Integrated photonic devices based on silicon-ITO heterojunction for optical modulation and detection

Abstract

Silicon photonics provides a promising platform for developing highly scalable, and potentially very low-cost on-chip photonic devices. However, due to the poor electro-optic effect of Si and weak light-matter interaction, Si-based modulators have a large device footprint, high power consumption, and low extinction ratio. On the receiver side, pure Si-based photodetectors with good responsivity above 1100 nm utilizing inter-band transition are hard to be employed. Schottky photodetectors utilizing sub-bandgap transition also suffer from poor responsivity and high thermionic losses due to the presence of metal. Henceforth, many questions remain unanswered as to whether Si alone can meet the required performance metrics of optical modulators and photodetectors. Si-plus photonics or finding an effective low-cost active material that can be combined with Si is the key to achieving the necessary performance metrics. As widely investigated novel materials, ITO has shown remarkable electro-optic properties for modulation and can serve as a metal substitute in Schottky photodetectors. In this thesis, Si-ITO heterojunction has been incorporated to attain non-trivial performance metrics of optical modulators and photodetectors. Along with it, novel waveguide platforms incorporating slow light technology are also explored to significantly enhance light-matter interaction.