Surface plasmon polaritons assisted diffraction in periodic subwavelength holes of metal films with reduced interplane coupling

TL;DR

This paper demonstrates enhanced mid-infrared transmission through metal films with subwavelength holes, driven by surface plasmon polaritons, with experimental results supported by theoretical analysis.

Contribution

It reveals the role of SPP-assisted diffraction in enhanced transmission and shows high-order peaks due to dielectric contrast in a periodic hole array.

Findings

Observation of anomalous transmission peaks up to Si(2,2)

Splitting of Si(1,1) peak at oblique incidence

Excellent agreement between theory and experiment

Abstract

Metal films grown on Si wafer perforated with a periodic array of subwavelength holes have been fabricated and anomalous enhanced transmission in the mid-infrared regime has been observed. High order transmission peaks up to Si(2,2) are clearly revealed due to the large dielectric constant contrast of the dielectrics at the opposite interfaces. Si(1,1) peak splits at oblique incidence both in TE and TM polarization, which confirms that anomalous enhanced transmission is a surface plasmon polaritons (SPPs) assisted diffraction phenomenon. Theoretical transmission spectra agree excellently with the experimental results and confirm the role of SPPs diffraction by the lattice.