High-efficiency interface between multi-mode and single-mode fibers

TL;DR

This paper introduces a re-programmable multi-plane light conversion method that efficiently interfaces multi-mode and single-mode fibers, enabling high coupling efficiency and auto-correction for fiber deformations in optical communication systems.

Contribution

The authors develop a simple, re-programmable MPLC-based interface achieving up to 70% coupling efficiency between MMFs and SMFs, with auto-correction capabilities for fiber deformations.

Findings

Achieved 30% to 70% coupling efficiency with 3-phase modulation.

Auto-correction of coupling efficiency through simple field monitoring.

Commercial devices suffice for real-time auto-correction in fiber interfaces.

Abstract

Multi-mode fibers (MMFs) and single-mode fibers (SMFs) are widely used in optical communication networks. MMFs are the practical choice in terms of cost in applications that require short distances. Beyond that, SMFs are necessary because of the modal dispersion in MMFs. Here, we present a method capable of interfacing an MMF with an SMF using a re-programmable multi-plane light conversion scheme (MPLC). We demonstrate that only 3-phase modulations are necessary to achieve MMF-to-SMF coupling efficiencies from 30\% to 70\% for MMF's with core diameters up to 200 microns. We show how the obtained coupling efficiency can be recovered if the output field of the MMF changes entirely, e.g. through strong deformation of the fiber, by simple monitoring of the field. Furthermore, we test the influence of the resolution of both essential devices (field reconstruction and MPLC) on coupling efficiencies. We find that commercially available devices with increased speed and efficiency, such as wavefront sensors and deformable mirrors, are sufficient for establishing an MMF to SMF interface which auto-corrects any decoupling in the kHz regime.