Figure 1.

The proposed IIMI structure. The incident medium (Region 0) was a semi-infinite glass substrate with refractive index n₀ serving as an incident medium. The resonant cavity (Region I) was made of a dielectric layer with refractive index n₁ and thickness d₁. The plasmonic medium (Region II) was a noble metal layer with refractive index n₂ and thickness d₂. The sample medium (Region III) was also the dielectric layer with refractive index n₃ which was the sample channel of the proposed SPR sensor.