Optically-Controlled Waveguide Architectures for Advanced Tunable and Reconfigurable THz Circuits

该项目将研究和开发一种简单而强大的方法，用于有效地产生基于新型波导架构的先进可调谐和可重构太赫兹（THz）组件。这些进步将提供实现可重新配置和高性能传感和通信系统所需的构建模块，这些系统将提供比当前微波和毫米波系统大得多的带宽。这是一个重要的技术领域，具有广泛的应用，将为社会带来重大利益。基于矩形波导结构的高性能可变太赫兹调制器和衰减器可应用于射电天文学、科学仪器和计量学。使用可编程电磁带隙结构的可调谐THz滤波器将使光谱传感和成像能够增强防御和安全筛选（例如，物质识别和检测）、化学和生物传感以及疾病或癌症诊断。利用光致衬底集成波导产生的更先进的可重构太赫兹电路将在自适应超高速无线通信中得到应用。通过使用所提出的技术，可以动态重新配置的虚拟电路图案将被实现，而无需复杂的电路制造和器件集成过程，从而导致使用传统方法无法实现的可调谐和可重新配置的THz电路。该项目还为学生提供了重要的教育机会。 该计划的研究生将接触到半导体物理，电磁波传播，微波工程，先进的THz系统设计和测试过程的全方位，从单个设备到电路/组件/系统级别。本科生将通过夏季和荣誉论文研究参与。PI将建议和指导来自代表性不足群体的学生。本计画的目标是探索三种光控波导架构，包括1）光控矩形波导调变器，2）光致电磁带隙结构，3）光致基板整合波导。波导或传输线部分中的传播THz模式与半导体衬底上的光致图案（通过电子-空穴对的空间调制光学生成形成）之间的相互作用允许高效地实现具有高性能的动态可调谐和可重构功能。可调谐性和可重构性是通过使用数字光刻设备芯片在梅萨或柱阵列结构上照射虚拟电路图案来实现的，而不使用预先图案化的电路和设备。所采用的梅萨或柱阵列结构将显着提高性能，包括更高的电导率，更高的空间分辨率和更高的控制速度，使得可以动态生成可重构的THz组件。这三种架构代表了可调性和可重构性的不断提高。特别是，光致基片集成波导结构可以为实现具有多种功能的实时可编程无源THz组件提供几乎无限的可能性。该项目将涉及半导体物理，传输线理论，太赫兹科学和技术，高频测试和表征，以实现和演示所提出的新方法和三种波导架构。如果成功，该项目将极大地推进知识，以展示基于可调谐/可重构波导的无源元件，并可能产生关于如何在未来THz系统中实现可调谐和可重构THz电路的范式转变。

This project will investigate and develop a simple and powerful approach for efficiently generating advanced tunable and reconfigurable terahertz (THz) components based on novel waveguide architectures. These advancements will provide the building blocks needed to implement reconfigurable and high-performance sensing and communication systems that will provide much larger bandwidths than current microwave and millimeter-wave systems. This is an important technological area with a wide range of applications that will generate significant benefit to the society. High-performance variable THz modulators and attenuators based on rectangular waveguide configuration can be applied to radio astronomy, scientific instrumentation, and metrology. Tunable THz filters using programmable electromagnetic bandgap structures will enable spectroscopic sensing and imaging for enhancing defense and security screening (e.g., substance identification and detection), chemical and biological sensing, and disease or cancer diagnostics. More advanced reconfigurable THz circuits generated using photo-induced substrate-integrated waveguides will find applications in adaptive ultra-high-speed wireless communications. By using the proposed techniques, virtual circuit patterns that can be dynamically reconfigured will be implemented without complex circuit fabrication and device integration processes, leading to tunable and reconfigurable THz circuits that could not be realized using conventional approaches. The project also provides significant educational opportunities for students. The graduate students in this program will be exposed to the full scope of semiconductor physics, electromagnetic wave propagation, microwave engineering, advanced THz system design and testing process, from single device to the circuit/component/system level. Undergraduate students will be involved through summer and honors thesis research. The PIs will advise and mentor students from underrepresented groups. The objective of this project is to explore three optically-controlled waveguide architectures including 1) optically-controlled rectangular waveguide modulator, 2) photo-induced electromagnetic bandgap structure, and 3) photo-induced substrate-integrated waveguide. The interaction between the propagating THz mode in the waveguide or transmission line sections and the photo-induced patterns (formed by spatially-modulated optical generation of electron-hole pairs) on the semiconductor substrate allows dynamically tunable and reconfigurable functions with high performance to be realized efficiently. The tunability and reconfigurability is realized by illuminating virtual circuit patterns on mesa- or pillar-array structures using a digital micromirror device chip without the use of pre-patterned circuits and devices. The mesa- or pillar-array structures employed will significantly improve the performance including higher conductivity, higher spatial resolution, and higher control speed, making it possible to dynamically generate reconfigurable THz components. The three proposed architectures represent increasing levels of tunability and reconfigurability. In particular, the photo-induced substrate-integrated waveguide architecture could potentially provide nearly unlimited possibilities for realizing real-time programmable passive THz components with multiple functionalities. The project will involve semiconductor physics, transmission line theories, THz science and technology, high frequency testing and characterization to implement and demonstrate the proposed novel approach and three waveguide architectures. If successful, the project will greatly advance the knowledge to demonstrate tunable/reconfigurable waveguide-based passive components and potentially produce a paradigm shift on how tunable and reconfigurable THz circuits will be realized in future THz systems.