EAGER - Directed Total Internal Reflection Devices

许多现代设备，如太阳能电池、照相机和光学探测器，都需要高透光率，并在相同的结构中存在电路。这带来了一个重大挑战：金属电线具有很强的吸收和反射能力，因此为了保持高效的电气通道，设备常常牺牲光学性能。如果这个看似不可避免的问题能够被绕过，大量的设备可以实现更高的性能，例如更大的光传输、更大的能效或更高的设备速度。这里提出的工作旨在通过实验演示一种全新的器件结构来实现这些目标，方法是开发一种新型电极，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线阵列组成。导线嵌入到与衬底折射率匹配的透明覆盖层中。通过定义具有倾斜顶表面的电极，由导线反射的光不会丢失，而是被引导到覆盖层内的大角度，从而产生几乎无损的全内反射。通过这种方式，原本会丢失的光又有机会到达基片。令人惊讶的是，对这种结构的光线分析预测，即使在半个表面覆盖着金属的情况下，也能实现完全的光学透明。这一概念的实验论证可能会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交指电极的概念已经从理论上提出，但尚未在实验上得到证明。目前的提议旨在产生透明的电极结构，以便探索制造策略，并研究在非理想化的真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方面。我们将从理论上研究双表面倾斜和抛物线电极表面的传输性能，并研究这些结构的性能随入射角的变化。为了制造具有明确表面倾斜度的电极，将使用光刻和阴影蒸发的组合。热蒸发过程中样品在图案化抗蚀剂层上的自动移动可生成非平面金属表面。发射后，所产生的成角度的金属线将被覆盖在透明覆盖层中，使用旋涂技术，并将测量可见光和近红外区的透射谱作为入射角的函数。结果将与没有表面倾斜的参比电极结构进行比较。阴影蒸发过程的灵活性将使各种电极表面形状的实验研究成为可能，包括具有亚波长阶跃的倾斜表面，以及双倾斜电极。拟议的实验是在实际光学设备中实施这一新概念的关键一步。

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.