Abstract

High birefringence Terahertz (0.1 to 10 THz) waveguides are desired in numerous applications including sensing, communications, and polarized terahertz filters [1]. In this paper, we have designed and analyzed a novel and relatively simple technique of attaining high birefringence in the THz wavelength regime without using elliptical air-holes as most of literature used to achieve high birefringence properties. Hexagonal lattice of three air-hole rings have been used in both core and cladding to reduce complexity. Instead of inserting single elliptical air-hole we introduced two circular air-holes of same size inside the core, and we define the air-hole pair as dual-hole unit as shown in Fig. 1(a). We used a cyclic-olefin copolymer (COC) with the trade name TOPAS as background material. In the cladding region, the spacing between two adjacent air-holes on two adjacent rings is denoted as Λ_s. Dcore denotes the core diameter, where diameter of the core and cladding air-holes are labeled as d_c and d respectively (see Fig.1 (a)). Λ_c stands for unit to unit distance whereas H is the centre to centre distance between two air-holes of a dual-hole unit. The air-hole diameter to pitch ratio in the cladding d/Λ_s is kept 0.90 throughout the simulation. The parameters used for the simulations are D_core =350 μm, d= 286 μm, Λ_s= 318 μm, Λ_c=49.3 μm, d_c= 22.68 μm and H=24.5μm. The axis of orientation of the dual-hole unit is rotated to obtain high birefringence as shown in Fig. 1(b).

© 2015 IEEE