Scaling SOI photonics to micron and sub-micron devices

Abstract

Scaling photonics devices in silicon on insulator (SOI) substrates has the potential to address important issues in the fields of optical telecommunications and optical interconnects. Silicon, is highly transparent in the infra-red spectral region and etching ribs or rectangular channels can create the condition for single-mode low-loss waveguiding. The high index difference between silicon and the surrounding media, typically SiO2 or air, is extremely favorable for the development of ultra-compact photonic devices. Active functionality can be performed by free charge injection in the waveguide resulting in a phase shift of the propagating fundamental mode. Moreover this technology is fully CMOS compatible allowing a low-cost monolithic integration of control electronics. Limitations deriving from an aggressive scaling of SOI waveguides are a lowered efficiency in the in-out coupling of light and higher propagation losses due to increased roughness scattering. We report on the perspectives and issues of scaling SOI photonics devices for both passive and active functionality. Results show that scaled waveguides can have very low bending radii down to the micrometer range. We also propose a new method and architecture for light phase modulation based on a Schottky barrier diode; a process flow will be analyzed and validated experimentally.