Mahmud Md Shamim, Rosenmann Daniel, Czaplewski David A, Gao Jie, Yang Xiaodong
Opt Express. 2020 Jul 6;28(14):21192-21201. doi: 10.1364/OE.397725.
Plasmon-phonon coupling between metamaterials and molecular vibrations provides a new path for studying mid-infrared light-matter interactions and molecular detection. So far, the coupling between the plasmonic resonances of metamaterials and the phonon vibrational modes of molecules has been realized under linearly polarized light. Here, mid-infrared chiral plasmonic metasurfaces with high circular dichroism (CD) in absorption over 0.65 in the frequency range of 50 to 60 THz are demonstrated to strongly interact with the phonon vibrational resonance of polymethyl methacrylate (PMMA) molecules at 52 THz, under both left-handed and right-handed circularly polarized (LCP and RCP) light. The mode splitting features in the absorption spectra of the coupled metasurface-PMMA systems under both circular polarizations are studied in PMMA layers with different thicknesses. The relation between the mode splitting gap and the PMMA thickness is also revealed. The demonstrated results can be applied in areas of chiral molecular sensing, thermal emission, and thermal energy harvesting.
超材料与分子振动之间的等离激元 - 声子耦合为研究中红外光与物质相互作用及分子检测提供了一条新途径。到目前为止，超材料的等离激元共振与分子的声子振动模式之间的耦合已在线偏振光下实现。在此，展示了在50至60太赫兹频率范围内吸收的圆二色性（CD）超过0.65的中红外手性等离激元超表面，在左旋和右旋圆偏振（LCP和RCP）光下都能与聚甲基丙烯酸甲酯（PMMA）分子在52太赫兹处的声子振动共振发生强烈相互作用。研究了在不同厚度的PMMA层中，两种圆偏振下耦合的超表面 - PMMA系统吸收光谱中的模式分裂特征。还揭示了模式分裂间隙与PMMA厚度之间的关系。所展示的结果可应用于手性分子传感、热发射和热能收集等领域。
