Improved Bend Waveguide Design for Terahertz Transmission

Bending waveguides with 90° corners based on a two-dimensional photonic crystal with metallic cylinders arranged in a square lattice are studied for THz wave guiding. Considering single- and double-line defects, five different designs are investigated and assessed in terms of their transmission performance. A better structure is proposed by increasing the number of rods in the bending arc, thus achieving superior performance of the transmission characteristics in comparison to that of the former five designs. A comparison of the improved bend waveguide with a linear waveguide shows a significant reduction of the bending losses. Transmission levels of up to 98% within a 2.5 THz bandwidth (from 1.2 to 3.7 THz) have been accomplished.