Abstract
In this research study we have targeted to fabricate a tapered optical fiber coated with zinc oxide doped with KCl to improve the humidity sensing capability of zinc oxide. The optical fiber was tapered through chemical etching method by HF acid (49.5%). The nano-crystalline Zinc Oxide (ZnO) was synthesized using single molecular precursor method doped with KCl. The resulting material was characterized with Fourier Transform Infrared spectroscopy (FTIR), X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). The sensing mechanism of this sensor is based on the change of the optical properties of the coating when the relative humidity increases. The humidity sensing characteristic has been estimated by measuring the Optical Permeability (OP) as a function of percentage of Relative Humidity (%RH) in the ranging from 5 to 98% inside a closed chamber. The tapered optical fiber tested with an overlay coating at the optimal working point achieves better sensitivity. The experimental results show that the 5.7 wt% KCl doped ZnO nano-fibers hold super-rapid response and recovery than normal ZnO coating.
Highlights
A wide range of optical fiber humidity sensors have been reported in the literature
We demonstrate a simple route for the synthesis of Potassium doped Zinc Oxide (ZnO) nano-fibers with super-rapid response and recovery to humidity
The tapered optical fiber was employed as a candidate to act as a prospective waveguide when carefully clad with KCl doped nano-crystalline ZnO film with a desired thickness as homogenous cast as possible (Corres et al, 2006b; Gaston et al, 2003)
Summary
A wide range of optical fiber humidity sensors have been reported in the literature. Most of these fiber optic humidity sensors work on the basis of a hygroscopic material coated over the optical fiber to modulate the light propagating through the fiber. INTRODUCTION A wide range of optical fiber humidity sensors have been reported in the literature. Many attempts have been made to fabricate nano-crystalline ZnO of unique properties for versatile applications in the area of transparent electronics, light emitting diodes, piezoelectric devices, spin electronics and chemical sensors (Shukla et al, 2009; Kersey, 1996).
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