Experimental Realization of High Transmittance THz 90 $^{\circ}$ -Bend Waveguide Using EMXT Structure

We present a high efficiency terahertz (THz) 90°-bend electromagnetic crystal (EMXT) waveguide using Si-based microelectromechanical systems technology. The 2-D EMXT consists of a periodical array of square-shaped gold rods (13 × 13 cells) deposited on a silicon substrate, and a 200-nm gold layer is further sputter-coated on the gold rod array. The dimension of each rod is 48 × 48 × 241 μm³, and the total size of the EMXT is 1756 × 1756 ×787 μm³. The 90°-bend waveguide is fabricated by removing three rows of rods from the EMXT. Through rigorous numerical simulation, it is found that transmittance higher than 90% are found in the whole range from 0.365 to 0.578 THz. The bending performance of the waveguide is further experimentally measured, where transmittance as high as 91.2% is observed at 0.5 THz. The proposed 90°-bend EMXT waveguide can be widely used for applications in THz circuit integrations and THz communications.