Linear and stable photonic radio frequency phase shifter based on a dual-parallel Mach–Zehnder modulator using a two-drive scheme

Abstract

We theoretically and experimentally demonstrate a linear and stable photonic RF phase shifter based on a dual-parallel Mach-Zehnder modulator (DPMZM) using a two-drive scheme. To avoid the effect of the residual optical carrier and overcome the lowest frequency limit from the optical filter, a local microwave signal and a signal up-converted from the under-phase-shifted RF signal are applied to the two RF inputs of the DPMZM, respectively. A phase-shifted RF signal is generated by beating the two first-order upper sidebands located in the passband of the optical filter. A continuous and linear phase shift of more than 360° and power variation of less than ±0.15 dB at 1GHz are achieved by simply tuning the bias voltage of the modulator. A phase tuning bandwidth of more than 17MHz and phase drift of less than 0.5° within 2000s are also observed.