Graded negative index lens with designable focal length by phononic crystal

摘要: We realize a flat lens with graded negative refractive index by two-dimensional phononic crystal. The index-grade is achieved gradual modification of the filling fraction along transverse direction to propagation. demonstrate that this can focusing and amplification parallel incident acoustic waves. A formula for profile derived which desired focal length be precisely designed aberrations image effectively reduced. This designable expected bear significance in applications such as coupling or integration various types devices.