Perfectly absorbing dielectric metasurfaces for photodetection
Perfectly absorbing dielectric metasurfaces for photodetection
复制标题
DOI：
10.1063/5.0019883
复制
发表时间：
2020-10-01
期刊：
影响因子：
5.6
通讯作者：
Brener, Igal
中科院分区：
文献类型：
--
作者：
Mitrofanov, Oleg;Hale, Lucy L.;Brener, Igal
纳米光子学实现了几种显著的光学功能，其中之一就是光学超薄表面对光的完美吸收。通过将基于有源半导体的元件构造为完全吸收全电介质的亚表面，可以将这一功能引入光电子器件，从而在提供导电性的同时改善光学性能。然而，完美的吸收需要几何和材料参数的精细组合，目前还没有通用的全介质亚表面设计满足所需的半导体和工作波长的这些条件。在这里，我们使用数值模拟，证明了具有亚波长大小互连通道的Mie谐振器允许这种完美的吸收要求的组合，以满足不同波长的工作和不同水平的本征材料吸收。通过对Mie腔中电偶极模和磁偶极模的共振波长和损耗的影响，揭示了互连通道在实现完全吸收中的关键作用。只需调节沟道宽度，就可以在715~840 nm的工作波长范围内获得理想的吸收，其中GaAs的本征吸收能级变化超过2倍。光学传输实验证实，这些亚表面共振地增强了光吸收。这项工作为在光学探测器中用电连接的、光学薄的、完全吸收的准表面取代块体半导体奠定了基础和指导方针。
Perfect absorption of light by an optically thin metasurface is among several remarkable optical functionalities enabled by nanophotonics. This functionality can be introduced into optoelectronic devices by structuring an active semiconductor-based element as a perfectly absorbing all-dielectric metasurface, leading to improved optical properties while simultaneously providing electrical conductivity. However, a delicate combination of geometrical and material parameters is required for perfect absorption, and currently, no general all-dielectric metasurface design fulfills these conditions for a desired semiconductor and operation wavelength. Here, using numerical simulations, we demonstrate that Mie resonators with subwavelength-size interconnecting channels allow this combination of perfect absorption requirements to be satisfied for different wavelengths of operation and different levels of intrinsic material absorption. We reveal the underlying physics and show that interconnecting channels play a critical role in achieving perfect absorption through their effects on the resonant wavelengths and losses for the electric dipole and magnetic dipole modes in Mie resonators. By adjusting only the channel widths, perfect absorption can be achieved for an optically thin GaAs-based metasurface at a desired wavelength of operation in a range from 715 nm to 840 nm, where the intrinsic absorption level in GaAs varies by more than a factor of 2. Optical transmission experiments confirm that these metasurfaces resonantly enhance optical absorption. This work lays out the foundation and guidelines for replacing bulk semiconductors with electrically connected, optically thin, perfectly absorbing metasurfaces in optical detectors.