Holographic tool kit for optical communication beyond orbital angular momentum

TL;DR

This paper introduces a holographic method for multiplexing and demultiplexing optical modes beyond orbital angular momentum, enabling over 100 modes to increase data capacity in future optical communication networks.

Contribution

It presents a novel holographic approach that encodes multiple spatial modes, including radial and azimuthal degrees of freedom, in a wavelength-independent manner.

Findings

Over 100 modes encoded on a single hologram

Wide wavelength range operation demonstrated

Mode multiplexing enhances optical communication capacity

Abstract

Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realising higher bit rates for next generation optical networks.