Highly-selective dual-band Terahertz metamaterial absorber with integrated circular split-ring resonators

Terahertz (THz) metamaterial absorbers have attracted significant attention for applications in sensing, detection, and stealth technologies owing to their ability to achieve engineered absorption at subwavelength scales. This work presents a high-performance THz metamaterial absorber incorporating circular split-ring resonators patterned in copper on a lead glass substrate. Full-wave simulations confirm two pronounced absorption bands with peak absorption exceeding 90% near 1.45 THz and 4.24 THz. The corresponding spectral linewidths are FWHM1 ≈ 0.0957 THz and FWHM2 ≈ 0.2039 THz, yielding quality factors of Q1 ≈ 15.15 and Q2 ≈ 20.79, respectively, indicating good frequency selectivity at both resonances. The absorption mechanism is further explained using retrieved effective electromagnetic parameters, which show resonant electric and magnetic responses accompanied by impedance matching to free space at the operating bands. An equivalent LC interpretation provides additional physical insight and a pathway for resonance tuning through geometric modification. These results demonstrate a simple, high-performance dual-band THz absorber suitable for compact multi-frequency THz platforms.