title: [Simulation and analysis of second-harmonic signal based on tunable diode laser absorption spectroscopy].
abstract: Tunable diode laser absorption spectroscopy (TDLAS) is a new gas detection technique developed recently with high spectral resolution, high sensitivity and fast time response. The second-harmonic signal of wavelength modulation spectroscopy (WMS) is often used as the detection signal for gas concentration inversion. Using Simulink, a visual modeling and simulation platform, the authors simulated the WMS signal based on TDLAS, and got the second-harmonic signal by using lock-in amplifier algorithm. Digital orthogonal algorithm was studied in this paper. The relationship between second-harmonic signals and the modulation indexes was analyzed by comparing changes of second-harmonic under different modulation indexes, in order to find out the optimized parameters for second-harmonic detection.
authors.affiliation: Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China. hanli@aiofm.ac.cn
authors.forename: Han
authors.initials: H
authors.lastname: Li
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Liu
authors.forename: Ya-Bai
authors.initials: YB
authors.lastname: He
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: He
authors.forename: Lu
authors.initials: L
authors.lastname: Yao
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Xu
authors.forename: Jiu-Ying
authors.initials: JY
authors.lastname: Chen
authors.forename: Song
authors.initials: S
authors.lastname: Yuan
authors.forename: Rui-Feng
authors.initials: RF
authors.lastname: Kan