The resonance properties of a plasmonic dipole antenna array depend on its geometry and the properties of its surrounding medium. The linear optical properties of an array of plasmonic dipole antennas can be modified with the inclusion of an epsilon-near-zero (ENZ) thin film. In this work, we numerically investigate the roles of the antenna dimensions, the ENZ film thickness and loss, and the separation between the antenna and the ENZ film in determining the linear optical response of the antenna–ENZ metasurface. The results show that for a sufficiently small separation, the linear optical properties of the antenna array are determined by the strong or ultrastrong coupling with the ENZ film and are only weakly dependent on the antenna geometry. We show that for metasurfaces with thick, lossy ENZ films, the lower polariton branch is not observable due to the high loss of ENZ films. Since the dependence of the upper polariton on antenna length is weak, this results in a single antenna-length-invariant resonance. However, in the presence of low-loss ENZ films, the lower polariton branch is also visible for antenna–ENZ metasurfaces with thicker ENZ films, indicating a strong coupling between the antenna array and the ENZ film. For a given antenna geometry, the coupling strength increases with increasing thickness of the ENZ film and can reach up to ∼50% of the zero-permittivity frequency of the ENZ film, indicating an ultrastrong coupling between the plasmonic antenna array and the ENZ film.

中文翻译：

---

等离子体天线阵列和亚波长 epsilon-near-zero 薄膜之间的耦合特性对结构和材料参数的依赖性

等离子体偶极子天线阵列的共振特性取决于其几何形状和周围介质的特性。等离子体偶极子天线阵列的线性光学特性可以通过包含近零 (ENZ) 薄膜的 epsilon 进行修改。在这项工作中，我们数值研究了天线尺寸、ENZ 薄膜厚度和损耗以及天线和 ENZ 薄膜之间的间隔在确定天线-ENZ 超表面的线性光学响应中的作用。结果表明，对于足够小的间隔，天线阵列的线性光学特性由与 ENZ 薄膜的强或超强耦合决定，并且仅微弱地依赖于天线几何形状。我们表明，对于具有厚、有损 ENZ 膜的超表面，由于 ENZ 薄膜的高损耗，无法观察到较低的极化子分支。由于上极化子对天线长度的依赖性很弱，这会导致单个天线长度不变谐振。然而，在存在低损耗 ENZ 膜的情况下，对于具有较厚 ENZ 膜的天线-ENZ 超表面也可以看到较低的极化子分支，这表明天线阵列和 ENZ 膜之间存在强耦合。对于给定的天线几何形状，耦合强度随着 ENZ 薄膜厚度的增加而增加，并且可以达到 ENZ 薄膜零介电常数频率的 50%，表明等离子体天线阵列和 ENZ 薄膜之间存在超强耦合。这会导致单个天线长度不变的共振。然而，在存在低损耗 ENZ 膜的情况下，对于具有较厚 ENZ 膜的天线-ENZ 超表面也可以看到较低的极化子分支，这表明天线阵列和 ENZ 膜之间存在强耦合。对于给定的天线几何形状，耦合强度随着 ENZ 薄膜厚度的增加而增加，并且可以达到 ENZ 薄膜零介电常数频率的 50%，表明等离子体天线阵列和 ENZ 薄膜之间存在超强耦合。这会导致单个天线长度不变的共振。然而，在存在低损耗 ENZ 膜的情况下，对于具有较厚 ENZ 膜的天线-ENZ 超表面也可以看到较低的极化子分支，这表明天线阵列和 ENZ 膜之间存在强耦合。对于给定的天线几何形状，耦合强度随着 ENZ 薄膜厚度的增加而增加，并且可以达到 ENZ 薄膜零介电常数频率的 50%，表明等离子体天线阵列和 ENZ 薄膜之间存在超强耦合。