Engineering of orbital angular momentum supermodes in coupled optical waveguides

TL;DR

This paper demonstrates the existence and control of orbital angular momentum supermodes in coupled optical waveguides, enabling filtering, cloning, and inversion of OAM modes through engineered couplings and dissipation.

Contribution

It introduces the concept of bright and dark OAM supermodes in coupled waveguides and shows how to manipulate them for optical mode control.

Findings

Existence of bright and dark OAM supermodes in coupled waveguides.

Complex mode couplings arise naturally in triangular arrangements.

Dissipation can be used to filter and manipulate OAM supermodes.

Abstract

In this work we demonstrate the existence of orbital angular momentum (OAM) bright and dark supermodes in a three-evanescently coupled cylindrical waveguides system. Bright and dark supermodes are characterized by their coupling and decoupling from one of the waveguides, respectively. In addition, we demonstrate that complex couplings between modes of different waveguides appear naturally due to the characteristic spiral phase-front of OAM modes in two-dimensional configurations where the waveguides are arranged forming a triangle. Finally, by adding dissipation to the waveguide uncoupled to the dark supermode, we are able to filter it out, allowing for the design of OAM mode clonners and inverters.