Optical frequency comb generation scheme using a novel Mach–Zehnder modulator with four arms

Abstract

We propose a simple and cost-effective ultra-flat optical frequency comb generator based on a novel Mach–Zehnder modulator which employs a 1×4 multimode interference coupler and four optical phase-modulator waveguides. A 25-tone optical frequency comb with flatness within 0.2 dB and an unwanted-mode suppression ratio of 27 dB is obtained. This approach may provide a new generation of combs that enable planar integration and may permit a direct link from the radio frequency to optical domain on a chip.