Single Laser on Optical Chip Sets Data Transmission Record

An international team of researchers has reportedly set a data transmission record using just a single laser and optical chip to transmit more than 1 Pbit/s. The researchers, from the Technical University of Denmark (DTU) and Chalmers University of Technology in Sweden, transmitted data at 1.8 Pbit/s, corresponding to double the total global internet traffic.

The demonstrated data transmission method used significantly less power than conventional approaches to data transmission and can help reduce the internet’s climate footprint, according to the team.

The light source in the team’s experiment was a custom-designed, frequency comb-producing optical chip; the chip used light from a single infrared laser to create a “rainbow” spectrum of different frequencies. The one frequency of the single laser could be multiplied into hundreds of frequencies in a single chip.

The experiment, based on this frequency comb setup, allowed each frequency to be isolated and used to imprint data. The frequencies could then be reassembled and sent over an optical fiber, thereby transmitting data.

The researchers ultimately used the demonstration to show that a single chip could easily carry a quantity of data — 1.8 Pbit/s — which with contemporary state-of-the-art commercial equipment would otherwise require more than 1000 lasers.

According to Victor Torres Company, a professor at Chalmers University of Technology and head of the research group that developed and manufactured the chip, the chip’s key quality is in its ability to produce a frequency comb with ideal characteristics for optical fiber communications. The chip demonstrated high optical power and covered a broad bandwidth within the necessary spectral region.

The chip, interestingly enough, was not optimized for this particular application. “In fact, some of the characteristic parameters were achieved by coincidence and not by design,” Company said.

The researchers also 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 strong potential for scaling.

According to Leif Katsuo Oxenløwe, head of the Center of Excellence for Silicon Photonics for Optical Communications at DTU, the group’s calculations show that it will be able to transmit up to 100 Pbit/s with a setup based on the same architecture. To do this, although the comb copies must be amplified, Oxenløwe said, the design manages to avoid losing the qualities of the comb.

The technology holds implications for the future of the internet’s power consumption needs. “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,” Oxenløwe said. “We have an opportunity to contribute to achieving an internet that leaves a smaller climate footprint.”

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. According to Oxenløwe, the more components the team can integrate in the chip, the more efficient the whole transmitter will be.

The research was published in Nature Photonics (www.doi.org/10.1038/s41566-022-01082-z).