Stacks of alternating conductive and non-conductive oxides for controlling electric fields at a spatial resolution of 100 nm in the core of a waveguide

• Autor(a) principal: Morgado, Carolina Gomes
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/91353
• topic: Video-rate holography; Rewritable holograms; IGZO; SiOxNy; Metamaterial; Slab Waveguide; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

Holography is a revolutionary display technology capable of creating a true three-dimensional 3D image. In Hollywood movies such as "Star Wars", advanced holograms at video-rate are often present and appreciated by the audience. Unfortunately, despite many efforts from the scientific community, fast rewritable high-quality holograms haven't been created yet. This work focuses on developing a structure capable of bringing this type of holography to life. To achieve this, a slab waveguide is proposed, where the core contains an electro-refractive material. By applying local electric fields with analog control and nano-precision inside the core, its refractive index will change locally. Light traveling along the core, when encountering the affected area, will be leaked into free space and create a hologram. These electric fields will be controlled through one of the conductive pillars of the cladding structure. For the latter, a novel metamaterial is being developed and this work centres on its optimization. For this, transparent conductive oxides (TCO) will be used, as metals will lead to parasitic scattering and absorption of light in the cladding. Hence, the optical properties of the alternating conductive and non-conductive oxide pillars of Indium Gallium Zinc Oxide (IGZO) and Silicon-Oxy Nitride (SiOxNy), respectively, need to be matched. In this study, the refractive index and extinction coefficient of both materials have been determined by spectroscopy ellipsometry (SE) and compared. IGZO pillars were created by optical photolithography and the appropriate etch time was optimized. Finite-difference time-domain (FDTD) simulations were carried out to be compared with future practical results of the structure altogether.