Study the enhancement of near electro-magnetic field via plasmonic effects using finite-difference time-domain method and near-field scanning optical microscopy

Abstract

In this study, we use the finite-difference time-domain (FDTD) method, the attenuated-total-reflection (ATR) fluorescent and the near field scanning optical microscopy (NSOM) to investigate into the enhancement of near electro-magnetic field via plasmonic effects. In order to enhance the near electro-magnetic (EM) field on the sensing surface, a metal particle layer is added under the Kretschmann configuration of the conventional surface plasmon resonance (SPR) sensor based on the attenuated-total-reflection method. The affiliation by the simulation and experimental results can help us to understand the mechanisms of surface plasmons and particle plasmons on the sensor surface, and the effects of the EM field enhancement are classified as the surface plasmon effect, particle plasmon effect, interparticle coupling effect, and gap mode effect. With the helps of the both techniques, we can understand more about the plasmonic effects in order to deign a novel ultrahigh-resolution plasmonic biosensor.