Space division multiplexed multicore erbium-doped fiber amplifiers

Abstract

We report on the recent development of multicore fiber amplifiers suitable for amplifying space division multiplexed signals. We have constructed 7-core amplifiers, where the cores could be pumped individually or simultaneously through the cladding, and studied the amplification and noise properties of these amplifiers. In the core-pumped amplifier, the net average gain was 25 dB, and noise figure was less than 4 dB. Using side-coupled cladding pumping, gain over 25 dB was obtained in each of the cores over a 40-nm bandwidth covering the C-band. We have further studied numerically the amplification and noise properties of a few-moded single/multicore erbium doped fiber amplifier with a doped region that extends beyond the few-mode core. We show that when excited by a multimoded pump, this can provide nearly uniform gain in C-band for modes such as, LP01, LP11, LP21, and LP02 over a wide range of pump power. Differential modal gain (DMG) between LP01, and LP02 was ~ 0.5 dB for a small signal gain of 32 dB at 1550 nm signal wavelength. The dependence of modal gain on the size of the doped core has also been studied.