Sideband suppression method for fiber optic phased array coherent LiDAR echo signal based on periodic matching.

The sideband effect of fiber optic phased array coherent LiDAR seriously reduces the accuracy of target frequency detection. A sideband suppression method based on periodic matching is proposed, for the first time, to improve the frequency detection accuracy. Firstly, a theoretical model of sideband amplitude based on the periodic matching method is established, and the influences of different periodic matching modes on the time-frequency distribution uniformity and the sideband amplitude of the echo signal are simulated and studied. It is found that the maximum amplitude of the sideband decreases as the percentage of scanning duration decreases within the combined period. The percentage threshold is negatively correlated with the signal-to-noise ratio of the echo signal. The experimental results indicate that the accuracy of the ellipsoidal micro-motion target frequency measurement has been increased by approximately 5 times compared to that without the sideband suppression. The above results validate the effectiveness of the proposed method. This method does not require the introduction of new optical devices, which helps to improve the accuracy of frequency measurement in fiber optical phased array LiDAR, laying a technical foundation for its practical application.