A Perfect Trap for Light

1/2 images 1 of 2 images or videos At TU Wien (Vienna) and The Hebrew University of Jerusalem, a "light trap" was developed in which a beam of light prevents itself from escaping. This allows light to be absorbed perfectly. Whether in photosynthesis or in a photovoltaic system: if you want to use light efficiently, you have to absorb it as completely as possible. However, this is difficult if the absorption is to take place in a thin layer of material that normally lets a large part of the light pass through. Now, research teams from TU Wien and from The Hebrew University of Jerusalem have found a surprising trick that allows a beam of light to be completely absorbed even in the thinnest of layers: They built a "light trap" around the thin layer using mirrors and lenses, in which the light beam is steered in a circle and then superimposed on itself - exactly in such a way that the beam of light blocks itself and can no longer leave the system. Thus, the light has no choice but to be absorbed by the thin layer - there is no other way out. This absorption-amplification method, which has now been presented in the scientific journal "Science", is the result of a fruitful collaboration between the two teams: the approach was suggested by Prof. Ori Katz from The Hebrew University of Jerusalem and conceptualized with Prof. Stefan Rotter from TU Wien; the experiment was carried out in by the lab team in Jerusalem and the theoretical calculations came from the team in Vienna.