{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:23:10Z","timestamp":1760242990775,"version":"build-2065373602"},"reference-count":14,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2015,4,22]],"date-time":"2015-04-22T00:00:00Z","timestamp":1429660800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["60977058","61475085"],"award-info":[{"award-number":["60977058","61475085"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Science and technology development project of Shandong province","award":["2014GGX101007"],"award-info":[{"award-number":["2014GGX101007"]}]},{"name":"Fundamental Research Funds of Shandong University","award":["2014YQ011"],"award-info":[{"award-number":["2014YQ011"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The division process used in a DFB diode laser-based optical gas sensor was studied to improve the immunity to laser power variation. Residual amplitude modulation (RAM) in wavelength modulation spectroscopy (WMS) detection was eliminated by intensity normalization using a division process. As a result the detected harmonic signals showed a significant improvement in line shape. For the first harmonic (1f) signal, Bias was improved from 38.7% to 1.2%; Baseline Difference was improved from 2.7% to 0.69% and Asymmetry was improved from 15.4% to 0.22%. For the second harmonic (2f) signal, the Asymmetry Coefficient was improved from 103% to 5.1%. Moreover the division process can further suppress the influence of unstable laser power. As a result, for the 1f signal, stable detection with a variation coefficient of 0.59% was obtained over a wide dynamic range (0.38\u20138.1 mW). For the 2f signal, stable detection with a variation coefficient of 0.53% was obtained from 0.64 mW to 8.27 mW. The test results showed a good agreement with the theoretical analysis and the proposed method has considerable potential application in gas sensing.<\/jats:p>","DOI":"10.3390\/s150409582","type":"journal-article","created":{"date-parts":[[2015,4,22]],"date-time":"2015-04-22T12:14:23Z","timestamp":1429704863000},"page":"9582-9591","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Immunity to Laser Power Variation in a DFB Diode Laser Based Optical Gas Sensor Using a Division Process"],"prefix":"10.3390","volume":"15","author":[{"given":"Hengtai","family":"Chang","sequence":"first","affiliation":[{"name":"School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun","family":"Chang","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qingjie","family":"Huang","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qiang","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Changbin","family":"Tian","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8768-2072","authenticated-orcid":false,"given":"Wei","family":"Wei","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuanyuan","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,4,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"491","DOI":"10.1134\/S1054660X08040257","article-title":"Measurement technique for methane concentration by wavelength scanning of a distributed-feedback laser","volume":"18","author":"Wang","year":"2008","journal-title":"Laser Phys."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"563","DOI":"10.1109\/JSEN.2013.2284279","article-title":"Optical measurement of water vapor concentration and gas pressure","volume":"14","author":"Wang","year":"2014","journal-title":"IEEE Sens. 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