Parabolic Mirrors Power Solar Lasers

Borrowing from modern telescope design, researchers have proposed a way to concentrate sunlight to boost laser efficiency. Researchers at the Scientific and Production Association in Uzbekistan said the new laser would convert 35 percent of the sun’s energy into a laser light, providing a considerable increase in the maximum power produced by current-day solar-pumped lasers, which typically achieve only 1 to 2 percent efficiency.

The new solar lasers would concentrate light with a small parabolic mirror 1 m in diameter that has a focal spot approximately 2 to 3 cm in diameter. The concentrated light would then strike a two-layer ceramic disk known as a neodymium and chromium co-doped YAG laser material.

One side of the disk would have a highly reflective coating; the other side would be antireflecting. When sunlight penetrates through the ceramic material, it excites the electrons in the material, causing them to emit laser light of a specific wavelength (1.06 µm). To control the searing heat produced by the concentrated sunlight, the ceramic disk would be mounted atop a heat sink through which water would be pumped.

The laser light would then travel to a prime focus and be reflected back to the ceramic surface before exiting the solar collector at an oblique angle. It’s this double pass that produces the gain in efficiency, enabling a greater fraction of sunlight to be converted into laser light.

Potentially, parabolic reflector lasers could be harnessed for the large-scale synthesis of nanoparticles and nanostructures, they said.

The study was published in AIP’s Journal of Renewable and Sustainable Energy.

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