Mode Conversion between Beams Carrying Orbital Angular Momentum with Opposite Topological Charges using Two-Dimensional Multimode Interference Waveguides

In this work, using investigation of odd order OAM modes in the two-dimensional MMI waveguides, a novel integrated optical OAM device is introduced to do mode conversion between beams carrying OAM with opposite topological charges. The proposed convertor is passive and the input and output ports can be swapped. The ability to produce high purity output mode (94% and 82% for OAM modes with l=±1 and l=±3, respectively), reciprocal behavior and compatibility with silicon on insulator technology are the remarkable features that make the proposed passive convertor utilizable in many classical and quantum communication systems.