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EAGER - Directed Total Internal Reflection Devices

EAGER - 定向全内反射装置

基本信息

批准号：
1650002
负责人：
Pieter Kik
金额：
$ 14万
依托单位：
The University of Central Florida Board of Trustees
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-09-01 至 2020-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1650002&HistoricalAwards=false
关键词：
EAGER Directed Total Internal Reflection

项目摘要

Many modern devices such as solar cells, cameras, and optical detectors require a high light transmission and the presence of electrical circuitry within the same structure. This poses a major challenge: metallic electrical wiring is highly absorptive and reflective, and consequently devices often sacrifice optical performance in order to maintain efficient electrical access. If this seemingly unavoidable problem could be bypassed, a large number of devices could achieve greater performance, for example larger optical transmission, larger energy efficiency, or higher device speed. The work proposed here aims to experimentally demonstrate an entirely new device structure to achieve these goals by developing a new type of electrode that turns the detrimental high reflection of metallic wires into an asset. The structure consists of an array of conductive wires on transparent substrate. The wires are embedded in a transparent cover layer that is index matched to the substrate. By defining electrodes with a tilted top surface, light reflected by the wires is not lost but instead directed to large angle inside the cover layer, resulting in a virtually lossless total internal reflection. In this way, light that would otherwise be lost is given another chance to reach the substrate. Surprisingly, a ray analysis of this structure predicts complete optical transparency even when half the surface is covered with metal. The experimental demonstration of this concept could have far reaching implications for a wide range of optical devices.The concept of using directed total internal reflection in order to develop a transparent interdigitated electrode has been theoretically proposed, but has not yet been demonstrated experimentally. The current proposal aims to generate transparent electrode structures in order to explore fabrication strategies and to investigate the achievable performance in a non-idealized real-world system. In addition, two key theoretical aspects will be addressed. The transmission performance of double surface tilt and parabolic electrode surfaces will be investigated theoretically, and the performance of these structures will be studied as a function of incidence angle. In order to fabricate electrodes with a well-defined surface tilt, a combination of photolithography and shadow evaporation will be used. Automated sample motion during thermal evaporation onto a patterned resist layer enables the generation of non-planar metal surfaces. After liftoff the resulting angled metallic wires will be covered embedded in a transparent cover layer using spin-coating, and transmission spectra in the visible and near-infrared regions will be measured as a function of incidence angle. The results will be compared with reference electrode structures that do not have a surface tilt. The flexibility of the shadow evaporation process will enable the experimental investigation of a wide range of electrode surface shapes, including tilted surfaces with subwavelength steps, as well as double-tilt electrodes. The proposed experiments constitute a critical step toward implementing this new concept in practical optical devices.

许多现代设备，如太阳能电池、相机和光学探测器，都需要高透光率，并且在同一结构中存在电路。这是一个重大挑战：金属电布线是高度吸收性和反射性的，因此，为了保持有效的电接入，器件常常牺牲光学性能。如果这个看似不可避免的问题可以被绕过，大量的设备可以实现更高的性能，例如更大的光传输，更高的能效或更高的设备速度。本文提出的工作旨在通过实验证明一种全新的器件结构，通过开发一种新型电极来实现这些目标，该电极将金属线的有害高反射转化为资产。该结构由透明衬底上的导电线阵列组成。导线嵌入在与衬底折射率匹配的透明覆盖层中。通过限定具有倾斜顶表面的电极，由导线反射的光不会损失，而是被引导到覆盖层内部的大角度，从而导致几乎无损的全内反射。以这种方式，否则将损失的光被给予另一次到达衬底的机会。令人惊讶的是，对这种结构的射线分析预测，即使一半的表面被金属覆盖，也是完全透明的。这一概念的实验演示可能对广泛的光学器件产生深远的影响。利用定向全内反射来开发透明叉指电极的概念已经在理论上提出，但尚未在实验上得到证实。目前的建议旨在产生透明电极结构，以探索制造策略，并调查在非理想化的现实世界系统中可实现的性能。此外，还将讨论两个关键的理论问题。本文将从理论上研究双面倾斜电极和抛物面电极的传输性能，并将研究这些结构的性能随入射角的变化。为了制造具有良好定义的表面倾斜的电极，将使用光刻和阴影蒸发的组合。在图案化的抗蚀剂层上的热蒸发期间的自动样品运动使得能够生成非平面金属表面。在剥离之后，将使用旋涂将所得成角度的金属线覆盖嵌入透明覆盖层中，并且将测量可见光和近红外区域中的透射光谱作为入射角的函数。将结果与不具有表面倾斜的参考电极结构进行比较。阴影蒸发工艺的灵活性将使实验研究的电极表面形状，包括倾斜表面亚波长的步骤，以及双倾斜电极范围广泛。提出的实验构成了在实际光学设备中实现这一新概念的关键一步。