We experimentally demonstrate a few-mode erbium doped fiber amplifier (FM-EDFA) supporting 6 spatial modes with a cladding pumped architecture. Average modal gains are measured to be >20dB between 1534nm-1565nm with a differential modal gain of ~3dB among the mode groups and noise figures of 6-7dB. The cladding pumped FM-EDFA offers a cost effective alternative to core-pumped variant as low cost, high power multimode pumps can be used, and offers performance, scalability and simplicity to FM-EDFA design.

Cladding pumped few-mode EDFA for mode division multiplexed transmission.

We experimentally demonstrate an inline few-mode erbium doped fiber amplifier supporting six spatial modes with reconfigurable differential gain control and excellent gain flatness obtained through mode-selective bidirectional pumping of a custom fiber with a radially profiled erbium dopant distribution. A signal gain of >20 dB was obtained for all the guided modes with a differential modal gain <;2 dB and good gain flatness across the C-band.

Reconfigurable Modal Gain Control of a Few-Mode EDFA Supporting Six Spatial Modes

A novel technological approach to space division multiplexing (SDM) based on the use of multiple individual fibers embedded in a common polymer coating material is presented, which is referred to as Multi-Element Fiber (MEF). The approach ensures ultralow crosstalk between spatial channels and allows for cost-effective ways of realizing multi-spatial channel amplification and signal multiplexing/demultiplexing. Both the fabrication and characterization of a passive 3-element MEF for data transmission, and an active 5-element erbium/ytterbium doped MEF for cladding-pumped optical amplification that uses one of the elements as an integrated pump delivery fiber is reported. Finally, both components were combined to emulate an optical fiber network comprising SDM transmission lines and amplifiers, and illustrate the compatibility of the approach with existing installed single-mode WDM fiber systems.

/pdf/multi-element-fiber-technology-for-space-division-1d6egbul8c.pdf

Multi-element fiber technology for space-division multiplexing applications

Space-division multiplexing has brought a fresh perspective to the optical fiber community over the last three years and many global players around the world have been involved with both the theoretical and the experimental questions raised by this promising approach. If this technology is to be introduced in the future optical fiber networks, this implies that most of the optical components of the transmission line, including the popular Erbium-doped fiber amplifiers that lie at the heart of fiber communications need to be reexamined. This study reviews the way the new generation of Erbium-doped fibers affects the recent findings on few-mode fibers and how they may further play a central role in the deployment of this technology.

Few-Mode Erbium-Doped Fiber Amplifiers: A Review

We show transmission of 20 wavelength-division-multiplexed (WDM) × 960-Gb/s space-division-multiplexed 32QAM modulated channels (spectral efficiency (SE) of 15 bits/s/Hz) over 60 km of few-mode fiber (FMF) with inline few-mode EDFA (FM-EDFA). Soft-decision FEC was implemented and used to achieve error-free transmission.

/pdf/20-960-gb-s-space-division-multiplexed-32qam-transmission-4l4tp45mj7.pdf

20 × 960-Gb/s Space-division-multiplexed 32QAM transmission over 60 km few-mode fiber

We successfully fabricate three-mode erbium doped fiber with a confined Er3+ doped ring structure and experimentally characterize the amplifier performance with a view to mode-division multiplexed (MDM) transmission. The differential modal gain was effectively mitigated by controlling the relative thickness of the ring-doped layer in the active fiber and pump launch conditions. A detailed study of the modal gain properties, amplifier performance in a MDM transmission system and inter-modal cross-gain modulation and associated transient effects is presented.

/pdf/three-mode-er3-ring-doped-fiber-amplifier-for-mode-division-4j2mhtodbo.pdf

Z Zhili Li

Papers

Three mode Er3+ ring-doped fiber amplifier for mode-division multiplexed transmission.