Design and manufacture of a reflective integrated optical coupler

• Main Author: Ponsini, Matthew
• Other Authors: Zhang, Xin
• Language: en_US
• Published: 2018
• Subjects: Mechanical engineering
• Online Access: https://hdl.handle.net/2144/30721

A primary focus of research in the field of integrated optics is the reduction of coupling losses into and out of waveguide structures. Grating couplers, taper couplers, and prism couplers each have limitations that restrict their viability for certain designs. This thesis presents a reflective optical coupler as an alternative means of coupling between a silicon-on-oxide waveguide and a target structure. Based on simulation results, the reflective coupler is found to have several advantages over standard grating and prism couplers. The reflective coupler has high coupling efficiency over a broad range of wavelengths, with a large drop in efficiency only occurring when the waveguide mode changes due to the wavelength variation. The reflective coupler is also able to couple at nearly any arbitrary angle with minimal additional coupling loss. Manufacture of the reflective coupler remains difficult, however. A specialized dicing saw was used to attempt to manufacture the coupler in a waveguide structure. However, the waveguide was damaged in an unexpected way during this manufacture process. As such, the experimental results indicate low coupling efficiency. In spite of this damage and other issues, the coupler still achieved coupling efficiency approaching 20dB, indicating that the coupler could be a valid structure should a more reliable manufacturing method be identified.