From coaxial to fiber: the optical revolution in submarine cables (1970–1995)

1. Bell Labs and partners commit to transatlantic fiber

   Jan 1, 1978Labels: Bell Labs, STC, TAT-8 project

   In 1978, organizations including Bell Labs and the UK’s Standard Telephones and Cables (STC) committed to the idea of a long submarine fiber link across the North Atlantic. This was a major shift from short-range demonstrations toward a project that would require dependable deep-ocean cable, repeaters (signal boosters), and repair practices. The commitment set the stage for the engineering work that later produced TAT-8.

   • Wired

2. First deep-sea fiber system trial in North Atlantic

   Aug 31, 1982Labels: Bell Labs, Simplex SL, North Atlantic

   From August 31 to September 12, 1982, a Bell Labs–Simplex SL lightguide fiber system was tested in deep water in the North Atlantic, about 500 miles from Bermuda. The trial demonstrated error-free high-speed transmission and showed the cable and splices could survive laying and recovery without fiber breaks. Proving deep-sea survivability was a key step toward long transoceanic fiber cables.

   • Atlantic Cable

3. ITU begins standardizing single-mode fiber

   Jan 1, 1984Labels: ITU-T, G 652, single-mode fiber

   As fiber optics moved from lab work toward real networks, international agreement on basic fiber characteristics became important. ITU-T Recommendation G.652 began in 1984, describing the key optical and physical properties for widely used single-mode fiber. This kind of standard helped manufacturers and network builders design equipment that would work reliably together across long distances.

   • ITU G 652

4. OPTICAN-1 live island test system deployed

   Jan 1, 1985Labels: OPTICAN-1, Canary Islands, submarine testbed

   In 1985, a live test system called OPTICAN-1 was deployed between two Canary Islands (Gran Canaria and Tenerife). This provided real operational experience with submarine fiber, including lessons about faults and insulation problems that could interrupt power or signals. These lessons fed into improved designs for later large systems.

   • Atlantic Cable
   • Wired

5. UK–Belgium No. 5 enters service

   May 4, 1986Labels: UK Belgium, English Channel, optical cable

   On May 4, 1986, UK–Belgium No. 5 went into international service across the English Channel. It is widely cited as the first international undersea communications cable system to use optical fiber instead of coaxial copper. This milestone showed that fiber could work in real undersea conditions and offered a clear path beyond the capacity limits of older coaxial systems.

   • Atlantic Cable
   • Optica

6. TAT-8 installed across the Atlantic

   Sep 1, 1988Labels: TAT-8, transatlantic cable, undersea reliability

   In the summer and fall of 1988, the TAT-8 system was installed between North America and Europe. It was designed as the first transatlantic optical fiber system and required tight control of reliability because repairs at sea are difficult and expensive. Its successful installation showed that fiber could be deployed on true ocean-crossing routes, not just short channels or island links.

   • Bell Labs

7. TAT-8 enters service with optical repeaters

   Dec 14, 1988Labels: TAT-8, optical repeaters, transatlantic service

   On December 14, 1988, TAT-8 entered service as the first transatlantic fiber-optic cable. It used opto-electrical regeneration (converting light to electrical signals and back) in undersea repeaters to keep the signal strong over long distances. Compared with coaxial copper systems, TAT-8 offered far higher capacity and became a turning point for global telecom infrastructure.

   • Bell Labs
   • Wired

8. TAT-9 enters service with flexible branching

   Jan 1, 1992Labels: TAT-9, branching multiplexer, undersea switching

   In 1992, TAT-9 began operation with higher capacity than TAT-8 and new undersea switching/branching features. It is noted for using undersea branching multiplexer technology so traffic could be switched between multiple landing points, helping manage changing demand and improving resilience. This reflected a broader move toward smarter, more configurable submarine network design.

   • TAT 9

9. ITU approves G.652 (03/93) single-mode fiber recommendation

   Mar 12, 1993Labels: ITU-T, G 652, single-mode standard

   On March 12, 1993, ITU-T approved the G.652 (03/93) version of its single-mode fiber recommendation. Having an up-to-date, widely adopted reference mattered as submarine and terrestrial systems scaled, because cable makers and equipment builders needed shared targets for loss (signal weakening) and other performance measures. Standards like this helped reduce incompatibilities as fiber networks expanded internationally.

   • ITU G 652

10. CANTAT-3 enters service with multi-gigabit capacity

    Jan 1, 1994Labels: CANTAT-3, multi-gigabit cable, Canada Europe

    In 1994, CANTAT-3 entered service, linking Canada to multiple European landing points with branching to Iceland and the Faroe Islands. With multi-gigabit-per-second design capacity, it illustrated how quickly submarine fiber systems advanced after TAT-8. These higher-capacity links supported broader international data traffic growth through the mid-1990s.

    • CANTAT 3
    • Atlantic Cable

11. SEA-ME-WE 2 begins service linking Europe and Asia

    Oct 18, 1994Labels: SEA-ME-WE 2, Europe Asia, multinational system

    On October 18, 1994, the fiber-optic SEA-ME-WE 2 system entered service, connecting countries across South-East Asia, the Middle East, and Western Europe. Its scale showed that fiber had become the default choice for very long, multinational submarine routes, replacing the older coaxial-era approach. This expansion also reflected growing demand driven by digital communications, not just voice calls.

    • SEA ME WE

12. By 1995, fiber displaces coaxial as the main new-build choice

    Jan 1, 1995Labels: fiber adoption, 1995 milestone, submarine shift

    By the mid-1990s, the key technical and operational hurdles for submarine fiber—deep-sea survivability, reliable repeaters, and interoperable standards—had largely been proven in service. Systems like UK–Belgium 5, TAT-8, and newer multi-gigabit projects made clear that coaxial copper could not keep up with demand. The period from 1970–1995 ends with fiber established as the core technology for new long-distance submarine cables.

    • Bell Labs
    • Atlantic Cable