Long-wave infrared magnetic mirror based on Mie resonators on conductive substrate

Abstract

Metal films are often used in optoelectronic devices as mirrors and/or electrical contacts. In many such devices, however, the π-phase shift of the electric field that occurs upon reflection from a perfect electric conductor (for which a metal mirror is a reasonable approximation) is undesirable. This is because it results in the total electric field being zero at the mirror surface, which is unfavorable if one wishes for example to enhance absorption by a material placed there. This has motivated the development of structures that reflect light with zero phase shift, as these lead to the electric field having an anti-node (rather than node) at the surface. These structures have been denoted by a variety of terms, including magnetic mirrors, magnetic conductors, and high impedance surfaces. In this work, we experimentally demonstrate a long-wave infrared device that we term a magnetic mirror. It comprises an array of amorphous silicon cuboids on a gold film. Our measurements demonstrate a phase shift of zero and a high reflectance (of ∼90%) at a wavelength of 8.4 µm. We present the results of a multipole analysis that provides insight into the physical mechanism. Lastly, we investigate the use of our structure in a photodetector application by performing simulations of the optical absorption by monolayer graphene placed on the cuboids.

Angular Control of Circularly Polarized Emission from Achiral Molecules via Magnetic Dipoles Sustained in a Chiral Metamirror

“…For the incident angle of 50°, a stronger near-field enhancement in the meta-atoms can be found for the case of LCP incidence, thus bringing a strong suppression of reflection for LCP. In previous studies, − Mie resonances associated with MD resonances excited in the high-index dielectric meta-atoms have also been reported to exhibit suppressed reflectance due to scattering/absorption.…”

Ultranarrow and Wavelength-Scalable Thermal Emitters Driven by High-Order Antiferromagnetic Resonances in Dielectric Nanogratings

“…Interestingly, there are two modes, i.e., EDs and EHs, vanishing among the whole waveband. It is due to the fact that their image counterparts are antiparallel with the actual modes. , In contrast, especially for MD modes, two pronounced resonant peaks appear at a short waveband. These two MDs, originating from hybrid Mie-FP modes in different orders, show distinct electric and magnetic field patterns that play essential roles in generating several antiferromagnetic resonances.…”

Large-Area Arrays of Quasi-3D Au Nanostructures for Polarization-Selective Mid-Infrared Metasurfaces

“…According to the generalized Snell’s law customized and optimized for a specific purpose, reflection can be obtained by using the MIM metasurface structure. Compared to the non-MIM structure, the nanoantenna array on the top surface can couple to its own dipolar image in the back-metal mirror , and hence can achieve a phase coverage of 2π. Furthermore, metasurfaces based on MIM stacks can significantly increase the efficiency compared to the non-MIM ones which is usually 10%–20%. , In addition, to help realize high efficiency abnormal reflection, MIM-based metasurfaces are also widely used for the research of frequency selective, perfect wave absorbers and thermal radiation devices in the mid-IR wavelength region.…”

“…According to the generalized Snell's law 65 customized and optimized for a specific purpose, reflection can be obtained by using the MIM metasurface structure. Compared to the non-MIM structure, the nanoantenna array on the top surface can couple to its own dipolar image in the back-metal mirror 66,67 and hence can achieve a phase coverage of 2π. Furthermore, metasurfaces based on MIM stacks can significantly increase the efficiency compared to the non-MIM ones which is usually 10%−20%.…”