空间激光通信相干激光光源线宽测量OA

In space laser communication systems,the linewidth of laser sources inevitably introduces laser phase noise,which deteriorates the signal-to-noise ratio and bit error rate at the receiver terminal,thereby ultimately degrading the overall communication performance of the system.Consequently,accurate measurement of laser source linewidth is a critical prerequisite for ensuring the performance specifications of laser communication terminals,as well as for the testing and evaluation of terminals in system integration test platforms.This paper systematically analyzes the heterodyne mixing calculation theories underlying two representative laser linewidth measurement methodologies:the dual-beam heterodyne method utilizing two independent lasers,and the non-zero delay self-heterodyne method.The quantitative relationships between the beat-frequency linewidth and the linewidth of the laser under test are derived for both methods,laying a solid theoretical foundation for experimental laser linewidth testing.An experimental test optical path is constructed to verify the two measurement schemes.Experimental results demonstrate that the linewidth of the tested laser measured by the dual-beam heterodyne method is 624 Hz,while that measured by the non-zero delay self-heterodyne method is 100 Hz,both of which meet the technical index requirement that the linewidth of the tested light source is less than 1 kHz.In addition,the experimental results and the internal and external error factors affecting laser linewidth measurement are comprehensively analyzed.It is found that the dual-beam heterodyne method is highly susceptible to laser frequency stability,whereas the non-zero delay self-heterodyne method exhibits higher measurement accuracy and is more applicable to the characterization of narrow-linewidth laser sources.This research provides significant guidance for the selection of laser linewidth testing methods for space laser communication terminals,the determination of applicable scopes of different schemes,the implementation of specific experimental operations,and the control of measurement errors.