发表机构
Aalto University（阿尔托大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一种逆向设计框架，联合优化多层时空周期结构的介电常数与时间调制，实现可编程频率-动量散射，支持多通道独立控制与频率-动量梳生成。
AI 中文摘要
时空变化电磁结构能够解锁静态介质无法实现波控制机制，包括频率转换、谐波产生以及频率和动量的联合控制。本文提出了一种针对多层时空周期结构的逆向设计框架，其中空间介电常数分布和时间调制轮廓被联合优化。所提出的平台包含多个像素化层，这些层沿一个或两个横向方向周期排列，并在时间上谐波调制，从而能够直接合成复杂的多通道频率-动量散射响应。我们展示了两个代表性功能：独立控制三个透射时空通道的幅度和相位，以及生成频率-动量梳。在这些示例中，我们考虑了连续和二进制介电常数分布。为了促进可重复性和进一步发展，我们免费提供优化框架的数值实现。这些结果表明，逆向设计的时变多层结构为可编程频率-动量复用和时空波包合成提供了一条紧凑且多功能的途径。优化代码公开可用，以促进所提出的逆向设计框架的可重复性和进一步发展。
英文摘要
Space-time-varying electromagnetic structures unlock wave-control mechanisms inaccessible to static media, including frequency conversion, harmonic generation, and joint control over frequency and momentum. Here, we introduce an inverse-design framework for multilayer space-time-periodic structures in which the spatial permittivity distribution and temporal modulation profile are optimized jointly. The proposed platform comprises multiple pixelated layers that are periodic along one or both transverse directions and harmonically modulated in time, enabling the direct synthesis of complex multichannel frequency-momentum scattering responses. We demonstrate two representative functionalities: independent control over the amplitudes and phases of three transmitted spatiotemporal channels and the generation of a frequency-momentum comb. Across these examples, we consider both continuous and binary permittivity distributions. To facilitate reproducibility and further development, we make the numerical implementation of the optimization framework freely available. These results demonstrate that inverse-designed time-varying multilayers provide a compact and versatile route toward programmable frequency-momentum multiplexing and the synthesis of space-time wave packets. The optimization code is made openly available to facilitate reproducibility and further development of the proposed inverse-design framework.
