**3. Optical fiber fabrication by additive manufacturing technology**

With the rapid development of modern technology and application fields, the requirements for optical fibers in terms of structure and materials are more complex and diverse, striving to achieve the customized structural design and free and flexible material combinations. However, traditional optical fiber manufacturing methods such as CVD or stack-and-draw are difficult to meet this demand. Optical fiber manufacturing based on CVD processes is limited by the lathe itself, which has limited structural flexibility, and it is difficult to realize the manufacture of complex optical fiber structures, and it is necessary to maintain a highly uniform radially symmetrical temperature and pressure during the manufacturing process [37]. Although the stack-and-draw can achieve a certain degree of structural complexity, the flexibility of materials is limited, and it is very time-consuming and labor-intensive [38]. AM technology provides huge opportunities for the development of new cylindrical fibers such as new structural fibers.
