相干光通信以较高的检测灵敏度引起了人们的重视，但因工程实现困难等问题而限制了该技术的应用.为此，提出了一种新的外差检测方法，利用发送端副载波调制和接收端副载波实现外差，提高了无线激光通信系统的检测灵敏度. 实验结果表明, 副载波调制/非光域外差检测方式具有接近20 dB 的外差增益，且误码率特性也优于直接检测.
Coherent optical communication attracts research interest due to its high detecting sensitivity.However, its application is limited by factors such as practical implementation. This paper presents a new heterodyne detection method that realizes frequency mixing of the sender subcarrier and the receiver subcarrier
to improve detection sensitivity of the wireless laser communication system. The experimental results show that the subcarrier modulation/non-optical heterodyne detection system has nearly 20 dB heterodyne gain and better error rate than direct detection.
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