Abstract
Surface plasmon polaritons (SPPs) and diffraction effects such as Rayleigh anomalies (RAs) play key roles in the transmission of light through periodic subwavelength hole arrays in metal films. Using a combination of theory and experiment we show how refractive index (RI) sensitive transmission features arise from hole arrays in thin gold films. We show that large transmission amplitude changes occur over a narrow range of RI values due to coupling between RAs and SPPs on opposite sides of the metal film. Furthermore, we show how to predict, on the basis of a relatively simple analysis, the periodicity and other system parameters that should be used to achieve this "RA-SPP" effect for any desired RI range.
Highlights
Light transmission through subwavelength diameter holes in metal films has been the focus of much research since the pioneering work of Ebbesen et al [1], and the mechanisms underlying the enhanced or extraordinary optical transmission in these systems have been the subject of much discussion
We find that it can lead to large increases in transmission amplitudes with respect to refractive index (RI) unit (RIU) of a substrate, up to 150%/RIU, because of strong coupling between the opposite sides of a thin metal film
The three-dimensional finite-difference time-domain (FDTD) [3, 9] method is used to model the system in Fig. 1, which consists of modeling a single unit cell with appropriate periodic boundary conditions and with absorbing layers placed in the lower and upper regions of z
Summary
Light transmission through subwavelength diameter holes in metal films has been the focus of much research since the pioneering work of Ebbesen et al [1], and the mechanisms underlying the enhanced or extraordinary optical transmission in these systems have been the subject of much discussion. In this paper we show how certain narrow spectroscopic features in the light transmission through a periodic array of holes in a thin gold film can be described by coupling a RA on one side of the film with a SPP Bloch wave (SPP-BW) on the opposite side. Both rigorous computational electrodynamics modeling and experiment are used to study this "RA-SPP" effect. We find that it can lead to large increases in transmission amplitudes with respect to RI unit (RIU) of a substrate, up to 150%/RIU, because of strong coupling between the opposite sides of a thin metal film.
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