Hybrid one-dimensional photonic crystals containing anisotropic metamaterials: Angle-driven photonic band gaps and angle-driven Tamm plasmon polaritons

Abstract

Herein, we realize a special class of photonic band gaps (PBGs) called angle-driven PBGs in hybrid one-dimensional (1D) photonic crystals (PhCs) composed of alternating anisotropic metamaterial and dielectric layers. At normal incidence, the effective refractive index of the anisotropic metamaterial is designed to be the same as that of the dielectric. Owing to the lack of refractive index contrast, the angle-driven PBG is closed at normal incidence. Under transverse magnetic (TM) polarization, the effective refractive index of the anisotropic metamaterial is angle-dependent since the isofrequency curve (IFC) is an ellipse or a hyperbola. Therefore, the angle-driven PBG under TM polarization is opened at oblique incidence. However, under transverse electric (TE) polarization, the effective refractive index of the anisotropic metamaterial is angle-independent since the IFC is a circle. Therefore, the angle-driven PBG under TE polarization remains closed. In hybrid 1D PhCs composed of alternating elliptical metamaterial and dielectric layers, we realize blueshift angle-driven PBGs under TM polarization. As the incident angle increases, the angle-driven PBG shifts towards shorter wavelengths. Empowered by the blueshift angle-driven PBG, broadband polarization selection and privacy protection can be achieved. In hybrid 1D PhCs composed of alternating hyperbolic metamaterial and dielectric layers, we realize zero-shift angle-driven PBGs under TM polarization. As the incident angle increases, the angle-driven PBG stays almost unchanged. Empowered by the zero-shift angle-driven PBG, wide-angle polarization selection can be achieved. In addition, blueshift and zero-shift angle-driven Tamm plasmon polaritons (TPPs) are realized by placing a metal layer in front of the hybrid 1D PhCs. Our work not only offers an elegant platform to realize angle-driven PBGs and angle-driven TPPs, but also facilitates the development of high-performance polarizers.