采用解析法对Nd:YAG单晶光纤的温度场研究

采用解析法对Nd:YAG单晶光纤激光器热效应相关的光纤温度场分布进行研究。建立了Nd:YAG单晶光纤热模型,在单晶光纤所满足的边界条件下通过解析求解热传导方程,得到在高功率808 nm泵浦光抽运下产生946 nm激光的单晶光纤温度场分布,并与传统Nd∶YAG激光晶体的温度场进行比较,然后分别与同泵浦条件下的有限元数值方法的分析结果进行研究对比,最后分析泵浦光参数、单晶光纤参数等对温度场的影响。结果表明,功率为86 W的泵浦光入射至单晶光纤端面的最高温升仅为30.98℃,明显优于同泵浦条件下传统Nd∶YAG晶体的端面温升结果94.37℃,与有限元数值法得到的Nd:YAG单晶光纤19℃温升结果相比,该解析法结果更接近于实验的测量值31℃,能够更精确描述晶体光纤温度场。本文可对单晶光纤激光器热效应的精确研究提供一定参考,进而有利于提高单晶光纤激光器的性能。

Research on temperature field in high-power Nd:YAG single crystal fiber laser by analytical method

Single Crystal Fiber(SCF)laser is widely applied into scientific research and engineering,owing to its superior thermal management,compact mechanical structure and high power output.In this paper,the temperature field of an Nd:YAG SCF laser related to thermal effect produced by pump laser is presented.By solving the heat conduction equation with the analytical method,the thermal model of Nd:YAG SCF is studied.The temperature distribution of Nd:YAG SCF producing a 946 nm laser by an 808 nm pumping light with power of 86 W is obtained.Results show that the maximum temperature rise at the incident end face of SCF is 30.98℃,obviously lower than that of an Nd:YAG crystal of 94.37℃under the same conditions.Besides,compared with a temperature rise of 19℃in SCF obtained by Finite Element Analysis(FEA),temperature rise calculated by analytical method are closer to the experimentally measured value of 31℃.This indicates that the analytical method is more realistic and accurate in describing the temperature field of Nd:YAG SCF.The temperature characteristics of the SCF and the influence of some important parameters are also studied.One of the key factors is the absorption coefficient of the SCF,which has an approximately linear relationship with its temperature rise.Another factor is the core radius of the SCF,which is proportional in value to the rise in temperature.The temperature rise increases with core radius,while decreasing with beam radius of 808 nm pump laser.The root mean square is applied to precisely describe the temperature affected by these parameters.According to the data analysis,uniform distribution in the temperature field can be realized by appropriately selecting the above parameters.The research can be a reference for controlling the thermal effect of single crystal fiber lasers and improving its performance.