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Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser

We report the theoretical and experimental study of calibration-free heterodyne phase-sensitive dispersion spectroscopy (HPSDS) in the mid-infrared using a direct current modulated mid-infrared quantum cascade laser (QCL). The modulation of QCL current at several hundred MHz or higher generates the...

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Detalles Bibliográficos
Autores principales: Wang, Zhen, Cheong, Kin-Pang, Li, Mingsheng, Wang, Qiang, Ren, Wei
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662406/
https://www.ncbi.nlm.nih.gov/pubmed/33138309
http://dx.doi.org/10.3390/s20216176
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author Wang, Zhen
Cheong, Kin-Pang
Li, Mingsheng
Wang, Qiang
Ren, Wei
author_facet Wang, Zhen
Cheong, Kin-Pang
Li, Mingsheng
Wang, Qiang
Ren, Wei
author_sort Wang, Zhen
collection PubMed
description We report the theoretical and experimental study of calibration-free heterodyne phase-sensitive dispersion spectroscopy (HPSDS) in the mid-infrared using a direct current modulated mid-infrared quantum cascade laser (QCL). The modulation of QCL current at several hundred MHz or higher generates the synchronous frequency and intensity modulation of the QCL emission. An analytical model of the phase of the beat note signal in HPSDS is derived by considering the absorption and dispersion processes and incorporating the QCL modulation parameters. In the experiment, a 4.5 μm QCL modulated at 350 MHz was used to measure N(2)O at 200 Torr in a 10 cm gas cell. The N(2)O concentrations inferred from the analytical model were compared with the nominal values to show good agreement over the concentration range of 189−805 ppm with a standard deviation <3%. When the QCL wavelength was locked at the line-center of the molecular transition, it was of interest to find that the theoretical model was simplified to that used for near-infrared HPSDS with an electro-optical modulator for laser modulation.
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spelling pubmed-76624062020-11-14 Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser Wang, Zhen Cheong, Kin-Pang Li, Mingsheng Wang, Qiang Ren, Wei Sensors (Basel) Letter We report the theoretical and experimental study of calibration-free heterodyne phase-sensitive dispersion spectroscopy (HPSDS) in the mid-infrared using a direct current modulated mid-infrared quantum cascade laser (QCL). The modulation of QCL current at several hundred MHz or higher generates the synchronous frequency and intensity modulation of the QCL emission. An analytical model of the phase of the beat note signal in HPSDS is derived by considering the absorption and dispersion processes and incorporating the QCL modulation parameters. In the experiment, a 4.5 μm QCL modulated at 350 MHz was used to measure N(2)O at 200 Torr in a 10 cm gas cell. The N(2)O concentrations inferred from the analytical model were compared with the nominal values to show good agreement over the concentration range of 189−805 ppm with a standard deviation <3%. When the QCL wavelength was locked at the line-center of the molecular transition, it was of interest to find that the theoretical model was simplified to that used for near-infrared HPSDS with an electro-optical modulator for laser modulation. MDPI 2020-10-29 /pmc/articles/PMC7662406/ /pubmed/33138309 http://dx.doi.org/10.3390/s20216176 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Letter
Wang, Zhen
Cheong, Kin-Pang
Li, Mingsheng
Wang, Qiang
Ren, Wei
Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser
title Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser
title_full Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser
title_fullStr Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser
title_full_unstemmed Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser
title_short Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser
title_sort theoretical and experimental study of heterodyne phase-sensitive dispersion spectroscopy with an injection-current-modulated quantum cascade laser
topic Letter
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662406/
https://www.ncbi.nlm.nih.gov/pubmed/33138309
http://dx.doi.org/10.3390/s20216176
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