- 1. 中国计量大学
- 2. 天津大学精密仪器与光电子工程学院
Research on negative curvature terahertz fiber based on nested triangle structure cladding
- Received Date:
27 March 2020
Abstract: In this paper, a new type of negative curvature terahertz fiber is designed, which consists of six cladding tubes evenly distributed in the cladding and nested with equilateral triangle structure. By using full vector finite element method and changing the thickness of cladding tube and triangle, the effective mode field area, core power ratio, confinement loss, dispersion and other parameters of negative curvature fiber are studied. Here, the thickness range of 70-100 μm is selected. It is found that the confinement loss of optical fiber can reach 0.005dB/cm at 2.36THz, the dispersion coefficient can float up and down at ± 0.1ps/THz/cm at 2.1-2.8 THz, the core power ratio can reach above 99% in the same frequency range. Compared with the known teraehrtz negative curvature fiber, the nested triangle negative curvature fiber has lower confinement loss and 2.1-2.8 THz transmission bandwidth. After that, when the cladding tube and the triangle thickness are kept at 90 μm, the bending degree of the triangle edge is changed, and the above properties are further studied. When the triangle edge is bent in and out, the transmission performance of the fiber is analyzed. It is found that when the triangle edge is bent inward, the transmission characteristics of terahertz wave is much better than that when the triangle edge is bent outward. When the triangle edge is bent inwards, the confinement loss is obviously reduced, reaching 0.002 dB/cm at 2.36 THz, compared with triangle straight edge, the confinement loss is reduced by 40% and still maintaining 99% core power ratio at certain frequency band. The designed terahertz fiber will have an important application value in the fields of sensors and imagers with low loss and wide bandwidth.