Numerical Demonstration of Angle-Independent Electromagnetic Transparency in Short-Wavelength Infrared Regime

Abstract

Realizing electromagnetic transparency in the visible light regime and beyond is an important challenge in both fundamental electromagnetics and angular-independent spectral filters for 6G communication and military applications. A conventional way of achieving electromagnetic transparency is based on Surface Plasmon Resonances (SPRs) of symmetric metallic spherical or cylindrical structures. However, symmetric objects have a constraint on their shape tunability, limiting them to visible wavelength applications. In this work, we address the limitation by designing floating nano-chips with a broken symmetry using a cluster of silver ellipsoids. We combine Bohren and Huffman analytic solutions and particle swarm optimization to accelerate the discovery of the optimum ellipsoid designs. The optimized nano-chips demonstrate clear angle-independent transparency at the 1450–1500nm wavelength window. This result is validated in full-wave Maxwell’s solution via three-dimensional finite-difference time-domain method. The proposed design method can be extended to electromagnetic applications that require a design and optimization of small objects ( $< \lambda /200$ ) compared to their operating wavelength.

Keywords

• Finite-difference time-domain (FDTD) method
• particle swarm optimization (PSO)
• plasmon induced transparency