Polymeric fiber sensor for sensitive detection of carbon dioxide based on apodized wavelength modulation spectroscopy

• Published in: Applied physics. B, Lasers and optics Lasers and optics, 2015-02, Vol.118 (2), p.219-229
• Main Authors: Jozdani, Mehran Mohammadi, Khorsandi, Alireza, Sabouri, Saeed Ghavami
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Computer simulation; Engineering; Fibers; Lasers; Mathematical models; Optical Devices; Optical fibers; Optics; Photonics; Physical Chemistry; Physics; Physics and Astronomy; Quantum Optics; Silicone resins; Spectroscopy; Wavelength modulation
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-014-5973-0

The performance of an optical sensor that employs an unbuffered polydimethylsiloxane (PDMS)-cladding fiber optic is demonstrated for the sensitive detection of CO 2 gas in the near-infrared region for around 1.57 µm using the apodized 2f/1f wavelength modulation spectroscopy method. The permeability and diffusion characteristics of the PDMS fiber have been theoretically examined and numerically simulated. The results of the simulation are verified by an experimental setup containing a DFB laser source and 5-m-coiled unbuffered PDMS fiber placed in a pre-vacuumed cell filled with about 980 ± 10 Torr of pure CO 2 gas. A minimum detectable absorption of ~0.9 × 10 −4 is measured, corresponding to a detection sensitivity of ~4.5 × 10 −11   cm - 1 / Hz 1 / 2 . The effect of the scaling k -factor on the apodized signal is subsequently studied, showing close agreement between the simulation and experimental results.