A Fourfold Star Petal–Shaped Polarization-Insensitive Broadband Plasmonic Metamaterial Absorber

This article proposes a fourfold star petal–shaped nanostructure, as a broadband plasmonic metamaterial absorber applicable in the frequency band of 390 THz to 750 THz. In this range, it provides a median absorbance of over 96% regardless of all polarization angles. The proposed absorber also exhibits stable performance in both TE and TM modes. A sandwiched metal-dielectric-metal layer construction is used to form this metamaterial absorber. The upper and lower metal layers are made of ultra-thin chromium (Cr) 15 nm layers separated by a 55 nm SiO 2 dielectric sheet. This absorber unit cell has a periodicity of 160 nm with a thickness of only 85 nm. The top layer is with a fourfold symmetrical arrangement, which contributes to polarization insensitivity. An analysis of absorption in TE and TM modes for several metals is also presented. This investigation shows that chromium (Cr) exhibits constant and maximum absorption across the whole visible spectrum. Furthermore, metamaterial parameter extraction, absorption study, field and current distribution, design steps, parametric variation, etc. are discussed. Due to its compact nature and high performance, the proposed structure may be a prospective contestant in energy harvesting for low-power devices, stealth technology in avionics, and biomedical sensors applications.