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 α_absL 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.