History of the Atlantic Cable & Undersea Communications
from the first submarine cable of 1850 to the worldwide fiber optic network

Japanese Submarine Cables
by Stewart Ash and Kaori Shikinaka

Japanese Submarine Cables

The First Hundred years

Submarine telegraph cables were first brought to the land of the rising sun by Carl Fredrick Tietgen (1829-1901), a Dane who in 1870 set up the Great Northern China and Japan Extension Company and fought off strong English competition to lay and operate new telegraph cables connecting Russia, China and Japan. As part of this contract, two cables were landed in Japan in June and November 1871: these were Nagasaki to Vladivostok 1,430km and Nagasaki to Shanghai 912km. Both cables went into commercial service on 1st January 1872. The cables were made in England by Hooper's Telegraph Works Company and armoured by Siemens Brothers. Both of these manufacturing companies were located on the River Thames in London.  The cables were laid by the Danish naval vessel Tordenskold.   

In order to maintain these cables, in 1872 Tietgen commissioned what is acknowledged to be the first ever purpose-built cable repair ship, the H.C. Ørsted, named after the Danish physicist Hans Christian Ørsted (1777-1851) who discovered that electric currents create magnetic fields.

H.C. Ørsted

In 1872, the steam ship Densimu Maru installed the first submarine telegraph cable to be owned by the Japanese government, linking two cities in Honshu and Kyushu across the Kanmon Straits. Its purpose was to connect Tokyo to the cables built by Great Northern via the domestic land line from Tokyo to Nagasaki.

Over the next few years many new cables were installed by Great Northern and other companies, but all were manufactured in England. In 1889 the Ministry of Communications became the monopoly operator of all telecommunications in Japan; it was responsible for all infrastructure, manufacturing and operation. The submarine cable network continued to expand and by the end of the century over 4,000km of cable had been laid, connecting many of the 3,900 islands that made up the Japanese Empire, at that time. It was not until 1896 that the Japanese Government purchased its first cable ship, the Okinawa Maru; this was built in England by Lobintzi & Co. The first Japanese-built cable ship was the Ogasawara Maru which was launched in 1906.

CS Okinawa Maru

At the beginning of the twentieth century, in the course of preparation for the Russo-Japanese War, General Gentaro Kodama, known in Japan as ‘the greatest resourceful general of the century’, became concerned over the international telecommunications situation, at a time when nobody else in the Japanese authorities seemed to pay much attention to the problem. Under his leadership a team of Japanese engineers built a long-distance submarine cable from Kyushu to Taiwan, including the construction of the cable stations, conducting route/site surveys, laying the cables with the Okinawa Maru, and manufacturing the terminal equipment. All this was accomplished, apart from the cable supply, without any advice or support from non-Japanese experts.

The first submarine cable to be manufactured in Japan had rubber insulation and was made in 1915. The first Gutta Percha insulated cable was made by the Furukawa Electric Co in 1922, at its Yokohama factory, for a contract with the Chinese Government.   In 1932 the Sumitomo Electric Cable & Wire Works built a new plant in Osaka to meet the increased demand for submarine cable from the Ministry of Communications. In 1935 the Nippon Submarine Cable Co Ltd. (NSCC)was established as a joint venture between Fujikura Ltd, Furukawa and Sumitomo. This combined the Osaka plant in Taisho-Ku with the existing Yokohama factory. In 1941, as demand continued to grow, a new factory was built on a different site in Yokohama and the old factory was closed.

After WWII, the operating model for the submarine cable industry in Japan was developed with significant American influence. A state owned telecommunications infrastructure was established, supported by an oligopoly of private companies manufacturing equipment. Two government owned corporations were set up, Nippon Denshin Denwa Kosha, also known as Nippon Telegraph and Telephone Public Corporation (NTT) in 1952, responsible for domestic telecommunications and Kokusai Denshin Denwa (KDD) in 1953, responsible for international telecommunications.

KDD’s first international submarine telephone cable was laid in 1964 between the mainland of the USA – Hawaii – Guam – Japan, and was jointly owned with AT&T. This system contained some cable manufactured by the Ocean Cable Company Ltd (OCC) but the repeaters were all made in the USA. OCC had previously been established to undertake the development of trans-Pacific cables, and in 1964 it was merged with NSCC to create a single submarine cable manufacturer.

The first submerged repeaters to be manufactured in Japan were made by Fujitsu Limited and the NEC Corporation in 1969. Both companies’ designs were used on the Hokkaido Uchiura Bay system. By 1970 the Japanese submarine cable supplier industry had become powerful in its own region and was beginning to compete with the major global submarine system suppliers (Alcatel Submarcom, AT&T and STC Submarine Systems) on the world stage.

From Coaxial to Fibre Cables

Trans-Pacific Cable 1 (TPC-1),  the first transpacific submarine telephone cable, installed in 1964, provided 138 x 3kHz voice channels, which significantly improved the quality of telephone circuits between the US and Japan and was a major contributory factor in the economic development of Japan at that time. However, the second transpacific submarine cable, TPC-2, connecting Hawaii, Guam and Okinawa, was not laid until 1975, over a decade later. This system added another 845 x 3kHz voice circuits to the existing Japan to US traffic. Over the next few years, in order to deal with the rapidly growing demand for international communications, an enormous amount of effort was expended by the Japanese industry as a whole in enhancing the bandwidth and voice circuit carrying capacity of coaxial cable systems.  

In the domestic market, Fujitsu and NEC Corp developed viable 36Mhz systems for NTT, which provided 2,700 x 4kHz voice channels.  This technology was first deployed in a shallow water system between Kure and Marsuyama in 1971. The first deep water application was the Okinawa – Miyakojima system, installed in 1975.  36MHz technology was even commissioned by KDD for the Japan – Korea international system, which went into service in 1981. However, to achieve this transmission performance, repeater spacing was reduced to 2nm. This meant that the power feed demands of such systems, made the technology impracticable for transoceanic systems.

In 1979, NTT commissioned from Fujitsu and NEC an experimental coaxial system (Sagami Bay No.4). This 15km cable loop contained four repeaters operating at 43.2MHz. It was able to provide 10,800 x 4kHz voice circuits but repeater spacing was reduced to 1.8nm. After this trial, in Japan as elsewhere it was finally accepted that for both domestic and international applications the technical and economic limits of submarine coaxial cables had been reached and an alternative technology was required.

Building on the pioneering work of Dr Charles Kao and Dr George Hockham at STL, Harlow UK, Corning Inc. succeeded in 1970 in producing the first “low-loss” optical fibre that surpassed the less-than-20dB/km benchmark by achieving a transmission loss of just over 16dB/km. This milestone was the catalyst for the start of research and development into the use of optical fibre for telecommunications systems. Use of the technology for land applications advanced rapidly, and by the late 1970s serious consideration was being given to applying it to the more challenging environment of submarine cable systems. Development work started in France, Japan, UK and USA at almost the same time, so for the first time, the Japanese industry was on a level playing field relative to its international competitors.

The first experimental fibre optic submarine cable system deployed in Japan was a 50km cable loop between Inatori and Kawazu. The cable was supplied by OCC and contained 5 graded-index multimode fibres. There were no submerged repeaters and the system was laid for NTT by the cableship Tsugaru Maru. Terminal Transmission equipment was provided by both Fujitsu and NEC Corp. The system operated at 1,310nm and tests were carried out at bit rates of 6.3, 32 and 100 Mb/s.  In 1981, NTT conducted the first sea trial of an optical regenerator using the cableship Tsugaru Maru;the trial system included a single regenerator repeater supplied jointly by Fujitsu and the NEC Corp.

The first Japanese experimental systems containing repeaters were deployed in 1982 by both KDD and NTT. The KDD system comprised a 50km loop from a single landing at Ninomiya; the loop contained two regenerating repeaters (one supplied by Fujitsu the other by NEC Corp). The system cable was supplied by OCC and contained 6 single-mode fibres. The cable was laid by the cableship KDD Maru. Terminal equipment was once again supplied by Fujitsu and NEC. The system operated at 1,310nm and a line rate of 300Mb/s, providing the equivalent of 4,000 voice circuits. The repeaters were powered by a 1.0A PFE on a double-end feed basis.

The NTT system comprised a 50km loop from a single landing at Yahatano; the loop contained two regenerating repeaters (one supplied by Fujitsu, the other by NEC Corp). The system cable was supplied by OCC and contained 6 single-mode fibres. The cable was laid by the cableship Kuroshio Maru. Terminal equipment was once again supplied by Fujitsu and NEC. The system operated at 1,310nm and a line rate of 400Mb/s, providing the equivalent of 2 x 5,760 voice circuits. The repeaters were powered by a 1.0A PFE on a double-end feed basis.

In 1984 KDD conducted a deep water trial using the cableship KDD Maru. A 50km length of OCC cable with six single-mode fibres also included two regenerating repeaters. This mini-system was deployed and recovered from a water depth of 7,000m. The repeaters supplied by Fujitsu and NEC Corp had a line rate of 280Mb/s, and operated at 1,310nm with a transmission speed of 295.6mBaud and a Line Code of 24B1P. The system was powered by a 1.6A PFE on a single-end basis. This design was to form the basis of the first generation of international commercial fibre optic submarine systems. With this final trial the Japanese industry was perfectly placed to address what would effectively be a brand new market for submarine cable systems, which would emerge in the next few years.

The Optical Era

Japan consists of four large islands, Honshu (the mainland), Hokkaido, Kyushu, and Shikoku, along with around 4,000 smaller islands. Because of this, submarine cables play an important role in Japan’s domestic telecommunication infrastructure. Therefore, it was not surprising that Japan became the first country in the world to implement submarine fibre technology commercially. By connecting optical fibre submarine cables to optical fibre land cables, it quickly built up a backbone network which stretched 4,500km from Asahikawa in Hokkaido to Okinawa in the South.

The first repeatered optical submarine system deployed in commercial service anywhere in the world was a Japanese domestic system owned by NTT. FS-400M was 300km long and was laid in 1986 by Kuroshio Maru between Hachinohe and Tomakomai, thus connecting Honshu and Hokkaido. The OCC-supplied cable contained six single mode fibres and the system used seven NEC Repeaters; operating at 1,310nm, 400Mb/s; 445.837mB and a Line Code 10B1C RZ. The PFE was double-end feed @ 1.8A.

The first international repeatered system involving Japanese technology was TPC-3, which was installed in 1988 and went into service in 1989. Segments AC and BC of this system were supplied by Japanese companies, and included OCC cable containing six single mode fibres (Seg AC 2,220km; Seg BC 1,531km) as well as Fujitsu and NEC repeaters operating at 1,310nm, 280Mb/s with a Line Code 24B1F.

In 1992 repeater development in Japan moved from regenerating technology to optical amplification. Deep water (6,000m) sea trials of the new repeater designs were carried out before they went into full production. The first optically-amplified submarine system to go into commercial service anywhere in the world was a 900km domestic link from Kagoshima in Kyushu to Okinawa. This system, owned by NTT, commenced manufacture in 1994 and was completed in 1995.

The first international optically-amplified system in the world was the long-haul system TPC-5, and the Japanese industry played a significant part in its construction. TPC-5 is a ring system connecting Japan, North America, Hawaii and Guam. The laying operation commenced in November 1993 with the landing of the cable in Ninomiya Japan. The total system length was some 24,500km and the final splice was not completed until August 1996. KDDI-SCS laid Segments T2 (Ninomiya – Miyazaki), Segment I (Miyazaki – Guam) and part of Segment J (Ninomiya - Bandon), a total of 5,900km. These were completed in October 1994, February 1995 and May 1996 respectively. The Japanese-manufactured equipment for these segments comprised OCC cable, repeaters from Fujitsu and NEC, and a number of Mitsubishi repeater amplifier units in OCC housings; the terminal equipment was supplied by Fujitsu, NEC and Toshiba.

By the mid 1990s Japan was a leading supplier of submarine optical fibre technology, a position it has maintained through the development of 10Gbit/s line rates, WDM and DWDM technologies up to the present day. This was further demonstrated at SubOptic 2010 by presentations on the emerging 40Gbit/s and 100GBits/s coherent technology. Clearly, Japan has been a major pioneer in the development of fibre optic submarine cable systems and remains a significant influence in the development of our industry today. Fujitsu and NEC, along with OCC, remain among the world’s leading suppliers of submarine systems; KDDI and the NTT group are unquestionably influential system operators, and KCS and NTT WEM are leading marine service providers. In addition, our industry has benefited greatly from the technological innovation and products provided by such companies as Fujikura, Furukawa, Hitachi and Sumitomo. One hundred and forty years on from its first exposure to submarine cables, Japan is critical to the future of the submarine cable industry.

Article text copyright © 2016 Stewart Ash

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Last revised: 3 October, 2016

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