**3.2 Silica optical fiber fabricated by additive manufacturing technology**

Although POFs realize low-cost AM technology and are widely used in shortdistance communication, silica fiber plays an irreplaceable role in the long-distance transmission process. Besides, silica material has unparalleled optical transparency, excellent electrical insulation, chemical resistance, and thermal stability. How to break through the traditional silica fiber manufacturing method and realize the AM of silica fiber has become a problem worthy of further study. In 2016, F. Kotz et al. proposed a soft lithography method and successfully mixed silica nanoparticles with monomer solution, combined with light curing to prepare "liquid glass," which provided a new way for silica glass fabricated by AM technology [47]. After that, the combination of organic matter and silica has been widely used in the AM of silica glass. For example, in order to bridge the gap between fused silica glass and polymer processing,

#### **Figure 5.**

*(a) Illustration of POF preform design, photos of annealed preform and preform after fiber draw. (b) The lightguiding images of fiber end faces at 630 nm and 515 nm, white-light output projected onto a screen, and relative schematic setup.*
