title: Accurate modal gain control in a multimode erbium doped fiber amplifier incorporating ring doping and a simple LP₀₁ pump configuration.
abstract: We experimentally validate a numerical model to study multimode erbium-doped fiber amplifiers (MM-EDFAs). Using this model, we demonstrate the improved performance achievable in a step index MM-EDFA incorporating a localized erbium doped ring and its potential for Space Division Multiplexed (SDM) transmission. Using a pure LP₀₁ pump beam, which greatly simplifies amplifier construction, accurate modal gain control can be achieved by carefully tuning the thickness of the ring-doped layer in the active fiber and the pump power. In particular, by optimizing the erbium-ring-doped structure and the length of active fiber used, over 20dB gain for both LP₀₁ and LP₁₁ signals with a maximum gain difference of around 2 dB across the C band are predicted for a pure LP₀₁ pump beam delivering 250 mW power at 980 nm.
authors.affiliation: Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK. qk1g11@orc.soton.ac.uk
authors.forename: Qiongyue
authors.initials: Q
authors.lastname: Kang
authors.forename: Ee-Leong
authors.initials: EL
authors.lastname: Lim
authors.forename: Yongmin
authors.initials: Y
authors.lastname: Jung
authors.forename: Jayanta K
authors.initials: JK
authors.lastname: Sahu
authors.forename: Francesco
authors.initials: F
authors.lastname: Poletti
authors.forename: Catherine
authors.initials: C
authors.lastname: Baskiotis
authors.forename: Shaif-Ul
authors.initials: SU
authors.lastname: Alam
authors.forename: David J
authors.initials: DJ
authors.lastname: Richardson