Highly sensitive dual-function sensor for refractive index and temperature using D-shaped microchannel photonic crystal fiber

An innovative ultra-sensitive, dual-functional sensor employing a D-shaped microchannel photonic crystal fiber (PCF) for refractive index (RI) and temperature measurements is proposed and comprehensively investigated. Its high-sensitivity is achieved through the incorporation of gold (Au) and magnesium fluoride (MgF₂) as plasmonic materials in the micro-rectangular channel. This configuration significantly enhances the interaction between the surface plasmon polaritons (SPPs) field and y-polarized evanescent field on external surfaces. Additionally, the integration of a temperature-sensitive fluid within the sensor allows for precise detection of temperature changes. Our simulations demonstrate a broad detection spectrum, covering RI values from 1.27 to 1.43 and temperatures ranging from 45°C to 100°C. The sensor achieves peak sensitivities of 31800nm/RIU for RI and 49 nm/°C for temperature. Besides, the sensor only has a cladding consisting of three air holes to enhance coupling and reduce the difficulty of preparation. Importantly, the sensor's performance remains robust against minor structural alterations in the PCF, indicating high fault tolerance. Given its high sensitivity, extensive detection range, and strong fabrication stability, this PCF-SPR sensor offers significant potential for applications in biochemical sensing and environmental monitoring.