Researchers create anti-lasers that absorb light instead of emitting it

Lasers are perfect source of light, however, scientists have reversed this concept and made them the perfect light absorber, what they call an anti-laser.

When lasers are provided with energy, they generate light of a specific color, now a team from the Vienna University of Technology has reversed the phenomenon by making it an object that absorbs light of a particular color and dissipates the energy almost completely.

The team developed the method, explained in the journal Nature, using computer simulations and based on random light scattering. “Waves that are being scattered in a complex way are really all around us - think about a mobile phone signal that is reflected several times before it reaches your cell phone,” said researcher Stefan Rotter.

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“This multiple scattering is made practical use of in so-called random lasers. Such exotic lasers are based on a disordered medium with a random internal structure that can trap light and emit a very complicated, system-specific laser field when supplied with energy,” he added.

The team’s random anti-laser is capable of absorbing waves randomly scattered in all directions. This ability can have many potential uses in everything, anywhere waves are captured ranging from phone antennas to medical equipment, wrote Science Alert.

To build their anti-laser, the team set up a series of randomly placed cylinders and sent microwave signals scattering through them. They used a waveguide place on the top with an antenna in its center to absorb the incoming waves, reaching an absorption rate of around 99.8% of the signals.

“So far, anti-lasers have only been realized in one-dimensional structures onto which laser light was directed from opposite sides,” said Rotter. “Our approach is much more general: we were able to show that even arbitrarily complicated structures in two or three dimensions can perfectly absorb a suitably tailored wave. In this way, this novel concept can also be used for a much wider range of applications."