Perfect magnetic mirror and simple perfect absorber in the visible spectrum

Abstract

Valagiannopoulos, C.A.; Tukiainen, A.; Aho, T.; Niemi, T.; Guina, M.; Tretyakov, Sergei; Simovski, Konstantin Perfect magnetic mirror and simple perfect absorber in the visible spectrum Known experimental artificial magnetic conductors for terahertz and optical frequencies are formed by arrays of nanoparticles of various shapes. In this paper, we show that artificial magnetic conductors for the visible spectrum can be realized as simple, effectively quasistatic resonating structures, where the effective inductance is due to the magnetic flux inside a uniform metal substrate, and the effective capacitance is due to electric polarization of a thin uniform dielectric cover. To illustrate the main potential application of artificial magnetic conductors, we concentrate on the perfect-absorption regime, achieved by adjusting the loss factor of the artificial magnetic conductor to match its real input impedance to free space. We provide approximate analytical design formulas and introduce a simple equivalent circuit to explain the physical mechanism of emulation of magnetic response and perfect absorption of light. A prototype of a nearly perfect absorber for optical (from green to ultraviolet) frequencies is designed and experimentally tested. The results confirm the theoretical predictions and show polarization insensitivity and angular independence of response in a wide range of incidence angles.

Wide-angle absorption of visible light from simple bilayers

“…Two zones of high absorption are recorded along a single wavelength λ 1 of the dielectric medium. The first one, appearing at the lower h 1 , is attributed to the aforesaid resonance of the equivalent LC circuit [17]. On the other hand, the second zone in the vicinity of a larger h 1 appears due to the periodicity of fields into the almost lossless λ 1 -periodic first layer; apparently, the squared field magnitudes (associated with A TE∕TM ) repeat their patterns every λ 1 ∕2.…”

“…In particular, one can achieve high absorption via a Huygens sheet formed by induced electric and magnetic surface currents [5,6]. Similarly, symmetric absorbers are devised by balancing effective electric and magnetic resistive sheets [7][8][9][10], whereas unilateral structures are obtained by depositing resonant particles or layers on lossy bases [11][12][13][14][15][16][17][18][19]. However, such designs usually require costly and complex fabrication processes, which hinder their practical applicability.…”

Parity-Time Symmetric Nonlocal Metasurfaces: All-Angle Negative Refraction and Volumetric Imaging

“…Different from a conventional absorber (such as, e.g., Refs. [32][33][34]), a CPA only provides full absorption when it is bilaterally illuminated, whereas its reflection and transmission are nonzero when excited from a single side. As shown in Appendix B, when a symmetric structure is bilaterally illuminated with waves having equal amplitude and relative phase difference Δϕ, the omnidirectional CPA operation requires that the reflection R and transmission T coefficients respect the condition…”

Transverse-electric Brewster effect enabled by nonmagnetic two-dimensional materials

“…It is thus reasonable to apply the local model of the Kubo formula [24,[31][32][33] to characterize graphene's surface conductivity σ s . We set the chemical potential as μ c = 0.2 eV, the relaxation time τ = 0.1 ps, and the temperature T = 300 K for graphene in the following, where all these parameters are viable in realistic experiments.…”