MgB_2-based negative refraction index metamaterial at visible frequencies: Theoretical analysis

摘要

The presented metamaterial consists of the matrix (magnesium diboride MgB_2 in a normal state, at room temperature) with randomly (or regularly) embedded spherical nanoparticles of a polaritonic crystal, SiC. The calculations demonstrate explicitly that the metamaterial exhibits negative refraction index behavior with low losses for a scattered wave. The result stands for both random and regular distributions of SiC nanoparticles inside the MgB_2 matrix. This favorable situation stems from the Drude-like behavior of both the low-energy, p_2(ω_(p_2) ≈ 1.9 eV), and the high-energy, p_1(ω_(p_1) ≈ 6.3 eV), plasmon modes of MgB_2 with plasmon losses, γ ≤ 0.25 eV. The effective medium parameters were calculated in the framework of the extended theories of Maxwell-Garnett [Philos. Trans. R. Soc. London, Ser. A 203, 385 (1904)] and Lewin [Proc. Inst. Electr. Eng. 94, 65 (1947)], and the obtained results are validated via ab initio finite difference time domain simulations.