A group of researchers from the Technical University of Denmark (DTU), Chalmers University of Technology in Gothenburg, Sweden and Optical Technologies R&D Center, Fujikura, Japan have, using a single light source, have transmitted 1.8Pb/s of data using a method that could significantly decrease power usage and help to reduce the internet’s climate footprint.
The light source used in the experiment is a custom-designed optical chip, which can use the light from a single infrared laser to create a spectrum of many colours, allowing the one frequency (colour) of a single laser to be multiplied into hundreds of frequencies in a single chip.
The chip produces a frequency comb, which allows each frequency to then be isolated and used to imprint data. The frequencies can be reassembled and sent over an optical fibre to transmit even a huge volume of data. The experimental demonstration showed that a single chip could easily carry 1.8Pb/s, which, with contemporary state-of-the-art commercial equipment, could 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. He reveals that this particular application was not the one for which the chip was originally intended. He says: “In fact, some of the characteristic parameters were achieved by coincidence and not by design. However, with efforts in my team, we are now able to reverse engineer the process and achieve, with high reproducibility, microcombs for target applications in telecommunications.”
The researchers also created a computational model to theoretically examine 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. Professor Leif Katsuo Oxenløwe, Head of the Centre of Excellence for Silicon Photonics for Optical Communications (SPOC) at DTU, explains: “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 100Pb/s. 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 utilise for spectrally efficient data transmission.”
Oxenløwe also believes that the solution could bode well for future power consumption of the internet. He says: “Our solution provides a potential for replacing hundreds of thousands of the lasers located at internet hubs and data centres, all of which guzzle power and generate heat. We have an opportunity to contribute to achieving an internet that leaves a smaller climate footprint.”
There is still some development work to be undertaken before the solution can be commercialised and implemented in current communication systems, Oxenløwe explains: “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. 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 was published in Nature Photonics.
