Fabrication and laser performance of cladding uniform core tapered fiber

• Published in: Optical fiber technology 2021-07, Vol.64, p.102561, Article 102561
• Main Authors: Lin, Xianfeng, Zhang, Zhilun, Chu, Yingbo, Wang, Yibo, Xing, Yingbin, Chen, Gui, Peng, Jinggang, Li, Haiqing, Dai, Nengli, Li, Jinyan
• Format: Article
• Language: English
• Subjects: Fiber characterization; Fiber design and fabrication; Fiber lasers; Tapered fiber
• ISSN: 1068-5200; 1095-9912
• DOI: 10.1016/j.yofte.2021.102561

•Design and fabricate an Yb-doped cladding uniform core tapered fiber (CUCTF).•The CUCTFs with two different structures are compared in experiment and theory.•The CUCTF with the wide to narrow structure has a better M2 factor. Compared with traditional uniform fiber, the long tapered fiber has the advantage of suppressing nonlinear effects and maintaining excellent beam quality. Both the cladding size and core size of the long tapered fiber reported so far vary simultaneously in a constant core-to-cladding diameter ratio (CCDR) along the length. In this work, we propose a technique for preparing cladding uniform core tapered fiber (CUCTF) with a varying CCDR, and have successfully fabricated CUCTF. The core diameters of narrow end and wide end are 31.2 μm and 52.5 μm, respectively. The cladding diameter is always 400 μm along the length. The laser performance of CUCTFs with different structures (wide to narrow, narrow to wide) are investigated based on a co-pumped fiber amplifier. Between them, the CUCTF with the wide to narrow structure has a better M2 factor of 1.455 due to mode filtering.