为了在太赫兹波段实现远距离宽频带传输, 设计了一种具有低吸收损耗的环烯烃共聚物(COC)作为基底材料双包层太赫兹光子晶体光纤。利用全矢量有限元法及模式选择理论, 数值模拟了该光纤的单模传输范围、限制损耗、色散以及有效模场面积等特性。结果表明: 优化结构参数可使在1～10 THz范围内基模限制损耗小于0.1 dB/m, 二阶模限制损耗大于1 dB/m。因此可以获得1～10 THz的宽频带单模传输并且在1.5～10 THz内群速度色散可以控制在±0.1 ps/(THz·cm)。

In order to realize long distance and broadband transmission of terahertz wave, a double-cladding terahertz photonic crystal fiber was designed based on Topas cyclic olefin copolymer with low loss. The single-mode transmission range, confinement loss, dispersion and effective area of the double-cladding terahertz photonic crystal fiber were investigated by using the full-vector finite element method (FEM) and the mode choice theory. The results show that the confinement loss of the fundamental mode is far less than 0.1 dB/m and the confinement loss of second-order mode loss is larger than 1 dB/m at frequency range of 1-10 THz by tailoring the structure parameters. The broadband single mode transmission operates at bandwidth of 1-10 THz, and the group velocity dispersion (GVD) can be controlled at ±0.1 ps/(THz·cm) in the range of 1.5-10 THz.