Compact broadband thermal absorbers based on plasmonic fractal metasurfaces

TL;DR

This paper introduces a compact plasmonic fractal metasurface that achieves broadband thermal absorption in the 6-14 microns range, promising advancements in infrared sensing and imaging.

Contribution

It presents the design, numerical analysis, and experimental validation of a compact fractal metasurface for broadband thermal absorption, outperforming previous approaches in size and efficiency.

Findings

Achieves broadband absorption from 6 to 14 microns.

Demonstrates similar absorption enhancement in small arrays as in infinite arrays.

Experimental results agree qualitatively with simulations.

Abstract

The ability to efficiently absorb thermal radiation within a small material volume is crucial for the realization of compact and high spatial resolution thermal imagers. Here we propose and experimentally demonstrate a compact plasmonic metasurface for broadband absorption in the 6 to 14 microns wavelength range. As opposed to previous works, our metasurface leverages strongly localized electromagnetic modes to achieve high absorption within a compact form factor. We numerically investigate the spectral response of finite arrays of fractals and show that the absorption enhancement provided by arrays with greater than 6x6 fractals covering a total area of only 30x30 microns squared is similar to that of an infinitely periodic array. Furthermore, we experimentally validate our metasurface's absorption enhancement and demonstrate a good qualitative agreement between the measured and simulated spectral responses. Owing to its ability to achieve broadband absorption enhancement in a compact footprint, our metasurface provides new avenues for the realization of next generation infrared sensors and bolometers.