Orbital angular momentum divider of light

TL;DR

This paper introduces a passive, coordinate transformation-based device that can divide the orbital angular momentum of light into smaller modes, enabling advanced OAM-based optical systems.

Contribution

The paper presents the first implementation of an OAM divider using coordinate transformation, capable of arbitrary and equal division of OAM modes.

Findings

Successfully demonstrated OAM division using coordinate transformation

Achieved proportional scaling of OAM in diffracted light

Extended scheme to arbitrary N-dividing of OAM

Abstract

Manipulation of orbital angular momentum (OAM) of light is essential in OAM-based optical systems. Especially, OAM divider, which can convert the incoming OAM mode into one or several new smaller modes in proportion at different spatial paths, is very useful in OAM-based optical networks. However, this useful tool was never reported yet. For the first time, we put forward a passive OAM divider based on coordinate transformation. The device consists of a Cartesian to log-polar coordinate converter and an inverse converter. The first converter converts the OAM light into a rectangular-shaped plane light with a transverse phase gradient. And the second converter converts the plane light into multiple diffracted light. The OAM of zeroth-order diffracted light is the product of the input OAM and the scaling parameter. The residual light is output from other diffracted orders. Furthermore, we extend the scheme to realize equal N-dividing of OAM and arbitrary dividing of OAM. The ability of dividing OAM shows huge potential for OAM-based classical and quantum information processing.