We study the collective effects of an ensemble of organic molecules confined in an optical cavity based on the Holstein–Tavis–Cummings model. By using the quantum Langevin approach and adiabatically eliminating the degree of freedom of the vibrational motion, we analytically obtain the expression of the cavity transmission spectrum to analyze the features of polaritonic states. As an application, we show that the dependence of the frequency shift of the lower polaritonic state on the number of molecules can be used in the detection of the ultra-cold molecules. We also numerically analyze the fluorescence spectrum. The variation of the spectral profile with various numbers of molecules provides signatures for the modification of molecular conformation.

我们基于 Holstein-Tavis-Cummings 模型研究限制在光腔中的有机分子集合的集体效应。利用量子朗之万方法，对振动运动的自由度进行绝热消去，解析得到腔透射谱的表达式来分析极化态的特征。作为一个应用，我们表明低极化状态的频移对分子数量的依赖性可用于检测超冷分子。我们还对荧光光谱进行了数值分析。光谱分布随不同分子数的变化提供了分子构象修饰的特征。