Wang Dunjian, Luo Jie, Sun Zhouzhou, Lai Yun
Opt Express. 2021 Feb 15;29(4):5247-5258. doi: 10.1364/OE.416632.
In this work, we demonstrate an approach to realize geometry-invariant multi-channel coherent perfect absorbers by embedding ultrathin conductive films in zero-index media. Coherent perfect absorption can be achieved for waves incidents from an arbitrary number of input channels as long as the total width of the channels equals to a critical value that is only determined by the length and material parameters of the conductive films instead of their shapes and positions. The absorption attributes to induced currents in the conductive films by the electric fields of incidence, and the shape- and position-independent characteristics originate from the uniformly distributed electric fields inside the zero-index media. By using dielectric photonic crystals and photonic-doped zero-index media, we numerically demonstrate such an interesting transformation from zero-index media to coherent perfect absorbers. Furthermore, ultrathin coherent perfect absorbers based on zero-index media are also demonstrated in waveguides. Our work reveals a unique mechanism to change the material responses between zero-index media and coherent perfect absorbers.
在这项工作中，我们展示了一种通过将超薄导电膜嵌入零折射率介质中来实现几何不变多通道相干完美吸收体的方法。只要通道的总宽度等于一个仅由导电膜的长度和材料参数而非其形状和位置决定的临界值，对于从任意数量输入通道入射的波都可以实现相干完美吸收。这种吸收归因于入射电场在导电膜中感应出的电流，而与形状和位置无关的特性源于零折射率介质内部均匀分布的电场。通过使用介电光子晶体和光子掺杂零折射率介质，我们通过数值方法证明了从零折射率介质到相干完美吸收体的这种有趣转变。此外，基于零折射率介质的超薄相干完美吸收体也在波导中得到了证明。我们的工作揭示了一种在零折射率介质和相干完美吸收体之间改变材料响应的独特机制。
