Application of Transformation Optics and 3D Printing Technology in Vortex Wave Generation

Electromagnetic waves carrying orbital angular momentum (OAM) may potentially increase spectrum efficiency and channel capacity based on their extra rotational degree of freedom. In this chapter, the vortex beams carrying OAM are realized by elaborately designed microwave devices using the transformation optics method. The first microwave device is a reflective vortex beam generator illuminated with plane waves. The vortex beams with different modes are generated in a wide frequency band ranging from 8 GHz to 16 GHz. The second designed device is a collimating lens, which can be used to reduce the divergent angle of the vortex beams illuminating to the collimating lens. The third device is an all‐dielectric lens used to achieve the omnidirectional vortex beam in the horizonal plane. Transformation optics technique provides an effective way to realize vortex waves, which can greatly facilitate the potential implementation of OAM waves in microwave wireless communication systems.