电化学法制备金属多孔rugate滤波片来实现在可见-红外区完美吸收器

We propose on the numerical design and electrochemical fabrication of perfect absorbers at the visible-IR regime based on porous metal rugate filters whose porosity oscillates sinusoidally along the film thickness direction. Preliminary simulation study indicates that perfect absorption efficiencies can be achieved for variable resonance wavelengths at normal incidence in the visible-IR regime by adjusting the structural parameters, particularly by setting the initial phase of the porosity sine wave to be 0 (this finding is counter-intuitive because dielectric rugate filters are generally used to realize high reflectivity, instead of high absorption, at the resonance wavelengths). The proposed metal rugate filter design is significantly different from the main-stream approach that utilizes planar periodic metal structures built on the device surface, and is promising for realizing perfect absorption efficiency for both TE and TM polarizations. Moreover, unlike the conventional designs which usually contain an insulating dielectric spacer layer, the proposed design of perfect absorbers utilizes only metals (e.g., nickel) as the building components and thus potentially enables more functionality, e.g., high conductivity, and more applications, e.g., for absorptive electrodes.We further propose to fabricate this novel type of absorbers by combining the well-established solution-based techniques of electrodeposition and dealloying. The proposed fabrication method is highly compatible with various substrate geometries (e.g., cylinders) and large sample sizes and are amenable to low-cost automated manufacturing.

我们提出基于金属多孔rugate薄膜来实现一种新型的可见-红外区域的完美吸收器，并将结合理论设计和电化学制备两个方面对其进行研究。所提议的吸收器的孔隙率沿膜厚方向呈正弦变化，前期理论计算表明：当该正弦函数的初始相位（即位于膜表面的相位）为零时，吸收器可在可见-红外区域对共振特征波长实现完美吸收；此完美吸收波长的位置又可由诸多结构参数（如周期性或平均孔隙率）调节；因该吸收器的设计本质上不同于基于膜表面周期结构的主流传统设计，从而可望对TE和TM偏振光同时实现完美吸收。另外，传统设计常因含由绝缘介质材料所组成的中间层而导电导热性欠佳，而我们的设计仅含金属组分，从而可实现更多功能及拥有更广阔应用前景，比如高导电性、高导热性、及用作吸收电极等。我们进一步提出结合电沉积及去合金技术来制备这种新型吸收器。此电化学方法经济方便，可自动化，适用于各种几何形状及大面积样品的制备，利于工业化大批量生产。

本项目结合理论设计和电化学制备两个方面着重研究了金属基多孔多层薄膜的新型的可见-红外区域的完美吸收器。通过调节金属沿膜厚方向孔隙率的变化，可在可见-红外区域对共振特征波长实现高吸收，其吸收行为（如吸收波长）可由诸多结构参数（如周期性或平均孔隙率）调节,还可实现对特定波长的高不对称性吸收。该吸收器的设计本质上不同于基于膜表面精细周期结构的主流传统设计（往往需要繁琐的纳米刻蚀技术才能实现），亦不含有传统设计中所需的绝缘介质材料所组成的中间层。因此无需使用昂贵纳米刻蚀技术制备，且因仅含金属组分从而可实现更多功能，拥有更广阔应用前景，比如高导电性、高导热性、及用作吸收电极等。我们进一步研究了制备金属基多层多孔薄膜的电化学方法,如电沉积法和去合金法, 开发出经济方便的新型电化学方法，可自动化，适用于各种几何形状及大面积样品的制备，利于工业化大批量生产。