Multipoint chemical vapor measurement by zeolite thin film-coated Fresnel reflection-based fiber sensors with an Array-Waveguide Grating

A simple multipoint volatile organic compounds (VOC) measurement by zeolite thin film-coated Fresnel reflection-based fiber sensor with an Array-Waveguide Grating (AWG) is proposed and demonstrated. The sensor comprise a polycrystalline silicalite thin film grown up on the cleaved end face of single-mode fiber. The chemical vapors concentration is measured by monitoring the reflection intensity, which is a function of the molecular adsorption in the crystalline micro-porous structure. Multipoint measurement is achieved by an AWG with 16 channels. Four of the 16 channels has been connected to the sensing channels as representative. The proposed VOC sensor performed with the sensitivity from 0.015 to 3.9 × 10−3 dB/ppm in the concentration range from 0 to 550 ppm.