March 10th, 2015PRIMALIGHT News, Research highlightsAndrea Fratalocchi 0 Comments

Writing in Nature Physics, Primalight in collaboration with St. Andrews, York and FOM Institute of Amsterdam Science Park, demonstrates a nano-optical chip that makes possible generating and controlling nanoscale rogue waves. The innovative chip was developed by an international team of physicists, led by Prof. A. Fratalocchi, and is expected to have huge applications for energy research and environmental safety.

Can you imagine how much energy is in a tsunami wave, or in a tornado? Energy is all around us, but mainly contained in a quiet state. But there are moments in time when large amounts of energy build up spontaneously and create rare phenomena on a potentially disastrous scale. How these events occur, in many cases, is still a mystery.

To reveal the natural mechanisms behind such high-energy phenomena, Dr Andrea Fratalocchi, assistant professor in the Computer, Electrical and Mathematical Sciences and Engineering Division of KAUST, led a team of researchers from Saudi Arabia and three European universities and research centers to understand the dynamics of such destructive events and controlling their formation in new optical chips, which can open various technological applications. The results and implications of this study have been published in the prestigious journal Nature Physics.

UntitledFigure 1. Full experimental image of a nanoscaled and ultrafast optical rogue wave retrieved by Near-Field Optical Microscope (NSOM).

“I have always been fascinated by the unpredictability of nature” Prof. Fratalocchi said “and I believe that understanding this complexity is the next frontier that will open cutting edge pathways in science and offer novel applications in a variety of areas.”

Dr. Fratalocchi’s team began the research by developing new theoretical ideas to explain the formation of rare energetic natural events such as rogue waves, large surface waves that develop out of the blue in deep water and represents a potential risk for vessels and open-ocean oil platforms.”

“Our idea was something never tested before!” Dr. Fratalocchi continued “We wanted to demonstrate that small perturbations of a chaotic sea of interacting waves could, contrary to intuition, control the formation of rare events of exceptional amplitude.”

A planar photonic crystal chip, fabricated at the University of St. Andrews and tested at the FOM institute AMOLF in the Amsterdam Science Park, was used to generate ultrafast (163 fs long) and subwavelength (203 mn wide) nanoscale rogue waves, proving that Fratalocchi’s theory was right. The newly developed photonic chip was offering an exceptional level of controllability over these rare events.

Prof TF Krauss, of the University of York, UK, who was involved in the development of the experiment and the analysis of the data, comments that “by realizing a sea of interacting waves on a photonic chip, we were able study the formation of rare high energy events in a controlled environment. We noted that these events only happened when some sets of waves were missing, which is one of the key insights our study.”

Prof. Kobus Kuipers, of FOM institute AMOLF, NL, who was involved in the experimental visualization of the rogue waves, was fascinated by their dynamics: “We have developed a microscope that allows us to visualize optical behavior at the nanoscale. Unlike conventional wave behavior, it was remarkable to see the rogue waves suddenly appear, seemingly out of nowhere, and then disappear again…as if they had never been there.”

Dr. Di Falco, leader of the Synthetic Optics group at the University of St Andrews said “The advantage of using light confined in an optical chip is that we can control very carefully how the energy in a chaotic system is dissipated, giving rise to these rare and extreme events. It is as if we were able to produce a determined amount of waves of unusual height in a small lake, just by accurately landscaping its coasts and controlling the size and number of its emissaries.”

fratax1Fig. 2. Andrea Fratalocchi led a team of researchers from Kaust and three European Universities and research centers to develop a new chip capable of generating nanoscaled rogue waves.

Dr Fratalocchi and the team believe their research represents a major milestone for KAUST and for the field. “This discovery can change once and for all the way we look at catastrophic events” concludes Dr Fratalocchi ”opening new perspectives in preventing their destructive appearance on large scales, or using their unique power for ideating new applications at the nanoscale.”.

The title of the Nature Physics paper is “Triggering extreme events at the nanoscale in photonic seas.’” The paper is accessible on the Nature Photonics website http://dx.doi.org/10.1038/nphys3263

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