Abstract
We demonstrate a silica diaphragm-based fiber tip Fabry–Perot interferometer (FPI) for high-pressure (40 MPa) sensing. By using a fiber tip polishing technique, the thickness of the silica diaphragm could be precisely controlled and the pressure sensitivity of the fabricated FPI sensor was enhanced significantly by reducing the diaphragm thickness; however, the relationship between the pressure sensitivity and diaphragm thickness is not linear. A high sensitivity of −1.436 nm/MPa and a linearity of 0.99124 in hydraulic pressure range of 0 to 40 MPa were demonstrated for a sensor with a diaphragm thickness of 4.63 μm. The achieved sensitivity was about one order of magnitude higher than the previous results reported on similar fiber tip FPI sensors in the same pressure measurement range. Sensors with a thinner silica diaphragm (i.e., 4.01 and 2.09 μm) rendered further increased hydraulic pressure sensitivity, but yield a significant nonlinear response. Two geometric models and a finite element method (FEM) were carried out to explain the nonlinear response. The simulation results indicated the formation of cambered internal silica surface during the arc discharge process in the fiber tip FPI sensor fabrication.
Highlights
In-fiber Fabry–Perot interferometric (FPI) pressure sensors have been widely used in various industrial fields owning to their outstanding advantages such as light weight, miniature size, immunity to electromagnetic interference, and survivability in harsh environments [1,2,3,4]
We demonstrated a high-sensitivity, high-pressure sensor based on fiber tip all-silica Fabry–Perot interferometer (FPI)
A high sensitivity (−1.436 nm/MPa) and good linearity (0.991) in a wide pressure range of 0 to 40 MPa were experimental demonstrated for an FPI sensor with a diaphragm thickness (d) of 4.63 μm
Summary
In-fiber Fabry–Perot interferometric (FPI) pressure sensors have been widely used in various industrial fields owning to their outstanding advantages such as light weight, miniature size, immunity to electromagnetic interference, and survivability in harsh environments [1,2,3,4]. A high sensitivity (−1.436 nm/MPa) and large measurement range (0–40 MPa) pressure sensor based on a fiber tip all-silica diaphragm FPI is experimentally demonstrated. By employing the proposed fiber tip polishing technique, the thickness of silica diaphragm can be precisely controlled and the pressure sensitivity of the FPI sensor was improved significantly with the reduction of diaphragm thickness, while the relationship is not linear. Geometric modeling and numerical simulation based on the proposed sensor structure indicated the formation of fiber tip cambered silica diaphragm, which may be resulted from the arc discharge process during FPI fabrication. Detailed analysis in both experiments and simulations was carried out to reveal the relationship between the sensitivity, linearity, and diaphragm thickness. The FPI sensor is suitable for extensive production due to the simplicity and consistence of the fabrication method
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