Design and numerical analysis of a novel dual-polarized refractive index sensor based on D-shaped photonic crystal fiber

Abstract

This paper presents a novel dual-polarized refractive index sensor based on D-shaped photonic crystal fiber. Unlike the traditional D-shaped structures, we use a micro-opening of the deposited gold film as microfluidic channel to excite the surface plasmon resonance (SPR) mode. The fiber consists of two layers of circular pores arranged in an octagonal lattice structure. By optimizing the structural parameters of the fiber, the proposed sensor detection range: the refractive index of the analyte changes from 1.26 to 1.36. Numerical simulation based on the finite element method shows that the average sensitivities in the x- and y- polarization modes are 1182 nm RIU−1 and 5736 nm RIU−1, respectively. When the refractive index of the analyte to be measured is 1.36, the highest sensitivity of the x and y polarization directions is 1298 nm RIU−1 and 11 039 nm RIU−1, respectively. Among them, the resonance wavelength and the resonance intensity increase with the refractive index of the sample to be tested. In addition, we further analyzed the effects of microfluidic channel size, deposited gold film thickness, sensing region length and the overall structure of the fiber (polishing depth, inner cladding pore size, etc) on sensor transmission characteristics.