Transient Hydraulic Pressure Sensor Based on Single-Hole-Dual-Core Fiber Bragg Grating

Transient hydraulic pressure is crucial for hydraulic pressure and pipeline leak detection in the fields of petroleum pipelines, gas pipelines, and so on. Real-time, long-distance, online, high-pressure, and high-precision measurement requirements can be precisely achieved through fiber optic sensing technology. In response to the need for pipeline leak detection, we propose a fiber-optic transient hydraulic pressure sensor based on single-hole-dual-core fiber Bragg grating (SHDC-FBG). By inscribing FBG on SHDCF using a deep ultraviolet laser, we conduct modal field analysis on the SHDCF and theoretical simulation analysis of the resonance wavelength of the SHDC-FBG. The simulation results closely match experimental data, demonstrating that air holes induce significant pressure-driven refractive index changes in the center core. Furthermore, the static and dynamic pressure sensing characteristics have been discussed. Experimental results indicate that the SHDC-FBG sensor exhibits a sensitivity of -5.4 pm/MPa within a wide dynamic hydraulic range of 0-20 MPa. To measure the hydraulic leak process, we compare the SHDC-FBG sensor with a conventional resistive pressure sensor. The experimental results show that the performance of the two sensors is essentially the same. Nevertheless, the compact size, low cost, and electromagnetic immunity make our sensor more competitive in harsh, long-distance environments.