Microchip laser operation of Tm,Ho:KLu(WO₄)₂ crystal

A microchip laser is realized on the basis of a monoclinic Tm,Ho-codoped KLu(WO₄)₂crystal cut for light propagation along the Ng optical indicatrix axis. This crystal cut provides positive thermal lens with extremely weak astigmatism, S/M = 4%. High sensitivity factors, M = dD/dP(abs), of 24.9 and 24.1 m(-1)/W for the mg- and pg- tangential planes are calculated with respect to the absorbed pump power. Such thermo-optic behavior is responsible for mode stabilization in the plano-plano microchip laser cavity, as well as the demonstrated perfect circular beam profile (M(2) < 1.1). Maximum continuous-wave output power of 450 mW is obtained with a slope efficiency of 31%. A set of output couplers is employed to achieve lasing in the spectral range of 2060-2096 nm. The increase of output coupler transmission results in deterioration of the laser performance attributed to the increased up-conversion losses.