Concise relation among the effective index of the TE01 mode of the metal rectangular waveguide and those of the TE1 and TM0 modes of the metal parallel-plate waveguide for terahertz waves

For terahertz waves, we analytically present a concise relation of the effective indices among the TE01 mode of the metal rectangular waveguides, the TE1 mode, and the TM0 mode of the infinite metal parallel-plate waveguides. With the assumption that the modal field in the metal rectangular waveguide is linearly polarized and separable, the effective index of the TE01 mode can be obtained from the combination of the effective indices of the associated TE1 mode and TM0 mode. We further find that the real part of the effective index of the TE01 mode is mainly determined by that of the TE1 mode, while for the imaginary part, the TM0 mode dominates. (C) 2018 Optical Society of America.