基于微波光子信号处理的时间展宽飞秒激光雷达
Time-Stretched Femtosecond Lidar Using Microwave Photonic Signal Processing
摘要：
提出了一种具有0.1兆赫兹更新速率和几微米分辨率的实时测距激光雷达，该雷达结合了色散傅里叶变换和瞬时微波频率测量。将时间展宽的飞秒激光脉冲通过全光纤马赫-曾德尔干涉仪，将检测光束插入干涉仪的一个臂的光路中，将位移编码为时间干涉图的频率变化。为了解决光探测器产生的微波脉冲在存储和实时处理方面的挑战，我们转向全光信号处理。使用强度调制器通过时域干涉图调制载波。之后，微波脉冲的频率变化被上传到一阶边带。最后，边带的频移通过一个锁频放大器转化为传输变化。在实验中，采用可编程光学滤波器实现了动态范围和探测灵敏度可调的实时测距系统。在15 mm探测范围内，标准差为7.64 μm，总平均误差为19.10 μm;在45 mm探测范围内，标准差为37.73 μm，总平均误差为36.63 μm。
英文摘要：
A real-time ranging lidar with 0.1 Mega Hertz update rate and few-micrometer resolution incorporating dispersive Fourier transformation and instantaneous microwave frequency measurement is proposed and demonstrated. As time-stretched femtosecond laser pulse passing through an all-fiber Mach-Zehnder Interferometer, where the detection light beam is inserted into the optical path of one arm, the displacement is encoded to the frequency variation of the temporal interferogram. To deal with the challenges in storage and real-time processing of the microwave pulse generated on a photodetector, we turn to all-optical signal processing. A carrier wave is modulated by the time-domain interferogram using an intensity modulator. After that, the frequency variation of the microwave pulse is uploaded to the first order sidebands. Finally, the frequency shift of the sidebands is turned into transmission change through a symmetric-locked frequency discriminator. In experiment, A real-time ranging system with adjustable dynamic range and detection sensitivity is realized by incorporating a programmable optical filter. Standard deviation of 7.64 μm, overall mean error of 19.10 μm over 15 mm detection range and standard deviation of 37.73 μm, overall mean error of 36.63 μm over 45 mm detection range are obtained respectively.
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