Highly Sensitive Black Phosphorus–Layered SPR-PCF Refractometric Sensor

This work presents a D-shaped surface plasmon resonance (SPR)-based photonic crystal fiber (PCF) sensor with a coating of gold-TiO₂ as a plasmonic material along with black phosphorus (BP) nano-films which works as a sensitivity enhancer functioning in visible to near-infrared spectrum. The affixed BP layers offer a direct bandgap, consequently advancing the proposed sensor’s performance. The designed sensor is employed for the detection of a broad range of refractive indices limiting from 1.3–1.4. Various fabrication procedures are discussed for layering of BP films on the PCF surface such as liquid peeling and pulsed laser precipitation technique. Along with the influence of BP layers, the thickness of gold and TiO₂ is also optimized for the extraction of favorable outputs. The dimensions of respective cladding air holes of the PCF are also influenced to assess the effectiveness of the proposed sensor. The dynamic sensitivity of the proposed sensor elevated from 9000 to 23,300 nm/RIU with the incorporation of the BP films in the designed PCF RI detector. Additionally, a high amplitude sensitivity of 7446.56 RIU⁻¹ is also achieved. The theoretical structure is numerically analyzed using the finite element method in COMSOL Multiphysics Software. The extracted enhanced sensitivity perfectly elaborates the efficacy of the BP layers in the PCF-SPR RI sensor and builds our suggested sensor as a prospective participant in modern plasmonic sensors.