Cooperative emission mediated by cooperative energy transfer to a plasmonic antenna
Cooperative emission mediated by cooperative energy transfer to a plasmonic antenna
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通过协同能量传输到等离子体天线介导的协同发射
作者：
T. Shahbazyan
我们开发了一种协同发射理论，该理论通过从量子发射器（QE）集合到等离子体天线的协同能量转移（CET）来介导，其速率等于单个 QE-等离子体能量转移速率的总和。如果天线辐射效率足够高，则传输的能量将以与整体尺寸大致相同的协作速率辐射出去。我们根据局部场推导了对于特征尺寸小于辐射波长的任何形状的等离激元结构有效的功率谱的协同珀塞尔因子和增强因子的显式表达式。辐射功率谱保留了等离激元共振线形，整体振幅随整体尺寸缩放。如果 QE 位于等离激元局部态密度 (LDOS) 几乎恒定的区域，例如在等离激元纳米腔内，我们证明 CET 速率与激发 QE 的数量呈线性关系，与实验一致，并且可以通过改变激发功率在很宽的范围内进行调整。对于分布在等离激元模式体积饱和的扩展区域中的 QE，我们表明协作 Purcell 因子具有独立于系统尺寸的通用形式。 CET 机制还结合了等离激元 LDOS 增强，从而提供了将发射速率控制在场增强限制之外的可能性。
We develop a theory of cooperative emission mediated by cooperative energy transfer (CET) from an ensemble of quantum emitters (QE) to plasmonic antenna at a rate equal to the sum of individual QE-plasmon energy transfer rates. If the antenna radiation efficiency is sufficiently high, the transferred energy is radiated away at approximately the same cooperative rate that scales with the ensemble size. We derive explicit expressions, in terms of local fields, for cooperative Purcell factor and enhancement factor for power spectrum valid for plasmonic structures of any shape with characteristic size smaller than the radiation wavelength. The radiated power spectrum retains the plasmon resonance lineshape with overall amplitude scaling with the ensemble size. If QEs are located in a region with nearly constant plasmon local density of states (LDOS), e.g., inside a plasmonic nanocavity, we demonstrate that the CET rate scales linearly with the number of excited QEs, consistent with the experiment, and can be tuned in a wide range by varying the excitation power. For QEs distributed in an extended region saturating the plasmon mode volume, we show that the cooperative Purcell factor has universal form independent of the system size. The CET mechanism incorporates the plasmon LDOS enhancement as well, giving rise to possibilities of controlling the emission rate beyond field enhancement limits.