Collaborative Research: Non-Hermitian wave mixing for highly efficient nonlinear light sources

第1部分：对复杂的光子系统和平台的日益增长的需求继续推动探索新的光学几何、概念和材料系统，以实现复杂和前所未有的功能。另一方面，这需要对光与材料的相互作用有更深的理解和精确的控制。现代技术特别感兴趣的一项研究活动，使其在计算、通信、传感和检测以及生物成像中的应用成为可能，这就是开发高效的相干光源，该光源可以提供比传统激光获得的波长更大的发射。通过非线性混波过程，不同颜色的光可以混合产生新的颜色，这是人们经常追求的策略。这些非线性光源的实现需要严格的物理条件，这是由光子动量守恒决定的。这对设计造成了严重的限制，并且到目前为止，阻碍了许多高度非线性材料的利用，例如半导体作为非线性光源。该项目将从理论和实验上探索克服这些困难的新策略，方法是通过在光子结构中设计光学损耗来控制非线性混频过程，创造从输入光子(泵浦光子)到具有所需波长(颜色)的信号光子的不可逆能量转换。这将使新的芯片级光源能够实际应用于医疗保健、信息技术和传感。协同作用，该项目包括旨在增加未来光子学科学家和工程师的多样性和人才库的外联活动。该团队将为研究生、本科生和高中生组织参与性活动、实验室开放参观和研究培训机会，重点是来自代表性不足群体的学生。第二部分：通过对混频过程中的光学损耗进行光谱和空间工程研究，为发展高效的非线性光源提供了一个完整的理论和实验平台。损耗工程通过去除在此过程中产生的空闲分量来实现非厄米相位匹配，从而允许使用不易用于厄米相位匹配的高度非线性材料。这也允许在没有严格的波导、色散工程或准相位匹配标准的情况下，在这种材料中发生非线性过程。实现这一目标的途径是：1)建立一个理论模型和平台来研究损耗工程对非线性混频过程的动力学和效率的影响；2)研究可控地引入非对称混波损耗和增益分布的设计策略和实验技术；以及3)用损耗工程演示光参量放大和在波导和谐振器中的高效非线性光源。非赫米性的结构及其对光学过程的影响，如果得到适当的理解和控制，将为探索新的光子器件和光源提供一个令人兴奋的机会。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。

Part 1: The growing demand for complex photonic systems and platforms continues to push for exploring new optical geometries, concepts and material systems to achieve sophisticated and unprecedented functionalities. These, on the other hand, require a deeper understanding and precise control of the interaction of light with material. One particular research activity of great interest to modern technology, enabling applications in computing, communication, sensing and detection, and bio-imaging, is the development of efficient coherent light sources that can provide emission at wavelengths beyond those obtained by conventional lasers. Nonlinear wave-mixing processes, by which light of different colors can intermix to produce new colors, are often the strategy pursued. The implementation of these nonlinear light sources requires stringent physical conditions dictated by the conservation of photon momentum. This poses serious limitations on the design and, to date, impede the utilization of many highly nonlinear materials such as semiconductors as nonlinear light sources. This project will explore theoretically and experimentally novel strategies to overcome these difficulties by engineering the optical losses in the photonic structures to control the nonlinear wave-mixing process, creating irreversible energy conversion from input photons (pump photons) to signal photons with the desired wavelength (color). This will enable the practical implementation of new chip-scale light sources toward applications in healthcare, information technology and sensing. Synergistically, this project includes outreach activities aiming at increasing the diversity and talent pool of future scientists and engineers in photonics. The team will organize participatory activities, lab open houses, and research training opportunities for graduate, undergraduate, and high school students, with a focus on students from underrepresented groups. Part 2: The proposed research will develop an integrated theoretical and experimental platform for developing efficient nonlinear light sources via spectral and spatial engineering of optical losses in wave-mixing processes. Loss engineering enables non-Hermitian phase matching by removing the idler component produced in the process, and thus allowing the use of highly nonlinear materials that do not lend themselves easily to Hermitian phase-matching. This also allows the nonlinear process to take place in such materials without stringent waveguiding, dispersion engineering or quasi-phase matching criteria. The approaches in pursuit of this goal are: 1) Developing a theoretical model and platform to study the impact of loss engineering on the dynamics and efficiency of nonlinear wave-mixing process; 2) Investigating design strategies and experimental techniques to controllably introduce asymmetric loss and gain profiles for wave-mixing; and 3) Demonstrate optical parametric amplification and efficient nonlinear light sources in waveguides and resonators by loss engineering. The structure of non-Hermiticity and its effects on optical processes, if properly understood and controlled, will present an exciting opportunity to explore novel photonic devices and light sources.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.