An efficient continuous-wave laser achieved with a high-quality Yb:Lu2O3 crystal grown by the heat exchange method

Abstract

The sesquioxide crystals are excellent gain materials for laser applications owing to their high thermal conductivity, low maximum photon energy, and other physical properties. However, the laser output performance is hindered by the absence of high-quality Lu₂O₃ single crystals. In this work, a Yb:Lu₂O₃ crystal with a size of 60 × 40 × 30 mm³ was successfully grown by the heat exchange method (HEM). The grown Yb:Lu₂O₃ crystal exhibits excellent crystallization quality and thermal and optical properties. Furthermore, the comparative analysis of the Yb:Lu₂O₃ crystal grown by the HEM and temperature gradient technique (TGT), combined with the Raman spectrum and the surface roughness, demonstrates that the HEM-grown crystal possesses more excellent crystallization quality. What's more, the HEM-grown Yb:Lu₂O₃ crystal achieved an efficient continuous-wave (CW) laser output power of 90.2 W at 1033 nm and a slope of efficiency of 77.1%. These results represent the most outstanding CW laser output performance to date in the series of bulk sesquioxides doped with Yb³⁺ ions.