1 Nanophotonics, Department of Photonics Engineering, Technical University of Denmark2 Department of Photonics Engineering, Technical University of Denmark3 Department of Micro- and Nanotechnology, Technical University of Denmark
The work described in this thesis covers the issues of producing materials for use as base material for fabricating photonic crystals and the design, fabrication and characterization of photonic crystal components. One of the aims is to investigate the possibilities of fabricating a silicon-on-insulator (SOI) material using standard cleanroom processing techniques. A standard silicon wafer is covered with a silica film by an oxidation process and subsequently covered with a thin silicon layer deposited from silane by a Low Pressure Chemical Vapor Deposition (LPCVD) process. Such a process sequence is in principle rather straightforward and benefits from being much cheaper compared to acquiring commercially available SOI substrates. Different issues as deposition temperature, surface roughness, crystallization, and silicon waveguide geometries have been investigated in order to reduce the optical loss in the deposited silicon films and to open for a potential use with photonic crystals. In relation to photonic crystal structures, different properties have been investigated by using modelling tools such as the plane wave expansion method and the Finite-Difference Time-Domain method. Furthermore different approaches to improve the performance of selected components have been carried out, by applying a method adopted from mechanical engineering called topology optimization. Also different approaches have been applied in order to investigate the loss in a cavity resonator. Finally, the fabrication of several components has been carried out with a subsequent characterization of the fabricated components.