Polarization insensitive metamaterial engineered multimode interference coupler in a 220 nm silicon-on-insulator platform

High-index contrast silicon waveguides exhibit strong birefringence that hinders the development of polarization-insensitive devices, especially for sub-micrometer silicon layer thickness. Here a polarization-independent 2 × 2 multimode interference coupler in a 220 nm silicon-on-insulator platform is designed and experimentally demonstrated for the first time. Leveraging the advanced control of electromagnetic properties provided by a …