How quickly can fibre optic cables transmit data?

With fibre optic cable data transfer speeds hitting new records, it’s interesting to see how quickly these pipes can distribute digital data

Wednesday, 30 June, 2021

It’s worth remembering that everything a digital device does is instructed using nothing more than zeroes and ones.

The binary state of on/off (0/1) is known in computing circles as a bit, and it’s the bedrock of every webpage, game, app, smart speaker and streaming media file.

Endless arrays of zeroes and ones (bits) are distributed together. A million bits form a megabit (Mb), a billion comprise a gigabit (Gb) and a trillion make up a terabit (Tb).

When you bundle eight bits together, you create one byte. This is a basic measurement of file storage – an iPhone with 32GB of storage can accommodate 32 billion bytes of information.

When you consider how many zeroes and ones it takes simply to display all the individual pixels making up this webpage, it’s easy to see why those numbers scale so quickly.

And every bit or byte has to be piped along cables into our homes.

Sometimes, these are copper phone lines. Known as ADSL and managed by Openreach, these have a maximum throughput of 11Mbps, meaning 11 million bits of data can be carried per second.

More commonly, our homes are connected by fibre optic cables, which can achieve significantly greater speeds.

Fibre optic cable data transfer speeds start at around 15Mbps, extending up to 1Gbps in many new-build homes and urban areas.

However, teams of scientists around the world are constantly pushing to increase fibre optic cable data transfer speeds even further.

Auf wiedersehen, peta

While megabits and gigabits have historically been the units of measurement for internet connectivity, new terminology will be needed in future.

The latest fibre optic cable data transfer speeds are measured in terabits (which readers who were paying attention earlier will know is a trillion bits per second).

And tomorrow’s cabling could be even quicker.

Earlier this year, an international team of researchers using a single-core multi-mode optical fibre cable recorded a data transmission speed of one petabit per second.

That’s a thousand terabits (or a million gigabits) of data being distributed each second along a cable with an industry-standard diameter of just 0.125mm.

The previous record was 0.4Pbps, which puts this particular achievement into perspective.

It’s also important to consider the wider context of the planet’s endlessly expanding data requirements.

Standard definition video recordings have given way to 4K online streaming, while games and apps become more data-intensive with every passing year.

We are using the internet in ways – and to an extent – previously unimaginable, and vast amounts of data are already being distributed online at any given moment.

Having infrastructure capable of piping this to local telephone exchanges more quickly will ensure domestic connections are fast enough to cope with these expanding data needs.

It’s why new homes are increasingly being cabled with gigabit connectivity – not necessary today, but vital for the future.

And it’s why so much effort is being invested in maximising fibre optic cable data transfer speeds in laboratories around the world.

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Neil is our resident tech expert. He's written guides on loads of broadband head-scratchers and is determined to solve all your technology problems!