AI 中文总结
针对现有时空超材料散射分析方法的局限性，提出通用框架STESEM，通过分解散射过程无需坐标变换，推导典型结构散射响应，为相关超材料设计奠定基础。
AI 中文摘要
时空超材料通过同时操控空间和时间自由度，为电磁波提供了前所未有的调控能力。然而，对其散射过程的分析描述仍零散不全，现有方法通常需要针对特定构型进行推导，或转换至专用参考系，这对于加速结构或多界面结构而言变得不切实际。在本教程中，我们提出时空事件散射与扩展方法（STESEM），这是一种用于任意时空界面处电磁散射的通用框架。通过将散射过程分解为局部相互作用事件，以及沿不变行波坐标的后续扩展，STESEM可直接在实验室坐标系中构建时空散射，无需坐标变换。该方法对任意入射波形和界面轨迹的散射振幅、频率转换和相位变换提供了统一描述。我们通过推导典型时空结构的完整散射响应来演示该框架，包括静止界面、瞬时界面、时空拐角、匀速运动界面、楔形体及加速边界。除提供解析解外，STESEM还揭示了这些不同现象背后的物理原理，并表明复杂的时空散射过程可由基本的运动界面相互作用构建。该框架为分析和设计先进的时空超材料奠定了系统基础，可扩展至色散、双各向异性及高维系统。
英文摘要
Space-time metamaterials offer unprecedented control over electromagnetic waves by enabling simultaneous manipulation of spatial and temporal degrees of freedom. However, analytical descriptions of their scattering processes remain fragmented, with existing approaches typically requiring configuration-specific derivations or transformations to specialized reference frames that become impractical for accelerated or multi-interface structures. In this tutorial, we introduce the space-time event scattering and extension method (STESEM), a universal framework for electromagnetic scattering at arbitrary space-time interfaces. By decomposing the scattering process into a local interaction event and a subsequent extension along invariant traveling-wave coordinates, STESEM formulates space-time scattering directly in the laboratory frame without requiring coordinate transformations. The method provides a unified description of scattering amplitudes, frequency transitions and phase transformations for arbitrary incident waveforms and interface trajectories. We demonstrate the framework by deriving the complete scattering responses of canonical space-time structures, including stationary and instantaneous interfaces, space-time corners, uniformly moving interfaces, wedges and accelerated boundaries. Beyond providing analytical solutions, STESEM reveals the physical principles underlying these distinct phenomena and shows that complex space-time scattering processes can be constructed from elementary moving-interface interactions. This framework establishes a systematic foundation for analyzing and designing advanced space-time metamaterials, enabling extensions toward dispersive, bianisotropic and higher-dimensional systems.
Comments19 pages, 3 figures
