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

We present a high efficiency terahertz (THz) 90^\circ-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\,\times\,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\,\times\,48\,\times\, 241 \mu{\rm m}³, and the total size of the EMXT is 1756\,\times\,1756\,\times\,787 \mu{\rm m}³. The 90^\circ-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^\circ-bend EMXT waveguide can be widely used for applications in THz circuit integrations and THz communications.