High-gain integrated in-line few-mode amplifier enabling 3840-km long-haul transmission

An integrated few-mode erbium-doped fiber amplifier (FM-EDFA) with high modal gain is suitable for the in-line amplification in mode-division multiplexing transmission (MDM) systems. We first experimentally demonstrate a dual-stage integrated FM-EDFA supporting three linear polarization modes. Consisting of integrated passive components with low insertion losses, the FM-EDFA has a similar structure and performance to widely used commercial single-mode EDFAs. The averaged modal gain of 25 dB, the differential modal gain (DMG) of <1.1 dB, and noise figures of 5-7 dB are simultaneously achieved. In addition, the DMG of the 3M-EDF itself is similar to 0.3 dB. Moreover, an MDM transmission experiment with the in-line few-mode amplification by our proposed FM-EDFA over a 3840-km few-mode fiber link for a 28-Gbaud quadrature phase-shift keying (QPSK) signal is demonstrated. (c) 2022 Chinese Laser Press

Automated summary

This article presents an integrated few-mode erbium-doped fiber amplifier (FM-EDFA) with high modal gain for in-line amplification in mode-division multiplexing transmission systems. The FM-EDFA has a similar structure and performance to commercial single-mode EDFAs and achieves high modal gain, low differential modal gain, and noise figures simultaneously. Additionally, the article demonstrates the use of the proposed FM-EDFA for in-line few-mode amplification in a transmission experiment.