At Aalto University's Department of Applied Physics, researchers have pioneered a method to create light vortices - small "hurricanes" within laser beams - that can potentially carry significant amounts of data. This advancement, developed through manipulating metallic nanoparticles, was designed by Doctoral Researcher Kristian Arjas and brought to life by Doctoral Researcher Jani Taskinen under the guidance of Professor Paivi Torma's Quantum Dynamics group. This innovation paves the way for new approaches in data transmission.
Balancing Order and Chaos
These light vortices, akin to hurricanes with a calm center surrounded by bright light, occur when the electric field within a beam directs light in different ways, creating a dark center. Previous studies showed that the type of vortices generated depended on the symmetry of the nanoparticle structures. For instance, square arrangements produced single vortices, while hexagonal ones created double vortices.
Arjas and Taskinen's breakthrough involved designing geometric shapes within a class called quasicrystals, theoretically capable of producing any vortex type. "This research is on the relationship between the symmetry and the rotationality of the vortex, i.e., what kinds of vortices can we generate with what kinds of symmetries. Our quasicrystal design is halfway between order and chaos," explained Torma.
Harnessing Unique Electric Fields
To achieve this, the team meticulously arranged 100,000 metallic nanoparticles, each one a fraction of a human hair's width. The key was placing particles where the electric field was at its weakest. "An electrical field has hotspots of high vibration and spots where it is essentially dead. We introduced particles into the dead spots, which shut down everything else and allowed us to select the field with the most interesting properties for applications," Taskinen noted.
This discovery could revolutionize the study of light's topological properties and serve as an early step toward powerful data transmission methods in light-based communication, such as telecommunications. According to Arjas, "We could, for example, send these vortices down optic fibre cables and unpack them at the destination. This would allow us to store our information into a much smaller space and transmit much more information at once. An optimistic guess for how much would be 8 to 16 times the information we can now deliver over optic fibre."
While practical applications and scaling up these designs require years of further engineering, the team's innovative research provides a strong foundation for future exploration. Aalto University's Quantum Dynamics group continues their work on related fields such as superconductivity and enhancing organic LEDs, utilizing the OtaNano infrastructure for cutting-edge studies.
Research Report:High topological charge lasing in quasicrystals
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Aalto University
Space Technology News - Applications and Research
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