Optical properties of metal-dielectric-metal microcavities in the THz frequency range

TL;DR

This study investigates the optical behavior of metal-dielectric-metal microcavities in the THz range, revealing their ability to support localized modes and efficiently convert far-field waves into near-field energy, with both experimental and theoretical insights.

Contribution

The paper provides a combined experimental and theoretical analysis of localized photonic modes in patterned metal-dielectric-metal structures at THz frequencies, including quantitative predictions of resonance and coupling mechanisms.

Findings

Structures support strongly localized electromagnetic modes.

Resonance positions are accurately predicted by the model.

Efficient conversion of far-field to near-field energy is demonstrated.

Abstract

We present an experimental and theoretical study of the optical properties of metal-dielectric-metal structures with patterned top metallic surfaces, in the THz frequency range. When the thickness of the dielectric slab is very small with respect to the wavelength, these structures are able to support strongly localized electromagnetic modes, concentrated in the subwavelength metal-metal regions. We provide a detailed analysis of the physical mechanisms which give rise to these photonic modes. Furthermore, our model quantitatively predicts the resonance positions and their coupling to free space photons. We demonstrate that these structures provide an efficient and controllable way to convert the energy of far field propagating waves into near field energy.