstrated. Previous work has shown that it is impossible to generate Nyquist pulses with more than three comb lines using a single intensity modulator. In our scheme, only one radio-frequency signal with relatively low power and only one direct-current voltage is needed, which effectively increases the system reliability and decreases the system complexity and cost.