[8a-Z19-1~11] 3.5 Laser system and materials

▼ [8a-Z19-6] High power Er:Lu₂O₃ ceramic laser at 2.8 μm

〇(P)Weichao Yao¹, Hiyori Uehara^1,2, Hengjun Chen¹, Hiroki Kawase², Ryo Yasuhara^1,2 (1.National Institute for Fusion Science, 2.The Graduate University for Advanced Studies (SOKENDAI))

Keywords:Ceramic laser

With the rapid developments of laser medical treatment, remote sensing and material processing, the requirements for mid-infrared lasers in the 3 μm wavelength region are becoming more and more urgent. Er-doped sesquioxide such as Er:Y₂O₃, Er:Lu₂O₃ and Er:Sc₂O₃ are promising laser materials for 3 μm laser generation because of the low phonon energy and high thermal conductivity. Among these three materials, since the thermal conductivity of Er:Lu₂O₃ is less affected by the doping concentration, this material has a greater advantage in laser application and has produced a higher output power at room temperature, i.e., 5.6 W from a crystal laser. Currently, despite these advantages of Er:Lu₂O₃, the difficulty in growing this crystals is the main limitation for its wide-spread applications.
Transparent ceramics greatly reduce the difficulty of making sesquioxide laser materials, and are likely to promote the applications of Er-doped sesquioxides. Up to now, 2.3 W of CW output power has been reported from an Er:Lu₂O₃ ceramic laser. In this work, we report the optimization of a high power Er:Lu₂O₃ laser and the generation of highest output power at room temperature. Figure 1 shows the characteristics of the Er:Lu₂O₃ laser. The threshold pump power of the laser was 1.4 W, and a maximum output power of 4.6 W was obtained for the absorbed pump power of 18.4 W. The slope efficiency was as high as 28%. After comparing the laser spectra for different output couplers and pump powers, we found that the laser wavelength has no change and remains at 2846 nm.