Atomically Smooth Gold Microflake-Enabled Fiber-Tip Fabry–Perot Interferometer for Temperature and Pressure Sensing
Yuqi Zhen, Xitao Tu, Jiajie Zhu, Yuanbiao Tong, Lufang Liu, Ni Yao, Pan Wang, Limin Tong, Lei Zhang
Abstract
Fiber-tip sensors based on the Fabry–Perot interferometer (FPI) are one of the most widely used devices for temperature and pressure measurements in space-confined scenarios. However, the deposited metal films with a polycrystalline structure tend to form microcracks under strain, which can undermine the optical quality factor and thus sensing performance of these fiber-tip sensors. Here, we demonstrate an atomically smooth gold microflake (GMF)-enabled fiber-tip FPI sensor with a Q factor as high as 628. Benefiting from the high reflectivity and flexibility of GMFs and the elasticity of the PDMS spacer, the fiber-tip FPI can maintain stable sensing performance under large deformation. For temperature sensing, the fiber-tip sensor exhibits a linear response to the temperature in the range 28–40 °C with a sensitivity as high as 1.74 nm °C –1 . To realize linear and sensitive pressure sensing, we design and fabricate a PDMS clamped-beam structure on the fiber tip using a soft lithography technique, achieving a sensitivity of 11.48 nm kPa –1 . Moreover, simultaneous measurement of the temperature and pressure is also demonstrated using the wavelength demodulation method. The simple and cost-effective fabrication of the clamped beam and the transferable GMFs allow for the facile integration of high-quality FP cavities on fiber tips, opening new opportunities for developing optical sensors with miniaturized sizes.