A model for confined Tamm plasmon devices

TL;DR

This paper presents a model for confined Tamm plasmon devices, accurately predicting their optical properties and mode confinement by combining a hard-mirror approximation with effective index theory, validated against numerical methods.

Contribution

It introduces a simplified analytical model for confined Tamm plasmon devices that aligns well with numerical results and enables easy calculation of lateral modes using waveguide theory.

Findings

The model accurately predicts resonant wavelengths of confined Tamm modes.

Lateral confinement by metallic discs can be analyzed with waveguide theory.

Good agreement between the model and numerical simulations was demonstrated.

Abstract

It is shown that cavities formed between a multilayer quarter-wave Bragg reflector and a metal mirror which support Tamm plasmons can be modelled by using a hard-mirror approximation including appropriate penetration depths into the mirrors. Results from this model are in excellent agreement with those found by numerical methods. In addition Tamm modes that are laterally confined by the presence of a metallic disc deposited on the Bragg reflector can be described by the effective index model that is commonly used for vertical-cavity surface-emitting lasers (VCSELs). This enables the lateral modes confined by a circular disc to be found from conventional weakly-guiding waveguide theory similar to that used for optical fibres. The resonant wavelengths of these linearly-polarised (LP) guided modes are calculated as functions of disc diameter and other parameters.