High pressure is key for better optical fibers

Date:
October 19, 2020
Source:
Hokkaido University
Summary:
Signal loss along optical communication networks could be cut in
half if silica glass fibers are manufactured under high pressure.



FULL STORY ========================================================================== Optical fiber data transmission can be significantly improved by producing
the fibers, made of silica glass, under high pressure, researchers from
Japan and the US report in the journal npj Computational Materials.


========================================================================== Using computer simulations, researchers at Hokkaido University,
The Pennsylvania State University and their industry collaborators theoretically show that signal loss from silica glass fibers can be
reduced by more than 50 percent, which could dramatically extend the
distance data can be transmitted without the need for amplification.

"Improvements in silica glass, the most important material for optical communication, have stalled in recent years due to lack of understanding
of the material on the atomic level," says Associate Professor Madoka
Ono of Hokkaido University's Research Institute of Electronic Science
(RIES). "Our findings can now help guide future physical experiments and production processes, though it will be technically challenging." Optical fibers have revolutionized high-bandwidth, long-distance communication all
over the world. The cables carrying all that information are mainly made
of fine threads of silica glass, slightly thicker than a human hair. The material is strong, flexible and very good at transmitting information,
in the form of light, at low cost. But the data signal peters out before reaching its final destination due to light being scattered. Amplifiers
and other tools are used to contain and relay the information before it scatters, ensuring it is delivered successfully. Scientists are seeking
to reduce light scatter, called Rayleigh scattering, to help accelerate
data transmission and 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 large voids between silica
atoms form when the glass is heated up and then cooled down, which is
called quenching, under low pressure.

But when this process occurs under 4 gigapascals (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 light scattering, and decrease signal loss by more than 50 percent.

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 ultra- transparent silica glass," Ono says.


========================================================================== Story Source: Materials provided by Hokkaido_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Yongjian Yang, Osamu Homma, Shingo Urata, Madoka Ono, John C. Mauro.

Topological pruning enables ultra-low Rayleigh scattering in
pressure- quenched silica glass. npj Computational Materials,
2020; 6 (1) DOI: 10.1038/s41524-020-00408-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201019103450.htm

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