Design of ultrahigh birefringent stress-induced polarization-maintaining fiber with hole-assistance

• Published in: Optical fiber technology Vol. 67; p. 102707
• Main Authors: Li, Meng, Li, Xuyou, Li, Haoyu
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.12.2021
• Subjects: Air-holes; Fiber design and tolerance; Modal birefringence; Polarization-maintaining fiber; Air-holes; Polarization-maintaining fiber; Fiber design and tolerance; Modal birefringence
• ISSN: 1068-5200; 1095-9912
• DOI: 10.1016/j.yofte.2021.102707

•A novel holes-assisted stress-induced polarization-maintaining fiber is designed combining stress and geometric birefringence, which can maintain excellent optical properties in both the Panda-type and Bow-Tie stress-applying parts.•With optimization of air-hole dimensions and positions, the proposed fiber demonstrates a three-fold increase in the birefringence compared to the traditional Panda-type polarization-maintaining fiber, meanwhile, the effective mode area and nonlinearity are ideal for sensing applications.•The designed fiber indicates excellent reflection and polarization dependent loss characteristics after the inscription of a Bragg grating.•The geometric dimensions of air-holes are deviation-tolerant as each air-hole parameters vary by up to 10% around the designated values.•The feasibility of the proposed fiber is verified, with a description of the actual fabrication process. We present a stress-induced ultrahigh-birefringence fine-diameter polarization-maintaining fiber (PMF). The proposed PMF is composed of an elliptical-core, with four elliptical side-holes distributed around it, and two symmetrical circular/bow-tie stress-applying parts (SAPs) creating a fiber with both geometric and stress birefringence. The influence of the air-hole dimensions and positions on the properties of the proposed PMF, including modal birefringence, effective mode area, and nonlinearity, is comprehensively investigated via numerical simulations. This characterization reveals that this novel design with appropriate parameters for the air-holes is capable of ultrahigh birefringence of 1.27 × 10−3 in Panda-type PMFs and 1.28 × 10−3 in Bow-Tie PMFs at a wavelength of 1550 nm. This result shows a three-fold increase relative to the birefringence of a conventional Panda-type PMF. The effective mode area is ideal for sensing applications and there is a significant improvement in the nonlinearity. Remarkably, the fiber still exhibits excellent reflection spectra characteristics after being inscribed into the grating. The fabrication process of the novel PMF is briefly introduced. The geometric dimensions of the side-holes in the proposed PMF are shown to be deviation-tolerant within the existing fiber manufacturing facility restrictions, and thus are promising for practical fabrication. In summary, the proposed PMF with improved polarization-maintaining ability is a promising candidate for wide use in high-precision optical fiber sensors and fiber communication systems, with the specifications of the fine-diameter PMF conforming to the trend of miniaturization in current fiber optic sensors.