Double-layered wide-bandgap photonic materials for efficient nonlinear applications without periodic poling

职务名称：双层宽带隙光子材料用于高效的非线性应用，而无需周期性极化开发高效，可扩展的非线性纳米光子学平台将使大量的经典和量子应用成为可能，包括波长转换，图像恢复，量子增强传感和防黑客量子通信。目前，有效的二阶非线性过程主要是通过在铁电材料（例如锂酸盐）中应用所谓的准相位匹配（QPM）技术来实现的，其中材料的极性被周期性地极化（反转）以实现不同波之间的相长相互作用。然而，QPM的制造在薄膜纳米光子学平台（例如，绝缘体上的硼酸锂）中是具有挑战性的，因为由于更强的波导色散，与其庞大的对应物相比，极化周期显著减小。此外，鉴于QPM通常是针对一个特定的非线性过程设计的，实际上很难在同一芯片上实现多个不同的非线性过程，因此严重限制了集成光子学的缩放潜力。最后，QPM技术不能容易地推广到诸如碳化硅和氮化铝的非铁电材料，因为除了在生长期间之外，没有已知的方法来改变它们的畴极性。该项目旨在开发一种新型的双层纳米光子学平台，用于高效的非线性应用，而无需周期性极化，为广泛的集成光子学社区面临的一些最紧迫的问题提供了一个优雅的解决方案，包括可调谐性，效率和可扩展性。双层器件的概念可以推广到大多数二阶非线性材料，如锂离子电池、碳化硅、氮化铝、氮化镓、磷化镓等，最后，本项目还将培养光学和量子光子学领域的本科生和研究生，并将研究成果融入相关课程和推广计划。本研究的核心思想是堆叠两层极性相反的二阶非线性材料，并将二阶横磁模作为相互作用的模波之一。这种配置允许同时实现相位匹配和良好的模态重叠，这大大简化了制造工艺，并且使得能够在同一芯片上可扩展地实现各种非线性工艺。研究小组将重点研究两种宽带隙光子材料，即，碳酸锂和碳化硅，它们由于其独特的材料性能而引起了人们的极大兴趣。这种双层纳米光子学材料将被研究用于几个重要的应用，包括高效的二次谐波产生，和频产生，以及在锂离子电池中的光学参量振荡，和量子频率转换，用于将可见光波段的单光子转换为碳化硅的电信波段。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。

Title: Double-layered wide-bandgap photonic materials for efficient nonlinear applications without periodic polingDeveloping efficient, scalable nonlinear nanophotonics platforms would enable a host of classical and quantum applications including wavelength conversion, image restoration, quantum-enhanced sensing and hacker-proof quantum communication. Currently, efficient second-order nonlinear processes are predominantly realized by applying the so-called quasi-phase-matching (QPM) technique in ferroelectric materials such as lithium niobate, where the polarity of the material is periodically poled (inverted) to achieve constructive interaction between different waves. However, fabrication of QPM is challenging in thin-film nanophotonics platforms such as lithium niobate-on-insulator, as the poling period is significantly reduced compared to their bulky counterparts due to stronger waveguide dispersion. In addition, given that QPM is customarily designed for one specific nonlinear process, it is practically difficult to implement multiple different nonlinear processes on the same chip, thus severely limiting the scaling potential of integrated photonics. Finally, the QPM technique cannot be easily generalized to non-ferroelectric materials such as silicon carbide and aluminum nitride, as there is no known method to alter their domain polarity other than during the growth period. This project aims to develop a novel double-layered nanophotonics platform for efficient nonlinear applications without periodic poling, which provides an elegant solution to some of the most pressing issues faced by the broad integrated photonics community, including tunability, efficiency and scalability. The double-layered device concept can be generalized to most of second-order nonlinear materials such as lithium niobate, silicon carbide, aluminum nitride, gallium nitride, gallium phosphide, etc., potentially transforming the way of nonlinear optical processes being implemented on these materials and improving the overall efficiency significantly.Finally, this project also trains undergraduate and graduate students in the area of optics and quantum photonics, and the research findings will be integrated into relevant courses and outreach programs. The core idea of this research is to stack two layers of second-order nonlinear materials with opposite polarity and employ the second-order transverse-magnetic mode as one of the interacting modes waves. This configuration allows achieving phase matching and good modal overlap simultaneously, which greatly simplifies the fabrication process and enables scalable implementation of various nonlinear processes on the same chip. The team of researchers will focus on two wide-bandgap photonic materials, i.e., lithium niobate and silicon carbide, which have generated a lot of recent interests due to their unique material properties. Such double-layered nanophotonics materials will be investigated for several important applications, including efficient second-harmonic generation, sum-frequency generation, and optical parametric oscillation in lithium niobate, and quantum frequency conversion for converting single photons in the visible band to the telecom band in silicon carbide.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.