Agarose coated spherical micro resonator for humidity measurements
Agarose coated spherical micro resonator for humidity measurements
复制标题
DOI：
10.1364/oe.24.021216
复制
发表时间：
2016-09-19
期刊：
影响因子：
3.8
通讯作者：
Semenova, Yuliya
中科院分区：
文献类型：
--
作者：
Mallik, Arun Kumar;Liu, Dejun;Semenova, Yuliya
提出了一种基于琼脂糖包覆二氧化硅微球谐振腔的新型光纤相对湿度传感器，并进行了实验验证。微谐振腔中的窃窃廊模式（WGMs）是用一根腰径约3.3 μ m的锥形光纤通过倏逝耦合激发的。谐振腔周围空气相对湿度的变化会引起琼脂糖涂层的折射率和厚度的变化。这些变化反过来导致WGM共振的光谱移位，这可以在适当的校准后与RH值相关。对该传感器的重复性、长期稳定性、测量精度和温度依赖性进行了研究。所提出的传感器的相对湿度灵敏度取决于琼脂糖凝胶的浓度，琼脂糖凝胶的浓度决定了沉积涂层的初始厚度。琼脂糖浓度分别为0.5%、1.125%和2.25 wt./vol的凝胶制备微谐振器。%表明，随着涂层材料初始厚度的增加，微谐振器的灵敏度增加，但也会导致质量因子(Q)的降低。在我们的实验中，在30%至70%的RH范围内，最高灵敏度为518 pm/%RH。所提出的传感器具有非常紧凑的外形、低滞后、良好的可重复性和对温度的低交叉灵敏度等优点。(C) 2016年美国光学学会
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 similar to 3.3 mu m 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. (C) 2016 Optical Society of America