A gift from God

The completion of an extremely low-loss fiber approaching the theoretical limit. Even the world-renowned Bell Labs praised it as a "gift from God" and bowed their heads in admiration at the miraculous achievement.

Researchers from around the world visit Fujikura to learn about the company's development of an extremely low-loss Optical Fiber with a loss of 0.47 dB/km. These visits to Fujikura allow cutting-edge information from around the world to be gathered effortlessly. As a result, it is as if the "god of technology" has descended upon the heads of Fujikura's researchers, and research and development gains momentum. And an even stronger tailwind begins to blow.

First, he developed "Optical Fiber with a silicon buffer layer," which gave momentum to its practical application. This became the standard specification of the Nippon Telegraph and Telephone Public Corporation and came into widespread use internationally. He then published the theoretical basis for low-loss Optical Fiber in "A paper on elucidating the causes of loss" (December 1976). At the time, many people had misconceptions about fiber. The common understanding was that the lack of reduction in loss was due to high impurities, or that using better quality materials would reduce loss. However, he proved that loss reduction was also determined by issues of fiber drawing and structure, in other words, the "fiber manufacturing method," and presented a method for understanding this in an easy-to-understand way. This paper would go on to make a significant contribution to the subsequent evolution of Optical Fiber. He received numerous invitations to give lectures at academic conferences around the world, and "Fujikura Theory and Method" was in high demand.

VAD

Fujikura's world-class achievement thus gave impetus to joint research with Nippon Telegraph and Telephone Public Corporation. There was a growing feeling that it was time to break away from Bell Labs' method (MCVD method) and establish a manufacturing method unique to Japan, and this was made the theme of the joint research. In March 1977, they succeeded in developing the VAD method (vapor phase axial deposition method). Although the VAD method was an economically advantageous method, it was predicted that the amount of residual hydroxyl groups would be greater than in the MCVD method, and that there would be large losses. Therefore, removing the water was considered to be the biggest breakthrough point.

Fujikura also demonstrated its capabilities in "water removal" using the VAD method. It developed a method for almost complete dehydration, obtained a patent for it, and announced a fiber that actually contained almost no water. Fujikura was also a leader in research into "how to ensure that fiber maintains stable performance regardless of the surrounding environment...in other words, under what conditions does fiber become weak or loss increase?" and as proof of its success, it developed a "unit cable with piano wires." This would prove extremely effective in the field tests by Nippon Telegraph and Telephone Public Corporation that began the following year in 1978.