High-Sensitivity Fiber-Optic Fabry–Perot Interferometer Temperature Sensor

Abstract

A novel structure of a fiber-optic Fabry–Perot interferometric (FFPI) temperature sensor is presented in this paper. The design of the sensor is analyzed and evaluated by the finite-difference time-domain (FDTD) method. Then, the proposed sensor is fabricated using a conventional single-mode fiber (SMF). A gold (Au) layer and a nickel (Ni) layer are sputtered and electroplated on the surface of the SMF, respectively. As a Fabry–Perot (FP) cavity, a micro-punch-hole is machined by focused ion beam (FIB) milling. Here, the structure of the FP cavity can be considered a pair of bimetallic strips. On the basis of the sharp difference in thermal expansion coefficient between the fused silica and the metallic materials, the temperature sensitivity of the proposed sensor was determined to be over 70 pm/°C in the 0 to +60 °C range. The standard deviation of temperature is less than 0.15 °C in 1 h.

Interval of Observation Plane in Visualization of Region near Defects in Billets Using Ultrasonic Computerized Tomography Method

“…In this simulation, we use the finite-difference time-domain (FDTD) method. [28][29][30][31][32][33][34] Figures 5 and 6 show the conditions of simulation for the spherical defect. The targets of the visualization are billets of duralumin and steel of 100 Â 100 Â 150 mm 3 .…”

High-Q Fabry-Pérot Cavity Based on Micro-Lens Array for Refractive Index Sensing

“…To achieve a high Q factor and a small mode volume in the FP cavity, the most common method is to substitute one of the plane mirrors with a concave mirror to achieve sufficient constraints on the light field [24][25][26]. Currently, the main preparation methods for concave mirrors are the CO 2 laser ablation [25,[27][28][29] and focused ion beam (FIB) etching technologies [30][31][32]. The CO 2 laser ablation technology offers a smooth surface and a simple process, but its stability is poor.…”