可调谐双曲超材料用于增强单光子发射
Tunable hyperbolic metamaterials for brightening single-photon emission
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中文总结 AI 辅助
本研究通过系统评估双曲超材料中自发辐射增强与光子输出耦合，提出辐射Purcell因子作为更可靠品质因数，并利用相变材料实现动态可调谐、明亮的单光子源。
中文摘要 AI 辅助
双曲超材料（HMMs）因其异常大的光子态密度而被广泛用于增强自发辐射，然而大的Purcell因子（>100）很少转化为更亮的发射，这既暴露了HMMs作为增亮平台的实际局限性，也暴露了Purcell因子本身作为品质因数的缺陷。在此，我们利用有效介质理论、传输矩阵计算和全波FDTD模拟，系统评估了金属-介质HMMs（TiO$_2$/Ag和相变Sb$_2$S$_3$/Ag）中的自发辐射增强和光子输出耦合。我们表明，Purcell因子超过100的平面HMMs的外部量子效率低于0.01，导致实际辐射Purcell因子（PF$_{rad}$）仅为1-2。将HMM纳米图案化为光子晶体可有效地将捕获的高k模式耦合到自由空间，使PF$_{rad}$提高一个数量级。引入相变材料Sb$_2$S$_3$进一步实现了双曲光谱窗口的动态调谐和对发射亮度的主动控制：优化的纳米结构设计在近红外区域达到PF$_{rad}$ ~ 10-15，相变时开关对比度超过15倍。这些结果确立了辐射Purcell因子作为工程量子发射器比传统Purcell因子更可靠的品质因数，并为基于双曲超材料的主动可调谐、明亮单光子源提供了实用途径。
英文摘要
Hyperbolic metamaterials (HMMs) are widely used to enhance spontaneous emission through their exceptionally large photonic density of states, yet large Purcell factors (>100) rarely translate into brighter emission, exposing both a practical limitation of HMMs as brightening platforms and a flaw in the Purcell factor itself as a figure of merit. Here we systematically evaluate spontaneous emission enhancement and photon outcoupling in metal-dielectric HMMs (TiO$_2$/Ag and phase-change Sb$_2$S$_3$/Ag) using effective medium theory, transfer matrix calculations, and full-wave FDTD simulations. We show that planar HMMs with Purcell factors exceeding 100 have external quantum efficiencies below 0.01, yielding an actual radiative Purcell factor (PF$_{rad}$) of only 1-2. Nanopatterning the HMM into a photonic crystal efficiently couples trapped high-k modes into free space, raising PF$_{rad}$ by an order of magnitude. Incorporating the phase-change material Sb$_2$S$_3$ further enables dynamic tuning of the hyperbolic spectral window and active control over emission brightness: an optimized nanostructured design reaches PF$_{rad}$ ~ 10-15 in the near-infrared, with switching contrast exceeding a factor of 15 upon phase transition. These results establish the radiative Purcell factor as a more reliable figure of merit than the conventional Purcell factor for engineering quantum emitters, and provide a practical route toward actively tunable, bright single-photon sources based on hyperbolic metamaterials.
发表机构
- Ludwig-Maximilians-Universität München（慕尼黑大学）
- Brno University of Technology（布尔诺理工大学）
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