Israeli and Austrian scientists have created the perfect light trap

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 Israeli and Austrian scientists have created an ideal light trap

If you want to use light efficiently, you must absorb it as fully as possible. This applies whether the light is used for photosynthesis, in which green plants convert light into oxygen and energy-rich organic compounds, or in a photovoltaic system, which uses solar panels for converting sunlight into electricity. However, difficulties arise if the absorption is to take place in a thin layer of material that normally transmits most of the light.

Research teams from the Hebrew University of Jerusalem and the Vienna University of Technology (TU Wein) have found an amazing trick that allows a beam of light to be completely absorbed by even the thinnest layers.

They built a “light trap” around a thin light-absorbing layer with the help of mirrors and lenses, in which the light beam is directed in a circle and then superimposed on itself in such a way that it can no longer leave the system. As a result, light has no choice but to be absorbed by a thin layer.

This absorption-amplification method was proposed by Prof. Ori Katz from the Hebrew University and conceptualized jointly with Prof. Stefan Rotter from the Technical University of Vienna. The experiment was carried out by the team laboratories in Jerusalem, and theoretical calculations were made by a team from Vienna.

The system for the experiment in Jerusalem was built by graduate students Evgeny Slobodkin and Gil Weinberg.

Professor Rotter explained: “The system has to be precisely tuned to the wavelength you want to absorb. But other than that, there are no limiting requirements. The laser beam does not have to have a certain shape, in some places it can be more intense than in others — almost perfect absorption is always achieved.

Even air turbulence and temperature fluctuations cannot damage the mechanism, as shown by experiments at the Hebrew University. This proves the reliability of the system and promises a wide range of applications in practice.

For example, this mechanism could be used to better capture light signals that are distorted when transmitted through the Earth's atmosphere. The new approach could also be of great practical importance for optimally obtaining light waves from weak light sources such as distant stars.< br />

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