We propose a method to design bifunctional acoustic lens using acoustic metamaterials that
possess separate functions at different directions. The proposed bifunctional acoustic lens
can be implemented in practice with subwavelength unit cells exhibiting effective anisotropic
parameters. With this methodology, we experimentally demonstrate an acoustic Luneburg-
fisheye lens at operational frequencies from 6300 Hz to 7300 Hz. Additionally, a bifunctional
acoustic square lens is proposed with different focal lengths for multi directions. This method …