介质镀膜空芯光纤在THz频段的传输特性

Transmission characteristics of hollow dielectric film-coated waveguide for THz radiation

理论分析了介质镀膜空芯光纤在THz频段的传输特性，得出了该光纤的特征方程及模式分布。利用射线光学原理计算了介质膜材料为聚酰亚胺、介质膜厚度为0．05mm的光纤的衰减常数随介质膜内直径的变化情况。得出其主模在THz频段的衰减常数小于1dB／m，该值远小于相同内径的金属圆波导在这一频段的衰减常数。模拟计算了介质膜厚度为0．05mm、内径为1mm，金属膜内径为1.05mm的介质镀膜空芯光纤在0～1THz的S参数，模拟结果显示该光纤在TFHz频段有很宽的通带，且在通带内衰减常数小于0．5dB／m。可用于THz频段电磁波远距离传输。

The transmission characteristics of the hollow dielectric film-coated waveguide for THz radiation are theoretically analyzed, and the eigenequation and the mode distribution of the waveguide are obtained. The relationship between attenuation coefficient and the bore diameter of the hollow waveguide is described based on the ray-optics principle. The attenuation coefficient of the dominant mode is less than 1 dB/m when the dielectric material is polyimide and the depth is 0.05 ram, which is far less than that of the same bore diameter metal circle waveguide for THz radiation. The transmission characteristics of the film-coated waveguide is simulated when the frequney of the electromagnetic wave ranges from 0 to 1 THz, and the attenuation coefficient is less than 0.5 dB/m in the passband of 0. 15-1.00 THz when the diameter of the dielectric film is 1 mm and the diameter of the metal film is 1.05 ram, so the hollow dielectric film-coated waveguide can be used for long distance delivery of THz radiation.