Laser damage mechanism and threshold improvement of nonlinear optical La3Ga5.5Nb0.5O14 crystal for a mid-infrared high-intensity laser
Laser damage mechanism and threshold improvement of nonlinear optical La3Ga5.5Nb0.5O14 crystal for a mid-infrared high-intensity laser
复制标题
中红外高强度激光用非线性光学La3Ga5.5Nb0.5O14晶体的激光损伤机制及阈值改进
DOI：
10.1364/ome.464578
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发表时间：
2022
影响因子：
2.8
通讯作者：
Huaijin Zhang
中科院分区：
文献类型：
--
作者：
Yuzhou Wang;Fei Liang;Dazhi Lu;Shuxian Wang;jiyang wang;Haohai Yu;Huaijin Zhang
激光损伤阈值（LDT）是高强度激光应用中光学器件的关键参数。了解强激光对光学材料的作用机理是提高材料激光透过率的基础。本文研究了最有希望用于中红外光参量啁啾脉冲放大（OPCPA）的非线性光学材料La3Ga5.5Nb0.5O14（LGN）晶体的激光损伤，阐明了其激光损伤机理。不同配体中的氧空位对LDTs有重要而独特的影响，并引入缺陷能级，通过吸收导带中的电子在LDTs的还原中起主要作用。F心的形成也通过双光子吸收降低LDTs。此外，在纳秒激光损伤过程中，导带中自由电子的线性吸收比缺陷能级引起的双光子吸收贡献更大。通过优化退火条件，测得LGN晶体的0%激光损伤概率为13.1J/cm 2，比生长态提高了24%，是中红外非线性光学晶体中最高的。研究结果不仅有助于进一步提高光学参量放大系统的激光放大性能，而且对进一步研究光学材料在强激光器中的应用具有一定的启发意义。
Laser damage threshold (LDT) is critical for optical devices in high-intensity laser applications. Understanding the influence mechanism of a high-intensity laser on optical materials is principal for improving the materials’ LDTs. Here, the LDT of La 3 Ga 5.5 Nb 0.5 O 14 (LGN) crystals, the most promising nonlinear optical material for mid-infrared optical parametric chirped-pulse amplification (OPCPA), were studied, and its laser damage mechanism was elucidated. Oxygen vacancies in different ligands have important and distinct effects on LDTs and introduce defect levels, playing primary roles in the reduction of LDTs by the absorption of electrons in the conduction bands. The formation of F-centers also decreases LDTs via two-photon absorption. In addition, the linear absorption of free electrons in the conduction bands contributes more than the two-photon absorption, induced by the defect level, in the nanosecond laser damage process. By annealing in optimized conditions, the 0% laser damage probability of the LGN crystals was measured up to 13.1 J/cm 2 , which is a 24% improvement compared with that of the as-grown sample, and the highest of the mid-infrared nonlinear optical crystals. The results can not only lead to further improvements in the laser amplification properties in OPCPA systems but also inspire further studies on the application of optical materials in high-intensity lasers.