Optical Single-Sideband Modulation Based on a Dual-Drive MZM and a 120° Hybrid Coupler

A novel scheme for implementing high-performance optical single-sideband (OSSB) modulation based on a dual-drive Mach-Zehnder modulator (MZM) and a 120° hybrid coupler is proposed and demonstrated. A RF signal is divided by the 120° hybrid coupler into two parts with equal powers and a phase difference of 120°, and then, led to the two RF ports of the dual-drive MZM. With a proper dc bias, an OSSB signal with the -1st and +2nd-order sidebands (or the +1st and -2nd-order sidebands) suppressed is generated. A numerical simulation and a proof-of-concept experiment are carried out. As compared with the conventional OSSB modulation based on a 90° hybrid coupler, the suppression of the +2nd (or -2nd)-order sideband improves evidently the performance when the OSSB modulation is applied in a radio-over-fiber system or an optical vector network analyzer.