提出一种红外波段低损耗的空芯反谐振光纤，石英包层管为半圆半椭圆拼接结构，采用全矢量有限元法进行设计与研究。半椭圆管的半短长轴与半圆管的半径相等，将半圆管与半椭圆管进行拼接，改变半圆的半径以及半椭圆管的半长轴来改变靠近纤芯处的负曲率以及远离纤芯的正曲率，进而研究包层管的正负曲率对空芯反谐振光纤的损耗特性的影响，设计应用于1.5~3.0 μm波段的低损耗空芯反谐振光纤。结果显示负曲率较小正曲率较大时限制损耗效果更好。当靠近纤芯处为圆形半管远离纤芯处为椭圆半管，圆形半径r_y=25 μm，椭圆的半长轴r_x=65 μm，半短长轴r_y=25 μm时，光纤最低限制损耗在波长2.1 μm处为8.22×10^-2 dB/km。

A hollow-core anti-resonant fiber is proposed with low confinement loss in infrared band. The cladding tube is a semicircular semi-elliptical splicing structure. The full vector finite element method is used for the simulation. The semi-minor axis of the semi-elliptical tube is equal to the radius of the semicircular tube. A semi-circular tube and a semi-elliptical tube are spliced to form a semi-circular semi-elliptical cladding tube. The negative curvature and the positive curvature are changed by improving the structure parameters of the tube. The purpose of this paper is to study the loss characteristics of the positive and negative curvature of the cladding tube, and to design a low loss hollow core anti-resonant fiber applied in the 1.5~3.0 μm band. The results show that the effect of limiting loss is better when the negative curvature decreases and the positive curvature increases. The lowest confinement loss is 8.22×10^-2 dB/km at the wavelength of 2.1 μm when the semi-circular tube is close to the core and the elliptical tube is far away from the core, as well as the circular radius r_y=25 μm, the semi-major axis of the ellipse r_x=65 μm, the semi-minor axis of the ellipse r_y=25 μm.