Photonic generation of multi-band phase-coded microwave pulses by polarization manipulation of optical signals

We report a photonic approach to generate multi-band phase-coded microwave pulses based on polarization manipulation of optical signals using a dual-polarization dual-parallel Mach-Zehnder modulator (DPol-DPMZM). Two radio frequency signals are sent to the DPol-DPMZM to realize carrier-suppressed double sideband (CS-DSB) modulation. A high-speed polarization modulator, driven by a three-level electrical coding signal s(t), is used to switch the modulation states of optical signals. For s(t)=1 or -1, the phases of the generated microwave signals are 0 or . For s(t)=0, a carrier-suppressed single sideband (CS-SSB) modulation is realized and there is no desired microwave signal recovered after photodetection. In this way, multi-band phase-coded microwave pluses are generated. The phase jump of the generated phase-coded pulses is determined by the polarity of s(t) instead of its amplitude, which is low power consuming and convenient. Compared to most existing photonic schemes that generate multi-band phase-coded signals in continuous wave (CW) mode, our scheme can directly generate multi-band phase-coded signal in pulse mode, which is pretty suitable for multi-band radar system application.