Data transmission over optical fibers can be significantly improved by producing the silica (SiO2) glass fibers under high pressures of 4 GPa (about 40,000 atmospheres), according to computer simulations done by researchers at Hokkaido University, The Pennsylvania State University, and their industry collaborators.1 The results show that signal loss from silica glass fibers can be reduced by more than 50%, which could dramatically extend the distance data can be transmitted without the need for amplification. If made practical, this would be a huge advance for the fiber-optic industry.
“Our findings can now help guide future physical experiments and production processes, though it will be technically challenging,” says Associate Professor Madoka Ono of Hokkaido University’s Research Institute of Electronic Science (RIES).
Scientists are seeking to reduce Rayleigh light scatter in optical fibers to help accelerate data transmission (and also to move closer towards quantum communication). Ono and her collaborators used multiple computational methods to predict what happens to the atomic structure of silica glass under high temperature and high pressure. They found that large voids form between silica atoms when the glass is heated and then cooled (quenched) under low pressure. But when this process occurs under 4 GPa, most of the large voids disappear and the glass takes on a much more uniform lattice structure.
Specifically, the models show that the glass goes under a physical transformation, and smaller rings of atoms are eliminated or “pruned,” allowing larger rings to join more closely together. This helps to reduce the number of large voids and the average size of voids, which cause Rayleigh scattering, and decrease signal loss by more than 50%.
The researchers suspect even greater improvements can be achieved using a slower cooling rate at higher pressure. The process could also be explored for other types of inorganic glass with similar structures. However, actually making glass fibers under such high pressures at an industrial scale is very difficult.
“Now that we know the ideal pressure, we hope this research will help spur the development of high-pressure manufacturing devices that can produce this ultratransparent silica glass,” Ono says.
Madoka Ono is part of the Laboratory of Nanostructured Functional Materials, RIES at Hokkaido University. Her research focuses on the properties of nonorganic and silica glass by both laboratory experiments and computational analyses.
Source: https://www.global.hokudai.ac.jp/blog/high-pressure-is-key-for-better-optical-fibers.
REFERENCE
1. Yongjian Yang et al., npj Computational Materials, (September 17, 2020); doi: 10.1038/s41524-020-00408-1.
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