Photonic Generation of Dual-Carrier Signals Using Optical Frequency Comb Pair for Frequency Diverse Array

We report a photonic generation method of dual-carrier frequency diverse array (FDA) signal based on dual optical frequency combs (OFCs). Only three Mach-Zehnder modulators (MZMs) are needed to generate five-channel dual-carrier FDA signals without any complicated frequency shift device, enabling spot beampatterns. Compared with the traditional FDA which can only produce “S”-shaped beampatterns, spot beampatterns allows for easier angle and distance estimation while minimizing unnecessary power enhancement. The method is theoretically analyzed and experimentally verified. A five-channel dual-carrier FDA signal with a carrier frequency of 4 GHz and a frequency offset of 1 MHz is generated, showing a remarkable power flatness of 1.4 dB with a spurious suppression ratio over 23 dB. We also experimentally demonstrated broadband FDA signals generation and verified the potential for more channels expansion which can achieve higher resolution of distance and angle. This approach shows great potential in the future application of FDA radar.