Quantitative tunable diode laser spectroscopy (TDLS) has established itself as a very powerful technique for the detection of gases in field applications such as industrial process control. Recent calibration-free techniques have made field measurements more robust. However, in many situations, the significant levels of laser intensity modulation gives rise to background signals that either limit detection sensitivity or distort the target signals, thereby making it difficult to extract useful information. This paper outlines the recent trends in calibration-free wavelength modulation spectroscopy (WMS) and focuses on the elimination of the undesirable effects of both linear as well as nonlinear intensity modulation. The approach is generic and should be useful with newer types of lasers that have shown significantly nonlinear power-current characteristics.

Date Published: 23 August 2011
PDF: 7 pages
Proc. SPIE 8173, Photonics 2010: Tenth International Conference on Fiber Optics and Photonics, 81731X (23 August 2011); doi: 10.1117/12.897883

Published in SPIE Proceedings Vol. 8173:
Photonics 2010: Tenth International Conference on Fiber Optics and Photonics
Sunil K. Khijwania; Banshi D. Gupta; Bishnu P. Pal; Anurag Sharma, Editor(s)