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Proceedings Paper

Porous silica coated spherical microresonator for vapor phase sensing of ammonia at a sub-ppm level
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Paper Abstract

A new type of fiber optic sensor for the detection and quantification of ammonia (NH3) vapor levels is proposed and experimentally demonstrated. This sensor is based on a spherical silica micro resonator coated with porous silica gel. Whispering gallery modes (WGMs) in the micro resonator are excited by evanescent coupling to a tapered fiber with a 3.3 μm waist diameter. The optical properties of the porous silica layer change when it is exposed to ammonia vapor, leading to a spectral shift of the WGM resonant wavelengths. The sensitivity of the proposed sensor has been tested by exposing it to different low level concentrations of ammonia: 4 ppm, 8 ppm, 12 ppm and 30 ppm at a constant relative humidity (50% RH) and constant temperature (23°C). The detection limit is calculated from experimental results as 57 ppb of ammonia for a 282 μm diameter porous silica coated microsphere.

Paper Details

Date Published: 30 May 2016
PDF: 4 pages
Proc. SPIE 9916, Sixth European Workshop on Optical Fibre Sensors, 99161Y (30 May 2016); doi: 10.1117/12.2236486
Show Author Affiliations
Arun Kumar Mallik, Dublin Institute of Technology (Ireland)
Gerald Farrell, Dublin Institute of Technology (Ireland)
Dejun Liu, Dublin Institute of Technology (Ireland)
Vishnu Kavungal, Dublin Institute of Technology (Ireland)
Qiang Wu, Northumbria Univ. (United Kingdom)
Yuliya Semenova, Dublin Institute of Technology (Ireland)

Published in SPIE Proceedings Vol. 9916:
Sixth European Workshop on Optical Fibre Sensors
Elfed Lewis, Editor(s)

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