Highly efficient 1610-nm in-band cw Tm:LSO laser

We demonstrate a highly efficient continuous-wave Tm:LSO laser in-band pumped by a FBG-locked Er-doped fibre laser at 1610 nm. A maximum output power of 3.2 W at 2055.1 nm is achieved with a slope efficiency of 51.7% with respect to the absorbed pump power. The beam quality factors M² at a maximum output power are measured to be 1.1 and 1.2 in horizontal and vertical directions, respectively.