Time:2017-11-08 Read:1248
It is well known that optical angular momentum is composed of spin angular momentum and orbital angular momentum (OAM). In the last two decades, optical OAM has attracted great interest due to its potential applications in various research fields, such as optical trapping, quantum computation, optical communications. The nonlinear generation process enables vortex beams to be obtained at new wavelengths, which opens up new possibilities for all-optical switching and manipulation of vortex beams. To get second harmonic generation of the vortex beam, there are two main methods. One is to manipulate the structure of nonlinear photonic crystals (NPCs). The other is to pattern the output facet of a nonlinear crystal, which combines both the nonlinear process and the beam spatial shaping. However, these two methods possess the same drawbacks, including complex fabrication and unchangeable nonlinear wave patterns. To solve these problems, we turn our attention to pre-shaping the fundamental wave (FW) before its incidence into a nonlinear crystal。
We experimentally demonstrated the generation of a dynamic nonlinear vortex beam array by utilizing a fundamental wave with a modulated phase structure, which was incident into a homogeneous nonlinear medium. In our experiment, one-dimensional and two-dimensional second harmonic vortex beam arrays were investigated, and the topological charge of second harmonic vortex beam of different order was measured. This study presents a method of dynamic control of the nonlinear vortex beam array, which may have applications in multiple-particles optical trapping, optical communication, and so on.