- The same country that implemented fibre optics on a large scale has broken the internet speed record in 2025. Which one is it?
- This record would mean being able to download the entire Movistar Plus+ catalogue… in a single second!
- The first submarine fibre optic cable dates back to the 1980s and could handle 40,000 phone calls simultaneously.
- Did you know that fibre optic cables are thinner than human hair?
The evolution of this technology has led to a wide range of uses and applications that were unthinkable a few years ago, thanks, among other things, to the contribution of submarine cables, through which 99% of global Internet traffic travels.
In this article, we will take an in-depth look at a number of interesting facts about fibre optics from different perspectives, including their composition, historical origins and different types.
Japan, the first country to implement large-scale fibre optic networks
Although fibre optics were first used for telecommunications in 1977 in the United States, it was Japan that became the first country to implement large-scale networks using this technology in the 1980s.
In 2025, this country is once again at the forefront of this technology, as researchers at the National Institute of Information and Communications Technology (NICT) have achieved a milestone in data transmission: 1.02 petabits per second, which translates to 125,000 gigabytes of data per second (Gbps), more than double the previous world record set in 2024 of 50,250 Gpbs.
To put these figures into context, we could sum it up by saying that all the content available on Movistar Plus+ could be downloaded in… one second!
As explained in the publication Interesting Engineering, this was achieved thanks to a fibre model with 19 internal cores. This record is not only about speed, but also about distance, as the transmission was achieved over a distance of approximately 1,800 kilometres (1,180 miles).
Thinner than a human hair
Within the types of fibre optics, there are differences in size between multimode and single-mode fibre.
Multimode fibre has a larger diameter than single-mode fibre, ranging from 50 to 100 micrometres (one thousandth of a millimetre).
Single-mode cable, on the other hand, is a single strand of fibreglass with a diameter ranging from 8.3 to 10 microns.
As these figures are so tiny, we can put them into context by comparing them to the size of a human hair, which can range from 15 to 170 microns, although most are between 60 and 110 microns.
Therefore, we can say that, despite variations depending on the type of fibre, cables using this technology are thinner than human hair.
The journey of fibre through submarine cables
The enormous evolution that has taken place in submarine cables can be seen in a fact that, although anecdotal, is representative.
The first cable connection between America and Europe dates back to 1858, specifically between Canada and the island of Ireland, when a telegraph cable was put into operation and Queen Victoria sent a congratulatory message to the then US President, James Buchanan. The message took 17 hours to arrive… and was considered a great success at the time.
From that first transoceanic connection to the present day, submarine cables have evolved enormously.
This is something that fibre optics is no stranger to: in 1988, TAT-8, the first cable using this technology, was inaugurated, with the capacity to support 40,000 simultaneous calls between France, the United Kingdom and the United States.
However, three years earlier, in 1985, fibre optics had already been used experimentally in OPTICAN-1 to test it and refine deployment, operation and repair techniques. This deployment, which cost $6.5 billion, was made possible by Telefónica and AT&T and sought to improve the deficiencies that had been detected in the PENCAN-2, which connected the island cities of Santa Cruz de Tenerife and Las Palmas de Gran Canaria by telephone.
The enormous importance of submarine cables can be seen in a fact that we have already mentioned: 99% of global Internet traffic passes through them, although not all of them are fibre optic.
Journey through light
Unlike other technologies, fibre optics transmit information through pulses of light based on two physical phenomena: refraction and total internal reflection.
In this way, the light pulses are reflected internally without escaping, thus allowing efficient transmission of information over long distances without significant losses.
As a curiosity, we can add that when looking at fibre optics, you cannot see the light. What’s more, it is counterproductive: since the light travelling through the cable is not in the visible spectrum—to which we must add its concentration and power—it can be harmful to the retina.
Shared paternity
As we mentioned in a recent post on the history of fibre optics, the ‘paternity’ of fibre optics is shared.
On the one hand, Indian physicist Narinder Singh Kapany is considered ‘the father of fibre optics’, while Chinese scientist Charles Kuen Kao is the ‘father of fibre optic communications’.
