Schwennicke Kai, Koner Arghadip, Pérez-Sánchez Juan B, Xiong Wei, Giebink Noel C, Weichman Marissa L, Yuen-Zhou Joel
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
Department of Electrical Engineering and Computer Science, and Physics, University of Michigan, Ann Arbor, MI 48109, USA.
Chem Soc Rev. 2025 Jun 30;54(13):6482-6504. doi: 10.1039/d4cs01024h.
This review outlines several linear optical effects featured by molecular polaritons arising in the collective strong light-matter coupling regime. Under weak laser irradiation and when the single-molecule light-matter coupling can be neglected (often in the limit when the number of molecules per photon mode is large), we show that the excited-state molecular dynamics under collective strong coupling can be exactly replicated without the cavity using a shaped (or "filtered") laser, whose field amplitude is enhanced by the cavity quality factor, shining on the bare molecules. As a consequence, the absorption within a cavity can be understood as the overlap between the polariton transmission and the bare molecular absorption, suggesting that polaritons act in part as optical filters. This framework demystifies and provides a straightforward explanation for a large class of experiments and theoretical models in molecular polaritonics, highlighting that the same effects can be achieved without the cavity with shaped laser pulses. With a few modifications, this simple conceptual picture can also be adapted to understand the incoherent nonlinear response of polaritonic systems. This review establishes a clear distinction between polaritonic phenomena that can be fully explained through classical linear optics and those that require a quantum electrodynamics approach. It also highlights the need to differentiate between effects that necessitate polaritons (, hybrid light-matter states) and those that can occur in the weak coupling regime. We further discuss that certain quantum optical effects like fluorescence can be partially described as optical filtering, whereas some others like cavity-induced Raman scattering go beyond this. Further exploration in these areas is needed to uncover novel polaritonic phenomena beyond optical filtering.
本综述概述了在集体强光 - 物质耦合 regime 中出现的分子极化激元所具有的几种线性光学效应。在弱激光照射下，当单分子光 - 物质耦合可以忽略时（通常在每个光子模式下分子数量很大的极限情况下），我们表明，在不使用腔的情况下，利用场振幅因腔品质因数而增强的整形（或“滤波”）激光照射裸分子，集体强耦合下的激发态分子动力学可以被精确复制。因此，腔内的吸收可以理解为极化激元透射与裸分子吸收之间的重叠，这表明极化激元部分地起到了光学滤波器的作用。这个框架揭开了分子极化激元学中一大类实验和理论模型的神秘面纱，并提供了一个直接的解释，强调了使用整形激光脉冲在不使用腔的情况下可以实现相同的效应。经过一些修改，这个简单的概念图景也可以用于理解极化激元系统的非相干非线性响应。本综述明确区分了可以通过经典线性光学完全解释的极化激元现象和那些需要量子电动力学方法的现象。它还强调了区分需要极化激元（即混合光 - 物质态）的效应和那些可以在弱耦合 regime 中发生的效应的必要性。我们进一步讨论了某些量子光学效应，如荧光，可以部分地描述为光学滤波，而其他一些效应，如腔诱导拉曼散射，则超出了这一范畴。需要在这些领域进行进一步探索，以发现超越光学滤波的新型极化激元现象。
