Low-loss silicon photonics waveguide filter based on highly-oxide graphene oxide gratings

• Main Authors: Nai-Wen Cheng, 鄭乃文
• Other Authors: Yung-Jr Hung
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/j3uj7w

碩士 === 國立中山大學 === 光電工程學系研究所 === 107 === This thesis focuses on the investigation of highly-oxidized graphene oxide grating for low-loss silicon photonics waveguide filters on silicon-on-insulator platfrom. Due to the high index contrast in silicon on insulator, it requires high-resolution definition of periodic structures on the sidewalls of silicon waveguides to enable narrowband reflection. Therefore, we propose a hybrid approach to achieve narrowband reflection by hybrid integrating graphene oxide gratings on silicon waveguides. The graphene oxide grating is defined by laser interference lithography and is transferred onto silicon waveguide with the help of PMMA. The graphene oxide material used in this work has a higher degree of oxidization confirmed by the XPS and XRD characterizations. The use of such a highly-oxidized graphene oxide makes the hybrid waveguide device have a lower propagation loss of only 3.1 dB/cm, in which 2.4 dB/cm comes from the intrinsic propagation of silicon planar waveguide. The resulting hybrid waveguide filter achieves an extinction ratio of 35 dB and a reflection bandwidth of around 1 nm. We further implement graphene oxide sampled gratings by double exposure to the interference fringes. We expect the resulting devices can be used for sensor applications. In addition, we noticed that the reflection bandwidth becomes wider for a longer waveguide grating which obeys the coupled mode theory. We attribute such bandwidth broadening to the linewidth variation of the silicon waveguide itself.