基于电光效应的相干检测星间跟踪技术

【作者】 潘湖迪；

【导师】 金韬；

【作者基本信息】 浙江大学 ， 物理电子学， 2005， 硕士

【摘要】 激光由于其自身功率密度高、方向性好，加之因频率高而带来的天线尺寸小、系统结构紧凑轻便，信息容量大等突出优点，因而在卫星系统中有很大的应用潜力。随着元器件的发展，卫星光通信技术日益成熟，并正向商业化方向发展，可以预计，卫星光通信必将成为下个世纪超大容量卫星通信的主要途径。 空间光通信中捕获、跟踪、对准（ATP）技术的采用是为了保证空间光通信系统建立可靠通信链路，是实现空间光通信需要首先突破和解决的关键技术。空间光通信ATP子系统中的瞄准误差等关键参数直接影响系统总体性能以及对总体设计指标的确定，在一定程度上还决定了空间光通信系统的重量、体积以及系统制作的复杂程度。因此，开展对ATP技术的研究对实现空间光通信有着重要的现实意义。 本文一种新颖的不使用CCD或四象限传感器的光束定向机理。它采用光束章动和相干检测技术，可实现高精度和极高灵敏度的光束定向。具有线性电光效应的LiNbO₃晶体完成光束章动功能。当信号光束进行圆形扫描时，周期性变化的相干光功率中将包含光束的方向信息，据此控制细瞄准镜调整光束方向，实现星间跟踪。 我们建立了整个定向系统的数学和计算机模型，计算结果表明只要维持足够低的激光器相位噪声就能实现高精度的光束定向。同时，我们构建了相应的实验系统来验证应用该技术进行光束定向的可行性。更多还原

【Abstract】 An optical communication link between satellites will play an important role in future free space communications with its advantages over conventional microwave links in its lighter weight, lower power and smaller size.Acquisition, Tracking and Pointing （ATP） technology is one of the key technologies for free-space laser communication systems. The pointing error of ATP system, which will cause power fading of the optical carrier detected by the receiver, limits the performance of laser communications system. According to that, it’s very necessary to carry out research on ATP technology.In the paper, a novel beam orienting mechanism utilizing no CCD or quadrant detectors is presented. High-precision and extreme-sensitivity beam orienting could be achieved by the application of beam nutating and coherent detecting technologies. LiNbO₃ crystals with linear electro-optic effect are utilized to perform the beam nutating function. The resulting periodic change in coherent optical power as the signal beam is scanned circularly contains the direction information of the beam. The direction information is fed back to control fine pointing mirror for inter-satellite tracking.Mathematical and computer simulation model of the entire orienting system is developed. The computer simulation results have shown high beam orienting precision provided low laser phase noises are maintained. An experimental system has been built to demonstrate the feasibility of using this technology for beam orienting.更多还原