Ultra-Wideband Single Negative Metamaterial Absorber for Solar Energy Harvesting from Mid-Infrared to Near Ultraviolet Regimes

Considerable challenges has been attributed in previous research works to the attainment of near-unity absorption in ultra-wideband four-folded metamaterial absorber (MMA) within the context of solar energy harvesting. In this study, a novel compact MMA design has been introduced, targeting the mid-infrared (mid-IR) to near-ultraviolet (NUV) spectral range. The absorber has been engineered to operate across resonance frequencies ranging from 100 THz to 1000 THz, attaining a maximum absorbance of 99.72% at resonating frequency of 344.8 THz and an average absorbance of 95.55%. The design incorporates a simple resonator structure, constructed on a substrate measuring 300 nm x 300 nm with a thickness of 55 nm. Polarization insensitivity has been achieved, and the absorber demonstrates stability over a wide range of incident angles. Electromagnetic (EM) characterization has revealed that the MMA exhibits epsilon-negative (ENG) metamaterial (MTM) behavior within the frequency range of 100 THz to 253 THz, 330.4 THz to 497 THz and 922.6 THz to 1000 THz. Between 253 THz and 330.4 THz, 497 THz to 922.6 THz a transition to mu-negative (MNG) MTM behavior has been observed. It is suggested by these findings that the proposed MMA design offers a promising solution for efficient solar energy harvesting across an ultra-wide spectral range.