摘要
对热键合、凹端面及不同直径Er∶YSGG晶体棒的中红外激光性能进行了系统对比研究。晶体经高温退火、定向切割、端面精密抛光后,测量得到其平面度和表面粗糙度分别小于0.1λ@633 nm和0.5 nm。通过精密加工实现了YSGG与Er∶YSGG室温光胶,然后进行了高温热键合,透过谱表明键合界面基本无损耗,达到了一体化。热焦距结果表明,热键合、凹端面能够有效改善和补偿高功率泵浦条件下晶体的热透镜效应,有利于提高晶体的激光性能。对比未键合、热键合及凹面热键合Er∶YSGG晶体在968 nm LD侧面泵浦条件下的激光性能发现,低频150 Hz以下,键合与凹面并未表现出优势,三种棒的最大输出功率和斜效率分别均在24 W和28%附近;但随重频增加,热效应逐渐加重,键合晶体良好散热能力和凹面热补偿效应使激光性能得到提高。在重频300 Hz下,未键合、热键合及凹面热键合三种棒的最大输出功率分别为15.54,17.85和18.33 W、斜效率分别为16.6%,18.3%和18.4%;重频600 Hz条件下,三种棒的最大输出功率分别为9.4,13.32和13.18 W、斜效率分别为6.7%,8.6%和9%。此外,对比研究了不同直径Er∶YSGG晶体的激光性能,在低于100 Hz的低频下,三种晶体的激光性能接近。但相比于3和4 mm键合凹面棒,直径2 mm棒有大的比表面积,拥有更好的热管理能力,使其在高重频条件下具有更好的激光性能。如在150 Hz条件下,2 mm凹面键合Er∶YSGG晶体棒获得了功率23.82 W、斜效率27.7%的中红外激光输出,大大高于直径3和4 mm棒的18 W和23%。在600 Hz,直径2 mm键合凹面棒中实现了功率13.18 W,斜效率9%的激光输出,相比于直径3和4 mm键合凹面棒的9 W,7%具有较大的改善。测量得到2 mm凹面键合Er∶YSGG晶体棒在150 Hz,200μs条件下的光束质量因子M_(x)^(2)/M_(y)^(2)=6.28/6.30,表明该激光具有良好的光束质量。综上,选择合适晶体棒直径,并将键合与凹面相结合是实现高性能2.79μm激光的有效方法。
This paper demonstrates a systematic comparative study on the mid-infrared laser performance of Er∶YSGG crystals with thermally bonded,concave end-face,and different diameter.After annealing at high temperature,orientation cutting,and precision polishing on the end face,the flatness and surface roughness are less than 0.1λ@633 nm and 0.5 nm.The room temperature optical glueing of YSGG and Er∶YSGG was realized by the precision machining,and then high temperature thermal bonding was carried out.The transmission spectra show that the bonded interface is basically integrated without loss.The thermal focal length shows that the thermal lens effect of crystals at high power pumping condition is improved and compensated efficiently by thermal bonded and concave end-face,which are beneficial to improve the laser performance of crystals.Compared with non-bonded Er∶YSGG,the laser performance under 968 nm LD side-pumping method of bonded and concave end-surfaces Er∶YSGG crystal do not show advantages at low frequencies below 150 Hz,the maximum output power and slope efficiency of the three crystal rods all are about 24 W and 28%,respectively.However,with the increase of repetition frequency,the thermal effect gradually increases,and the laser performance of bonded and concave end-face crystals is improved due to their perfect heat dispassion and concave thermal compensation effect.Under the repetition frequency of 300 Hz,the maximum output power of non-bonded,bonded and concave bonded rods is 15.54,17.85 and 18.33 W,corresponding to the slope efficiency of 16.6%,18.3%and 18.4%,respectively.Under the repetition frequency of 600 Hz,these rods'maximum output power and slope efficiency are 9.4,13.32 and 13.18 W,6.7%,8.6%,and 9%,respectively.In addition,the laser properties of Er∶YSGG crystals with different diameters are studied,and the laser properties of these three crystals are similar under the low frequencies below 100 Hz.However,compared with the 3 and 4 mm bonded concave rods,the 2 mm diameter rod possesses a larger specific surface area and better thermal management capability,which is beneficial to improve the laser performance.For example,at 150 Hz,a maximum output of 23.82 W is obtained with a slope efficiency of 27.7%by Er∶YSGG concave bonded crystal rod with 2 mm diameter,which is much higher than 18 W and 23%that is achieved with the 3 and 4 mm crystal rods.Besides,by using a concave bonded rod with 2 mm diameter,the maximum output power of 13.18 W is achieved with a slope efficiency of 9%under the higher repetition frequency of 600 Hz,which is better than that of 9 W and 7%for the concave bonded rod with diameter of 3 and 4 mm.The beam quality factor M2x/M2y of Er∶YSGG laser is measured by using 2 mm concave bonded crystal rod at 150 Hz,200μs,the values are 6.28/6.30,which indicates that the laser has good beam quality.In conclusion,choosing an appropriate crystal rod diameter and combining bonded with concave surfaces effectively achieve high-performance 2.79μm lasers.
作者
程毛杰
董昆鹏
胡伦珍
张会丽
罗建乔
权聪
韩志远
孙敦陆
CHENG Mao-jie;DONG Kun-peng;HU Lun-zhen;ZHANG Hui-li;LUO Jian-qiao;QUAN Cong;HAN Zhi-yuan;SUN Dun-lu(University of Science and Technology of China,Hefei 230026,China;Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;Anhui University,Hefei 230601,China;Advanced Laser Technology Laboratory of Anhui Province,Hefei 230037,China)
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2024年第2期571-579,共9页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(51872290,52102012)
安徽省先进激光技术实验室青年基金项目(AHL2020QN02)资助。
