Seven-octave ultrabroadband metamaterial absorbers via Q-weighted mode density modulation

TL;DR

This paper introduces a metamaterial absorber that achieves near-perfect absorption over seven octaves from 100 Hz to 12,800 Hz by engineering mode density and losses, significantly advancing broadband absorption technology.

Contribution

The study presents a novel Q-weighted mode density approach to design ultra-broadband metamaterial absorbers covering seven octaves, surpassing previous bandwidth limitations.

Findings

Achieved near-perfect absorption from 100 Hz to 12,800 Hz.

Engineered Q-weighted mode density for broadband absorption.

Enhanced bandwidth capabilities of metamaterial absorbers.

Abstract

Absorption is a crucial parameter in shaping wave propagation dynamics, yet achieving ultra-broadband absorption remains highly challenging, particularly in balancing low-frequency and broad bandwidth. Here, we present a metamaterial absorber (MMA) capable of achieving simultaneous spectral coverage across a seven-octave range of near-perfect absorption from 100 Hz to 12,800 Hz by engineering the quality-factor-weighted (Q-weighted) mode density. The Q-weighted mode density considers mode density, resonant frequencies, radiative loss, and intrinsic loss of multiple resonant modes, providing a comprehensive approach to govern broadband absorption properties. By optimizing the number of resonant modes and managing intrinsic losses, our approach achieves an intensive Q-weighted mode density across an ultra-wide bandwidth, enabling ultra-broadband absorption with high efficiency. These findings significantly advance the bandwidth capabilities of state-of-the-art MMAs and pave the way for the development of ultra-broadband metamaterial devices across various wave systems.