Jena Helmholtz Institute Using Air Deflection Laser Beam

A novel method is used to deflect the laser beam using only air. The interdisciplinary research team reported in the journal Nature Photonics that invisible gratings made solely of air not only do not suffer damage from lasers, but also retain the original quality of the beam. The researchers have applied for a patent for their method.

Technology and Principles
This innovative technology utilizes sound waves to regulate the air in the area where the laser beam passes through. We generated gratings using acoustic density waves, "explained first author and doctoral student Yannick Schr ö del. DESY and students at the Jena Helmholtz Institute.

With the help of special speakers, researchers shaped patterns of dense and sparse areas in the air, forming stripe gratings. Similar to how different air densities in the Earth's atmosphere bend light, the density pattern acts as a grating that changes the direction of the laser beam.

However, compared to deflection in the Earth's atmosphere, deflecting light through diffraction gratings can more accurately control lasers, "Schroeder said. The characteristics of a grating are influenced by the frequency and intensity of sound waves (in other words, volume)

Laboratory results and potential
In the initial laboratory testing, strong infrared laser pulses could be redirected in this way, with an efficiency of 50%. According to the numerical model, efficiency should be significantly improved in the future. In the first test, scientists had to turn up the volume of special speakers.

Our mobile sound level is about 140 decibels, equivalent to the sound level of a jet engine a few meters away, "explained Christoph Heyl, a scientist at DESY and the Jena Helmholtz Institute responsible for the research project. Fortunately, we are within the ultrasonic range and our ears cannot receive it.

The team sees great potential for high-performance optical technology. In the experiment, researchers used an infrared laser pulse with a peak power of 20 gigawatts, which is equivalent to the power of approximately 2 billion LED bulbs. Lasers with this power level or even higher can be used for material processing, fusion research, or the latest particle accelerators.

Within this power range, the material characteristics of mirrors, lenses, and prisms greatly limit their use, and these optical components are easily damaged by strong laser beams in practice, "Heyl explained. In addition, the quality of the laser beam will also be affected. In contrast, we have successfully deflected the laser beam in a way that ensures quality without contact.

Further applications and insights
Scientists emphasize that the acoustic control principle of lasers in gases is not limited to the generation of gratings. It may also be transferred to other optical components, such as lenses and waveguides.

We have been considering this method for a long time and quickly realized that extreme sound levels are necessary. Initially, these seemed technically infeasible, "Haier explained. However, we did not give up and ultimately found a solution with the support of researchers from Darmstadt University of Technology and Inoson Company. Firstly, we tried our technology with ordinary air. For example, in the next step, we will also use other gases to utilize other wavelengths, optical properties, and geometric shapes.

The direct deflection of light into the ambient air has been confirmed, opening up promising applications, especially as a fast switch for high-power lasers. At present, we can only imagine the potential of non-contact light control and its extension to other applications, "Heyl explained. Modern optics is almost entirely based on the interaction between light and solid matter. Our method has opened up a new direction.

Source: Laser Network