Fig. 1.

(A) Schematic of the nanowire metamaterial which possesses indefinite permittivity. (B) Isofrequency contours of light with 1.5-μm vacuum wavelength. The inner and outer circles are the contours in air and in silicon respectively. The hyperbola (black curves) is the contour in the indefinite material. (C) Isofrequency contour of the nanowire metamaterial in x-z plane, which is parallel to the nanowires, inside the first BZ defined by the period of nanowire array. Every point on the colorful curves represents an allowed propagating mode inside the bulk metamaterial. The red curve is one branch of the hyperbolic isofrequency contours calculated from effective media approximation. The dotted lines are the theoretical asymptotes of the hyperbola and the yellow circle in the center with radius of k₀ represents the isofrequency contour of light in air. The curves from the simulation bend and become flatter close to the BZ boundary due to Bragg diffraction effect. The data were obtained from full wave simulation of the silver nanowire array embedded in Al₂O₃ matrix at 1-μm wavelength.