High Power-Efficiency, Low DMG Cladding-Pumped Few-Mode Er/Yb/P Co-Doped Fiber Amplifier for Mode Division Multiplexing

Mode division multiplexing (MDM) is considered to be an efficient solution to alleviate the exponentially increasing “capacity crunch”. Here, we numerically and experimentally demonstrate a high power-efficiency, low differential mode gain (DMG) few-mode amplifier based on an M-type double-cladding Er/Yb co-doped phosphosilicate fiber. With a large-signal power of 4.1 dBm, the average DMG of <1.5 dB and the maximum gain of >28 dB were achieved for the LP
₀₁
, LP
₁₁
, LP
_21,
and LP
₀₂
mode groups over the 1535–1565 nm range. Additionally, the saturation output power was measured in excess of 35 dBm, with a pump conversion efficiency (PCE) of >31%. This cladding-pumped few-mode Er/Yb co-doped fiber amplifier enables combined mode-division and wavelength-division multiplexed over large-capacity long-haul MDM transmission.