本振激光强度调制激光外差光谱遥测技术研究

RESEARCH ON LASER HETERODYNE SPECTRUM TELEMETRY TECHNOLOGY BASED ON LOCAL OSCILLATOR LASER INTENSITY MODULATION

针对当前用于大气温室气体柱浓度/廓线探测的信号光强度调制激光外差探测方法存在的信光损失,与本振激光波长调制激光外差探测方法存在的光谱反演模型复杂这两个问题,提出了基于本振激光强度调制的激光外差探测方法。对此,结合平衡探测技术,搭建了1套以1.571μm窄线宽半导体激光器作为本振光源的双通道平衡外差光谱探测系统,开展系统性能分析以及大气CO_(2)柱总量测量研究。区别于已有文献报道的激光外差光谱探测方法,系统采用光开关对本振激光进行强度调制,利用平衡探测技术消除本振激光强度背景噪声的影响。结果表明,相比传统的信号光强度调制激光外差探测方法,该方法能够将外差信号信噪比提高3.7倍,对应的CO_(2)柱总量测量精度提升3.36倍。以上研究表明,基于本振激光强度调制的激光外差探测方法能够有效的提高激光外差光谱探测系统性能。

Aiming at the problems of signal light intensity modulated laser heterodyne detection method used to detect the concentration/profile of atmospheric greenhouse gas column at present,such as signal light loss and complex spectral inversion model of local oscillator laser wavelength modulated laser heterodyne detection method,a laser heterodyne detection method based on local oscillator laser intensity modulation was proposed.In view of this,a dual-channel balanced heterodyne spectrum detection system with a 1.571 μm narrow linewidth semiconductor laser as a local oscillator light source was built by combining the balanced detection technology,and the system performance analysis and the measurement of atmospheric CO_(2) column abundance was carried out.Different from the laser heterodyne spectrum detection method reported in the current literature,the system used an optical switch to modulate the intensity of the local oscillator laser,and used balanced detection technology to eliminate the influence of background noise of local oscillator laser intensity.The results showed that compared with the traditional laser heterodyne detection method with signal light intensity modulation,this method can improve the signal-to-noise ratio of heterodyne signal by 3.7 times,and the corresponding measurement accuracy of CO_(2) column abundance was improved by 3.36 times.The above research shows that the laser heterodyne detection method based on local oscillator laser intensity modulation can effectively improve the performance of the laser heterodyne spectrum detection system.