Abstract

An all-optical humidity sensor based on direct and exhaustive guided-mode attenuation in an in-house developed zinc oxide (ZnO) nanoparticle-immobilized bare solgel fiber is reported. The main objective of the present work is to enhance the sensitivity considerably while realizing a throughout linear response over a wide dynamic range. The developed sensor is characterized and performance characteristics of the sensor are compared with an optical fiber humidity sensor employing an evanescent wave absorption scheme in a straight and uniform probe, with ZnO nanoparticles-immobilized solgel film as humidity sensing cladding. Sensor response is observed to be linear over a wide dynamic range of 5%–95% relative humidity (RH). The observed linear sensitivity is 0.0103/% RH, which is $\sim 9$ times higher than the sensor employing the evanescent wave absorption scheme. In addition, sensor response is observed to be very fast, highly reversible, and repeatable.

© 2013 Optical Society of America

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