Single & Multimode Silica Optical Fibers Drawn from 3D Printed Preforms

October 7, 2019 by Bridget O'Neal 3D Printing 3D Printing Materials

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In the recently published, ‘Silica optical fiber drawn from 3D printed preforms’ the authors created single and multimode fibers that can be used to create designs and parts for a range of networks, likely related to telecommunications and Internet of Things (IoT) technology.

Silica optical fibers are ‘the holy grail of 3D printing optical fiber,’ according to the authors, due to a ubiquitous nature and levels of low loss; in fact, the researchers state that there is not another alternative able to compete. For this study, the researchers investigate the process of creating a silica preform through both 3D printing and thermal processing—no small feat, considering it requires temperatures over T = 1900 ℃. To avoid this issue, the researchers tried using a lower melting polymer—a hybrid polymer-glass mix—via DLP printing. Steps involved in this process include:

Photocurable resin preparation
3D printing of preforms
Core fabrication
Thermal debinding
Final fiber drawing

Fabrication of the step-index silica optical fiber using 3D printing.

The researchers polymerized the mixed resin with the DLP printer and went on to fabricate arbitrary structures. They designed the preform with Inventor CAD, and then it was 3D printed, cured with UV light. After debinding, the researchers placed the preform into a quartz tube for support, with a lower drawing temperature to eliminate water, air, and residual polymers.

“As the temperature gradually increased, the polymer is ablated leaving behind the silica nanoparticles, which come closer together leading to preform shrinkage,” state the researchers. “Sintering at higher temperatures fuses them together.”

Refractive index difference profile

The quality of the fiber was examined with an optical microscope, demonstrating the cross-section of both 3D printed single and multi-mode.

a) experimental configuration of loss measurement b) loss spectrum of the 3D printed multimode.

Fibers, with both minimum and maximum eclipse diameters, showed more elevated uniform tension. With ‘increased loss’ the potential for interfacial scattering is suggested, with ‘significant contribution’ from water—meaning that the bubbles may be holding trapped water. The researchers theorize that this could be resolved with the use of:

Higher purity, drier starting chemicals
Sintering and debinding
Removal of the outer silica tube

“In conclusion, whilst there remains considerable scope to improve the transmission properties of this fiber, the first single mode and multimode silica optical fibers have been drawn from a 3D printed preform. The relative ease in which this was achieved suggests additive manufacturing will disrupt optical fiber fabrication,” concluded the researchers.

“Unlike conventional labor-intensive, lathe-based methods, the design and fabrication are not limited by a centrally spun or finely stacked preform, enabling configurations such as improved multicore and complex optical fibers, such as optimized Fresnel fibers, to be made. More broadly, painstakingly difficult complex patterns, multicore and multi-size and shaped fibers can be made that are not otherwise possible. This work, building off the original polymer versions, marks a new and exciting time for fiber fabrication and application.

3D printing is a technology very centered around materials usage, from silicate bone scaffolds to printing with silicone and epoxies, composites, and more. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.