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光与金属纳米手性结构作用可展现超强的等离激元圆二色性. 然而, 光激发下金属纳米手性结构的光力与光热的协同作用效应如何影响其圆二色性, 仍缺乏深入的理解. 本研究针对具有相邻同手性中心的金纳米棒三聚体, 探讨了圆偏振光激发下的不对称光力与光热的协同作用效应对其手性结构及相应等离激元圆二色性质的影响. 基于有限元法的模拟计算表明: 在光热温度梯度场激活金纳米棒手性三聚体的结构动态变化的同时, 左旋/右旋圆偏振光产生的不对称光扭矩将导致金纳米棒三聚体几何结构(特别是手性中心的扭转角)出现不对称变化, 从而使金纳米棒三聚体的等离激元圆二色光谱响应呈现明显的偏振依赖性. 进一步的实验研究表明: 基于这种不对称光力与光热的协同作用效应, 左旋和右旋圆偏振光能够用于调控等离激元圆二色光谱响应的不对称增强和抑制. 本研究不仅为研究光学调控纳米等离激元手性组装结构奠定了理论基础, 也为实验设计和制备物理方法调控的先进纳米光子学器件提供了重要参考.Nano-plasmonic chiral structures exhibit stronger plasmonic circular dichroism than most organic materials. In addition to the circular dichroism response, the interaction between light and nano-plasmonic chiral structure also involves the photothermal and optomechanical effects. However, the synergy between the photothermal and optomechanical effects under circularly polarized light excitation remains poorly understood. This work investigates the synergy of the photothermal and optomechanical effects in chiral gold nanorod trimers. The asymmetric photothermal and optomechanical effects in gold nanorod trimers with adjacent homochiral centers are analyzed by finite element simulation. The simulation results show that the dynamic structure of the chiral gold nanorod trimer is activated when the photothermal temperature reaches the threshold value. At the same time, the asymmetric optical torque generated by left- and right-handed circularly polarized light will lead to asymmetric changes in the geometry of the gold nanorod trimer, especially in the twist angle of the chiral center, so that the spectral response of the gold nanorod trimer is polarization-dependent. More significantly, based on the synergy of the photothermal and optomechanical effects, experimental results show that the chiral gold nanorod oligomers can be used to control the asymmetric enhancement and suppression of the plasmonic circular dichroic spectral response through the enantioselective interaction of left- and right-handed circularly polarized light. This study provides an important reference for designing advanced nano-photonics devices.
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Keywords:
- nano-plasmonic chirality /
- circular dichroism /
- asymmetric optomechanical effect /
- asymmetric photothermal effect
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