Layered Babinet complementary patterns acting as asymmetric negative index metamaterial

Abstract

Abstract Azimuthal orientation and handedness dependence of the optical responses, accompanied by asymmetric transmission and asymmetric dichroism, were demonstrated on multilayers constructed with subwavelength periodic arrays of Babinet complementary miniarrays, illuminated by linearly and circularly polarized light. In case of single-sided illumination asymmetric optical responses were observed at the spectral location of maximal cross-polarization that is accompanied by radiative electric dipoles and weak, slowly-rotating in-plane magnetic dipoles on the nano-objects; where the outgoing waves are elliptically (almost circularly) polarized. The negative index material phenomenon was demonstrated, where the electric and magnetic dipoles overlap both spatially and spectrally. The negative index material (NIM) phenomenon is accompanied by electric multipoles that add up non-radiatively and correlates with the strong, pronouncedly-tilted, rotating magnetic dipoles characteristic on the nano-entities, where the outgoing waves are linearly (slightly elliptically) polarized. By illuminating the multilayer with two counter-propagating circularly polarized beams it was proven that asymmetrical normal component displacement currents at the bounding interfaces, arising along flat and tilted bands, accompany the asymmetric copolarized and cross-polarized transmission. The latter correlates with the asymmetric dichroism in the cross-polarized signal observed in case of single-sided circularly polarized light illumination. The dispersion maps in the single-sided asymmetrical co-polarized reflectance and absorptance indicate flat bands of analogous and complementary extrema, proving the partially dichroic nature of the observed asymmetric phenomena. The Tellegen (chirality) coefficients exhibit a maximum in a spectral region coincident with the asymmetric transmission (maximal polarization rotation in the 90° azimuthal orientation). The multilayer is proposed as an ultrathin NIM and nonreciprocal nanophotonic element.

Keywords

• Azimuthal orientation
• Chirality
• Asymmetric transmission
• Circular dichroism
• Displacement current
• Magnetic dipoles