There is growing interest in using strongly coupled organic microcavities to tune molecular dynamics, including the electronic and vibrational properties of molecules. However, very little attention has been paid to the utility of cavity polaritons as sensors for out-of-equilibrium phenomena, including thermal excitations. Here, we demonstrate that non-resonant infrared excitation of an organic microcavity system induces a transient response in the visible spectral range near the cavity polariton resonances. We show how these optical responses can be understood in terms of ultrafast heating of electrons in the metal cavity mirror, which modifies the effective refractive index and subsequently the strong coupling conditions. The temporal dynamics of the microcavity are strictly determined by carriers in the metal, including the cooling of electrons via electron–phonon coupling and excitation of propagating coherent acoustic modes in the lattice. We rule out multiphoton excitation processes and verify that no real polariton population exists despite their strong transient features. These results suggest the cavity polaritons to be promising as sensitive probes of non-equilibrium phenomena.

中文翻译：

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有机微腔中强耦合的超快热改性

使用强耦合有机微腔来调节分子动力学（包括分子的电子和振动特性）的兴趣日益浓厚。但是，很少有人将腔极化子用作不平衡现象（包括热激发）的传感器。在这里，我们证明了有机微腔系统的非共振红外激发会在腔极化子共振附近的可见光谱范围内引起瞬态响应。我们展示了如何根据金属腔镜中电子的超快加热来理解这些光学响应，这会改变有效折射率，进而改变强耦合条件。微腔的时间动态严格取决于金属中的载流子，包括通过电子-声子耦合对电子进行冷却，以及激发晶格中传播的相干声模。我们排除了多光子激发过程，并验证了尽管它们具有很强的瞬态特征，但没有真正的极化子种群存在。这些结果表明腔极化子有望作为非平衡现象的敏感探针。