Theory and implementation of exceptional points of degeneracy for oscillators and array radiators based on spatial combiners

高性能电子产品在各种社会应用中都很重要。基于所提出的研究工作的改进预计将在节能电子和产生的振荡频率质量方面取得重大进展，这两个方面都是现代电子系统的关键特征。提出的工作探索了一种产生频率稳定、噪音低、不浪费功率的电磁波的新方法。预计提供振荡所需的功率在传统振荡器设计技术使用的功率的二分之一到十分之一之间。提出的研究的另一个主要成果是以一种有效的方式产生高辐射功率的改进方法，同时在技术上比其他现有解决方案更简单。众所周知，利用半导体实现的单一信号源无法提供高功率水平，因此毫米波的高功率产生非常具有挑战性。本工作采用的解决方案是将多个独立辐射振荡器的辐射功率组合起来；由于简并条件的自锁效应，期望振荡频率是纯的，即具有低噪声，并在特定方向上产生高功率辐射水平。虽然研究的重点是探索如何在射频系统中首次使用退化条件，但所获得的理论知识也将有助于解决各种其他问题，例如制造高灵敏度传感器。研究人员将通过研究为参与的研究生提供跨学科培训；他们将指导本科生进行研究，促进科学技术的多样性；他们还将向科学和外行观众传播研究成果，以促进广大民众对电磁学和电子学的兴趣。提出的研究活动旨在首先提供基于耦合模式电路和传输线中的异常简并点（EPD）的微波和毫米波（mm-wave）电路的理论基础。其次，本研究将探索和实现各种新颖的应用，如分布式振荡器的鲁棒振荡条件和由阵列网格振荡器制成的空间功率合成器。这个新发明是基于最近发现的支持简并带边缘（DBE）的耦合波导中存在巨大共振的物理现象。DBE是两个或多个导模之间建立临界耦合时发生的一种非常特殊的简并状态。本提案的目标是两个相关成果：(1)基于DBE的硅基技术（包括CMOS）中振荡器的新操作原理的理论和演示；(2)通过在平面耦合模式结构中存在的特殊简并点处工作的阵列紧密锁定振荡元件组成的空间功率合成器，理论和演示了一种新的辐射工作原理。新的工作原理将在微波和毫米波下进行理论和实验研究，并与现有的振荡器和空间合成器技术进行比较。该研究有望在能源效率、负载变化时更稳健的振荡、更低的相位噪声以及提高振荡和辐射频率的稳定性方面提供优势。在微波或毫米波电路领域，有关简并条件的概念尚未被探索甚至提出。该项目的成果可能使未来几代高效率振荡器，分布式放大器以及新型网格振荡器成为微波和毫米波通信系统的骨干。

High performance electronics is important in a variety of societal applications. Improvements based on the proposed research effort are expected to be significant in terms of energy-efficient electronics and of the quality of the generated oscillating frequency, which are both key features in modern electronic systems. The proposed work explores a new method to generate electromagnetic waves with stable frequencies with low noise and without wasting power. It is expected that the power necessary to provide oscillations is between one-half and one-tenth of that used by conventional oscillators design techniques. The other major outcome of the proposed research is an improved way to generate radiated high power in an efficient fashion, while being technologically simpler than other current solutions. It is known that high power generation at millimeter waves is notoriously challenging because single sources realized using semiconductors cannot provide high power levels. The solution adopted in this work is based on combining the power radiated by many individual radiating oscillators; thanks to a self-locking effect due to the degeneracy condition the oscillation frequency is expected to be pure, i.e., have low noise, and to produce high power radiation levels at a specific direction. Although the research is focused on exploring how to use for the first time the degeneracy condition in radio frequency systems, the acquired theoretical knowledge will also be useful for solving a variety of other problems, such as making highly sensitive sensors. The investigators will provide interdisciplinary training to participating graduate students through research; they will mentor undergraduate students in research fostering diversity in science and technology; and they will disseminate research to both scientific and layman audiences for the broad population to foster interest in electromagnetics and electronics. The proposed research activity aims at providing first a theoretical foundation of microwave and millimeter wave (mm-wave) circuits that are based on the exceptional point of degeneracy (EPD) in coupled-mode circuits and transmission lines. Second, this research will explore and implement various novel applications such as robust conditions of oscillation in distributed oscillators and spatial power combiners made of array grid oscillators. The novelty is based on the recently discovered physical phenomenon of giant resonance in coupled waveguides that support a degenerate band edge (DBE). A DBE is a very special degeneracy condition occurring when critical coupling is established between two or more guided modes. This proposal targets two related outcomes: (1) Theory and demonstration of a novel principle of operation for oscillators in silicon-based technology, including CMOS, based on the DBE; (2) Theory and demonstration of a novel principle of operation of radiation by spatial power combiners made of arrayed, tightly locked oscillating elements operating at an exceptional point of degeneracy (EPD) present in planar coupled-mode structures. The new principle of operation will be theoretically and experimentally investigated at microwaves and millimeter waves, and compared to existing technology of oscillators and spatial combiners. The proposed research is expected to provide advantages in terms of energy efficiency, more robust oscillation in the presence of load variations, lower phase noise, and improved stability of the frequency of oscillation and radiation. The proposed concepts related to degeneracy conditions have not yet been explored or even proposed in the area of microwave or millimeter-wave circuits. Outcomes of this project may enable future generations of high-efficiency oscillators, distributed amplifiers, as well as novel grid oscillators, which are the backbone of any communication system at microwave and mm-waves.