Superior Nonlinear Optical Single Crystals and An Open-Source Modeling Package for Classical and Quantum Light Generation

非技术性的描述。自1960年第一台激光器问世以来，激光器已经改变了科学和技术领域。激光使从原子尺度到天文学的基础科学得以实现，并有许多应用，例如信息存储和检索，医学成像和外科手术，环境监测和航空，仅举几例。对于如此广泛的用途，重要的是要跨越广泛的电磁频谱频率（颜色），从x射线和紫外线，到可见光和红外线以及更远的范围。然而，激光被设计成只能在几个狭窄的频率窗口内发射光。那么，如何才能获得如此宽的可调谐电磁频谱呢？答案就在非线性光学领域，专门的材料将不同颜色的光子结合和分裂，产生不同颜色的新光子，这个过程被称为非线性频率转换或谐波产生。我们现在正处于量子通信新时代的门槛，量子通信使用两个光子的量子纠缠，爱因斯坦称之为“幽灵般的远距离作用”。这种安全的互联网线路被认为对国家安全至关重要，从保护电网、水和食品分配网络到金融系统。纠缠光子是利用非线性光学晶体将光子一分为二而产生的。这需要比目前使用的光学晶体更好的非线性光学晶体。特别是，缺乏在红外线和紫外线中起作用的材料。该项目将解决寻找具有优异性能的新型非线性光学晶体的重大材料挑战。PI还将传达这些令人惊叹的光学和量子现象的兴奋和基本原理，并努力帮助培养多样化，有能力的劳动力来应对这些技术挑战。技术描述。该项目的中心目标是合成和表征非线性光学单晶，其成分优化了最高的二阶非线性光学系数，并具有最大的透明度，从而实现有效的频率转换。该项目有两个主要目标。首先，在“超越粉末走向单晶”的主题下，研究人员将在理论指导下对粉末理论和实验文献中提出的最有前途的非线性光学单晶进行识别、合成和综合线性和非线性光学张量测定。第二个重点是非线性建模和光频率转换。在表征非线性光学中这种高阶张量特性时，实验数据的精确建模至关重要；目前还缺乏用于此的分析建模工具。该项目正在开发一个开源代码，用于预测和准确模拟这些晶体的实验非线性光学响应。非线性的频率转换装置正在探索最有前途的晶体组成。该项目正致力于展示至少12种新的单晶，同时开发一个开源建模包。该项目每年资助两名研究生和一名本科生的培训，以培养光学材料和技术领域多元化和包容性的劳动力。学生有机会学习和发展晶体生长，以及一套完整的非线性光学表征和建模工具。通过与伙伴机构的接触，与代表性不足的学生群体进行强有力的接触和接触。该奖项反映了美国国家科学基金会的法定使命，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。

Nontechnical Description. Lasers have transformed the science and technological landscape since the first was built in 1960. Lasers enable fundamental science from the atomic scale to astronomical and have numerous applications, such as information storage and retrieval, medical imaging and surgery, environmental monitoring, and aviation, to name a few. For such a broad array of uses, it is important to span a broad electromagnetic spectrum of frequencies (colors), ranging from x-rays and the ultraviolet, through the visible and the infrared and beyond. However, lasers are designed to emit light only within a few narrow windows of frequencies. So, how can such a broad tunable electromagnetic spectrum be obtained? The answer lies in the field of nonlinear optics, where specialized materials combine and split photons of various colors to generate new photons with different colors, a process called nonlinear frequency conversion or harmonic generation. We are now at the threshold of a new era of quantum communications that employs quantum entanglement of two photons that Einstein called “spooky action at a distance.” Such secure internet lines are considered critical for national security, from protecting power grids, distribution networks for water and food, and the financial system. Entangled photons are generated by splitting a photon into two using nonlinear optical crystals. This needs nonlinear optical crystals superior to those presently in use. In particular, there is a lack of materials that function in the infrared and the ultraviolet. The project will address the grand materials challenge of finding new nonlinear optical crystals with superior properties. The PI will also communicate the excitement and fundamentals of these amazing optical and quantum phenomena and work to help develop a diverse, able workforce to meet these technology challenges.Technical Description. The central goal of this project is to synthesize and characterize nonlinear optical single crystals with compositions that optimize the highest second order nonlinear optical coefficients with the largest transparency towards efficient frequency conversion. The project has two primary thrusts. First, under the theme of Beyond Powders towards Single Crystals, investigators will perform theory-guided identification, synthesis, and comprehensive linear and nonlinear optical tensors determination of the most promising nonlinear optical single crystals suggested by theory and experimental literature on powders. The second thrust is on Nonlinear Modeling and Light Frequency Conversion. In characterizing such higher ranked tensor properties in nonlinear optics, accurate modeling of the experimental data is critical; analytical modeling tools for this are currently absent. The project is developing an open-source code for predicting and accurately modeling the experimental nonlinear optical response from these crystals. Nonlinear frequency conversion devices are being explored for the most promising crystal compositions. The project is working towards demonstrating at least a dozen new single crystals, as well developing as an open-source modeling package. The project funds the training of two graduate and one undergraduate student every year towards a diverse and inclusive workforce in the area of optical materials and technologies. The students have an opportunity to learn and develop crystal growth as well as a full suite of nonlinear optical characterization and modeling tools. Strong outreach and engagement with underrepresented student groups occurs through engagement with partner institutions.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.