AI 中文总结
研究聚焦强耦合光 - 物质系统中极化激元传输，通过扩展FDTD模拟开发微扰框架，利用DBR腔完整模态设计模式转换器，实现分子激发长距离低损耗传输，突破分子极化激元传输局限。
AI 中文摘要
我们展示了如何扩展时域有限差分（FDTD）模拟以对超快非线性显微镜进行建模，从而能够预测任意电磁环境中的空间分辨泵浦 - 探测信号。聚焦于强耦合光 - 物质系统中的极化激元传输，我们开发了一个微扰框架来研究纳米光子结构中混合光 - 物质激发的超快传播。首先将该框架应用于标准分布式布拉格反射器（DBR）腔，重现了多模塔维斯 - 卡明斯模型中极化激元传输的既定结果。接着考虑同一腔的完整模态图景，包括通常在单模描述中被忽略的低于光线的导模。利用这些模式设计了紧凑的模式转换器，可将辐射腔极化激元转换为类光子导极化激元并再转换回来，利用导模进行低损耗传输。尽管存在分子退相，这使得分子激发能传输超过一毫米，比当前传输实验超出一个数量级。我们还计算了泵浦 - 探测差分传输信号，提供了该机制的实验特征。结果表明光子腔的模态图景可被设计以绕过通常被认为是分子极化激元传输固有局限的限制。
英文摘要
We show how finite-difference time-domain (FDTD) simulations can be extended to model ultrafast nonlinear microscopy, enabling the prediction of spatially-resolved pump--probe signals in arbitrary electromagnetic environments. Focusing on polariton transport in strongly coupled light--matter systems, we develop a perturbative framework to study the ultrafast propagation of hybrid light--matter excitations in nanophotonic structures. We first apply the framework to a standard distributed Bragg reflector (DBR) cavity, reproducing established results for polariton transport from a multimode Tavis--Cummings model. We then consider the full modal landscape of the same cavity, including guided modes below the light line that are typically neglected in single-mode-family descriptions. Exploiting these modes, we design compact mode converters that transfer radiative cavity polaritons into photon-like guided polaritons and back, utilizing the guided modes for low-loss propagation. Despite molecular dephasing, this enables transport of molecular excitation over a millimeter, an order of magnitude beyond current transport experiments. We further compute the pump--probe differential transmission signal, providing an experimental signature of the mechanism. Our results show that the modal landscape of a photonic cavity can be engineered to bypass limitations commonly assumed to be intrinsic to the transport of molecular polaritons.
Comments27 pages, 14 figures
