Thin heterogeneous SOI waveguides for thermo-optical tuning and filtering

This work presents an analysis and simulation of novel heterogeneous silicon-on-insulator (SOI) waveguide structures for reconfigurable optical add/drop multiplexers (ROADMs) with thermo-optic tuning and multi-reflector beam expanders. New structure design includes p+ side-doping of SOI ridge waveguide with 220 nm×16 μm silicon core. It provides quasi mono-mode behavior due to strongly mode-dependent optical losses by free charge absorption. These silicon heterogeneous waveguides are used to investigate ROADMs including nano-structured 2D gratings for fiber coupling and polarization diversity, nano-grooves or p+ doping reflector strips for multi-reflector beam expanders and local heaters for wideband thermo-optic tuning.