基于平衡探测器的光轴偏差检测技术

发布时间：2018-06-08 21:01

本文选题：相干探测 + 平衡探测器　；参考：《中国科学院大学(中国科学院光电技术研究所)》2017年硕士论文

【摘要】：相干光通信由于其灵敏度较高,传输距离长等优点广泛应用于星地通信中。为了实现对微弱信号的探测,在无法协调激光器的发射功率与信号接收质量的情况下,需要对探测器的接收灵敏度提出很高的要求。平衡探测方式比其他探测方式具有更高的探测灵敏度与信噪比,甚至接近量子极限。在星地激光通信中,由于通信距离较远,信号光在传输时受到大气信道的二次调制,使得接收机端接收到的信号通常极其微弱。这就对接收机端的对准精度和探测灵敏度提出了很高的要求[1],接收机端的光轴对准是实现星地通信的关键。怎样利用信号光来完成光轴角偏差精密检测是一个关键问题。本文针对此问题开展研究,并与实际需求结合紧密,具有重要的应用价值。本文提出在微弱信号光情况下,运用平衡探测器对光轴偏差角度进行检测,并将误差信号通过反馈电路调整快反镜的角度进行矫正,实现精跟踪的目的,通过理论分析证明该技术方案合理可行。文章对平衡探测器的工作原理、以及应用它进行光轴偏差检测的原理,进行了详细说明;并搭建隔离度光学实验系统进行验证、核对实验结果进行误差分析;最后对影响平衡探测器性能的因素进行了分析,通过MATLAB仿真给出了不同带宽条件下信噪比与响应一致性系数之间的关系;仿真结果证明与单端探测相比确实能够提高信噪比,抑制本振光的强度噪声。这些工作对相干光通信光学终端系统的设计具有一定的参考价值。
[Abstract]:Coherent optical communication is widely used in satellite-ground communication due to its high sensitivity and long transmission distance. In order to detect the weak signal, the sensitivity of the detector must be very high when the laser's transmitting power and the signal receiving quality can not be coordinated. The balanced detection method has higher detection sensitivity and signal-to-noise ratio than other detection methods, and even approaches the quantum limit. In satellite-to-ground laser communication, because of the long distance, the signal light is modulated by the atmospheric channel in the transmission, so the signal received by the receiver is usually very weak. Therefore, the alignment accuracy and detection sensitivity of the receiver are very high [1], and the optical axis alignment at the receiver is the key to the realization of satellite-ground communication. How to use signal light to complete the precision detection of optical axis angle deviation is a key problem. This paper aims at this problem, and it is closely combined with the actual demand, which has important application value. In this paper, in the case of weak signal light, the balance detector is used to detect the deviation angle of the optical axis, and the error signal is corrected by adjusting the angle of the fast mirror through the feedback circuit to achieve the purpose of fine tracking. Theoretical analysis shows that the technical scheme is reasonable and feasible. In this paper, the working principle of the balance detector and the principle of using it to detect the optical axis deviation are explained in detail, and the isolation optical experimental system is set up to verify and verify the experimental results for error analysis. Finally, the factors affecting the performance of the balanced detector are analyzed, and the relationship between SNR and response consistency coefficient under different bandwidth conditions is given by MATLAB simulation, and the simulation results show that the SNR can be improved in comparison with single-ended detection. Suppress the intensity and noise of the local oscillator. These works have certain reference value for the design of optical terminal system of coherent optical communication.
【学位授予单位】：中国科学院大学(中国科学院光电技术研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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