相干激光通信系统中大气湍流的表征方法和测量技术研究
文献类型：学位论文
| 作者 | 周健 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 孙建锋 |
| 关键词 | 相干激光通信 大气湍流 外差效率 大气相干长度 剪切干涉法 |
| 其他题名 | Characterization and Measurement Technology of Atmospheric Turbulence in Coherent Laser Communication System |
| 中文摘要 | 采用激光作为载波的激光通信技术具有数据传输速率高、保密性强、抗干扰能力强等优点，同时，采用相位调制/外差探测的相干光通信方式，可以显著提高探测系统的灵敏度。但是对于远距离相干激光通信系统而言，激光在大气信道中传输时受湍流影响严重，使得探测器接收到的信号光产生波前畸变，在与本振光混频时，波前相位畸变将引起两波前严重失配，影响外差效率，外差探测效率直接影响到相干接收机的信噪比，最终导致数据流比特误码率严重上升。因此，在高速相干激光通信中，深入研究大气湍流对通信系统性能影响的表征方法和大气湍流的测量技术，是一项具有十分重要意义的研究课题。 本论文针对相干激光通信质量受大气湍流限制的问题，通过K-L函数展开法模拟经过大气湍流扰动后的波前相位分布，研究计算了不同的接收口径与大气相干长度比值下的外差效率，发现了外差效率与接收口径和大气相干长度的比值成e指数函数关系，建立了表征大气湍流强度的大气相干长度与表征相干光通信系统性能的外差效率之间的物理模型。通过剪切干涉法实时测量大气相干长度，运用大气相干长度和外差效率的统计对应关系，即可计算得到外差效率，实时评价大气湍流对外差接收系统性能的影响。这种表征相干激光通信系统中大气湍流对系统性能影响的方法和测量技术，对相干光通信系统的结构设计和性能分析具有重要参考价值。 |
| 英文摘要 | The laser communication technology using laser beam as the information carrier has many advantages, such as high data transfer rate, security, strong anti-interference ability and so on. In coherent laser communication, the heterodyne efficiency of the received signal light and the local oscillator beam in the receiver plane directly affects its bit error rat. One of the most important factors that affect the efficiency of the heterodyne signal is the wave-front matching conditions of the local oscillator beam and the signal beam. Phase distortion of signal light will result in wave-front mismatching, thereby reducing the coherent efficiency, resulting in a sharp rise of the final data stream bit error rate. For long-distance coherent laser communication systems, in addition to the wave-front aberration caused by the manufacturing and calibration inaccuracy of the optical system in the recerving end, the wave-front aberration mainly comes from the process of laser propagation through atmospheric turbulence. Based on the high-speed coherent laser communication characteristics, this research using K-L function expansion method to simulate the aberrated wavefront phase distribution, calculates the heterodyne efficiency under specific atmospheric coherence length, gives the relationship between the atmospheric coherence length which characterizing the atmospheric turbulenc intensity and the heterodyne efficiency which characterizing the coherent optical communication system performance. Using shearing interferometry to measure real-time atmospheric coherence length, with the relationship given above, we can get an immediate estimate of the hererodyne efficiency, and a real-time evaluation of the effect of atmospheric turbulence on heterodyne receiver system performance.This research gives a method of measuring and evaluating the impact of atmospheric turbulence on laser communication system, lay the foundation for future practical applications. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16843]  |
| 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 | 周健. 相干激光通信系统中大气湍流的表征方法和测量技术研究[D]. 中国科学院上海光学精密机械研究所. 2014. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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