Investigation of mode couplings between core and cladding of terahertz anti-resonant fibres

Abstract

In this study, we numerically investigated mode couplings in terahertz (THz) anti-resonant fibres (ARFs) and found that the mode couplings were determined by the diameter ratio of the core and cladding tubes. Moreover, the optimal diameter ratio was affected by the change in the number of cladding tubes, bent radii and the refractive index of the gas filled in fibre. Mode couplings provide novel theories for fundamental mode suppression and higher-order mode suppression. In THz ARFs, taking the semielliptical tubes as anti-resonant elements can significantly improve the suppression ability of mode couplings.