Multiple-Ring-Core FM-EDF for Weakly-Coupled MDM Amplification With Low Differential Modal Gain

Jinglong Zhu,Mingqing Zuo,Dawei Ge,Zhangyuan Chen,Yongqi He,Juhao Li,Lei Shen,Yu Yang

doi:10.1109/jphot.2021.3051455

Jinglong Zhu, Mingqing Zuo + Show 6 more

Open Access

https://doi.org/10.1109/jphot.2021.3051455

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Abstract

Recently weakly-coupled mode-division multiplexing (MDM) transmission systems and networks based on ultralow-modal-crosstalk few-mode fiber (FMF) have attracted much interest, for which optical amplification technologies with low modal crosstalk and two-dimension mode-wavelength gain flattening are highly desired. In this paper, we propose for the first time a design method for few-mode Erbium-doped fiber (FM-EDF) with multi-ring-core (MRC) structures of both index and Erbium doping, which has high compatibility with the transmission MRC-FMF and low differential modal gain (DMG) with simple pump injection requirement. By sharing the boundaries of ring areas for both index and Erbium doping, the design method also helps to reduce the complexity of preform fabrication. We show by simulation that at 1550-nm signal wavelength, a 6-mode MRC-EDF can achieve a minimum DMG of 0.35-dB with only LP 11 pump light injection and a 10-mode MRC-EDF can achieve a minimum DMG of 0.60-dB with LP 01 and LP 03 pump lights injection. Besides, the tolerance of DMG to the variation of fiber parameters induced by fabrication is analyzed. The proposed FM-EDF is beneficial for the practical applications of weakly-coupled MDM transmission systems and networks.

Highlights

Mode division multiplexing (MDM) technology has been widely investigated as a promising candidate for capacity enhancement of optical communication systems and networks [1], [2], in which different modes or mode groups in multimode fibers (MMF) or few mode fibers (FMF) areVol 13, No 1, February 2021exploited as independent spatial channels for data transmission
We propose for the first time a design method for few-mode Erbium-doped fiber (FM-EDF) with multiring-core (MRC) structures of both index and Erbium doping, which has high compatibility with the transmission MRC-few-mode fiber (FMF) and low differential modal gain (DMG) with simple pump injection requirement
We show by simulation that at 1550-nm signal wavelength, a 6-mode MRC-EDF can achieve a minimum DMG of 0.35-dB with only LP11 pump light injection and a 10-mode MRC-EDF can achieve a minimum DMG of 0.60-dB with LP01 and LP03 pump lights injection

Summary

Introduction

Mode division multiplexing (MDM) technology has been widely investigated as a promising candidate for capacity enhancement of optical communication systems and networks [1], [2], in which different modes or mode groups in multimode fibers (MMF) or few mode fibers (FMF) are. Weakly-coupled MDM approaches have attracted much interest [5], [6], in which the modal crosstalk for FMFs, optical components and their connections are significantly suppressed so that each mode can be independently received without MIMO processing. Some weakly-coupled FMF designs with simple structures have been proposed such as step-index circular-core (SI-CC) FMF with high index difference between fiber core and cladding [7], it’s hard for them to be extended to support more independent modes. A design method for FM-EDF with MRC index and Erbium doping structures is proposed for the first time, which has high compatibility with the transmission MRC-FMF and low DMG with simple pump injection requirement. The proposed weakly-coupled MRC-EDF is promising for weakly-coupled MDM amplification and transmission

Principles of Weakly-Coupled FM-EDFA

Design of 6-Mode Weakly-Coupled FM-EDFA

Conclusions