Type

Journal Article

Authors

Dejan Liu
Yuliya Semenova
Vishnan Kavungal
Arun Mallik

Subjects

Physics

Topics
fiber optics sensors refractive index relative humidity optical resonators temperature dependence engineering micro optical devices microstructured fibers

Agarose Coated Spherical Micro Resonator for Humidity Measurements (2016)

Abstract A new type of fiber optic relative humidity (RH) sensor based on an agarose coated silica microsphere resonator is proposed and experimentally demonstrated. Whispering gallery modes (WGMs) in the micro resonator are excited by evanescent coupling using a tapered fiber with ~3.3 μm waist diameter. A change in the relative humidity of the surrounding the resonator air induces changes in the refractive index (RI) and thickness of the Agarose coating layer. These changes in turn lead to a spectral shift of the WGM resonances, which can be related to the RH value after a suitable calibration. Studies of the repeatability, long-term stability, measurement accuracy and temperature dependence of the proposed sensor are carried out. The RH sensitivity of the proposed sensor depends on the concentration of the agarose gel which determines the initial thickness of the deposited coating layer. Studies of the micro- resonators with coating layers fabricated from gels with three different Agarose concentrations of 0.5%, 1.125% and 2.25 wt./vol.% showed that an increase in the initial thickness of the coating material results in an increase in sensitivity but also leads to a decrease of quality factor (Q) of the micro resonator. The highest sensitivity achieved in our experiments was 518 pm/%RH in the RH range from 30% to 70%. The proposed sensor offers the advantages of a very compact form factor, low hysteresis, good repeatability, and low cross sensitivity to temperature.
Collections Ireland -> Dublin Institute of Technology -> Conference Papers
Ireland -> Dublin Institute of Technology -> College of Engineering and Built Environment
Ireland -> TU Dublin -> Conference Papers
Ireland -> Dublin Institute of Technology -> Colleges
Ireland -> TU Dublin -> School of Manufacturing and Design Engineering
Ireland -> TU Dublin -> Colleges
Ireland -> Dublin Institute of Technology -> School of Manufacturing and Design Engineering
Ireland -> TU Dublin -> College of Engineering and Built Environment

Full list of authors on original publication

Dejan Liu, Yuliya Semenova, Vishnan Kavungal, Arun Mallik

Experts in our system

1
Dejan Liu
TU Dublin
Total Publications: 3
 
2
Yuliya Semenova
TU Dublin
Total Publications: 136
 
3
Vishnan Kavungal
Dublin Institute of Technology
Total Publications: 3
 
4
Arun Mallik
TU Dublin
Total Publications: 26