Experimental and numerical characterization of a D-shaped PCF refractive index sensor

Highly sensitive D-shaped plasmonic photonic crystal fiber (PCF) sensor is proposed, analyzed and fabricated for refractive index (RI) sensing. The reported sensor relies on the coupling between the core guided mode and the surface plasmon mode at the metallic/dielectric interface. The resonance frequency is a function of the analyte RI within a range of 1.33–1.354. Therefore, the reported D-shaped PCF holds great potential as a highly sensitive RI sensor to detect an unknown analyte refractive index within the tested RI range. The geometrical parameters are studied to maximize the sensor sensitivity by using full vectorial finite element method. Then, the optimum design is fabricated by using stack and draw technique. The fabricated PCF sensor achieves high sensitivity of 294.11 nm/RIU with a resolution of $$3.4 \times 10^{ - 4} \;{\text{RIU}}$$ 3.4 × 10 - 4 RIU . The reported RI sensor can be used for glucose concentration detection where the analyte refractive index changes with the glucose concentration within the studied RI range. Hence, this design will play a significant role in the biomedical sensor industry.