摘要
激光雷达不仅能够获取目标表面对激光反射率的信息,而且还能获得目标的三维几何信息。因此,激光雷达技术无论在民用还是军用都有重要的应用价值,同时,它也是其它探测方式的重要补充。为实现小型化、高帧频和高距离精度,各国开始研究激光雷达的焦平面成像技术。调频/连续波(FM/cw)激光成像雷达系统能够实现高速、高帧频、高距离分辨率的无扫描激光四维成像。在该激光雷达系统中,光源的调制特性决定了激光距离成像的距离精度,而光源的功率则决定了激光成像的距离,因此,高功率输出的啁啾线性调幅光源是该激光雷达系统的关键器件,制作出调制性好,功率高的光源具有非凡的意义。
本文分析了几种调制方式的基本原理及特点,结合研究状况和实际条件确定了采用种子源与光纤放大器连接形成高扫频精度、高调制带宽、大功率的啁啾线性调幅光源以满足激光雷达系统的要求。高扫频精度、高调制带宽的种子源满足了雷达系统对光源调制特性的要求,光纤放大器高达18W的输出峰值功率满足了雷达系统对光源输出光功率的要求。分析了雷达系统对光源各部件的要求,进行了数值仿真。建立了对线性扫频信号进行分析的时频分析方法。搭建了对种子源及光纤放大器进行性能测试的系统。
在实验方面,根据对光源的理论分析和对线性扫频信号处理方法的优化,设计了对种子源中的调制器、激光器以及光纤放大器进行测试的系统,并完成了对各器件的测试。对用电吸收调制器进行光调制的种子源和用M-Z铌酸锂波导调制器进行光调制的种子源进行了研制及测试,对它们的性能进行了对比研究;对种子源后接的能实现线性放大,具有高放大倍数、低噪声的光纤放大器的性能进行了测试;进行了FM/cw激光探测实验研究并对外场实验做了一些准备。完成了对本光源的实验研究。
Laser radar can not only obtain the information of laser reflectivity of target surface, but also can obtain the three-dimensional information of the object. Therefore, laser radar technology whether in civil or military has important application value, and at the same time, it also is an important way to complement other detection. To realize miniaturization, high frequency and high precision frame, many countries begin the study of laser radar imaging technology with focal plane. Frequency modulation/continuous wave (FM/cw) nonscanning imaging radar system is a laser based 4D imaging sensor with the characteristics of high speed, high frame-rate and high ranging accuracy. In the laser radar system, the characteristic of modulation of the light determines the accuracy of distance from imaging, and the power of the laser source decides the imaging range. Therefore, the source of linear chirp modulated amplitude with high power output is a key component of this radar system. It has special significance to produce a laser source with good modulation and high power.
The paper analyses the basic principle and characteristics of modulation method. Combining research status with actual conditions adopted the way that connecting a seed laser source with high precision, high frequency sweep of bandwidth to a fiber amplifier. We made a linear chirp amplitude and 18W peak power laser source with high sweep frequency modulation bandwidth and high sweep accuracy to meet the requirements of the radar system. I analysed the requirements of the source on all parts and performed numerical simulation. I used modern methods to optimize the time-frequency analysis of linear sweep frequency signal processing. We built the test system for seed source and fiber amplifiers.
In the experiment, according to theoretical analysis of the sourcesin and the optimization of linear sweep frequency signal processing methods, I designed the test system of the laser modulator and the laser source of the seed source and the fiber amplifier, and completed each device testing. In the linear area of the laser modulator, we can modulate the laser strength linearly by electricity signal. Studyed and tested the modulation of electro-absorption modulator seed source and M-Z Lithium Niobate electro-optic modulator seed source. We also studied the amplification of the fiber amplifier to the optical signals. I performed FM/cw detection experiment and prepared for outfield experiment. I finished this experiment and study of the light source.
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