Nanofabrication and characterization of 3D photonic metamaterials from visible to THz regime

Abstract

In this work, I report on the fabrication and characterization of three-dimensional (3D) metamaterial structures with enhanced optical properties from visible (VIS) to terahertz (THz) spectrum regimes. The 3D metamaterials were fabricated by Direct Laser Writing (DLW) and coated utilizing Atomic Layer Deposition (ALD), using a compact custom build deposition system. Importantly, the fabricated 3D structures are mechanically and chemically stable. ALD depositions of zinc oxide (ZnO) are performed for each structure, showing a wide range of applications depending on unit cell size and geometry. Briefly, utilising nanoscale optical measurements I demonstrated periodicity-dependent optical resonances, enhanced sensitivity for refractive index detection of the surrounding medium, and asymmetric transmission for linearly polarised light. The proposed laser printing technique and conformal deposition recipes are ideal candidates for fabricating complex 3D metamaterial designs in a wide range of wavelengths leading to a collection of applications ranging from narrow-band filters and optical switches to direction selective absorbers and isolators. Hence, the study presented here may act as a guiding tool for integration of such 3D devices with technologies focusing on enhanced sensing, imaging, energy harvesting and telecommunications.