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A Width Measurement Method of Line Shape Based on Second Harmonic Peak and Modulation Amplitude

Authors :
Shan Lin
Jun Chang
Jiachen Sun
Zihan Wang
Minghui Mao
Source :
Sensors, Vol 23, Iss 1, p 476 (2023)
Publication Year :
2023
Publisher :
MDPI AG, 2023.

Abstract

The line width of different line shapes is a very important parameter in absorption spectroscopy sensing techniques. Based on the high sensitivity and low noise properties of wavelength modulation spectroscopy, we report a novel line width measurement method. After theoretically proving the relationship between line width, modulation amplitude and the amplitude of the second harmonic at the center frequency, the absorption lines of CH4 near 6046.96 cm−1 and CO2 4989.97 cm−1 were chosen for simulation, and the relative errors of the line width between our method and theoretical data were kept at about 1%. A distributed feedback laser diode operating near 1653 nm with three different concentrations of CH4 was used for experimental validation, and the results were consistent with the numerical simulation. Additionally, since only the peaks of second harmonic need to be measured, the advantages of wavelength modulation can be utilized while reducing the difficulty of data acquisition.

Details

Language :
English
ISSN :
14248220
Volume :
23
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Sensors
Publication Type :
Academic Journal
Accession number :
edsdoj.7a5cc070371a4bf8be8792ab7510c8f3
Document Type :
article
Full Text :
https://doi.org/10.3390/s23010476