A compact integrated planar-waveguide refractive-index sensor based on a corrugated metal grating

In this paper, a theoretical model of a new planar integrated surface plasmon-polariton (SPP)-excitation-based refractive-index sensor is presented and comprehensively investigated. The main principle of operation of this device is based on energy transfer by means of a corrugated metal grating between a p-polarized guided mode propagating in a waveguide layer and the SPP propagating in the opposite direction in a metal layer. The corrugated grating is engraved in the metal layer in contact with the sensed medium. This device is free from any moving parts and can be simply integrated into any planar-waveguide system. Our sensor simulations are based on the transfer-matrix method with the mode-matching technique and have been performed at commercialized telecom wavelengths.