Skip to content

Jumper Cord

Welcome to HANYO

Read more
Jumper Cord

Attneuator

Welcome to HANYO

Read more
Attneuator

WDM

Welcome to HANYO

Read more
WDM

PIGTAIL

Welcome to HANYO

Read more
PIGTAIL

A research group at the Technical University of Denmark (DTU), which was the first to break the one-terabit barrier in 2009, has today managed to squeeze 43 terabits per second over a single optical fiber with just one laser transmitter. In a more user-friendly unit, 43Tbps is equivalent to a transfer rate of around 5.4 terabytes per second — or 5,375 gigabytes to be exact. Yes, if you had your hands on DTU’s new fiber-optic network, you could transfer the entire contents of your 1TB hard drive in a fifth of a second — or, to put it another way, a 1GB DVD rip in 0.2 milliseconds.

The previous record over a single optical fiber — 26 terabits per second, set by Karlsruhe Institute of Technology way back in 2011 — had remained unbroken for a surprisingly long period of time. DTU set a series of single-fiber world records in 2009 and 2011, but had since been forced to sit in Karlsruhe’s shadow — until now. This was obviously a pain point for the DTU researchers — the press release [Danish] announcing the new world record actually calls out Karlsruhe by name. I guess a bit of friendly competition never hurt anyone though, right?

Colorful fiber optic

The main thing about this world record is DTU’s use of a single laser over a single fiber. There have been plenty of network demonstrations of hundreds or even thousands of terabits (petabits) per second with multiple lasers over multiple fibers — but those demos are so far removed from the reality of fiber-optic networking that they’re not really worth discussing. When we talk about commercial fiber-optic links, we’re nearly always talking about single-laser-single-fiber, because that’s what the entire internet backbone is built upon. In other words, the techniques used by DTU to hit 43Tbps actually have a chance of making it into real-world networks in the next few years. You might soon be able to download a TV show or movie in quite literally the blink of an eye. [Read: Infinite-capacity wireless vortex beams.]

How did the DTU hit 43Tbps and steal the world record away from Karlsruhe? Well, rather amusingly, they kind of cheated. While the researchers did only use a single laser, it used multi-core fiber. This is still a single filament of glass fiber, but it has multiple individual channels that can each carry their own optical signal. In this case, DTU used multi-core optical fibers with seven cores, produced by Japanese telecom giant NTT. Back in 2011 when Karlsruhe set its 26Tbps record (with a single-core fiber), multi-core fibers were both difficult and expensive to manufacture — now, in 2014, it would seem the bugs have been ironed out and NTT is moving ahead with commercial deployments. The photo at the top of the story, incidentally, is an experimental hollow-multi-core fiber developed by DARPA.

NTT's 7- and 19-core multi-core fiber

NTT’s 7- and 19-core multi-core fiber

Wavelength-division multiplexing

Wavelength-division multiplexing

Beyond the DTU’s use of multi-core fiber, there’s sadly very little info on how they actually squeezed 5.4 terabytes of data per second over a single fiber. The usual method of boosting speeds over fiber is either SDM or WDM (spatial and wavelength-division multiplexing) — i.e. using different frequencies of light for each signal, or staggering each signal by a few microseconds, so that the signals don’t collide.

Currently, the fastest commercial single-laser-single-fiber network connections max out at just 100Gbps (100 Gigabit Ethernet). The IEEE is currently investigating the feasibility of either a 400Gbps or 1Tbps Ethernet standard, with ratification not due until 2017 or later. Obviously DTU’s 43Tbps won’t have much in the way of real-world repercussions for now — but it’s a very good sign that we’re not going to run out of internet bandwidth any time soon. (Customers of awful ISPs excepted, of course.)