介质金属膜椭圆太赫兹空芯光纤的传输特性研究

Transmission Characteristics of Elliptical Terahertz Hollow Fiber with Dielectric and Metallic Inner Coatings

在金属空芯光纤(MHF)内加介质膜是降低光纤传输损耗的有效方法。采用有限元法研究了介质膜对椭圆MHF在太赫兹波段传输特性的影响。分析结果表明,介质膜的干涉效应使得光纤传输特性随频率变化具有周期性。介质膜能够改变光纤传输模式,增加截止波长和单模传输带宽,提高光纤和光源的耦合效率并降低传输损耗。然而介质膜在低损耗窗口减小了模式双折射。分析结果为光纤结构选择、设计和制作提供了重要参考。

Adding dielectric coatings inside the metallic hollow fibers （MHF） is an effective way to reduce the transmission loss. Effects of dielectric coatings on the transmission characteristics of elliptical MHF in the terahertz region are numerically investigated by using finite element method. The dielectric coating changes the transmission modes in the elliptical MHF. Transmission characteristics of the elliptical hollow fiber vary periodically with the frequency owing to the interference effect of the dielectric coating. With the dielectric coating, the elliptical hollow fiber has a longer cutoff wavelength, broader single-mode bandwidth, higher coupling efficiency to the incoming light, and smaller transmission loss. However, it reduces the modal birefringence in the low-loss transmission windows. The results provide an important reference for the fiber design, structure optimization, and fabrication techniques.