Multicore erbium doped fiber amplifiers

We review recent progress of multi-core erbium-doped fiber amplifiers (MC-EDFA). We confirmed by demonstrating a core-pumped MC-EDFA that MC-EDFs have practical amplification characteristics and core-to-core crosstalk. Three types of cladding-pumped MC-EDFAs are also reviewed, one uses free space optics, other uses a fiber bundled fan-in, and the other uses a side-coupled pump combiner for cladding pumping. Finally, we demonstrate a desktop-type prototype of a cladding-pumped MC-EDFA using the pump combiner that consumes power of 33 W and has size of 430x430x99 mm(3) (widthxdepthxheight).