2.794μm高重复频率Fe^(2+):ZnSe被动调Q激光器脉冲特性理论分析与实验研究  

Theoretical Analysis and Experimental Study of Pulse Characteristics of Fe^(2+)∶ZnSe Passively Q-switched 2.794μm Laser with High Repetition Rate

作　　者：熊正东 姜玲玲 程庭清[1] 江海河[1,2] Xiong Zhengdong;Jiang Lingling;Cheng Tingqing;Jiang Haihe(Institute of Health and Medical Technology,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,Anhui,China;University of Science and Technology of China,Hefei 230031,Anhui,China)

机构地区：[1]中国科学院合肥物质科学研究院健康与医学技术研究所,安徽合肥230031 [2]中国科学技术大学,安徽合肥230031

出　　处：《中国激光》2023年第6期1-7,共7页Chinese Journal of Lasers

基　　金：国家重点研发计划(2018YFB0407204)。

摘　　要：3μm波段被动调Q激光可饱和吸收体的损伤阈值较低,在高峰值功率、高重复频率条件下非常容易出现损伤。理论分析了可饱和吸收体的初始透过率和输出镜的反射率对被动调Q激光输出脉冲宽度的影响。采用两种具有不同初始透过率的Fe^(2+)∶ZnSe晶体进行了氙灯泵浦的Er,Cr∶YSGG激光器被动调Q实验研究。结果表明,具有低初始透过率的可饱和吸收体能够获得较低的脉冲宽度,且具有高初始透过率的可饱和吸收体能够通过提高输出镜的反射率来压缩脉冲宽度,脉冲宽度与晶体棒直径无关,实验结果与理论结果吻合。通过优化腔内布局实现了高重复频率、高峰值功率的2.794μm被动调Q激光输出,激光器在60 Hz重复频率下分别获得了单脉冲能量4.7 mJ和7.0 mJ的调Q激光输出,脉冲宽度分别为97.0 ns和72.6 ns。研究结果为被动调Q激光器的设计提供了理论指导。Many materials have been proved to be suitable for passively Q-switched lasers in the 3μm waveband,and only a few relatively stable materials such as Fe^(2+)∶ZnSe crystals can achieve a large energy output.However,as the Fe^(2+)∶ZnSe crystal has a low damage threshold(1.5-2.0J/cm2@100 ns)in the 3μm waveband,it can easily be damaged when operating at high peak power and high repetition frequency.Hence,to reduce the risk of damage during normal operation,it is necessary to analyze the pulse characteristics of Fe^(2+)∶ZnSe crystals in passive Q-switched lasers to reduce the possibility of damage to the saturable absorber and realize laser operation at a high peak power and high repetition rate.Based on the measurement results,a high-repetition-rate Fe^(2+)∶ZnSe crystal passively Q-switched laser system with a concave-convex resonator structure is developed to compensate for the thermal focal length.The Er,Cr∶YSGG crystal has dimensions ofФ3 mm×100 mm.Concave mirror M1 is used as the all-reflection mirror(R1=200 mm),M2 is used as the output mirror(R2=-216 mm),and the reflectivity of the convex surface is 70%at 2.79μm.By optimizing the internal component layout of the 60 Hz Er,Cr∶YSGG passively Q-switched laser,the high repetition frequency and high peak power of the 2.794μm passively Q-switched laser can be achieved.Figure 5 shows the experimental waveforms of the 60 Hz passively Q-switched laser with two Fe^(2+)∶ZnSe crystals.The single pulse energy of the lasers is 4.7 mJ and 7.0 mJ,with pulse widths of 97.0 ns[Fig.5(a)]and 72.6 ns[Fig.5(c)],respectively.Objected Lasers with high repetition rate and nanosecond pulse width around 3μm waveband are required to improve the conversion rate of optical parameters and reduce the thermal effect when they are used in mid-infrared parametric pumping and hard tooth tissue ablation.The Q-switched technology is widely used to generate lasers with high peak power and narrow pulse width.Currently,the high-peak-power laser output at 3μm waveband has been obtai

关 键 词：激光器 固体激光器 Er Cr∶YSGG激光 被动调Q Fe^(2+)∶ZnSe 

分 类 号：TN248.1[电子电信—物理电子学]