Theoretical model of a planar integrated refractive index sensor based on surface plasmon-polariton excitation

A theoretical model of a new integrated planar surface plasmon-polariton (SPP) refractive index sensor is presented and comprehensively investigated. The main principle of operation of this device is based on high efficiency energy transfer between a p-polarized guided mode propagating in a waveguide layer of the structure and the SPP propagating in the opposite direction in a metal layer separated from the waveguide layer by a dielectric buffer. The high efficiency energy transfer is realised by means of a properly designed Bragg grating imprinted in the waveguide layer. This device is compact, free from any moving parts and can easily be integrated into any planar scheme. Our simulations for the sensor operating at the well developed and commercialised telecom wavelengths are based on coupled mode theory.