Xie Chao-Hong, Jiang Xiao-Ming, Liu Bin-Wen, Guo Guo-Cong
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100190, P. R. China.
Small. 2025 Feb;21(7):e2409705. doi: 10.1002/smll.202409705. Epub 2025 Jan 14.
Improved birefringence, given its capacity to modulate polarized light, holds a lively role in the optoelectronic industry. Traditionally, alkaline-earth metal halides have possessed low birefringence due to their nearly optical isotropic properties. Herein, the substitution of interlayer anion with linear S─S unit that meticulously engineered by reduced valence state and strong covalent bond is integrated into the optically isotropic BaF, offering the new salt-inclusion chalcogenide BaFS. Notably, it has dramatically enhanced optical anisotropy, thereby significantly boosting birefringence of 0.238@546 nm, achieved by overall considering experimental observations with theoretical analysis. Theoretical investigation has established the significant effect of the covalent S─S bond on the birefringence index. Additionally, BaFS demonstrates a remarkable laser-induced damage threshold (LIDT, 12.0 × AgGaS@1064 nm), illuminating a promising pathway for designing materials with significant birefringence properties in laser applications.
由于具有调制偏振光的能力，双折射的改善在光电子工业中发挥着重要作用。传统上，碱土金属卤化物由于其近乎光学各向同性的性质而具有低双折射。在此，通过降低价态和强共价键精心设计的线性S─S单元对层间阴离子进行取代，并将其整合到光学各向同性的BaF中，得到了新的包盐硫族化物BaFS。值得注意的是，它显著增强了光学各向异性，从而通过综合考虑实验观察结果和理论分析，在546nm处将双折射显著提高到0.238。理论研究已经证实了共价S─S键对双折射指数的显著影响。此外，BaFS还表现出显著的激光诱导损伤阈值（LIDT，12.0×AgGaS@1064nm），为在激光应用中设计具有显著双折射特性的材料开辟了一条有前景的途径。
