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.

まずは「シリコン緩衝層付き光ファイバ」の開発で、実用化への弾みをつける。これは電電公社の標準仕様になるとともに国際的にも広く使用されるようになる。続いて低損失光ファイバの理論的裏付けを「損失要因の解明についての論文」として発表（1976年12月）。当時、ファイバについて多くの人々の間に誤解があった。ロスが低下しないのは不純物が多いからではないか、もっと良質の材料を使用すればロスは減るのではないか......というのが常識的な理解であった。しかし、そればかりではなく、ロスを減らすのは線引きの問題とか構造の問題、つまり「ファイバの製造方法」でも決まるのだということを証明し、それをわかりやすく知る方法を発表したのである。この論文はその後の光ファイバの進化に多大な貢献を果たすことになる。世界中の学会からも招待講演の依頼が相次ぎ、「フジクラ理論＆メソッド」は引く手あまたのモテモテぶりだった。

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.