Modeling and Design Optimization of High Frequency Micro and Nano Structures Exploiting Adjoint Sensitivity Analysis

在过去的几年中出现了许多高频技术，提供了有趣的功能。例如，超材料引入了具有自然界中不存在的特性的材料。它们被用于建造在不同频率范围内工作的小型化天线、传感器和滤波器。等离子体器件利用金属-介电界面来引导衍射极限以下的光。这使得光子器件的尺寸更小，从而有望实现光子处理单元的更多集成。提出了用于高频能量采集和视距通信的纳米天线。由于最近太赫兹源和探测器的可用性，太赫兹（THz）应用也出现了。所有这些技术利用的材料，其性质可能取决于源值（非线性），取决于频率（色散），或取决于激发方向（各向异性）。这些特性的不同组合可能存在于这种高频结构中。这些复杂的属性使得对这些设备进行精确建模需要大量的时间和内存。这些结构的优化通常需要估计目标响应相对于所有参数的灵敏度。估计这些灵敏度的经典方法需要对这些时间密集型结构进行反复模拟，这可能是令人望而却步的。***在本提案中，我们将利用我们在伴随灵敏度分析方面的专业知识来开发通用伴随灵敏度方法。这些方法将适用于一般的高频结构，其材料可能表现出非线性、色散和各向异性的任何组合。使用我们的方法，期望的响应或目标函数的灵敏度将被估计使用最多一个额外的模拟，而不管参数的数量。伴随灵敏度将应用于超材料结构、等离子体结构、纳米天线、太赫兹滤波器和频率选择表面的设计优化。我们将开发的伴随技术应用于宽带隐身领域，在该领域，斗篷可以拥有大量可优化的参数。我们还将利用伴随灵敏度分析来提高不同样品的太赫兹成像和光谱的准确性。***拟议的研究涉及加拿大和世界的重要研究领域，包括能量收集、太赫兹医学成像和大型电子物体的宽带隐身。它将产生新技术，加拿大公司将利用这些技术创造新产品或开发现有产品。它也将培养一批高素质的人才（HQP）在建模，设计优化，制造和表征先进的高频微纳米结构。**

A number of high frequency technologies emerged over the past few years that offer interesting functionalities. Metamaterials, for example, introduced materials with properties that do not exist in nature. They are used in building miniaturized antennas, sensors, and filters that operate in different frequency ranges. Plasmonic devices utilize metal-dielectric interfaces to guide light below the diffraction limit. This allows the implementation of photonic devices with much smaller dimensions thus promising more integration of photonic processing units. Nano antennas (nantennas) were presented for high frequency energy harvesting and line-of-sight communication. Terahertz (THz) applications also emerged thanks to the recent availability of THz sources and detectors. All these technologies utilize materials whose properties may be dependent on source values (nonlinear), dependent on frequency (dispersive), or dependent on the direction of excitation (anisotropic). Different combinations of these properties may exist in such high frequency structures. These complex properties make the accurate modeling of these devices time- and memory-intensive. Optimization of these structures often requires estimating sensitivities of the target response with respect to all parameters. The classical approach for estimating these sensitivities requires repeated simulations of these time-intensive structures which may be prohibitive.***In this proposal, we will build on our expertise in adjoint sensitivity analysis to develop universal adjoint sensitivity approaches. These approaches will apply to general high frequency structures whose materials may exhibit any combination of nonlinearity, dispersion, and anisotropy. Using our approaches, the sensitivities of the desired response or objective function will be estimated using at most one extra simulation regardless of the number of parameters. Adjoint sensitivities will be applied to the design optimization of metamaterial structures, plasmonic structures, nantennas, and THz filters and frequency selective surfaces. We will apply our developed adjoint techniques to the area of wideband cloaking where a cloak can possess a large number of optimizable parameters. We will also utilize adjoint sensitivity analysis to improve the accuracy of THz imaging and spectroscopy of different samples.***The proposed research addresses important areas of research for Canada and the world including energy harvesting, THz medical imaging, and wideband cloaking of electrically large objects. It will result in novel technologies that will be utilized by Canadian companies to create new products or develop existing ones. It will also train a good number of high quality personnel (HQP) on modeling, design optimization, fabrication, and characterization of advanced high frequency micro and nano structures. **