A method for dual-channel signal frequency recovery in optical frequency comb receiving system

The traditional electric field reception technology has the contradiction between the measurement bandwidth, speed, and accuracy. The under-sampling electric field measurement system of the optical frequency comb can down convert all signals within a wide frequency band to a low frequency for reception and measurement, thus solving the above contradiction. Due to the use of undersampling reception, the original carrier frequency of the signal was lost. For this purpose, a dual frequency pulse light source is used for electric field sampling, and the residual matching method is used to recover the signal frequency information. However, when there are two or more different signals in the test signal, it is difficult to pair the down conversion components, resulting in a sharp increase in the error rate of the system's frequency recovery. In response to the above issues, this article proposes a frequency recovery method based on signal feature matching. By extracting features from dual channel signals, accurate grouping of down converted signals can be achieved. Then use the remainder matching method to accurately recover the frequency. The simulation results demonstrate that when the system receives four different signals simultaneously, the frequency recovery error rate is about 0.4%, which is about 1/3 of the original.