A team from the Vienna University of Technology have reversed the concept of ‘laser a perfect source of light‘ and made them the perfect ‘light absorber‘, what they call an anti-laser.
The team developed the method 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.
“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.
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.”