Propagation characteristics of adjustable abnormal hollow beams in gradient negative refractive index material

Abstract

In this paper, the propagation characteristics of adjustable abnormal hollow (AAH) beams in gradient negative refractive index material are investigated theoretically and numerically. We focus on analyzing and discussing the intensity pattern, beam width and axial intensity of AAH beam, and give the mathematical expressions of these physical quantities. The results show that the AAH beams can have many different evolution forms. In general, the intensity pattern of AAH beam changes periodically during the propagation, but solitons can be formed under special parameters. Through parameter control, the beam width of AAH beam can be widened or compressed in one or two transverse directions, or even constant in one transverse direction and periodically changed in the other transverse direction. The evolution of axial light intensity of AAH beam can also show different transmission types such as concave type, flat-top type and convex type.