Model for confined Tamm plasmon devices

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 verticalcavity 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.

Observing and controlling a Tamm plasmon at the interface with a metasurface

“…Correspondingly, most of the approaches proposed so far involved the integration of a control element into the very structure of the Bragg mirror [4,6,11,12,13,14], which may not always appear feasible. It has also been shown that the wavelength of a Tamm plasmon could change (although irreversibly) as a result of the lateral confinement of its fields achieved by patterning the metal film on the microscale [3,15,16].In this Letter we report on the first experimental observation of a near-IR Tamm plasmon at the interface between a Bragg mirror and a nano-patterned metal film acting as a nondiffracting optical metasurface. We found that the discrete framework of the metasurface exposed Tamm plasmon to external perturbations, such as changes of the refractive index in an adjacent medium, which enabled us to dynamically control the wavelength of this weakly coupled optical state in a simple yet efficient way.…”

“…Correspondingly, most of the approaches proposed so far involved the integration of a control element into the very structure of the Bragg mirror [4,6,11,12,13,14], which may not always appear feasible. It has also been shown that the wavelength of a Tamm plasmon could change (although irreversibly) as a result of the lateral confinement of its fields achieved by patterning the metal film on the microscale [3,15,16].…”

Confined Tamm optical states coupled to quantum dots in a photoconductive detector

“…This increased confinement is shown to blueshift the mode. 9,10,22,23 Therefore, by changing the size of the micrometer scale structures, the confinement changes, and the mode can be spectrally tuned. By breaking the symmetry of the structures, the degeneracy of the polarization of the mode can be lifted and control the polarization of the light it couples to.…”

“…4(a), we plot the computed wavelength values of the circularly symmetric linearly polarized LP 0m modes 24 as a function of disk size. This plot was obtained using a novel approach based on the effective index method 22,25 to determine the index profile of the circular cylindrical waveguide, as well as a hard mirror approximation for the cavity. 26 Full details of this approach, which offers more physical insight into the analysis of confined Tamm modes, are given in our recent paper.…”

“…26 Full details of this approach, which offers more physical insight into the analysis of confined Tamm modes, are given in our recent paper. 22 While the smallest disk sizes tend toward single mode operation, the larger devices are predicted to support a number of spatial modes. Accordingly, the spectral response arises from the convolution of the spectral mode with the QD distribution (which is much broader than the individual separation between the confined modes) and from the coupling of the incoming mode into several spatial modes.…”