Broadband, Polarization-insensitive and Wide-angle Optical Absorber based on Fractal Plasmonics

TL;DR

This paper presents a fractal plasmonic absorber with broadband, polarization-insensitive, and wide-angle light absorption capabilities, suitable for ultrathin light trapping applications.

Contribution

It introduces a novel Sierpinski nanocarpet structure that achieves broadband, angle-independent absorption with high extinction across a wide optical range.

Findings

Achieves 85-99% extinction over 400-700 nm range

Maintains performance over incident angles from 0° to 80°

Effective for both TE and TM polarization states

Abstract

In this paper, a plasmonic absorber consisting of a metal-dielectric-metal stack with a top layer of Sierpinski nanocarpet is theoretically investigated. Such compact absorber depicts broadband angle-independent behavior over a wide optical wavelength range ($400-700$ nm) and a broad range of angles of light incidence ($0-80^{\circ}$). Including several feature sizes, such fractal-like structure shows widely strong extinction ($85-99$%) response for either transverse electric or magnetic polarization states under normal incidence. Underlying mechanisms of absorbance due to excited surface plasmon modes as well as electric/magnetic dipole resonances are well revealed by investigating electric field, magnetic field and current distributions. The proposed absorber opens a path to realize high-performance ultrathin light trapping devices.