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Thanks to a team of University of Otago/ Dodd-Walls Centre scientists, we could be very soon seeing the next-generation of faster, more energy efficient internet. The team’s breakthrough results about a novel device have been published in the world’s premiere scientific journal Nature this morning.

The internet is one of the single biggest consumers of power in the world. With data capacity expected to double every year and the physical infrastructure used to encode and process data reaching its limits there is huge pressure to find new solutions to increase the speed and capacity of the internet.

Principal Investigator Dr Harald Schwefel and Dr Madhuri Kumari’s research has found an answer. They have created a device called a micro-resonator optical frequency comb made out of a tiny disc of crystal. The device transforms a single color of laser light into a rainbow of 160 different frequencies - each beam totally in sync with each other and perfectly stable. One such device could replace hundreds of power-consuming lasers currently used to encode and send data around the world. The work was born out of Dr Schwefel’s previous research at the prestigious Max Planck Institute in Germany and his collaboration with Dr Alfredo Rueda who did some of the preliminary research.

The internet is powered by lasers. Every email, cell phone calls and website visit is encoded into data and sent around the world by laser light. In order to cram more data down a single optical fibre the information is split into different frequencies of light that can be transmitted in parallel. According to Dr Kumari, the current infrastructure is struggling to cope with demand as internet consumption increases significantly. Lasers only emit one color at a time. What this means is that, if an application requires many different colors at once, there should be many lasers too. All of them cost money and consume energy. The idea of these new frequency combs is that one color is launched into the micro-resonator and a whole range of new colors comes out.

According to Dr Schwefel, it’s a really cool energy saving scheme and it replaces a whole rack of lasers with small energy efficient device. Dr Schwefel expects the devices to be incorporated in sub-oceanic landing stations where all the information from land based fibers is crammed into the few sub-oceanic fibers available in less than a decade, perhaps within a few years. According to him, to develop the device for the telecommunications industry they will need to start working with major telecommunications companies. For now, they have started the process by collaborating with a New Zealand-based optical technology company.

The breakthrough is the first milestone in a government funded collaboration between scientists at the University of Otago and the University of Auckland who are part of the Dodd-Walls Centre for Quantum and Photonic Technologies - a virtual organization gathering New Zealand’s top researchers working in the fields of light and quantum science. The research project has been awarded nearly one million dollars of Marsden Fund money to develop and test the potential of micro-resonator frequency combs.

The optical frequency combs are based on a very unusual optical effect that happens when the intensity of light builds up to extremely high levels. A single color of visible light is send into the crystal disc along with a microwave signal and because the crystal disc is such high quality, the light and microwave radiation gets trapped inside. The light and microwave radiation keeps pouring in and bouncing around and around inside the crystal. In most situations light never changes color but in this case the intensity becomes so high that the light and the microwave radiation start merging and making different colors. The phenomenon is known as a non-linear effect and it has taken the team many years to optimize.

The only other group in the world making devices of competing quality is a collaboration from Harvard and Stanford Universities in the US, also published in this month’s Nature, but currently Drs Schwefel and Kumari hold the record for the most efficient device. Essentially this means that their crystals don’t leak any light. The trick is to have an extremely high quality crystal. Harald’s group is a world experts in crafting crystal discs in his University of Otago lab.

The internet is just one of the possible applications for the new optical frequency combs. Another use is high-precision spectroscopy — using laser light to study and identify the chemical composition, properties and structure of materials including diseases, explosives and chemicals. Dr Kumari’s next mission will be to explore this application amongst other possibilities. According to her, optical frequency combs have literally revolutionized every field of applications they have touched. From vibrational spectroscopy and distance measurement to telecommunications. She is now thus looking forward to see the benefits of her technological research in the field.

Click here to view the published paper.