摘要：探索具有深紫外相位匹配能力的新型非线性光学材料是当前研究热点.本文从硼氧阴离子框架出发,发现由π共轭BO_(3)基团组成一维(BO_(2))∞链的电子离域导致了极化特性增强,可实现非线性光学性能的优化.据此,本文预测了以(BO_(2))∞链为阴离子框架的CaBO_(2)F体系.重点研究了三种能量最低的结构CaBO_(2)F-Ⅰ,CaBO_(2)F-Ⅱ和CaBO_(2)F-Ⅲ,设计了热力学上可进行的反应路径.第一原理计算表明,CaBO_(2)F-Ⅰ,CaBO_(2)-F-Ⅱ和CaBO_(2)F-Ⅲ具有较宽的带隙,合适的双折射(0.076–0.108@1064 nm)和较大的倍频系数(2.1–2.7×KDP).其中,计算得到CaBO_(2)F-Ⅰ的最短相位匹配波长在约为195 nm(基于HSE06带隙修正剪刀算符),证明了含有定向电子离域的(BO_(2))∞链是深紫外非线性光学材料的潜在阴离子框架.本文通过将机理研究与验证性的结构预测相结合实现了自上而下设计深紫外非线性光学结构模板,该研究为探索新型非线性光学材料提供了新的策略.

摘要：Finding crystals with high birefringence(Δn),especially in deep-ultraviolet(DUV)regions,is important for developing polarization devices such as optical fiber *** materials are usually discovered using experimental techniques,which are costly and inefficient for a large-scale ***,we collected a database of crystal structures and their optical properties and trained atomistic line graph neural network to predict theirΔ*** estimate the level of confidence of the trained model on new data,D-optimality criterion was *** trained graph neural network,we searched for novel materials with highΔn in the Materials Project database and discovered two new DUV birefringent candidates:NaYCO_(3)F_(2) and SClO_(2)F,with highΔn values of 0.202 and 0.101 at 1064 nm,*** analysis reveals that strongly anisotropic units with various anions andπ-conjugated planar groups are beneficial for highΔn.