High-sensitivity refractive index sensor with cascaded dual-core photonic crystal fiber based on vernier effect

Abstract

A cascaded dual-core photonic crystal fiber (DC-PCF) refractive index sensor is proposed. The sensor is composed by cascading a single-mode fiber with a DC-PCF, thus realizing the vernier effect. The central air hole of the DC-PCF is filled with different refractive indices. The refractive index sensitivity is investigated using the full vector finite element method (FEM). The simulation results show that the cascade structure of the DC-PCF with three different air hole diameter parameters has high sensitivity up to −303376 nm/RIU in the refractive index range of 1.362–1.366, and the highest sensitivity of the cascade corresponds to a resolution of 3.30 × 10−7. The sensitivity is increased by 37 times compared to the DC-PCF without vernier effect.By replacing the central air hole material, the sensor can be used for temperature sensing, magnetic field sensing and water quality analysis.