Design and theoretical analysis of a dual-core photonic crystal fibre temperature sensor with enhanced sensitivity across an extended temperature range

We present a novel dual-core photonic crystal fiber (DC-PCF) temperature sensor with a unique arrangement of circular air holes, enabling ultra-high sensitivity and stability. The DC-PCF features dual solid cores separated by a ring of air holes, functioning as dual waveguides. This highly birefringent structure operates on the principle of mode coupling between the two cores. The sensor is designed for temperature measurement by connecting one core to a broadband light source and the other to an optical spectrum analyzer. Numerical analysis and simulations using the finite element method (FEM) in COMSOL Multi-physics demonstrate its effectiveness over a broad 0–1400°C range. Due to its core asymmetry, the 8 cm-long DC-PCF sensor achieves a high-temperature sensitivity of 25 pm/°C, surpassing previous designs. Its compact and robust structure makes it a promising solution for precise high-temperature measurements, with significant potential for industrial applications.