吸收介质膜/金属空芯光纤的太赫兹波传输特性

介质/金属结构空芯光纤是一种有发展前景的太赫兹波传输媒质.介质膜在有效增加内面反射率从而降低传输损耗的同时,其材料吸收会引起附加损耗.讨论了介质材料吸收对太赫兹空芯光纤结构参数的影响.计算结果表明,相比于无吸收的理想介质,吸收介质的最优膜厚变小.最优折射率变大.综合考虑了光纤内直径、介质膜折射率和传输波长等因素,分析了介质膜的材料吸收容限.分析结果表明,吸收容限随光纤内直径减小或传输波长增大而减小.当光纤内直径很小或传输波长很大时,吸收容限可能不存在.分析结果对介质/金属太赫兹空芯光纤的设计和材料选择具有重要参考价值.

Characterization of Terahertz Hollow Fiber with an Absorptive Inner-Coating Dielectric Layer

Dielectric-coated metallic hollow fiber is one of the promising media for THz transmission. The dielectric layer enhances the reflection rate and hence lowers the transmission loss, whereas it brings additional loss due to its material absorption. The influence of dielectric absorption on the structure parameters of the hollow fiber is theoretically discussed. Calculation results show that the optimum refractive index of an absorptive dielectric layer is greater than that of a perfect transparent dielectric layer. The optimum thickness of the dielectric layer to minimize the loss of Hen mode becomes smaller due to the absorption. The absorption tolerance is also investigated when considering such factors as inner diameter, refractive index, and transmission wavelength. It is shown that absorption tolerance decreases when the inner diameter becomes smaller or when the transmission wavelength becomes larger. In extreme cases of small inner-diameter or large transmission wavelength, the absorption tolerance is not existent. The calculation results are useful to the structure design and material selection in the fabrication of terahertz hollow fibers.