Electromagnetic study of magneto-optic surface plasmon resonance effects for biosensing applications

Abstract

Biosensors are gaining interest in scientific research because of their wide variety of applications. Surface plasmon resonance (SPR) based biosensors are the most common platform for label-free biomolecular interaction analysis. In this paper, we present simulations of a magneto-optic SPR (MOSPR) biosensor by using a three-dimensional finite integration technique (FIT). In the past SPR based biosensors have been modeled with the FIT, here, we extend this technique by incorporating the anisotropic material Co for a MOSPR sensor. The MOSPR biosensor uses the properties of surface plasmon polaritons (SPPs) and transverse magneto-optic Kerr effect (TMOKE) simultaneously in the presence of an external magnetic field. We study the magneto-optical activity on the Au/Co/Au trilayer structures with opposite magnetization. The magneto-optic activity strongly depends on the metallic layer thicknesses and the refractive index of the dielectric. The simulation exhibits the electric and magnetic field distributions along the trilayer system. Based on the FIT simulations, we investigate the sensitivity of a MOSPR biosensor by changing the refractive index of the adjacent dielectric material from 1.33 to 1.40. Furthermore, we compare the performance of a MOSPR sensor to a SPR one. Finally experimental and simulation results of a MOSPR sensor in Kretschmann configuration are compared, verifying the used approach.