Production Method Reduces Photonic Chip Errors, Cost

Research from Eindhoven University of Technology has shown an improved method of constructing optical fiber arrays, which could significantly improve efficiency and lower the cost of developing photonic chips. The research specifically addresses improvements to optical fiber coupling, which is used to guide light in and out of the chip, and requires alignment with submicrometer precision. Current methods are labor-intensive and time consuming and therefore unsuitable for large-scale production, or are unable to meet the alignment requirements altogether.

A prototype of the fiber array assembly machine designed by Matthijs Van Gastel, Ph.D. candidate at Eindhoven University of Technology. Courtesy of Eindhoven University of Technology.

Doctoral student Matthijs Van Gastel’s optical fiber array positions the fibers next to one another and affixes them to a glass plate. Among the problems with current methods is the inability to compensate for variance in production quality. To overcome this, Van Gastel’s design used a camera system to measure the position of the fiber and account for these production tolerances.

Once measured, the glue can be cured to attach the fiber. Glue, however, tends to shrink, which can disturb alignment. Additionally, over the years its shape tends to deform, which can also disturb alignment.

To test the suitability of this method, Van Gastel performed simulations and experiments. The results showed high predictability of the glue’s behavior, making it a suitable technique for the alignment of the optical fibers.

The method employs an entirely new machine setup, which uses three translational motion axes to align the fibers on the substrate. The high-precision motion axes are able to align the fibers with nanometer accuracy. Due to the compact and modular design, the alignment machine can be easily expanded to larger production lines.

In testing a prototype of the assembly machine, Van Gastel demonstrated that the machine is able to assemble a 16-fiber array within 4 min. In comparison, traditional methods can take 2 min to 1 h per fiber. The finished arrays also showed up to 18× smaller alignment errors when compared with currently employed fiber arrays.

The work may prove an important step to large-scale adaptation of photonic chips by providing a faster, more accurate, and more cost-effective assembly process of optical fibers.

The thesis was published by Eindhoven University of Technology on March 25 (https://pure.tue.nl/ws/portalfiles/portal/168798048/20210325_Gastel.pdf).