Polarization-maintaining terahertz anti-resonant fibers based on mode couplings between core and cladding

Abstract

This study numerically investigated the index-induced mode coupling between the fundamental mode in core and the fundamental mode in cladding tubes in THz anti-resonant fibers (ARFs), and then, this index-induced mode coupling was applied for designing polarization-maintaining ARFs. Simulated results indicate that in the polarization-maintaining ARFs based on index-induced mode coupling, when the core diameter approaches the diameter of cladding tubes, ARFs can realize a birefringence which maintaining the polarization of incident light. Besides, the birefringence property which is realized by deforming the core boundary or categorizing the core boundary into two orthometric anti-resonant boundaries can be enhanced by the index-induced mode coupling. Based on the index-induced mode coupling, this paper proposed three compact polarization-maintaining ARFs, and the highest birefringence index exceeded 4 × 10−4.