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 a large frequency range. However, under-sampling during the down-conversion process often results in missing frequency information, necessitating multiple OFCs for recovery. This article proposes a frequency-phase-mapping method with a single OFC is proposed to recover the missing frequency information. First, 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 a complex unit circle without
$2\pi $
-blur. A dimension-expanding procedure is proposed by introducing multimeasuring 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 20 dB, the frequency range is 1–12 GHz, and the measuring times are 2, demonstrating the proposed method’s efficiency.