Design and Efficient coupling of TE01 mode in small-core THz Bragg fibers
H. Y. Yao1*, J. Y. Jiang1, Y. S. Cheng1, Z. Y. Chen1, T. H. Her2, T. H. Chang1
1Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
2Department of Physics & Optical Science, The University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America
* presenting author:姚欣佑,
We report a design of small-core, multiple-layer Bragg fiber for guiding the terahertz (THz) signal using TE01 mode, which is composed of alternating high-refractive-index dielectric (high-density polyethylene) and low-refractive-index dielectric (air). The propagation loss of the THz wave traveling inside this small-core Bragg fiber is less than 0.5 dB per centimeter ranging from 0.95 THz to 1.50 THz, which is better than that of the traditional metallic tube. Furthermore, a novel scheme is proposed to excite and extract the very high-purity TE01 mode in the Bragg fiber by employing Y-type mode converters. Based on this scheme, for the first time, one can characterize the Bragg TE01 mode in experiment and further apply such wave-guiding system in THz communication or beam-wave interaction for THz generation.

Keywords: Terahertz waveguide, Bragg fiber, Mode converter