Spectroscopic ellipsometer for the infrared

研制了红外光谱范围的光谱椭偏仪。结合现有的椭圆计，这将用于研究材料和系统的光学特性，特别是介电函数，在从远红外（0.04 eV）到深紫外光谱范围（8.50 eV）的宽光谱范围内。在红外光谱区产生介电函数的激励，主要是声子模式、自由电荷载流子和电子跃迁，将通过线形分析确定并研究它们之间的相互影响。特别感兴趣的是光学各向异性材料，特别是具有单斜或三斜晶体结构的材料。由于至少两个晶体轴不是相互正交的，一些物理量，如介电函数张量或有效质量张量，具有不消失的非对角线元素，因此可以发生新的效应，如违反LO-TO规则或形成奇异光轴。这些不消失的对角线元素对（块状）材料和人工光子系统的光学响应以及潜在的物理过程的影响将被研究。这将首先通过实验确定介电张量，并通过拟合理论线形模型以及光学各向异性系统的更一般理论来补充。

A spectroscopic ellipsometer for the infrared spectral range is to be acquired. In conjunction with the ellipsometers already available, this will be used to study the optical properties, in particular the dielectric function, of materials and systems in a wide spectral range from the far infrared (0.04 eV) to the deep ultraviolet spectral range (8.50 eV). The excitations contributing to the dielectric function in the infrared spectral region, typically phonon modes, free charge carriers and also electronic transitions, will be determined by line shape analysis and investigated for their mutual influence. Of particular interest are optically anisotropic materials, especially with a monoclinic or triclinic crystal structure. Since at least two crystal axes are not orthogonal to each other, some physical quantities, such as the tensor of the dielectric function or the effective mass tensor, have non-vanishing off-diagonal elements, so that new effects can occur, such as the violation of the LO-TO rule or the formation of singular optical axes. The influence of these non-vanishing side diagonal elements on the optical response of (bulk) materials and also artificial photonic systems as well as the underlying physical processes will be investigated. This will be done first of all by experimental determination of the dielectric tensor and complementary by fitting to theoretical line shape models as well as more general theories of optically anisotropic systems.