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

对复杂光子系统和平台的需求不断增长，继续推动探索新的光学几何形状，概念和材料系统，以实现复杂和前所未有的功能。另一方面，这些需要对光与材料的相互作用有更深入的理解和精确的控制。现代技术非常感兴趣的一个特定的研究活动，使计算，通信，传感和检测，以及生物成像中的应用成为可能，是开发高效的相干光源，其可以提供超过传统激光器所获得的波长的发射。非线性混波过程，即不同颜色的光可以混合产生新的颜色，通常是追求的策略。这些非线性光源的实现需要严格的物理条件，由光子动量守恒决定。这对设计造成了严重的限制，迄今为止，阻碍了许多高度非线性材料如半导体作为非线性光源的利用。该项目将在理论和实验上探索新的策略，通过设计光子结构中的光损耗来控制非线性混频过程，从而克服这些困难，从输入光子（泵浦光子）到具有所需波长（颜色）的信号光子产生不可逆的能量转换。这将使新的芯片级光源能够在医疗保健、信息技术和传感领域的应用中得到实际应用。协同作用，该项目包括旨在增加光子学未来科学家和工程师的多样性和人才库的外联活动。该小组将组织参与性活动，实验室开放日，并为研究生，本科生和高中生的研究培训机会，重点是来自代表性不足的群体的学生。第2部分：拟议的研究将开发一个综合的理论和实验平台，通过混合过程中的光学损耗的光谱和空间工程开发高效的非线性光源。损耗工程通过去除过程中产生的闲频分量来实现非厄米相位匹配，并且因此允许使用不容易进行厄米相位匹配的高度非线性材料。这也允许非线性过程发生在这样的材料没有严格的波导，色散工程或准相位匹配标准。实现这一目标的途径是：1）建立一个理论模型和平台，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）研究设计策略和实验技术，可控地引入非对称损耗和增益分布以实现混频;利用损耗工程演示波导和谐振腔中的光参量放大和高效非线性光源。非厄米性的结构及其对光学过程的影响，如果得到正确的理解和控制，将为探索新型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知识价值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.