Pole-based analysis of coupled modes in metal–insulator–metal plasmonic structures

Abstract

A second-order transfer function analysis is performed on plasmonic modes with disparate quality factors. This generalized analysis technique is applied to the coupling of modes in metal–insulator–metal structures in the mid-wave infrared, which are systematically studied, both experimentally and with computational modeling. Coupling between these disparate modes is observed from the asymmetric Fano-like lineshape at the resonant crossings in both finite element method simulations and angle dependent spectra. The pole analysis method applied to both experimental and numerical data allows for extraction of the coupling coefficient for this system and is applicable to other plasmonic and photonic coupled resonances.