Photonic Generation of Precisely $\pi$ Phase-Shifted Binary Phase-Coded Microwave Signal

A novel photonic approach to generating a precisely π phase-shifted binary phase-coded microwave signal is proposed and experimentally demonstrated. A phase modulator is employed to generate two ±1st-order sidebands and an optical carrier. Due to the inherent ±π/2 phase shifts of the two ±1st-order sidebands, a binary phase-coded microwave signal with a precise phase shift of π is generated through beating one sideband with the optical carrier at a time, which is realized by joint use of a polarization-maintaining fiber Bragg grating and a polarization modulator to select one of the two sidebands and the optical carrier. The generation of a binary phase-coded microwave signal with a precise π phase shift and with a tunable frequency from 18 to 22 GHz is experimentally demonstrated.