Test of mode-division multiplexing and demultiplexing in free-space with diffractive transformation optics

TL;DR

This paper demonstrates the design, fabrication, and testing of diffractive optical elements for mode-division multiplexing in free-space optical communication, showing potential for compact, efficient telecom applications.

Contribution

It introduces a novel approach using diffractive optics fabricated by electron beam lithography for mode multiplexing and sorting in free-space optical systems.

Findings

Successful fabrication of high-resolution diffractive optical elements

Effective multiplexing and demultiplexing demonstrated in free-space

Potential for integration into next-generation telecom platforms

Abstract

In recent years, mode-division multiplexing (MDM) has been proposed as a promising solution in order to increase the information capacity of optical networks both in free-space and in optical fiber transmission. Here we present the design, fabrication and test of diffractive optical elements for mode-division multiplexing based on optical transformations in the visible range. Diffractive optics have been fabricated by means of 3D high-resolution electron beam lithography on polymethylmethacrylate resist layer spun over a glass substrate. The same optical sequence was exploited both for input-mode multiplexing and for mode sorting after free-space propagation. Their high miniaturization level and efficiency make these optical devices ideal for integration into next-generation platforms for mode-division (de)multiplexing in telecom applications.