Pfalzgraf Ivonne, Suntsov Sergiy, Kip Detlef
Appl Opt. 2021 Feb 10;60(5):1428-1433. doi: 10.1364/AO.416630.
In this work, we present a fiber sensor designed to measure simultaneously spatial inhomogeneities of the refractive index and temperature in liquid media, for example, induced by biochemical reactions. The sensor's constituent elements are Fabry-Perot microresonators fabricated in standard single-mode optical fibers by diamond blade dicing. To allow simultaneous measurements of different refractive indices, the sensor comprises two open cavities approximately 2 mm apart. With a small Si inlay inserted into one of the resonators used for temperature measurements, the sensor allows for immediate compensation of crosstalk between temperature- and composition-induced fluids' refractive index changes. The measurements were evaluated by phase tracking of the characteristic Fourier transform components of the sensor's backreflected spectra. The temperature sensitivity of the Si inlay is 0.063 rad/°C (79 pm/°C), and an accuracy of 0.01°C is obtained. Meanwhile, the two refractive index sensing (open) cavities show a sensitivity of 1168 and 1153 nm/RIU for temperature-compensated measurements. Finally, the sensor performance to measure spatial distributions is demonstrated by measuring the diffusion behavior of sucrose in water, which allows precise monitoring of hydration effects and breaking of bonds at elevated temperatures.
在这项工作中，我们展示了一种光纤传感器，其设计目的是同时测量液体介质中例如由生化反应引起的折射率和温度的空间不均匀性。该传感器的组成元件是通过金刚石刀片切割在标准单模光纤中制造的法布里 - 珀罗微谐振器。为了能够同时测量不同的折射率，该传感器包括两个相距约2毫米的开放腔。通过在用于温度测量的其中一个谐振器中插入一个小的硅镶嵌物，该传感器能够立即补偿温度和成分引起的流体折射率变化之间的串扰。通过对传感器背向反射光谱的特征傅里叶变换分量进行相位跟踪来评估测量结果。硅镶嵌物的温度灵敏度为0.063 rad/°C（79 pm/°C），并获得了0.01°C的精度。同时，两个折射率传感（开放）腔在温度补偿测量中显示出1168和1153 nm/RIU的灵敏度。最后，通过测量蔗糖在水中的扩散行为来展示该传感器测量空间分布的性能，这使得能够精确监测高温下水合作用和键的断裂情况。
