Nikolov, Vladislav Zdravkov

The invention refers to a method for coupling of waveguides, providing simultaneous interfacing and polarization and mode conversion between waveguides supporting modes and polarization states with similar or substantially different characteristics, and to a chip (100) comprising a converter structure, and to such converter structure. The invention merges functionalities of mode spot size conversion, mode coupling and transfer, mode type conversion, polarization conversion/rotation and polarization splitting. The converter structure is based on vertically stacked waveguides forming a vertical directional coupler (1) connected with different polarization branches (8) integrated into the chip (100).