Giant optical anisotropy in a quasi-one-dimensional crystal
Giant optical anisotropy in a quasi-one-dimensional crystal
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DOI：
10.1038/s41566-018-0189-1
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发表时间：
2018-07-01
期刊：
影响因子：
35
通讯作者：
Ravichandran, Jayakanth
中科院分区：
文献类型：
--
作者：
Niu, Shanyuan;Joe, Graham;Ravichandran, Jayakanth
光学各向异性是线性和非线性光学元件的基本构件，例如偏振器、波片和相位匹配元件(1-4)。在固体均匀材料中，方解石和金红石(5，6)等晶体的光学各向异性最强。增强各向异性光-物质相互作用的尝试通常依赖于人造各向异性微/纳米结构(形成双折射)(7-11)。在这里，我们展示了合理设计的硫化钛钡(BaTiS_3)单晶的巨大光学各向异性。这种材料在中长波红外显示出前所未有的高达0.76的宽带双折射，以及一个大的二向色性窗口，吸收边位于1.6微米和4.5微米，光在一个容易接近的解理面上沿着两个晶轴偏振。异常大的各向异性是准一维结构的结果，结合组成离子的合理选择，使不同轴上的极化率差异最大化。
Optical anisotropy is a fundamental building block for linear and nonlinear optical components such as polarizers, wave plates, and phase-matching elements(1-4). In solid homogeneous materials, the strongest optical anisotropy is found in crystals such as calcite and rutile(5,6). Attempts to enhance anisotropic light-matter interaction often rely on artificial anisotropic micro/nanostructures (form birefringence)(7-11). Here, we demonstrate rationally designed, giant optical anisotropy in single crystals of barium titanium sulfide (BaTiS3). This material shows an unprecedented, broadband birefringence of up to 0.76 in the mid-to long-wave infrared, as well as a large dichroism window with absorption edges at 1.6 mu m and 4.5 mu m for light with polarization along two crystallographic axes on an easily accessible cleavage plane. The unusually large anisotropy is a result of the quasi-one-dimensional structure, combined with rational selection of the constituent ions to maximize the polarizability difference along different axes.