High-quantum-efficiency Er(3+) fiber lasers pumped at 980 nm

Significant improvements in the operation of Er(3+)-doped silica fiber lasers operating at wavelengths between 1.5 and 1.6 microm are reported. The use of 980 nm as the pump wavelength provides an output that is limited mainly by the quantum efficiency of the lasing process. It is thus considerably more efficient than previous results using ~810-nm 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.