Design and analysis of a miniaturized UWB plasmonic absorber in visible light spectrum

This paper proposes a miniaturized UWB resonating THz unit-cell absorber in the visible light spectrum 400–700 THz with an average absorption of more than 95%. This novel structure is tuned to desired photonic spectrum by plasmonic electric and magnetic resonance with the suitable choice of the metal-insulator-metal stacked layers. The arrangement has a metal of thickness 15 nm on top and bottom layers constituted on a SiO2 substrate of 50 nm thickness. The stronger energy concentration due to plasmonic resonance provides higher absorbing efficiency. In this work, an investigation on absorption, S11, and surface impedance for various metals like Chromium (Cr), Gold (Au), Magnesium (Mg), Platinum (Pt), and Titanium (Ti) is presented. It is identified that Chromium (Cr) presents stable and maximum absorption in the entire visible spectrum. A study on different incident and polarization angles is also reported for TE and TM modes. Lumped equivalent models (T and π) for the proposed absorber are also presented. This structure can be utilized to harvest photonic energy for evoking low-power enabled IoT devices and sensors in biomedical applications.