Efficient Gd³⁺, Lu³⁺ co-doped KY(WO4)2:Tm³⁺ channel waveguide lasers

摘要

Integrated planar and channel waveguide lasers in the KY(WO4)2 (= KYW) host material is a subject of heavy investigation. Waveguide lasers based on Yb³⁺-doped KYW with slope efficiencies as high as 82.3% and output powers of several hundreds of milli-Watts have demonstrated the potential for highly efficient integrated lasers in this material, as well as low thresholds [1, 2]. Recently, lasers based on Tm³⁺-doped KYW with planar and channel geometries reported maximum slope efficiencies of 13% and maximum output powers of 32 mW [3, 4]. The higher efficiencies of the lasers based on Yb³⁺ compared to the ones based on Tm³⁺ can partly be attributed to the absence of detrimental up-conversion effects in Yb³⁺. However, slope efficiencies of 44% and 68% in thulium-doped bulk KGd(WO4)2 crystals and also fiber lasers suggest that there is significant room for improvement in terms of slope efficiency in thulium-doped KYW [5, 6].