18 W single-frequency 1550 nm Er:Yb co-doped fiber amplifier cladding-pumping at 1018 nm

Abstract A continuous wave (CW) 1550 nm single-frequency fiber amplifier based on a double-clad Er:Yb co-doped fiber, featuring off-peak cladding-pumping at 1018 nm, is demonstrated for the first time to our knowledge. Compared with the traditional single-mode Er:Yb co-doped fiber amplifiers (EYDFA) pumping at 9xx nm, for which the threshold of Yb-band amplified spontaneous emission (ASE) at 1. 0 μ m region was several watts level, the Yb-band ASE threshold was enhanced to 17.0 watts. Experimentally, a homemade 1018 nm fiber laser was used as the pump source, which can provide an average power of ∼ 76 W. The 1550 nm signal power of 18.0 W was achieved, when the pump power was 71 W. This result indicates that off-peak pumping at 1018 nm is a promising scheme for achieving high-power single-frequency EYDFA at 1. 5 μ m region.