A team of engineers has developed a photonics chip capable of modelling natural phenomena such as tsunamis and tornadoes. The research, published in Nature Physics, makes it possible to generate and control nanoscale rogue waves, which could change how communities prepare for natural disasters.
The chip was developed by an international team of physicists led by Andrea Fratalocchi from the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia.
How large amounts of energy build up spontaneously and create rare phenomena on a potentially disastrous scale, in many cases, is still a mystery.
To reveal the natural mechanisms behind such high-energy phenomena, the research team set out to understand the dynamics of such destructive events and control their formation in new optical chips.
Fratalocchi's team began their research by developing new theoretical ideas to explain the formation of rare energetic natural events such as rogue waves − large surface waves that develop spontaneously in deep water and represent a potential risk for vessels and open-ocean oil platforms.
‘Our idea was something never tested before,’ 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 in Scotland and tested at the FOM institute AMOLF in Amsterdam, was used to generate ultrafast (163fs long) and subwavelength (203nm wide) nanoscale rogue waves, proving that Fratalocchi's theory was correct. The photonic chip offered an exceptional level of controllability over these rare events.
By using light in a confined spoptical chip, it made it possible to control how the energy is dissipated to form natural disasters such as tsunamis, explained Andrea Di Falco, leader of the Synthetic Optics group at the University of St Andrews. ‘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,’ she said.
‘By realising a sea of interacting waves on a photonic chip, we were able study the formation of rare high energy events in a controlled environment,’ added Thomas F Krauss, head of the Photonics Group and Nanocentre Cleanroom at the University of York in the UK, who was involved in the development of the experiment and the analysis of the data.
To visualise the rogue waves, the FOM institute AMOLF developed a near-field scanning optical microscope (NSOM) that allowed the team to observe the optical behaviour at the nanoscale. ‘Unlike conventional wave behaviour, 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,’ said Kobus Kuipers, head of nanophotonics at the institute.
In the future, the research could open up the possibility of preventing the destruction caused by natural disasters, according to Fratalocchi. ‘This discovery can change once and for all the way we look at catastrophic events, opening new perspectives in preventing their destructive appearance on large scales.’
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