An acoustic Maxwell’s fish-eye lens based on gradient-index metamaterials

Yuan Bao-guo^{1, 2}, Tian Ye¹, Cheng Ying^{1, 3, †,}, Liu Xiao-jun^{1, 3, ‡,}

(a) The real part (black solid curve) and imaginary part (red dashed curve) of the relative effective refractive index n_r as a function of frequency for the SAM unit with w = 0.1 cm and a = 3.2 cm. (b) The n_r as a function of a for the SAM unit at 2 kHz.