抗紫外光损伤铌酸锂晶体及其应用研究

Although lithium niobate is a useful material for integrated optics and nonlinear photonic science, but photorefractive effects (optical damage) hindered its application in the UV region. Zirconium-doped lithium niobate crystal achieves a breakthrough in lithium niobate with high optical damage resistance ability in the ultraviolet band. However, the microscopic mechanism of its anti-UV damage is unclear; UV SHG (second harmonic generation) application is not implemented..This project will grow a series of doping (Zr, Hf, Sn) lithium niobate crystal, study its performance of UV optical damge resistance and UV photorefractive center, revealing its anti-UV damage mechanisms, clarifing the correlation between crystal doping, composition and its anti-UV damage performance, to establish the structure-performance relationship between UV photorefractive centers and perfomance of the resistance to UV optical damage; the same time, achieve the UV SHG on lithium niobate crystals, and optimize their the phase matching temperature to room temperature, to get the excellent lithium niobate crystals with UV second harmonic generation used at room temperature.

铌酸锂晶体对于集成光学和非线性光子学是一种有用的材料，但是光折变（光损伤）阻碍了它在紫外光区的应用。掺锆铌酸锂晶体打破了这一禁锢，使得铌酸锂具有了很强的抗紫外光损伤能力。但其抗紫外光损伤的微观机制还不清楚，其紫外倍频应用也没有实现。.本项目将就一系列掺杂（锆、铪、锡）铌酸锂晶体，通过对其抗紫外光损伤性能和紫外光折变中心的研究，揭示铌酸锂抗紫外光损伤机制，弄清晶体掺杂、组分与抗紫外光损伤的关联性，建立铌酸锂紫外光折变中心与抗紫外光损伤性能间的构效关系；同时，提高晶体的抗光损伤性能，实现铌酸锂晶体的紫外倍频，并优化其相位匹配温度至室温，获得性能优异的在室温下使用的紫外倍频铌酸锂晶体。

铌酸锂晶体的紫外光折变特性阻碍了它在紫外光波段的信号传输及非线性倍频等应用，本项目对掺锆等掺杂铌酸锂晶体的紫外抗光损伤及其紫外倍频进行了实验研究。通过对一系列不同掺杂不同浓度的掺杂铌酸锂晶体的紫外抗光损伤强度的研究，结果表明掺锆晶体的紫外抗光损伤强度达到1.6×10 5 W/cm2 @ 351 nm 以上，掺锡晶体的紫外抗光损伤强度达到5.0×10 4 W/cm2 @ 351 nm以上，掺钇晶体的紫外抗光损伤强度达到1.0×10 4 W/cm2 @ 351 nm以上。其紫外光折变性能测试结果显示晶体在达到掺杂阈值浓度时其光折变性能最弱，衍射效率最低至0.1%，其折射率变化在仅10 -6量级。经过对晶体的吸收谱、载流子类型等的研究，发现以晶体中O 2- -M Nb n- 为光折变中心的缺陷结构与铌酸锂晶体的抗光损伤特性有着紧密的联系。同时，通过对锆镁双掺铌酸锂晶体的掺杂浓度的调控，实现了室温下可见波段非线性倍频的位相匹配，提高了掺锆铌酸锂晶体的位相匹配温度。上述研究结果表明，以掺锆为代表的一系列掺杂铌酸锂晶体具备良好的紫外抗光损伤性能，能成为紫外倍频的候选材料。