Researchers at the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland developed a new method to cut diamond into specific shapes using a microscope, followed by grinding and polishing. On 2017-9-5, this technology was presented at the International Conference on Diamond and Carbon Materials. This new technology has unique significance for spectroscopy and high-energy laser optical components.

Similar to prisms, diffraction gratings consist of parallel fine grooves that disperse light into spectral components. Diffraction gratings are made from glass and silicon materials and can change the color of laser light.

A research team led by Professor Niels Quack from the Department of Engineering at the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland discovered that single-crystal diamond can also be fabricated into diffraction gratings. This discovery opens up new possibilities in the field. Diamond has excellent thermal conductivity, which is 5 to 10 times that of other materials. Diamond has extremely high hardness and performs well under UV rays, infrared, and other visible light beams. Diamond is chemically inert and cannot be corroded even by highly corrosive chemicals. This also means that diamond is difficult to process and manufacture. This new cutting method is very effective.

Cutting diamond using oxygen

The technology discovered by the research team is pioneering. It uses this technology to etch diamond into millimeter-level single-crystal diamond discs. The surface finish is very high, and the distance between grooves is only a few micrometers. In the study, the research team used diamond produced by the chemical vapor deposition method.

Diamond etching involves the following steps: First, a hard film is deposited on the surface of the diamond. Then, using oxygen plasma, oxygen ions are formed on the diamond surface through the action of an electric field. In areas not covered by the hard film, oxygen ions cause carbon atoms to detach from the diamond surface. By adjusting the strength of the electric field, the shape of the diamond etching can be changed. We carved triangular grooves with a groove spacing of a few micrometers to make diffraction gratings. By adjusting processing parameters, a set of crystal planes with clear boundaries is selectively revealed. Using this processing method, we can produce atomically smooth V-shaped grooves, which is impossible to achieve with laser cutting.