LD抽运复合YAG晶体温度场及热透镜效应研究  

Investigation on temperature and thermal lens effects of laser diode pumped composite YAG rods

作　　者：李锋[1] 刘蓉[1] 白晋涛[1] 侯洵[1] 

机构地区：[1]西北大学光子学与光子技术研究所

出　　处：《激光技术》2008年第1期101-104,共4页Laser Technology

基　　金：陕西省教育厅专项基金资助项目(05JK185D4JK125)

摘　　要：为了研究复合Nd∶YAG激光晶体棒在端面抽运下的温度分布及热透镜效应,采用数值分析法得到了端面抽运激光晶体棒内温度场的数值解,当抽运光功率为18W、光斑半径0.2mm时,吸收系数为3.5/cm的复合晶体内最大温度为73.8℃;同时还得到了径向梯度折射率引起的轴向传播光相位延迟分布ΔΦt(r),并与相同条件下的普通晶体作了比较。结果表明,采用复合晶体可以大幅度降低激光晶体内的温升,并减小端面变形导致的透镜效应;复合晶体内的相位延迟分布ΔΦt(r)与普通晶体的相似,且不满足对半径r的二次方关系;热透镜和参考球面镜透镜的相位延迟分布之间存在畸变Δφ,在r较小(r<wp)时,相位延迟分布ΔΦt(r)可近似等效于一球面透镜,其等效焦距fGR IN值与普通晶体的接近,在r较大(r>wp)时,畸变Δφ随r增大而急剧增大。Temperature field and thermal lens effect of laser diode end pumped composite Nd：YAG rod were investigated through numerical analysis methods. Numerical solutions of temperature field were obtained. The maximum temperature was 73.8℃ for composite laser crystal with an absorption coefficient of 3.5/cm, under pump power of 18W with 0.2mm beam radius. And also phase-retardation distribution △Φt （r）of the axial transmission light caused by radial temperature gradients was obtained. Comparing with conventional rod, the results show that composite rod leads a lower temperature rise in laser rod, as well as reduces distortion of pump end which brings on lens effect of laser crystal. Phase-retardation distribution △Φt （r） in composite rod is similar to that of conventional laser rod, but it doesn＇t accord with radius quadratic relationship, there is an aberration △φ between the phase retardation of the thermal lens and referenced spherical lens. △Φt （r） corresponds with that of a spherical lens approximately at r 〈 ωp, and the equivalent foci fGRIN approaches to the same value of conventional rod, whereas △φ increases quickly with the increase of laser beam radius at r 〉 ωp.

关 键 词：激光物理 温度场 数值分析 复合YAG激光晶体 热透镜效应 

分 类 号：O734[理学—晶体学]