Side-Hole Dual-Core Photonic Crystal Fiber for Hydrostatic Pressure Sensing

We propose a novel side-hole dual-core photonic crystal fiber (SHDC-PCF) which is used as the sensing element of the hydrostatic pressure sensor. There are two solid fiber cores separated by one small air hole in the triangular lattice photonic crystal structure region. Two large air holes are employed in the cross-section outside of the photonic crystal structure region, which essentially provides a built-in transducing mechanism to enhance the pressure-induced index change for the SHDC-PCF. The mode coupling between two fiber cores of the SHDC-PCF under different hydrostatic pressure is numerically investigated. The SHDC-PCF based pressure sensor is simply formed by using a segment of SHDC-PCF spliced to two single mode fibers. Our simulations show that there is a linear relationship between the hydrostatic pressure applied on the SHDC-PCF and the peak wavelength shift of the sensor output spectrum. A hydrostatic pressure sensor based on a 10-cm SHDC-PCF has shown a sensing range from 0 to 500 MPa and a sensitivity of 32 pm/MPa. The performances of hydrostatic pressure sensors based on SHDC-PCFs with different structure parameters are presented.