Optimization of THz-Time Domain Spectroscopy Reflectivity for a 1THz Energy-Harvesting Metamaterial

Metamaterials, a new synthetic set of materials with repeating patterns of metals and dielectrics, have the ability to manipulate electromagnetic waves. In this study, three-dimensional metamaterials are designed and fabricated to manipulate 0.1 - 1 THz radiation into a well-organized, functional source of plasmons that are rectified by rectenna into a direct current. The metamaterial consists of copper and a photosensitive polymer, SU-8, in an alternating micron-scale patterns fabricated using various techniques, including photolithography, wet and dry etching of metals and oxides, thermal evaporation of thin-layer metals, and electrodeposition of bulk copper.

In order to investigate the absorption of 1 THz radiation for metamaterial, a THz-Time Domain Spectroscopy (THz-TDS) is used to measure the reflectivity of the metamaterial. The geometries of the metamaterials, including the height and the spacing of SU-8 pillars, the thickness of copper, the flatness of the metamaterial surface, have an impact on the reflectivity. In this study, an optimization of the metamaterial geometry is achieved.