Flat optical frequency comb generation by using one DPMZM and superposed harmonics

Abstract

In this work, we propose a novel approach to the generation of flat optical frequency comb (OFC) by using dual-parallel Mach–Zehnder modulator (DPMZM) and superposed harmonics, where the superposed harmonics drive only one child Mach–Zehnder modulator of DPMZM. By adjusting precisely the modulation indices and phases of harmonics as well as the biases for DPMZM, flat OFCs are generated. In the experiment, a 9-line OFC with 0.26-dB flatness is achieved when the superposed fundamental tone and third harmonic drive the DPMZM; a 13-line OFC with 0.58-dB flatness is achieved when the fundamental tone, second harmonic, and third harmonic drive the DPMZM simultaneously.