Photonic Generation of Frequency Tunable Binary Phase-Coded Microwave Waveforms

A novel photonic approach to generating a precisely π phase-shifted binary phase-coded microwave waveform with ultra-wide frequency tunable range is proposed and experimentally demonstrated. In the proposed system, a polarization modulator (PolM) functions in conjunction with a polarization controller (PC) and an optical polarizer (Pol) as an equivalent Mach-Zehnder modulator (MZM) with the bias point switchable by applying a binary-coding signal to the PolM. To generate a phase-coded microwave signal at a specific microwave frequency, the binary-coding signal is combined with a microwave signal at that frequency and applied to the PolM. By switching between the two quadrature transmission points or the maximum and the minimum transmission points, a phase-coded microwave waveform at the fundamental or doubled frequency is generated. The proposed technique is experimentally evaluated. A phase-coded microwave waveform at the fundamental and doubled frequency is generated. The tunability of the approach is also experimentally demonstrated.