With the introduction of the high-speed communication standard "5G" and the popularization of remote working, global communication traffic continues to grow, and the risk of fiber optic (optical fiber) communication networks running into capacity shortages in the 2020s has emerged. Previous efforts have been made to improve existing optical fibers or increase the number of cables, but these have reached the limits of their performance and installation space. Therefore, not only communication standards, but also research on promoting a dramatic increase in communication traffic through optical fiber itself has become a top priority.
Transmission test of new generation optical fiber
Japan's "Information and Communications Research Institute" (NICT, an agency affiliated with the Ministry of Internal Affairs and Communications of Japan, "Intelligence" in Japanese means "information") Hideaki Furukawa, director of the photonic network system research department, sounded the alarm on the situation by pointing out that "if communication traffic continues to increase, the limits of current optical fiber will be exceeded in the 2020s." According to statistics from Japan's Ministry of Internal Affairs and Communications, Japan's domestic communication volume has increased more than 10 times in 10 years.
The reason is the increased access to smartphones and personal computers. As the performance of these terminal products improves, videos have also become an object for people to transmit to each other. When transmitting information, the digital signals carrying the information are converted into optical signals and transmitted through fiber optic cables. Optical fibers are spread all over the world in the form of submarine cables and have become indispensable for communicating with the world. It can be said that optical fiber is the "hero behind the scenes" supporting modern society.
The current optical fiber (left) has one optical signal channel, but the new generation optical fiber (right) will have multiple channels (picture provided by Japan Information and Communications Research Institute)
Previously Respond to increases in traffic by increasing the transmission capacity of each fiber. The transmission capacity in 2005 was 1 trillion bits per second per root, but now it is in the tens of trillions.
However, current optical fiber can only increase the transmission capacity to 100 trillion bits. If more information were transmitted, the lasers used for communications would be too strong, risking the fiber melting. If the threat materializes, communications will come to a standstill, which will have an impact on business efficiency and labor reform.
Forecasts from Japan's "Electronic Information Technology Industry Association" show that global communications volume is expected to increase 15 times in the 10 years to 2030, and will continue to increase in the future. In order to solve this problem, optical fiber companies in Japan and abroad are promoting the development of a new generation of optical fiber called "Multi core".
Previous optical fibers had only one optical signal channel called "Core", but multi-core optical fibers will have 3 4 cores. Just as the number of vehicles that can travel will increase as the number of lanes on the road increases, if the number of optical signal channels increases, the transmission capacity will also increase several times.
In addition, to accurately transmit optical signals, it is necessary to avoid interference from other signals, but the diameter of an optical fiber is only 0.125 mm, which is about the same thickness as a hair. Therefore, the distance between fiber cores is only about 0.05 mm, and interference with optical signals leaking from adjacent fiber cores has been a problem.
One solution is to add a layer of low-refractive index glass as a material around the fiber core to avoid leakage to the surroundings. By adding fluorine to the glass, only the refractive index of the peripheral parts is reduced, allowing the optical signal to remain in the core of the fiber.
The Japan Information and Communications Research Institute conducted a transmission test using an optical fiber with four cores in March and successfully achieved a transmission of 610 trillion bits per second. It has set a world record in terms of transmission capacity for optical fibers of the same thickness as today. In this case, even if there are multiple fiber cores, the thickness of the optical fiber will not change.
Multi-core optical fiber can be used together with existing optical fiber, so it is considered to be gradually replaced.
Japan's Sumitomo Electric Industries laid multi-core optical fiber in Italy for the first time in the world in 2019, and the Japanese Information and Communications Research Institute gave positive comments on the related performance. According to the vision of Japan's "Electronic Information and Communications Society", starting around 2025, optical fibers with four cores will begin to be used in short-distance communication networks of less than 10 kilometers. It is expected to be used in submarine optical cables from around 2030.
To further improve the performance of each optical fiber, there is also the possibility of developing "Multimode" optical fiber that thickens the fiber core and allows optical signals to pass through multiple channels in one fiber core. via. Practical use of integrated multi-core technology is expected to wait until the second half of the 2030s.
In the field of new generation optical fiber, Japanese companies are at the forefront in research and development. A report released by the Japan Patent Office in 2018, which is responsible for patent-related matters, shows that in the multi-core field of optical fiber, the top four companies in the world in terms of number of patent applications have been Fujikura, Sumitomo Electric, NTT and Furukawa Electric Industries, ranked by Japanese companies. exclusive. In the multi-mode field, the 24th position is also monopolized by Japanese companies such as NTT, Sumitomo Electric and Fujikura. Fujikura plans to commercialize multi-core optical fiber by the mid-2020s.
Of course, companies outside Japan are also promoting the development of new generation optical fibers. Corning, an American special glass manufacturer, ranks first in the number of multi-mode optical fiber patents and has also successfully achieved large-capacity transmission in the multi-core field. Italy's Prysmian Group also has research achievements in new generation optical fibers. As with smartphones and base stations, global competition in optical fiber is likely to become increasingly fierce.
In the 5G era, do you think the role of optical fiber is important?