Theoretical Analysis of Diffraction Grating-Based SPR Sensor Using the Rigorous Coupled Wave Analysis Method

Surface plasmon resonance (SPR) sensors are crucial for highly sensitive, label-free detection in various applications, including biosensing and environmental monitoring. This study investigates the sensitivity and performance of diffraction grating-based SPR sensors using rigorous coupled wave analysis (RCWA). The analysis focuses on single- and bi-layered metallic structures composed of copper, gold, and silver. The results reveal that single-layer silver sensors exhibit the highest sensitivity of 169.37°/RIU followed by Au and Cu with a sensitivity of 168.4°/RIU and 167.9°/RIU respectively. Further, to enhance the stability and reliability, bilayered configurations were introduced, incorporating protective coatings of one metal over the other. Among the bilayered configurations, Ag-Cu demonstrated the greatest sensitivity of 175°/RIU followed by Ag-Au with a sensitivity of 173.25°/RIU and Au-Cu with the sensitivity of 168.5°/RIU. This study establishes the potential of bi-metallic SPR sensors for achieving superior sensitivity and stability, highlighting their applicability in advanced detection systems. The novel insight into the interplay between material properties and sensor performance offers a roadmap for designing next-generation plasmonic sensors.