Scandinavian group sets transmission record with single laser and chip

25 Oct 2022

DTU (Denmark) and Chalmers University, Sweden, are “first in world” to deliver >1 petabit/s by integrated optical transmitter.

An international group of researchers from Technical University of Denmark (DTU) and Chalmers University of Technology in Gothenburg, Sweden, have achieved unprecedented data transmission speeds and claim to be the first in the world to transmit more than 1 petabit per second using only a single laser and a single optical chip.

The researchers succeeded in transmitting 1.8 Pbit/s, which they say “corresponds to twice the rate of total global Internet traffic”. The light source is a custom-designed optical chip, which uses the output from a single infrared laser to create a “rainbow” spectrum of many frequencies. By this means, the one frequency of a single laser can be multiplied into hundreds of frequencies in one chip.

All the frequencies are fixed at a specific interval from each other, which explains why it is called a frequency comb. Each colour (or frequency) can then be isolated and used to imprint data. The experiment showed that a single chip could easily carry 1.8 Pbit/s, which – using conventional equipment – would otherwise require the deployment of more than 1,000 lasers.

Victor Torres Company, professor at Chalmers UT, is head of the research group that developed and manufactured the new chip. He commented, “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.”

The achievement is described in Nature Photonics.

Potential for scaling

Interestingly, the chip was not optimized for this particular application. “In fact, some of the characteristic parameters were achieved by coincidence and not by design,” said Torres Company. “However, with efforts in my team, we are now capable to reverse engineer the process and achieve with high reproducibility microcombs for target applications in telecommunications.”

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.

Professor Leif Katsuo Oxenløwe, Head of the Centre of Excellence for Silicon Photonics for Optical Communications at DTU, commented, “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.

“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.”

The researchers say that their achievement bodes well for the future power consumption of the Internet. Katsuo Oxenløwe added, “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.”

NTT achieves optical transmission of 2Tbits/s per wavelength

Japan-based telecoms services provider NTT Corporation has succeeded in what it calls “the world’s fastest optical transmission experiment of digital coherent optical signals exceeding 2 Tbits/s per wavelength”. In the experiment, NTT developed an ultra-wideband baseband amplifier IC module and digital signal processing technology that can compensate for distortion in the optical transceiver circuit.

The NTT researchers then demonstrated the transmission and receipt of digital coherent optical signals exceeding 2 Tbits/s per wavelength and succeeded in a 240 km optical amplification repeater transmission experiment of an optical signal of 2.02 Tbits/s.

They stated, “This result suggests that further scalability of digital coherent optical transmission technology can achieve both a large capacity per wavelength, which is more than double the conventional level, and a long transmission distance. This core technology is expected to lead the development of the all-photonics network of the IOWN and 6G initiatives.