2.7-W Ho3+-doped silica fibre laser pumped at 1100 nm and operating at 2.1 μm

The basic performance characteristics of a Ho3+-doped silica fibre laser that operates in a single transverse mode at ∼2.1 μm and is pumped with the 1100-nm output from a free-running Yb3+-doped silica fibre laser are presented. We measure a maximum slope efficiency (with respect to launched pump power) of 35% and we generate a maximum output power of 2.7 W at an optical-to-optical efficiency of 18% with respect to the incident pump power. The wavelength of the output is length tuned from 2090 nm to 2100 nm when the αabsL product varies from 1.2 to 2.7. The use of the free-running output from a Yb3+-doped silica fibre laser to pump the Ho3+-doped silica fibre laser is very convenient and allows significant scaling of the output power.