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12 August 2008 Long-period gratings in chemical sensing
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Proceedings Volume 7099, Photonics North 2008; 70992C (2008)
Event: Photonics North 2008, 2008, Montréal, Canada
A chemical sensor system consisting of a coated long period grating, which was spliced into a fiber loop cavity, has been prepared and characterized. Designer coatings based on polydimethylsiloxane and nanostructured organically modified silica (ORMOSIL) materials were prepared to provide enhanced sensitivity for a variety of key environmental pollutants. Upon microextraction of the analyte into the polymer matrix, an increase in the refractive index of the coating resulted in a change of the attenuation spectrum of the long period grating. The grating was interrogated using ring-down detection as a means to amplify the optical loss and to gain stability against misalignment and laser power fluctuations. Chemical differentiation of cyclohexane and xylenes was achieved and a detection limit of 300 ppm of xylenes vapour in air was readily realized for PDMS coatings. Ormosil-type coatings were capable of detecting lead cations at concentrations below 1 ppm in water.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jack A. Barnes, R. Stephen Brown, Judy Cipot-Wechsler, Cathleen M. Crudden, Jenny Du, Hans-Peter Loock, and Krista Plett "Long-period gratings in chemical sensing", Proc. SPIE 7099, Photonics North 2008, 70992C (12 August 2008);

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