The interaction between light and the time-varying medium exhibits non-Hermitian characteristics, leading to intriguing phenomena, such as parametric amplification, momentum gaps, and temporal refraction. In this study, we introduce the concept of the conformally evolved spatiotemporal modulation, where the space- and time-dependent permittivity function ε (x,t) undergoes rescaling over time, i.e., ε (x,t + Δt) = ε (sx,st). In such systems, spatiotemporal interfaces are no longer modulated at a uniform speed, enabling us to generate a special type of geometric optical comb with exponentially distributed frequency spacing under monochromatic incidence. Compared with traditional linear frequency combs, these optical combs exhibit several distinct properties. First, the excitation of geometric harmonics can drastically amplify the output signal through cascade field enhancement with the appropriate modulation speeds. Second, the designed geometric comb showcases a significant reduction of ambiguous peaks in the autocorrelation, resulting in suppression of reverberation and resolution enhancement for radar detections.

中文翻译：

---

支持共形时空调制的几何频率梳


光与时变介质之间的相互作用表现出非厄米特性，从而导致有趣的现象，例如参数放大、动量间隙和时间折射。在这项研究中，我们引入了共形演化时空调制的概念，其中空间和时间相关的介电常数函数 ε (x,t) 随着时间的推移进行重新缩放，即 ε (x,t + Δt) = ε (sx ，英石）。在这样的系统中，时空界面不再以均匀的速度调制，使我们能够生成一种特殊类型的几何光梳，在单色入射下具有指数分布的频率间隔。与传统的线性频率梳相比，这些光梳表现出多种不同的特性。首先，几何谐波的激励可以通过以适当的调制速度进行级联场增强来大幅放大输出信号。其次，设计的几何梳显着减少了自相关中的模糊峰值，从而抑制了混响并增强了雷达检测的分辨率。