低语长廊波浪
材料科学
光学
谐振器
耦合模理论
光电子学
折射率
物理
作者
Arun Kumar Mallik,Gerald Farrell,Manjusha Ramakrishnan,Vishnu Kavungal,Dejun Liu,Qiang Wu,Yuliya Semenova
出处
期刊:Optics Express
[The Optical Society]
日期:2018-11-19
卷期号:26 (24): 31829-31829
被引量:30
摘要
A novel fiber optic sensing configuration for simultaneously measuring ammonia vapor (NH 3 ) concentration and relative humidity (RH) in air is proposed and experimentally demonstrated.The system comprised two silica whispering gallery mode (WGM) microsphere resonators coated with different polymer layers.One of the microspheres was dip-coated with sol gel silica polymer and another with a 0.5 % wt./vol.agarose hydrogel.WGMs in both microspheres were excited simultaneously by evanescent coupling using a single adiabatic fiber taper.The optical properties of both coating layers change due to their exposure to ammonia and water molecules in the surrounding atmosphere, resulting in the spectral shifts of the WGM resonances relevant to each of the microspheres.By measuring the relevant WGMs' spectral shifts, the NH 3 concentration in air and the RH can be determined simultaneously.The experimentally demonstrated sensitivity of the proposed sensor array to ammonia was estimated as 19.07 pm/ppm (NH 3 molecules in air) and its sensitivity to relative humidity as 1.07 pm/% RH.Detailed studies of the coatings' cross-sensitivity and temperature dependence are also presented.The proposed sensor array is compact, highly sensitive and potentially low cost.
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