用EDFA提高激光雷达的信噪比

Signal-to-noise ratio improvement in lidar system utilizing EDFA

提出了掺铒光纤放大器(EDFA)应用于激光雷达接收系统光学前置放大器以提高雷达探测性能和作用距离的方法。回波信号功率是影响雷达探测分辨率的因素,它随着探测距离的增大而减小。讨论了光电检测前放大回波信号的技术,结合激光雷达回波信号的特点对EFDA主要应用特性(增益特性、噪声特性)进行理论分析。建立了雷达信号传输模型,讨论了大气消光与大气湍流对回波信号的影响。将PIN-FET用作光电探测,给出了没有采用光放大和采用EDFA光学前置放大情况下的信噪比。数值模拟结果显示,将EDFA用作激光雷达接收机极大地提高了雷达系统的信噪比,探测距离越远探测性能的改善越明显。

A method was presented that an Er-doped fiber amplifier used as an optical preamplifier of the lidar system receiver to enhance the performance and its range. Extending the lidar system measurement range resulted in a degradation of the signal-to-noise ratio. One factor that limited detection resolution was the value of the backscatter optical signal power,which degraded as detecting range increased. A technique that could effectively enhance the receiver sensitivity by improving the signal-to-noise ratio could lead to extension of measurement range. The theory used of an optical preamplifier system in a directed detection lidar system,as a means of improving receiver sensitivity and consequently sensor range was introduced. The main application properties of the optical preamplifier,Er-doped fiber amplifier,such as gain and noise characteristics were analyzed with the signal of lidar. The major source of noise was amplified spontaneous emission beat noise. Conjunction with the lidar range equation and PIN-FET noise sources,signal-to-noise ratios were deduced with and without optical preamplifier including the effects of atmospheric transmission and turbulence. Using optical pre-amplification before photo-detection in directed detection lidar for wind measurement improved the signal-to-noise ratio. The numerical simulation reveals that signal-to-noise ratio of a lidar system with an Er-doped fiber amplifier preamplifier is improved greatly,especially the larger range.