High quantum efficiency Er³⁺-fibre lasers pumped at 980nm

Significant improvements in the operation of Er3+ doped silica fibre lasers operating at wavelengths between 1.5-1.6 µm are reported. The use of 980nm as the pump wavelength provides output that is limited mainly by the quantum efficiency of the lasing process. It is thus considerably more efficient than previous results using ~810nm pumping where excited state absorption degrades the lasing performance. Operation at three discrete output wavelengths is observed and is accounted for by studying gain across the lasing bandwidth