Perfectly absorbing dielectric metasurfaces for photodetection

Abstract

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.

Structured light excitation of toroidal dipoles in dielectric nanodisks

“…There are also superdipole states [7,8] 63 formed by the constructive overlap of those two moments, and 64 the magnetic anapole [9], referring to the destructive overlap 65 of a magnetic dipole moment and its corresponding toroidal 66 moment. Electric field confinement in a dielectric nanoparti-67 cle via anapole excitation has been recently demonstrated to 68 enhance light harvesting [10] that is crucial for photovoltaic 69 systems [11,12] and photodetectors [13][14][15]. More recently, 70 boosting toroidal response in a metasurface of Si nanopar-71 ticles has led to a 30-fold increase in light absorption [16].…”

SUTD-PRCM Dataset and Neural Architecture Search Approach for Complex Metasurface Design

“…Due to the interaction between an electromagnetic (EM) wave and metasurfaces in some specific geometrical arrangements, metasurfaces can exhibit remarkable electromagnetic wave responses that have attracted great interests [1][2][3][4]. Metasurfaces have served as an important technology in many applications such as heat transforming [5], cloaking [6,7], hologram [8], conversion [9], absorption [10,11], scattering reduction [12], polarization [13][14][15], transmission [16], color [17,18], metalense [14,15], programmable metasurfaces [19][20][21], and many others [22][23][24][25]. These applications are made possible by the rapid advancement in micro-and even nano-fabrication technologies and computational modeling over the past decades.…”

Highly Efficient Near-Infrared Detector Based on Optically Resonant Dielectric Nanodisks

“…The confluence of nanophotonics and optoelectronics offers an unprecedented ability to control light matter interactions. Dielectric metasurfaces allow the improvement of both the light collection efficiency [ 8 ] and bandwidth [ 9 ], which are two crucial components in the photodetector design. Many semiconductors have a high refractive index in the NIR and visible range of the electromagnetic spectrum that leads to unique optical properties such as a non-radiating anapole state localizing the electric field inside semiconductor nanoparticles [ 10 ].…”