Thin heterogeneous optical silicon-on-insulator waveguides and their application in reconfigurable optical multiplexers

A new type of optical waveguides in silicon-on-insulator (SOI) nanostructures is proposed and studied. Their optical properties and the possibility of their application in tunable optical filters and reconfigurable multiplexers are discussed based on the results of numerical simulation by the BPM and FDTD methods. A new design of heterogeneous waveguide structures containing additional regions with a high concentration of free charge carriers in the form of a p — n junction, which are located at the edges of a multimode strip waveguide (the cross section of the silicon core being ~0.22 × 35 μm), is proposed. This doping provides single-mode behaviour of the heterogeneous waveguide due to low optical losses in the fundamental mode and to enhanced losses in highest modes. Heterogeneous waveguides can be used for the fabrication of different photonic elements including new types of tunable optical filters and reconfigurable multiplexers based on the multireflection technology.