| 题名 | 激光章动的空间光-单模光纤自动耦合系统的设计与实现 |
| 作者 | 高建秋 |
| 学位类别 | 硕士 |
| 答辩日期 | 2016 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 陈卫标 |
| 关键词 | 光通信 光纤耦合 指向误差 激光章动 数据采集卡 |
| 其他题名 | Design and Realization of An Automatic System Based on Laser Nutation for Coupling Spacelight into Single Mode Fiber |
| 中文摘要 | 空间激光到单模光纤（single mode fiber, SMF）耦合是基于光纤器件的自由空间激光通信（Free-Space Optical Communication, FSO）的关键技术之一。然而环境温度和重力等因素使接收光轴与入射光束间存在静态角度偏差，发射、接收等平台的振动，大气震荡，跟踪探测器噪声及转台机械噪声等导致入射光束与接收光轴之间的夹角存在随机抖动，会严重影响空间光到单模光纤的耦合效率。基于激光章动的空间光到单模光纤的自动耦合系统，是一种利用模式匹配的思想，章动快反镜（fast steering mirror, FSM）的章动信号作为调制信号，根据光电探测器（PIN管）输出功率的变化得到光纤端面脱靶量并实时控制补偿快反镜从而补偿抖动偏差，提高单模光纤耦合效率的闭环控制系统。 本文主要研究了基于激光章动的空间光到单模光纤自动耦合系统的设计与实现，论文的主要工作内容包括： 1、根据模场匹配的基本原理，得到了理想情况下耦合效率的计算模型，当爱里斑半径与单模光纤模场半径比值为1.711时，耦合效率最大为81.45%。分析了存在静态角偏差及随机抖动时耦合效率的表达式，得到了耦合效率与抖动幅度及爱里斑半径与单模光纤模场半径比值之间的关系曲线，为激光章动耦合方案的提出提供了理论依据。 2、提出了基于激光章动的自动耦合方案和自动耦合算法，通过自动耦合算法的理论仿真，给出了脱靶量的计算流程，分析了激光章动频率与抖动频率的关系、脱靶量精确度的影响因素，用Maltab仿真分析了不同偏移量及不同章动幅度时耦合效率的变化规律，验证了算法的可行性。 3、利用Labview软件设计了系统的自动控制上位机，软件采用DAQmx助手及Labview及Matlab混合编程技术完成3通道信号的同步采集，补偿电压的输出及数字信号的处理，前面板可实现通道波形显示和各参数的输入。 4、完成了基于激光章动的空间光到单模光纤自动耦合系统的测试实验，主要内容包括系统光路平台的搭建， 耦合系统静态/动态性能分析，激光通信链路系统动态性能分析。在闭环情况下，系统的耦合效率明显提高，系统的响应带宽为40Hz，在章动信号频率为500Hz时，可补偿的最大抖动电压为58mV，对应角度约160urad。 |
| 英文摘要 | Space light to single mode fiber(SMF) coupling is one of the key technologies in free space optics communication(FSO) based on fiber devices. However, factors such as ambient temperature and gravity introduce angle deviation between receiving optical axis and incident beam. Platform vibration, atmospheric turbulence, tracking detector noise and turntable mechanical noise bring random jitter into the laser communication link, which will seriously effect coupling efficiency from space to SMF. The automatic controlling system from space light into SMF based on laser nutation is a closed loop control system which use nutation signal as modulation signal, utilize the change rule of photoelectric output voltage to calculate the miss distance on fiber end face and then control the compensation fast steering mirror in real time. At last, the coupling efficiency of the system is increased. This thesis focuses on the design and realization of an automatic controlling system based on laser nutation for coupling space light into SMF. The main contents of the thesis are presented as follows: 1. According to the theory of mode field matching, the calculation module of coupling efficiency in ideal conditions is obtained. When , the max coupling efficiency is 81.45%.The coupling efficiency expression in the presence of static angular deviation and random angular jitter is analyzed. The relationship between the coupling efficiency and jitter amplitude and is calculated. All above provide theoretical basis for putting forward the coupling scheme based on laser nutation. 2. The automatic controlling scheme and automatic controlling algorithm based on laser nutation are proposed. After that, the theoretical simulation is finished, the calculation flow is provided. Then, the relationship between laser nutation frequency and jitter frequency and the influencing factor of miss distance accuracy is analyzed. At last, using Matlab to simulate the coupling efficiency change rule with different offset and different nutation amplitude, the results prove the feasibility of the algorithm. 3. The software of the controlling system is designed by Labview. By using the DAQmx assistant and the technology of the mixed programming between Labview and Matlab, the software can finish three channels synchronization acquisition, compensation voltage output and digital signal processing. The front panel can realize waveform display and parameters input. 4. A series of experiments are conducted including building light path platform, analyzing the static and dynamic performance of the coupling system. The experimental results show that in the case of closed loop, the coupling efficiency is obviously proposed. The responsive bandwidth is 40Hz, when the frequency of nutation signal is 500Hz, the maximum jitter voltage that can be corrected is about 58mV corresponding to an angle of about 160urad. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/17014]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 高建秋. 激光章动的空间光-单模光纤自动耦合系统的设计与实现[D]. 中国科学院上海光学精密机械研究所. 2016. |
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