Hybrid plasmonic biosensor for simultaneous measurement of both thickness and refractive index

A novel hybrid plasmonic biosensor using a sub-wavelength reflection metal grating is proposed and analyzed. The simulation results show that the hybrid plasmonic-cavity (HPCM) are wavelength dependent on both the refractive index (RI) and thickness of the surrounding analyte layer, with a sensitivity of 448 nm/RIU (refractive index unit) and 75 nm/μm, respectively. However wavelength related to the cavity resonant mode (CRM) is only sensitive to the environmental refractive index changes. In principle it is possible to determine both RI and thickness of the coating layer simultaneously.