High birefringence single-polarization composite structured anti-resonant fiber

Abstract

We propose a highly birefringent, single-polarization composite structured anti-resonant fiber (CS-ARF). The proposed CS-ARF has an elliptical core, two symmetrically spaced arrays of elliptical air holes, and a six-tube anti-resonant structure. The birefringence and single-polarization characteristics of the proposed CS-ARF were analyzed in detail in the mid-infrared band using the finite element analysis method. The results show that the fiber can achieve birefringence up to the order of 10−2 and single-polarization transmission with a confinement loss (CL) below 10−5 dB/m in the mid-infrared band. When the refractive index of the elliptical core is set at na = 2.70, the designed CS-ARF maintains single polarization in the range of 2.5 μm to 3.197 μm with an extinction ratio of up to 1.08 × 107. In addition, we found that by setting the refractive index of the elliptical core, the CL in the y-polarization direction can be effectively adjusted.

Keywords

• Optical fibers
• Anti-resonant layers
• High birefringence
• Single-polarization
• Mid-infrared