基于布拉格光纤的磁场调制液晶太赫兹开关

利用中空布拉格光纤结构，设计了一种新型的磁场调制液晶太赫兹开关.通过在包层中采用周期交错的高密度聚乙烯和向列相液晶E7，并施加外磁场控制液晶的取向来改变液晶的折射率，从而实现开关的功能.该设计使开关宜于与光纤耦合，损耗小且能实现单模传输.采用有限元法模拟了开关的各项参数，数值计算表明，此开关的消光比可达2634 dB.关键词：太赫兹开关布拉格光纤液晶

Magnetically tunable liquid crystal terahertz switch based on Bragg fiber

A novel magnetically tunable liquid crystal terahertz switch is designed to reduce the coupling loss. The main structure of the switch is the hollow-core Bragg fiber with its cladding constructed by periodically setting of high density polyethylene and nematic liquid crystal E7 The refractive index of the E7 can be changed by the application of outside magnetic field and thus alter the loss property of the Bragg fiber dramatically to achieve its function as a switch. The main advantage of this switch is that it can eliminate the loss of coupling with fibers,and what is more,this switch can select the basic mode and is easy to be controlled. This article uses the finite element method to obtain the parameter of the switch and the simulated value of the extinction ratio reaches 2634 dB.