Document Type

Conference Paper

Rights

Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence

Disciplines

1.3 PHYSICAL SCIENCES, 2.2 ELECTRICAL, ELECTRONIC, INFORMATION ENGINEERING

Publication Details

Authors' version. Proc. SPIE 9916, Sixth European Workshop on Optical Fibre Sensors, 99161Y (30 May 2016): https://www.spiedigitallibrary.org/conference-proceedings-of-spie/9916/1/Porous-silica-coated-spherical-microresonator-for-vapor-phase-sensing-of/10.1117/12.2236486.short?SSO=1

Abstract

A new type of fiber optic sensor for detection and quantification of ammonia (NH3) vapors 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 constant relative humidity (50% RH) and constant temperature (230 C). The response and recovery times are measured as 100 and 570 seconds respectively.

DOI

https://doi.org/10.1117/12.2236486

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