fig5

Figure 5. (A) The IFC in the HMM, quoted with permission from Poddubny et al.^[28]; (B) The metal-dielectric multilayer film, quoted with permission from Wood et al.^[30]; (C) The nanowire array (the left panel) and the negative refraction analyzed through the IFC (the right panel), quoted with permission from Liu et al.^[32]; (D) The enhanced spontaneous emission in multilayer HMM, quoted with permission from Lu et al.^[35]; (E) The enhancement during the topological transition between elliptic and hyperbolic dispersions, quoted with permission from Schulz et al.^[62]; (F) The transition between positive and negative refractions in HMM, quoted with permission from High et al.^[102]; (G) The magnifying super lens, quoted with permission from Liu et al.^[104]; (H) The strategy of complex frequency composed of multiple real frequencies (the upper panel) and related imaging of the super lens (the lower panel), quoted with permission from Guan et al.^[105]; (I) The band structures and schematics of the HMM (the upper panel) and the 2D hypercrystal (the lower panel), quoted with permission from Galfsky et al.^[106]; (J) The schematic of the 1D hypercrystal (the upper panel) and the dispersionless band gap (the lower panel), quoted with permission from Xue et al.^[108]; (K) The phase variation compensation in the IFC (the upper panel) and the forward dispersionless and backward monotonic increasing band gap in magnetized 1D hypercrystal (the lower panel), quoted with permission from Hu et al.^[109]. IFC: Isofrequency contour; HMM: hyperbolic metamaterial; 2D: two-dimensional.