An ultra broadband metamaterial absorber based on metal-dielectric-metal technology for THz spectrum

This paper introduces a novel ultra-broadband Metamaterial Absorber (UBMA) demonstrating significant absorption capabilities across a wide terahertz frequency range from 2.42 THz to 6.11 THz. The 3.7 THz bandwidth represents 87% of the central frequency. The proposed UBMA comprises three layers: a star-shaped metal patch on top, a dielectric substrate in the middle, and a metallic ground plane below. Simulations using CST Microwave Studio software reveal that the design achieves high absorption at five distinct frequencies: 2.47, 3.45, 4.89, 6.01, and 6.87 THz, with absorption rates of 99% for the first four peaks and 90% for the fifth peak. The study of electric field and surface current distribution provides insights into the absorption mechanism. While the UBMA exhibits polarization-independent performance, its angular response shows some sensitivity to the incident angle, especially beyond 30° Despite this, the absorber maintains over 70% absorptivity up to a 45° incidence angle for both TE and TM polarizations within specific frequency ranges. The simple structure combined with high absorption efficiency makes the UBMA suitable for THz imaging, detection, and stealth applications, although its angular sensitivity must be considered for certain applications.