by Staff Writers
Vienna, Austria (SPX) Jul 17, 2013
Random Lasers are tiny structures emitting light irregularly into different directions. Scientists at the Vienna University of Technology have now shown that these exotic light sources can be accurately controlled.
The light they emit is as unique as a fingerprint: random lasers are tiny devices with a light emission pattern governed by random scattering of light.
Understanding the underlying details of random lasing action has only been achieved recently. Now scientists at the Vienna University of Technology have presented a method to steer the radiation emitted by a random laser into a pre-determined direction. What has started out as a curious idea now has the potential to become a useful new type of light source.
Randomness instead of Mirrors
"It consists of a granular material in which light is randomly scattered and forced onto complicated paths." Along these paths the light is amplified. At which position it eventually exits the laser depends on the random inner structure of the laser material.
"The essential point is the way in which the random laser is pumped", says Stefan Rotter. "Our idea is to pump the laser not uniformly, but rather with a specific pattern, which is optimized such as to generate exactly the laser beam we want", says Rotter. The pumping pattern selectively stimulates certain regions of the random laser, which then cooperatively produce light emission in a very well defined direction.
Finding the right Pumping Pattern
As all random lasers are different, this optimization process has to be carried out for each device individually - but once the solution is known, the same laser beam can be created again and again. In principle, one could also steer the laser beam from a given direction to any other direction by changing the pumping pattern appropriately.
Stefan Rotter's team is cooperating with a research group in Paris, where random lasers are fabricated and studied in the lab. Together, the researches now want to test their findings in the experiment. If the experimental results indeed show that random lasers can be forced to relinquish their randomness, this would constitute a major step towards technological applications of these exotic new light sources.
Vienna University of Technology
Space Technology News - Applications and Research
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