Mode splitting of surface plasmon resonances in super-period metal nanohole gratings

TL;DR

This paper reports the experimental observation of mode splitting in surface plasmon resonances within super-period metal nanohole gratings, highlighting the coupling effects between different resonance modes under TM polarization.

Contribution

It provides the first experimental demonstration of mode splitting in super-period nanohole gratings and explains the underlying coupling mechanism.

Findings

Mode splitting observed in zeroth and first order transmissions

Splitting more prominent in first order transmission

Coupling between subwavelength nanohole resonance and super-grating resonance

Abstract

We experimentally observed the surface plasmon resonance mode splitting in a super-period metal nanohole grating under the transverse magnetic polarization excitation. The mode splitting was observed in the zeroth order transmission and also in the first order diffracted transmission. However, the mode splitting phenomenon is more evident in the first order transmission than in the zeroth order transmission. It is explained that the mode splitting is due to the coupling between the surface plasmon resonance mode in the subwavelength period metal nanohole arrays and the resonance mode of the metal super-grating.