The national major scientific equipment development project based on deep ultraviolet (DUV) solid-state lasers equipment passed assessment in 2013.

After more than 10 years of effort, the researchers became the first in the world to grow large-size potassium beryllium fluoroborate crystals, which was found to be the first nonlinear optical crystal that could be used to generate DUV lasers light by direct frequency-doubling.

On this basis, the researchers invented prism coupling technology (patented in China, the United States, and Japan) and took the lead in developing advanced technology involving direct frequency doubling to generate DUV lasers.

Due to this technology, China is the only country in the world capable of developing a practical and precise DUV solid-state laser sources and was the first to develop its practical frontier equipment.