Reconfigurable Photonic generation and transmission of multi-format radar signals

Abstract

In this paper, photonic generation and transmission technique for multi-format microwave waveform is proposed. In the center office, a broadband optical source (BOS) is utilized as optical carrier. And the main component is a dual-polarization dual-drive Mach–Zehnder modulator (DPol-DDMZM) followed by a polarization division multiplexed emulator (PDME). The DPol-DDMZM consists of two sub-DDMZMs to generate two orthogonally polarized optical signals. The system we proposed is conveniently reconfigured to generate different waveforms. By applying phase modulation (PM) to the orthogonal polarization states, a polyphase-coded microwave waveform with a tunable center frequency multiplication factor can be generated. By tuning the differential group delay (DGD) of the two polarizations by the PDME, the multiplication factor can be easily adjusted. In addition, if the carrier is suppressed at the upper and lower DDMZM, broadband dual-chirp microwave signal can be generated, transmitted over fiber and detected at a base station. The chromatic dispersion induced power fading is eliminated. The approach is investigated by simulations. Polyphase-coded signal with a repetition rate of 4 Gbit/s is demonstrated. And dual-chirp signal with a bandwidth of 8 GHz is carried out. Besides, the practical feasibility of the system is further studied by analyzing the power of the BOS, the relative time delay of PDME and the photonic integrated circuit (PIC) replica of the generator.