快速腔长扫描光腔衰荡光谱仪及其在痕量气体测量中的应用

Rapidly Swept Cavity Ring-Down Spectrometer and Its Trace-Level Gas Detection Application

基于PZT快速腔长扫描技术和可调谐连续DFB激光器,搭建了一套快速腔长扫描光腔衰荡光谱探测装置,通过PZT快速腔长扫描实现激光单纵模与光腔纵模的模式匹配与破坏,以完成腔内光信号的独立衰减以及对此衰减过程快慢的测量.实验表明该装置不仅测量灵敏度高达10^(-9)量级,而且稳定性强,装置简单且易于操作。通过对CH_4气体在1653.72 nm附近的吸收光谱测量,并用HITRAN数据库模拟校准,验证了该装置的定量测量能力。利用该装置通过固定激光波长测量吸收峰中心值方法对大气中CH_4气体含量变化进行了探测.

Based on near-infrared continuous-wave diode lasers, a rapidly swept cavity ringdown spectrometer was developed. By rapidly sweeping the cavity length based on a PZT transducer, the longitude mode between the laser source and cavity was matched and dis-matched. Thus, the optical signal inside cavity finished its ring down and the measurement of the ring-down rate. The experiments show that not only the significant advantage in sensitivity achieve 10-9 cm-1 , but also the great stable and reliable performances of the spectrometer. The quantitative capability of the instrument was also demonstrated by measuring theabsorption spectroscopy of CH4 around 1653.72 nm. The instrument was used to monitor the concentration changes of ambient CH4 by measuring the absorbing peak value with a fixed wavelength source.