Microwave seminar | 04 September 2025

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.

Main paper/arXiv, related to the seminar, and other references, up to 5
[1] N. Wang, S. Huang, Z. Zhou, D. P. Tsai, J. Zhu, and Y. Li, Natl. Sci. Rev. 12, nwaf199 (2025).
[2] C. Ge, N. Wang, X. Wang, and Y. Li, Phys. Rev. Lett. 134, 237001 (2025).
[3] S. Huang, Z. Zhou, D. Li, T. Liu, X. Wang, J. Zhu, and Y. Li, Sci. Bull. 65, 373 (2020).
[4] S. B. Huang, X. S. Fang, X. Wang, B. Assouar, Q. Cheng, and Y. Li, Appl. Phys. Lett. 113, 233501 (2018).
[5] Y. Li and B. M. Assouar, Appl. Phys. Lett. 108, 063502 (2016).