1.5-µm upconversion pumping of a continuous-wave Er 3+ :LiYF 4 waveguide laser operating at 2.8 µm

We report on the first, to the best of our knowledge, experimental characterization of an upconversion-pumped room-temperature continuous-wave (CW) operation of an Er 3+ :LiYF 4 channeled waveguide laser at 2810 nm. Pumping as well as the measurement of the upconversion excitation spectrum was achieved with a tunable CW Cr 4+ :YAG laser operating in the 1400–1525 nm range. The optimum upconversion pumping wavelength was determined to be 1513 nm and corresponded to the pump wavelength where the green upconversion of the Er 3+ :LiYF 4 medium was reduced. During CW operation at 2.8 µm, a maximum output power of 43 mW was obtained with 753 mW pump power at 1513 nm, corresponding to a power slope efficiency of 6.6%.