Bidirectional surface wave splitters excited by a cylindrical wire

Abstract

Bidirectional surface wave splitters excited by a cylindrical wire in the microwave frequency have been proposed and fabricated. Compared to the bidirectional subwavelength-slit splitter, the novelty of the proposed structure is the coupling mechanism from the cylindrical wire to the surface gratings. By designing the grating structures with different depths and the feeding wire, electromagnetic waves at the designed frequencies will be confined and guided in the predetermined opposite directions. The finite integral time-domain method is used to model the splitters. Experimental results are presented in the microwave frequencies to verify the new structure, which have very good agreements to the simulated results. Based on the same coupling mechanism, a bidirectional surface wave splitter excited by a cylindrical wire in the terahertz (THz) frequencies is further been proposed and modeled. The simulation results demonstrate the validity of the THz splitter.

Three-dimensional subwavelength components utilizing THz surface plasmons

“…A typical THz SP splitter based on the gratings of rectangular grooves [18] is shown in Figure 1(a), in which the thickness of the grating is small and less than λ, and hence is called as a 3D SP splitter. As a comparison, the splitters in [3][4][5] have very large thickness (larger than several tens of wavelengths), and thus are nearly 2D splitters.…”

“…The 3D bidirectional SP splitter had very good performance in splitting surface waves [18] with compact size. When the operating frequency is closer to the SP frequency of the grating, the EM wave will be strongly confined on the grating surface; when the operating frequency is far away from the SP frequency, the EM wave will not be coupled into the structure.…”

“…The diameter of the feeding metal wire is 80 µm, and its extended height over the grating surface is 60 µm. Figure 2 demonstrates the simulated field distributions on the xz-plane that passes the center line of the metal wire and the one-dimensional (1D) field distribution of electric field intensities along the line z=202 µm [18]. In simulations, THz SPs are introduced by adding a waveguide port on the short coaxial cable constructed by the outer conductor at the bottom of the metal wire.…”

“…Such parameters are also used in further simulations of THz SP splitters. From Figure 2, it is observed that the EM waves along the left-side gratins are evidently stronger than those along the right-side gratings at 0.5 THz, while nearly all EM waves at 1 THz are guided along the left-side gratings [18]. In [18], the experimental verifications in the microwave frequencies were conducted.…”

“…In this paper, we firstly make a review on the three-dimensional (3D) bidirectional and multi-directional THz SP splitters [18,19] based on the gratings of rectangular grooves with a finite thickness, in which a simple and efficient method was employed to excite the THz SPs on the 3D gratings by using a metallic wire. Then a 3D bidirectional THz SP splitter with transverse confinement and a 3D bending THz SP splitter are proposed.…”