Frequency-Phase-Mapping Method in Microwave Frequency Measurement With Single Optical Frequency Comb

The optical-frequency-comb-based (OFC-based) sampling method is of better efficiency than a heterodyne receiver when measuring non-cooperative signals over large frequency range. However, under-sampling during the down-conversion process often results in missing frequency information, necessitating multiple OFCs for recovery. This paper proposes a frequency-phase-mapping method with single OFC is proposed to recover the missing frequency information. Firstly, an asymmetric two-branch electro-optical-modulating structure is designed to acquire the phase difference caused by the time delay. Then, the acquired phase difference is mapped into the signal frequency by complex unit circle without 2π-blur. A dimension-expanding procedure is proposed by introducing multi-measuring to enhance the robustness performance. The influence of frequency range, signal-to-noise-ratio (SNR) and measuring times are analyzed in detail. The experiment indicates that the correct ratio of frequency recovery can reach 93.5% when the SNR is 20dB, frequency range is 1G-12GHz and the measuring times are 2, demonstrating the proposed method’s efficiency.