Print‐and‐draw: microstructured optical fibers from 3D‐printed fused silica preforms

Microstructured optical fibers can guide light using carefully arranged air holes along their length. These fibers have a wide range of important technological and scientific applications across many disciplines - for example, by allowing light to be guided with ultralow loss within a hollow core. However, preforms for microstructured fibers are currently made almost exclusively using the stack-and-draw method. This method severely limits the complexity of achievable fiber structures. For example, it is highly difficult to make non-circular structures, thereby hindering the realization of novel advanced structures. We demonstrate that additive manufacturing of preforms using photocurable silica nanocomposites can be used to produce complex structures, including cladding elements with stadium shapes, which were previously considered only theoretically possible. Preforms containing anti-resonant hollow-core structures with record long length and high resolution were 3D-printed with wall thicknesses of less than 1 mm over a total length of more than 300 mm. After being converted into pure silica glass, the preforms were processed into optical fibers. We demonstrate for the first time that fiber features down to 500 nm thickness can be realized from 3D-printed preforms. We further demonstrate a double-nested anti-resonant hollow-core fiber with more truncated cladding elements than previously made by stacking of laser-cut capillaries. Contrary to previous fibers with only circular cladding elements, the surface tension-driven contraction of the now possible non-circular cladding elements cannot be counter-balanced with air-pressure. We therefore examined the impact of cladding element curvature and wall thickness on the contraction, which will help guide future novel preform designs. This work paves the way for 3D-printing to start the next revolution in microstructured fibers, by enabling designs that were previously impossible to make.