Thermal Effects Investigation On LD End-pumped Yb³⁺ -doped Potassium-Gadolinium Tungstate Crystal

Thanks to the unique advantages of diode-pumped all solid-state lasers, such as high efficiency, compactness, high stability and long lifetime, it has attracted more and more attention in the realm of lasers. In this paper, the thermal lensing study based on the heat transfer of diode-pumped Yb³⁺:KGd(WO₄)₂(Yb:KGW)and Yb³⁺:KY(WO₄)₂ (Yb:KYW) laser crystal was presented. Moreover, the continuous-wave output characteristics of diode-pumped Yb:KGW and Yb:KYW was also demonstrated here.1. The main properties, advantages, applications and developments of Yb³⁺- doped Potassium - Gadolinium Tungstate laser crystals were introduced briefly. The background and significance of the research on thermal effects of diode-pumped solid-state lasers were mentioned. The main content of the paper was presented briefly as well.2. The theoretical analysis of the thermal lensing investigation based on the heat transfer of diode-pumped Yb:KGW and Yb:KYW was presented. The model of Yb:KGW and Yb:KYW crystal under the heat transfer was established based on the characteristic of end-pumped anisotropic laser crystal. Numerical analysis on steady-state thermal conduct equation of LD end-pumped laser crystal considering the heat transfer was also presented in the paper. Moreover, the experimental measurement principle of thermal lens focal lens was also introduced.3. Thermal lensing effects of diode-pumped Yb:KGW based on the heat transfer was presented. Based on the features of LD end-pumped Yb:KGW laser crystal, the model was established. Considering the convective heat transfer on the side faces, the temperature distribution, pumped-face distortion and thermal focal length under different pump power were obtained by solving anisotropy heat conductive equation through finite difference method. Under the absorbed pump power of 14 W, the highest temperature located at the center of the pumped face was 272.8℃﹑the highest distortion was 0.48μm, and the thermal lens focal length was 4.8 cm. Moreover, the continuous-wave output characteristics of diode-pumped Yb:KGW was also demonstrated here.4. Thermal lensing effects investigation of diode-pumped Yb:KYW based on the heat transfer was also presented here. Based on the features of LD end-pumped Yb:KYW, the model was established. Considering the convective heat transfer on the side faces, the temperature distribution, pumped-face distortion and thermal focal length under different pump power were obtained by solving anisotropy heat conductive equation through finite difference method. Under the absorbed pump power of 14 W, the highest temperature located at the center of the pumped face was 243.8℃﹑the highest distortion was 0.28μm, and the thermal lens focal length along x and z axis were - 4.9 cm and 5.4 cm, respectively. Moreover, the continuos-wave output characteristics of diode-pumped Yb:KYW was also demonstrated here.