High-Density Photonic Chip Integration with Extreme Skin-Depth Waveguides

非技术性：芯片规模的光子设备可以将大量光学系统微型化到单个微小芯片中，使其便携，并允许在实验室之外的各种光学应用。光子芯片与电子电路的集成也可以带来广泛的应用，例如，在高速光通信、化学和生物传感、高精度光谱以及无人驾驶汽车的光检测和测距方面。随着电子设备对高密度集成电路的支持发生了革命性的变化，许多光学应用对提高光子芯片的集成密度提出了更高的要求；它在芯片中提供了更多的功能和更低的功耗。然而，由于光的波动性，高密度光子芯片的集成是极其困难的，目前的方法依赖于复合半导体材料的折射率对比度。德克萨斯理工大学的研究将探索一种替代方法，使用全电介质和高度各向异性的超材料，即人工工程人造材料，以提高光子芯片的集成密度。拟议的研究将在与当前半导体铸造工艺兼容的单片绝缘体上实现，并提供低成本的解决方案；因此，这项研究将在工业上产生更广泛的影响，加速光子芯片在许多应用中的实际应用。教育和推广活动是该项目的高度优先事项，将为本科生和研究生提供实践经验，特别是代表人数较少的学生群体。技术：在许多应用中，实现高密度光子芯片集成是非常必要的，因为更多的构建块在单个芯片上提供更多功能(类似于电子产品)。然而，目前的光限制方法依赖于纤芯和包层材料的折射率对比度，光的波动特性阻碍了光子器件的进一步小型化，即包层中的逝去波引起了波导串扰。该项目的目标是显着地抑制波导串扰，并设计和实现超紧凑型片上光子器件和电路。本项目将通过对极端集肤深度波导中的特殊耦合现象进行基本分析和实验演示来实现这一目标。为了从根本上理解这种现象，我们将探索极端集肤深度波导中的各向异性耦合机制，并将在硅片上实验演示具有低串扰的超长耦合长度。还将评估特殊联轴器的制造公差，并将所有表征结果与数值和分析结果进行比较。该项目还将探索有源介质在各向异性包层中的作用，并将利用各向异性超材料实现各种无源和有源超致密光子器件。该项目的成果将科学地揭示特殊耦合的基本机制，它可以抑制光学串扰，并将通过在芯片上提供更多功能来在技术上促进光子应用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical: Chip-scale photonic devices can miniaturize a bulk optical system into a single tiny chip, making it portable and allowing various optical applications outside of the laboratory. The integration of photonic chips with electronic circuitry can also lead to a broad range of applications, for example, in high-speed optical communication, chemical- and bio-sensing, high-precision spectroscopy, and light detection and ranging for driverless automobiles. As electronic devices have been revolutionized in support of high-density integrated circuits, increasing the photonic chip integration density is highly desired in many optical applications; it offers more functionality and lower power consumption in a chip. However, due to the wave nature of light, high-density photonic chip integration is extremely difficult, and the current approach relies on the index-contrast of composite semiconductor materials. Research at Texas Tech University will explore an alternative approach of using all-dielectric and highly anisotropic metamaterials, i.e. artificially engineered man-made materials, to increase the photonic chip integration density. The proposed research will be implemented on a monolithic silicon-on-insulator wafer, which is compatible with the current semiconductor foundry process and provides a low-cost solution; thus, this research would have a broader impact in industry as well, accelerating the practical use of photonic chips in many applications. Educational and outreach activities are a high priority of this project and will provide hands-on experiences for undergraduate and graduate students, especially underrepresented groups of students.Technical: Realizing a high-density photonic chip integration is highly desired in many applications, as more building blocks provide more functionalities on a single chip (analogous to electronics). However, current approaches of light confinement rely on the index-contrast of core and cladding materials and further miniaturization of photonic devices is hampered by the wave nature of light, i.e., the evanescent wave in the cladding causes waveguide crosstalk. The goal of this project is to suppress the waveguide crosstalk significantly and to devise and implement ultracompact on-chip photonic devices and circuitry. This project will pursue this goal through fundamental analysis and experimental demonstration of the exceptional coupling phenomena in the extreme skin-depth waveguides. An anisotropic coupling mechanism in the extreme skin-depth waveguides will be explored to fundamentally understand the phenomena and extremely long coupling lengths with low crosstalk will be experimentally demonstrated on a silicon chip. The fabrication tolerance of the exceptional coupling will be assessed as well, and all the characterization results will be compared with numerical and analytical results. The project will also explore the effect of active media in anisotropic claddings and will implement various passive and active ultracompact photonic devices with anisotropic metamaterials. The outcomes of this project will scientifically reveal the fundamental mechanism of an exceptional coupling that can suppress optical crosstalk and will technically advance photonic applications by providing more functionalities on a chip.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.