Substrateless metamaterials at mid-infrared frequencies

TL;DR

This paper demonstrates the fabrication of substrateless mid-infrared metamaterials using free-standing metal films with periodic holes, exhibiting extraordinary transmission and resonant features due to surface plasmon interactions.

Contribution

It introduces a novel fabrication method for substrateless mid-infrared metamaterials with high Q-factor resonances and potential for advanced optical applications.

Findings

Achieved high transmittivity in mid-infrared range

Observed extraordinary transmission peaks with Q-factor up to 22

Demonstrated negative dielectric constant at specific frequencies

Abstract

We report on the fabrication and mid-infrared transmission properties of free-standing thin metal films, periodically patterned with holes at periods down to 2 microns and area of 3x3 mm2. Square grids were fabricated by electron beam lithography and deep-etching techniques and display substrateless holes, with the metal being supported by a patterned dielectric silicon nitride membrane. The mid-infrared transmission spectra of the substrateless grid display extraordinary transmission peaks and resonant absorption lines with a Q-factor up to 22. These spectral features are due to the interaction of the radiation with surface plasmon modes. The high transmittivity and the negative value of the dielectric constant at selected frequencies make our substrateless structures ideal candidates for the fabrication of mid-infrared metamaterials.