Design of low loss single-mode terahertz Bragg fibers based on a confinement loss diagram

In this paper, the confinement loss diagram (CLD) is combined with the modal filtering approach to design low loss single-mode terahertz (THz) Bragg fibers. To filter out the TM₀₁ mode, the confinement loss diagram is exploited to locate a cutoff point which allows the use of a larger air core. Consequently, a lower loss can be obtained while only the HE₁₁ can propagate effectively. The designed Bragg fiber can achieve simulated propagation loss around 0.2 dB/m to 0.5 dB/m in the range of 0.7 THz to 1.4 THz, with only 10 layers of Bragg cladding.