平顶光端面抽运DPL中热效应对输出功率的影响

用平顶光束描述由多根光纤紧密排列耦合并经透镜整形后的抽运光分布，给出了平顶光束的光强分布，对晶体热效应引起的热致衍射损耗随抽运功率和抽运光束半径的变化规律进行了数值计算，讨论了晶体热效应引起的热致衍射损耗对基横模高斯光束输出功率的影响，并实验验证了基横模高斯光束输出功率随抽运功率的变化规律．结果表明：热致衍射损耗使基横模高斯光束输出功率明显降低．随着抽运光束半径的增大，热致衍射损耗减小，对基横模高斯光束输出功率的影响就减小；抽运功率越大，热致衍射损耗越大，对基横模高斯光束输出功率的影响就越大．

Influence of the Thermal Effect on the Output Power in a Flat-topped Beam End-pumped DPL

The flat-topped beam is applied to describe the pump profile, formed by multi-fiber compactarranged coupling and then being reshaped by lens. The pump profile of the flat -topped beam is given. Variation relations of the thermal induced diffraction losses caused by the thermal effect with variations of the pump power and the waist radius of pump beam have been numerically calculated. The influence of the thermal effect on the fundamental transverse mode output power has been discussed further. Experimental test on the variety regulation of the output power with pump power has also been done. The results show that the thermal induced diffraction losses reduce the output power obviously. With increasing of the waist radius of pump beam, the thermal induced diffraction losses and its effect becomes small; The higher the pump power , the bigger the thermal induced diffraction losses, and the stronger the influence on the output power of the fundamental transverse mode.