Refractive index sensing characteristics of D-shape double core photonic crystal fiber based on surface plasmon resonance

Abstract

A refractive index (RI) sensor and its sensing characteristics based on surface plasmon resonance (SPR) of D-shape double core photonic crystal fiber (DC-PCF) are researched theoretically in this letter. The basic sensor principle is the SPR light intensity modulation of polished D-shape DC-PCF. The influence of the polished angle and depth on the DC-PCF SPR characteristics is discussed extensively by using the finite element method (FEM). The effects of the coated metal type and its layer thickness on the resonant intensity are also analyzed. The relationship between the analyte RI and resonant wavelength is numerically simulated. The theoretical results show that the sensor’s RI sensitivity exhibits about 2000 nm/RIU with the structure parameters of 60° polished angle, 58.5μm polished depth and 70nm thickness of the silver layer. Furthermore, if the single wavelength laser is chosen, the detection of the two core light intensity difference will improve the ability of resistance to environmental interference. The simple sensor structure and high sensitivity can make this technology for online refractive index measurement in widespread areas.