A Broadband Nanosensor based on Multi-Interference of Surface Plasmon Polaritons

A novel broadband refractive index nanosensor based on multi-interference of surface plasmon polaritons is reported. It is composed of a metallic nanoslit flanked by periodical grooves on its two sides. Extraordinary high-throughput, high-resolution, and high-sensitivity detections can be realized by observing the shift of the resonant wavelength. The sensor covers a large range of the refractive index change due to both the narrow linewidth of the single resonant peak in the broadband spectrum and the sensitive shift of the peak position withthe refractive index change. A theoretical model is developed to well predict the optical response of the sensor. An excellent linearity between the resonant wavelength and the refractive index can be achieved. The sensitivity, which is 620 nm/refractive index unit, can be further increased by tuning the period of the grooves and the high throughput; high resolution can be simultaneously achieved by adding the number of grooves.