Controlling an acoustic wave with a cylindrically-symmetric gradient-index system*
Zhang Zhea),b), Li Rui-Qia), Liang Bina),c), Zou Xin-Yea), Cheng Jian-Chuna),b)†
       
(a) Schematic illustration of the proposed model; ((b), (c), (d), and (e)) the ray trajectories predicted from Eq. ( 2 ) for four particular cases, i.e., α is equal to −1, 1, 2, and 3 respectively, where the core radius r c is much smaller than the shell radius R .