Design optimization of nano-grating surface plasmon resonance sensors.

In this study, we propose nano-grating surface plasmon resonance (NGSPR) sensors and show the design optimization process. NGSPR sensors with line width less than 50 nm show narrow reflection peaks from the excitation of localized surface plasmon polaritons. The wavelength of resonance reflection can be customized by adjusting the grating period. We predict that a refractive index sensitivity of more than 400 nm/RIU can be obtained using an optimized structure. Sharp reflection resonance peaks with FWHM of 0.03 eV will further enhance the sensitivity of the sensors. The simple optical configuration of normal incidence and high refractive index sensitivity make it possible for NGSPR sensors to be used as portable biosensors for high-throughput screening applications.