Field enhancement of tapered focuser with spoof surface plasmon polaritons

Focuser concentrates the energy in a region through the lens, which can enhance the interaction between the field and the matter. It has important application value in engineering. With the tapered structure of the spoof SPPs transmission line, the electromagnetic wave in the gap between adjacent structures is transformed into a planar waveguide mode. These electromagnetic waves are confined in the gradually decreasing gap, resulting in a large amount of energy accumulation at the tip of the taper to form a field focusing effect. In this paper, a type of spoof SPPs focuser is designed, a focusing method of SPP wave is established through a conical transmission line on the surface at microwave band, and the application range of its focusing effect is explored.