关键词: 偏振分束器/
太赫兹/
调整结构/
多孔光纤
English Abstract
Dual-core terahertz polarization splitter based on porous fibers with near-tie units
Wang Jing-Li1,Liu Yang1,
Zhong Kai2
1.Department of Opto-Electronic Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China;
2.Key Laboratory of Optoelectronic Information Science and Technology(Ministry of Education), Tianjin University, Tianjin 300072, China
Fund Project:Project supported by the Key laboratory of Opto-electronic Information Technology, Ministry of Education(Tianjin University), China (Grant No. 2014KFKT003), the National Natural Science Foundation of China (Grant No. 61571237), the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61405096), the Open Fund of State Key Laboratory of Advanced Optical Communication Systems and Networks, Shanghai Jiao Tong University, China (Grant No. 2015GZKF03006), and the Research Center of Optical Communications Engineering & Technology, Jiangsu Province, China (Grant No. ZSF0201).Received Date:01 August 2016
Accepted Date:18 October 2016
Published Online:20 January 2017
Abstract:Terahertz (THz) radiation, which is defined as the electromagnetic wave with a frequency ranging from 0.1 THz to 10 THz, has attracted widespread attention in recent years because of its unique possibilities in many fields. High-performance THz polarization splitter, a key device in THz manipulation, is of great significance for studying the THz devices. In the present paper, a novel dual-core THz polarization splitter is proposed, which is based on porous fiber with near-tie units. The introduction of near-tie units into the fiber core can enhance asymmetry to realize high mode birefringence. And the results show that the porous THz fiber exhibits high birefringence at a level of 10-2 over a wide frequency range. An index converse matching coupling (ICMC) method, which exhibits several advantages (such as short splitting length, high extinction ratio, low loss, and broad operation bandwidth), is used to allow for the coupling of one polarization mode within a broad operation band, while the coupling of the other polarization component is effectively inhibited. The splitting length is equal to one coupling length of x- or y-polarization component for which inter-core coupling occurs, and short splitting length means low transmission loss. Unlike the reported filling method, an adjusting structure method is proposed in the paper to satisfy the condition of index converse matching coupling. The full vector finite element method (FEM), which is based on the variational principle and the subdivision interpolation, is used to analyze the guiding properties of the proposed THz polarization splitter. The FEM is a widely used numerical method in physical modeling and simulation. Simulation results show that the THz polarization splitter operates within a wide frequency range of 0.5-2.5 THz. The splitting length does not exceed 2.5 cm in the whole frequency range and the minimum is only 0.428 cm. At 2.3 THz, the material absorption losses of x- and y-polarization are both less than 0.35 dB, and the extinction ratios for x- and y-polarization are 2.9 and 19.2 dB, respectively. Moreover, by comparing with a THz polarization splitter with filling method, the proposed THz polarization with adjusting structure method is easier to realize, the operating frequency range is wider, the splitting length is shorter, and the material absorption loss is lower. Finally, we note that the fabrication of such THz porous fiber designs could be realized by several methods, such as a capillary stacking technique, a polymer casting technique, a hole drilling technique, etc.
Keywords: polarization splitter/
terahertz/
adjusting structure/
porous fiber
