Cristiano Cordeiro, a researcher and professor at the University of Campinas’ Physics Institute, has developed a method for fabricating optical fibers that is faster, simpler, and cheaper than conventional processes. The procedure roughly resembles the extrusion method used to produce pasta: Pressure is brought to bear on a ductile material so as to force it through a die, producing fiber with the appropriate inner structure, Cordeiro said.
“ The conventional process requires very large and expensive machinery and takes almost a week. Our process can be completed with bench-mounted equipment that’s at least 100 times cheaper and takes less than an hour from feedstock to end product. It will enable many more researchers and labs to produce their own optical fiber,” Cordeiro said. “ Of course, this is all done with much more rigor and precision.”
The conventional process, Cordeiro said, requires several steps and complex equipment, such as a drawing tower. First, a preform is produced, which is a large-scale version of the fiber with a diameter between 2 and 10 cm. The structure is heated and drawn in a highly controlled manner by the tower.
“ Our method simplifies the process at an enormously reduced cost. The device we designed carries out a single continuous process starting with polymer pellets and ending with the finished fiber,” Cordeiro said.
The technique can fabricate all-solid fiber, in which light passes through a core with a higher refractive index, as well as microstructured fiber containing an array of longitudinal holes, which enhances control of optical properties and brings increased function — including the opportunity to guide light with low energy loss in an air channel. The researchers used titanium dies with suitable designs to create the microstructures.
“ To simplify the fabrication of special optical fiber, we deployed equipment and techniques that are becoming more affordable and accessible thanks to the popularization of 3D printing,” Cordeiro said. “ The only machine required is a compact horizontal extruder similar to the device used to produce filament for 3D printers. It’s about the size of a microwave oven and is far less costly than a draw tower. The titanium die with solid parts and holes is coupled to the extruder exit.”
Owing to the fiber’s intricate inner structure, the researchers produced the dies by additive manufacturing using 3D printers. Specialist firms can provide additive manufacturing services; the only piece of equipment needed to produce the fiber is the horizontal extruder.
Cordeiro developed the method during a research internship at the University of Adelaide in Australia, supported by a scholarship from Sao Paulo Research Foundation and by a partnership with his host, Heike Ebendorff-Heidepriem.