Design of a highly sensitive surface plasmon resonance sensor using aluminum-based diffraction grating

A highly-sensitive grating-based surface plasmon resonance (SPR) sensor is proposed. The angular interrogation method has been used to study the performance of the sensor, and high sensitivity is obtained if the −1st diffraction order is used to excite surface plasmon (SP). The sensitivity as well as the width of the SPR curves and reflective amplitude is considered for designing the sensor. Compared with the conventional gold (Au)-based or silver (Ag)-based SPR sensor, it is found that the aluminum (Al)-based sensor has the best performance. The oxidation problem of an Al-based SPR sensor has been addressed by coating it with an ultrathin gold film on the surface. Numerical simulations based on rigorous coupled wave analysis (RCWA) show that the sensitivity of the optimized sensor is 245°/RIU (degree per refractive index unit).