Design and efficient coupling of TE 01 mode in small-core THz Bragg fiber

We report a design of small-core, multiple-layer Bragg waveguide for guiding the terahertz (THz) signal using TE01 mode, which is composed of alternating high-index dielectric (HDPE) and low-index dielectric (air). The propagation loss is less than 0.1 dB per centimeter ranging from 0.95 THz to 1.20 THz, which is better than that of the traditional metallic tube. Furthermore, a novel scheme is proposed to excite and extract the TE01 mode in the Bragg fiber by employing Y-type mode converters. Based on this scheme, for the first time, one can generate the Bragg TE01 mode and further apply such wave-guiding system in THz communication or beam-wave interaction for THz generation.