Artificial solid fog creates a pleasant laser light

Aerobornitride scatters the light of a laser beam evenly in all directions. Credit: Florian Rush

With a porosity of 99.99%, it consists almost exclusively of air, which makes it one of the lightest materials in the world: Aerobornitride is the name of the material developed by an international research group led by the University of Kiel. Scientists suggest that in this way they created a central basis for the propagation of laser radiation in a wide range. Based on the combination of boron and nitrogen, they developed a special three-dimensional nanostructure that scatters light very strongly and practically does not absorb it. When laser irradiated, the material emits uniform illumination, which, depending on the type of laser, is much more efficient and powerful than LED. Thus, lamps for car headlights, projectors or indoor lighting using laser light can become smaller and brighter in the future. The research team presents its results in the current issue of the famous journal The bonds of naturethat was published today.

More light in a small space

In research and industry, laser light It has long been considered the "new generation" of light sources, which could even exceed the effectiveness of LEDs (LEDs). “For a very bright or large amount of light, you need a large number of LEDs and, therefore, space. But the same amount of light can be obtained with one laser “A diode that is one thousand smaller,” emphasizes Dr. Fabian Schütt. A material scientist from the Functional Nanomaterials working group at Kiel University is the first author of the study, which involves other researchers from Germany, England, Italy, Denmark and South Korea.

Powerful small light sources allow for numerous applications. The first test applications, such as car headlights, are already available, but laser lamps are not yet widespread. On the one hand, this is due to the intense directional light of laser diodes. On the other hand, light consists of only one wavelength, therefore it is monochromatic. This leads to an unpleasant flicker when the laser beam hits the surface and is reflected there.

Artificial solid fog creates a pleasant laser light

The boron nitride, on which the new light material is based, is also called “white graphene” because of its similar atomic structure. Courtesy: Julia Sickmann, CAU.

Porous structure scatters light very strongly

“Previous developments in the field of laser lighting usually work with phosphors. However, they produce relatively cold light, are not stable in the long run, and are not very effective, ”says Professor Rainer Adelung, Team Leader. The Kiel research team takes a different approach: they developed a high dispersion nanostructure of hexagonal boron nitride, also known as “white graphene,” which almost does not absorb light. The structure consists of a filigree network of countless small hollow microtubes. When a laser beam hits them, it is extremely scattered inside the network structure, creating a uniform light source. “Our material acts more or less like an artificial fog that produces a uniform, pleasant light stream,” Schütt explains. Strong scattering also contributes to the fact that disturbing flicker is no longer visible to the human eye.

The nanostructure not only ensures that the material withstands intense laser radiation, but can also scatter waves of various lengths. Red, green and blue laser light coloured can be mixed to create specific color effects in addition to plain white – for example, for use in innovative room lighting. Here, extremely light laser diodes can lead to completely new design concepts in the future. “However, in order to compete with LEDs in the future, the efficiency of laser diodes must also be improved,” says Schütt. The research team is now looking for industrial partners to take a step from the laboratory to the application.

  • Artificial solid fog creates a pleasant laser light

    Inside a thin network of hollow tubes measuring just a few micrometers, the incident laser beams are so scattered that a uniform white light is obtained. Credit: Kiel University

  • Artificial solid fog creates a pleasant laser light

    Due to its internal structure, the material can scatter waves of various lengths, i.e. green, red and blue laser light. Credit: Fabian Schütt

A wide range of applications for aviation materials

Meanwhile, researchers from Kiel can use their method to develop highly porous nanostructures for various materials, in addition to boron nitride, as well as graphene or graphite. Thus, more and more new light materials, the so-called “aeromaterials”, are created, which allows them to be used especially innovatively. For example, scientists are currently collaborating with companies and other universities on the development of self-cleaning air filters for aircraft.

Crystal creates a breakthrough in the supercontinuum

Additional Information:
Fabian Schutt et al. Conversion-efficient high-performance laser diffusers for high brightness lighting, The bonds of nature (2020). DOI: 10.1038 / s41467-020-14875-z

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Kiel University

Artificial solid fog creates a pleasant laser radiation (2020, March 19)
restored March 19, 2020

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