10 December 1996 Quasi-distributed fiber optic chemical sensing using telecom optical fibers
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Abstract
The concept of fully- or quasi-distributed chemical sensing using OTDR techniques has attracted much research interest. Much of the work to date in this area has employed large core non-telecom grade optical fiber. Typically, this has been PCS fiber from which the cladding has been removed and replaced with sections of doped polymers. Evanescent wave interactions between the guided light and the coatings provided the sensor modulation. In this paper we report the use of telecom-grade optical fibers to which analyte- sensitive reagents are attached via a novel configuration at the fiber tip. This approach enables the use of low attenuation fibers, good quality directional couplers and direct, as opposed to evanescent wave, interactions. In order to exploit fully the low attenuation and commercially available OTDR units, it is necessary to operate at one of the telecom windows, usually 850 nm. This requires the use of appropriate NIR dyes. We report some initial results for pH sensing using this approach. We also present results for O2 single point sensing using blue-excited fluorescence and comment on factors concerning the use of fluorescence quenching in distributed systems.
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V. Murphy, V. Murphy, Brian D. MacCraith, Brian D. MacCraith, Thomas M. Butler, Thomas M. Butler, Colette M. McDonagh, Colette M. McDonagh, Brian Lawless, Brian Lawless, } "Quasi-distributed fiber optic chemical sensing using telecom optical fibers", Proc. SPIE 2836, Chemical, Biochemical, and Environmental Fiber Sensors VIII, (10 December 1996); doi: 10.1117/12.260600; https://doi.org/10.1117/12.260600
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