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Using only a single light source, scientists have set a world record by transmitting 1.8 petabits per second. Their data transmission method uses significantly less power and could help reduce the internet's climate footprint.
An international group of researchers from Technical University of Denmark (DTU) and Chalmers University of Technology in Gothenburg, Sweden, has achieved dizzying data transmission speeds and is the first in the world to transmit more than 1 petabit per second (Pbit/s) using only a single laser and a single optical chip. One petabit corresponds to 1 million gigabits.
In the experiment, the researchers succeeded in transmitting 1.8 Pbit/s, which corresponds to twice the total global internet traffic at any one time, but carried only by the light from one optical source. The light source is a custom-designed optical chip that can use the light from a single infrared laser to create a rainbow spectrum of many colors, i.e. many frequencies. Thus, the one frequency (color) of a single laser can be multiplied into hundreds of frequencies (colors) in a single chip.
All the colors are fixed at a specific frequency distance from each other, just like the teeth on a comb, which is why it is called a frequency comb. Each color (or frequency) can then be isolated and used to imprint data. The frequencies can then be reassembled and sent over an optical fiber, thus transmitting data -- even a huge volume of data, as the researchers have discovered.
One single laser can replace thousands
The experimental demonstration showed that a single chip could easily carry 1.8 Pbit/s that, with contemporary state-of-the-art commercial equipment, would otherwise require more than 1,000 lasers.
Victor Torres Company, professor at Chalmers University of Technology, is head of the research group that has developed and manufactured the chip.
"What is special about this chip is that it produces a frequency comb with ideal characteristics for fiber-optical communications. It has high optical power and covers a broad bandwidth within the spectral region that is interesting for advanced optical communications," says Torres Company.
Interestingly enough, the chip was not optimized for this particular application.
"In fact, some of the characteristic parameters were achieved by coincidence and not by design," he says. "However, with efforts from my team, we are now capable to reverse engineer the process and achieve, with high reproducibility, microcombs for target applications in telecommunications."
Enormous potential for scaling
In addition, the researchers created a computational model to examine, theoretically, the fundamental potential for data transmission with a single chip identical to the one used in the experiment. The calculations showed enormous potential for scaling up the solution.
"Our calculations show that, with the single chip made by Chalmers University of Technology and a single laser, we will be able to transmit up to 100 Pbit/s," says Professor Leif Katsuo Oxenlowe, head of the Center of Excellence for Silicon Photonics for Optical Communications (SPOC) at DTU. "The reason for this is that our solution is scalable -- both in terms of creating many frequencies and in terms of splitting the frequency comb into many spatial copies and then optically amplifying them, and using them as parallel sources with which we can transmit data. Although the comb copies must be amplified, we do not lose the qualities of the comb, which we utilize for spectrally efficient data transmission."
Reduces internet power consumption
The researchers' solution bodes well for the future power consumption of the internet.
"In other words, our solution provides a potential for replacing hundreds of thousands of the lasers located at internet hubs and data centers, all of which guzzle power and generate heat. We have an opportunity to contribute to achieving an internet that leaves a smaller climate footprint," says Katsuo Oxenlowe.
Even though the researchers have broken the petabit barrier for a single laser source and a single chip in their demonstration, there is still some development work ahead before the solution can be implemented in our current communication systems.
"All over the world, work is being done to integrate the laser source in the optical chip, and we're working on that as well," says Katsuo Oxenlowe. "The more components we can integrate in the chip, the more efficient the whole transmitter will be, i.e., laser, comb-creating chip, data modulators, and any amplifier elements. It will be an extremely efficient optical transmitter of data signals."
The experiment in which the researchers transferred 1.8 Pbit/s and the subsequent calculations have been published in Nature Photonics.
Source: Technical University of Denmark
Published October 2022