Simple and compact, all-fibre retro-reflector for cladding-pumped fibre lasers

Proposed is an all-fibre retro-reflector realised via shaping a fibre end into a right-angled cone for a pump reflector in cladding-pumped fibre lasers. The conical-shaped fibre-optic retro-reflector allows folded, total internal reflections for pump beams that propagate in the inner cladding of a double-clad fibre. The proposed scheme was applied to a cladding-pumped ytterbium-doped fibre laser and readily achieved over 55% of reflection for the unabsorbed pump throughput, thereby generating 29% more signal output power than without the pump retro-reflector