A microwave photonic system with switchable functions based on cascaded polarization modulators

Abstract

A novel scheme based on two cascaded polarization modulators (PolMs) is proposed to implement optical-single-sideband modulation (OSSB) with tunable carrier-to-sideband ratio (OCSR) and a microwave photonic phase shifter. Switching between the two functions can be realized by adjusting the DC bias of the second PolM. An experiment is carried out. OSSB modulated signals with an operation bandwidth from 5 to 35 GHz are achieved and two OSSB modulated signals with tunable OCSRs from -26 to 46 dB and from -25 to 55 dB are demonstrated. When the system is switched to be a microwave photonic phase shifter, a full 360 degree phase tuning range can be realized. The proposed scheme features a compact structure and dual switchable functions, which may find applications in microwave photonics.