Hybrid bilayer plasmonic metasurface efficiently manipulates visible light

Abstract

Two highly coupled plasmonic metasurfaces exhibit much higher conversion efficiency and extinction ratio than individual ones.

Advances in Full Control of Electromagnetic Waves with Metasurfaces

“…[ 48 ] However, such limit tends to be transcended by breaking the radiation symmetry with a fi nite-thickness (yet subwavelength) metasurface, for instance, a bilayer design consisting of V-shaped particles and their Babinet-inverted apertures (Figure 1 f), where a transverse electric current and a transverse magnetic current are supported on the top and bottom layers consisting of structures with subwavelength lateral sizes, respectively. [ 59 ] The bilayer metasurface thus results in discontinuities on both transverse magnetic fi eld and transverse electric fi eld, respectively. By breaking the radiation symmetry with structural asymmetry, a full control of transmitted light with higher effi ciency becomes possible.…”

“…By using the bilayer structure, the manipulation effi ciency of anomalous transmitted light with cross polarization was improved to 17% (36%) in experiment (simulation) covering the long end of visible light, which resulted from the strong intraand interlayer coupling among adjacent unit cells. [ 59 ] To further improve the manipulation effi ciency, based on MTA structures, refl ected light was completely suppressed (Figure 2 a), by judiciously selecting the fi lling ratio and reactance of building blocks, in the meantime, ensuring impedance matching to the environment. The achieved anomalous transmission efficiency was as high as 70% at a wavelength of 3 µm in simulations when the ohmic loss was minimized.…”

Coherent control of double deflected anomalous modes in ultrathin trapezoid-shaped slit metasurface

“…The normal beam propagates along the z axis with intensity of ~26.4% while the anomalous beam can be redirected to the right side with deflection angle of ~−32° and intensity of 5%. Particularly, the other weak diffraction mode cannot be ignored and redirected to the left side with deflection angle of ~32° and intensity of 1.1%, so-called opposite anomalous beam39. Compared to previous metasurfaces1234567891039, the opposite anomalous beam can be greatly enhanced by trapezoid-shaped slit structure.…”

“…This type of metasurface is known not to display polarization conversion2. For 0.5 <  λ / p x  < 1 in the trapezoid-shaped slit metasurface, so there should be three diffraction orders exist39, the anomalous refraction, normal refraction and the opposite anomalous refraction as illustrated in Fig. 1(a).…”

“…Generally, the input signal beam will be restricted to experience coherent modulation in two channels30. Less attention has been paid to the metasurface with multiple-order anomalous refracted beams3839, which can provide a promising opportunity to realize multichannel signal modulation. It is worth investigating how this gradient metasurface is modulated in the coherent regime.…”