Design of a dual-core dual-hole fiber for hydrostatic pressure sensing

We propose a novel dual-core dual-hole fiber (DCDHF) for hydrostatic pressure sensing. Two fiber cores and two air holes are employed in the cross-section of the DCDHF. The mode coupling between two fiber cores of the DCDHF is sensitive to the pressure-induced index change which ensures the detection of the pressure applied to the DCDHF. Two large air holes are employed to enhance the pressure-induced index change for the DCDHF which essentially provides a built-in transducing mechanism to enhance the sensitivity for the DCDHF-based pressure sensor. The DCDHF-based pressure sensor is simply formed by splicing a segment of DCDHF to two segments of single mode fibers and its operation principle is introduced in details. Simulations show that there is a linear relationship between the pressure untilized on the DCDHF and the wavelength shift of the output spectrum at one fiber core of the DCDHF with a fixed length when the polarized light is injected into another fiber core of the DCDHF. DCDHFs with different structure parameters for pressure sensing are also investigated.