Active controllable optical phase shifters employing the localized particle plasmon resonance in the near infrared of n-doped metal oxide nanoparticles

常规的氧化还原电致变色（EC）材料具有借助于电化学电势控制EC膜的光吸收的能力。虽然Kramers-Kronig关系预测这种效应伴随着通过薄膜的波的光学相移，但由于所提到的强吸收，很难在宽光谱范围内检测相移。因此，本计画的目标是利用无机掺杂金属氧化物奈米粒子（NP）的电容性电致变色效应来研究与主动控制光学相移。它们表现出局部粒子等离子体共振（LSP），在近红外的窄带中具有强吸收，伴随着几乎整个光学范围内的光学相移，具有低吸收。我们的相移概念的基本思想是成功地证明了在理论上通过评估的折射率和吸收系数的TiO 2 NP膜使用一个简化的有效介质的方法（Bruggeman模型）。在实验中，EC膜中的自由电子密度将通过允许相移连续变化的外部电压而变化。这个跨学科的项目一方面需要金属氧化物NP化学合成的专业知识，包括尺寸和掺杂水平的控制以及用于模板印刷的浆料的制备。另一方面，它需要的专业知识，将这些NP材料作为薄膜集成到微加工EC电极。这也涉及到理论建模，光电化学表征和应用和概念验证。申请人的互补专业知识已在最近的BMBF项目中得到成功证明。在这个项目中，我们将确定相移能力的光谱范围及其对化学材料成分，掺杂水平和NP尺寸的依赖性。对于近红外的LSP共振和光学响应的表征，我们将进行UV-Vis-NIR光谱和光谱椭圆偏振。相移能力将被调查的一组离散的波长与空间分辨迈克尔逊干涉仪。这些实验数据进一步用于材料和设备的综合理论建模。金属氧化物NP电极的相移能力将在两组不同的实验中得到证明：基于微结构相位光栅（衍射角和可控强度的离散集）的光学相位调制器和控制极角和方位角的创新连续光束转向系统。这需要对电势分布进行广泛的FEM模拟，并计算空间分辨的所得材料相关相变。

Conventional redoxactive electrochromic (EC) materials have the capability to control the optical absorption of an EC film by means of an electrochemical potential. Although the Kramers-Kronig relations predict that this effect is accompanied by an optical phase shift for a wave passing through the film, it is hard to detect the phase shift over a broad spectral range because of the strong absorption mentioned. Therefore, the goals of this project are the investigation and active control of the optical phase shift employing inorganic n-doped metal oxide nanoparticles (NP) with capacitive EC effect. They exhibit a localized particle plasmon resonance (LSP) with strong absorption in a narrow band in the near infrared accompanied by an optical phase shift over almost the complete optical range with low absorption. This basic idea of our phase shifting concept was successfully proven in theory by evaluating the refractive index and absorption coefficient of a TiO2 NP film using a simplifying effective media approach (Bruggeman model). In the experiment the free electron density in the EC film will be varied by means of an external voltage allowing a continuous variation of the phase shift. This interdisciplinary project demands on one hand the expertise of the chemical synthesis of metal oxide NP including the control of size and doping level and the preparation of pastes for stencil printing. On the other hand, it requires the expertise to integrate these NP materials as thin film into microfabricated EC electrodes. This also involves the theoretical modeling, optoelectrochemical characterization and the application and proof of concept. The complementary expertise of the applicants has been successfully demonstrated in a recent BMBF project. In the project we will determine the spectral range of the phase shifting capability and its dependence on the chemical material composition, doping level and NP size. For the characterization of the LSP resonance in the near infrared and the optical response, we will perform UV-Vis-NIR spectroscopy and spectral ellipsometry. The phase shifting capability will be investigated for a discrete set of wavelengths with a spatially resolving Michelson interferometer. These experimental data are further used for a comprehensive theoretical modelling of materials and devices.The phase shifting capability of the metal oxide NP electrodes will be proven in two different sets of experiments: an optical phase modulator based on a microstructured phase grating (discrete set of diffraction angles and controllable intensity) and an innovative continuous beam stearing system controlling the polar and azimuthal angle. This requires an extensive FEM simulation of the potential distribution and the calculation of the spatially resolved resultant material-related phase change.