Huang Jijie, Wang Han, Li Dongfang, Qi Zhimin, Zhang Di, Lu Ping, Chen Hou-Tong, Yarotski Dmitry A, Lin Pao-Tai, Zhang Xinghang, Wang Haiyan
School of Materials, Sun Yat-Sen University, Guangzhou, Guangdong 510275, China.
School of Materials Engineering, Purdue University, West Lafayette, Indiana 47906, United State.
ACS Appl Mater Interfaces. 2020 May 20;12(20):23076-23083. doi: 10.1021/acsami.0c03487. Epub 2020 May 11.
Tetragonal tungsten bronze (TTB) materials are one of the most promising classes of materials for ferroelectric and nonlinear optical devices, owing to their very unique noncentrosymmetric crystal structure. In this work, a new TTB phase of LiNbBaTiO (LNBTO) has been discovered and studied. A small amount of a secondary phase, LiTiO (LTO), has been incorporated as nanopillars that are vertically embedded in the LNBTO matrix. The new multifunctional nanocomposite thin film presents exotic highly anisotropic microstructure and properties, e.g., strong ferroelectricity, high optical transparency, anisotropic dielectric function, and strong optical nonlinearity evidenced by the second harmonic generation results. An optical waveguide structure based on the stacks of α-Si on SiO/LNBTO-LTO has been fabricated, exhibiting low optical dispersion with an optimized evanescent field staying in the LNBTO-LTO active layer. This work highlights the combination of new TTB material designs and vertically aligned nanocomposite structures for further enhanced anisotropic and nonlinear properties.
四方钨青铜（TTB）材料因其非常独特的非中心对称晶体结构，是铁电和非线性光学器件中最有前途的材料类别之一。在这项工作中，发现并研究了一种新的LiNbBaTiO（LNBTO）的TTB相。少量的第二相LiTiO（LTO）以纳米柱的形式垂直嵌入LNBTO基体中。这种新型多功能纳米复合薄膜呈现出奇异的高度各向异性的微观结构和性能，例如强铁电性、高光学透明度、各向异性介电函数以及由二次谐波产生结果证明的强光非线性。基于SiO/LNBTO-LTO上的α-Si堆叠构建了一种光波导结构，在优化的倏逝场保留在LNBTO-LTO有源层的情况下，该结构表现出低光学色散。这项工作突出了新型TTB材料设计与垂直排列的纳米复合结构相结合，以进一步增强各向异性和非线性特性。
