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Proceedings Paper

Long period grating-based fiber-optic PH sensor for ocean monitoring
Author(s): Ke Wang; Denis Klimov; Zbigniew Kolber
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Paper Abstract

A fiber-optic PH sensor is developed based-on the long period grating (LPG). The LPG is fabricated by using CO2 laser with a point-by-point technique. Then the grating portion is coated with PH sensitive hydrogel. The hydrogel, made of PVA/PAA, swells its volume in response to the PH change in the surrounding environment and results in a change in the refractive index. As a result, the LPG can response to the refractive index change in the coating by shifting its wavelength. Therefore, change in refractive index can be measured by tracking the wavelength shift using an optical spectrum analyzer (OSA). In this research, the LPG is dip-coated by the hydrogel. A chemostat is designed to simulate the marine environment. The PH in the chemostat is varied by controlling the CO2 concentration in the sea water. A PH resolution 0.046/nm using the OSA has been obtained. This sensor is designed to monitor the sea water PH change in a long term basis.

Paper Details

Date Published: 12 October 2007
PDF: 5 pages
Proc. SPIE 6770, Fiber Optic Sensors and Applications V, 677019 (12 October 2007); doi: 10.1117/12.742088
Show Author Affiliations
Ke Wang, Monterey Bay Aquarium Research Institute (United States)
Denis Klimov, Monterey Bay Aquarium Research Institute (United States)
Zbigniew Kolber, Monterey Bay Aquarium Research Institute (United States)

Published in SPIE Proceedings Vol. 6770:
Fiber Optic Sensors and Applications V
Eric Udd, Editor(s)

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