*Additive Manufacturing of Optical Waveguides DOI: http://dx.doi.org/10.5772/intechopen.105349*

At present, the additive manufacturing of polymer optical fiber preform mainly includes melt extrusion and light curing. Although the melt extrusion method has relatively low cost, the resolution of the manufacturing preform is low. While the light-curing technology is just the opposite. The manufacturing cost is higher than that of melt extrusion, and the resolution is also high, which is suitable for manufacturing preform with complex structures, such as bandgap optical fiber preform.

For the silica optical fiber preform, there are two main additive manufacturing methods. The first method is to combine silica and organic matter to form the resin, then use additive manufacturing technologies, such as light or heat curing, to shape, and finally obtain the optical fiber through debinding, sintering, and fiber drawing. This manufacturing method has a very high fabricating resolution and becomes the main way of additive manufacturing of silica optical fiber preform. However, due to the introduction of organic matter, an additional debinding process is required in the later stage, even if a small amount of organic matter remains, it will cause high loss. The second method is to directly sinter or melt the silica powder by laser. This method can effectively avoid the organic matter, but its development is also restricted by the problems of manufacturing accuracy and ceramics caused by phase transformation. The technologies above make full use of the advantages of additive manufacturing technology in molding, such as short time, low labor cost, and low material cost, and fully reflect its potential in the manufacturing of complex geometry silica optical fiber.

Although optical fiber fabricated by additive manufacturing has so many advantages, loss, manufacturing size, and multi-materials are still the factors limiting its development, and it is also the research direction in future. For the loss of additive manufacturing optical fiber, especially for the silica optical fiber, the loss mainly comes from microbubbles, microcracks, stripes between layers during printing, organic matter not removed during debinding process, and the purity of raw materials. For the manufacturing size, the main problems rise from the loss caused by incomplete removal of internal organic matter during debinding due to the large size of preform, and the cracking caused by uneven stress distribution during debinding, sintering, or cooling process. For the additive manufacturing of multi-material optical fiber, the integration of glass, semiconductor, crystal, metal, or polymer into the so-called hybrid fiber is also another research focus of additive manufacturing of fibers, and the key point is how to balance the relationship between melting point and thermal expansion coefficient of each material. At present, a large number of researchers have carried out systematic research on the above problems. We have reason to believe that just like the development trend of traditional optical fiber, the optical fiber fabricated by additive manufacturing will also experience the development trend of reducing loss, multi-structure, and multi-material and bring revolutionary changes to the optical fiber manufacturing industry with its unparalleled advantages.

*Hybrid Planar - 3D Waveguiding Technologies*
