Recent progress on deep-ultraviolet coherent light sources

The practical deep-ultraviolet (DUV, below 200nm) coherent light sources, which are considered as puzzles of laser field, can provide a kind of unique tool to explore the front fields of biology, physics, chemistry, material etc.. The methods to obtain the DUV coherent light sources are reviewed and compared, and all-solid-state DUV lasers are precise and practical compared with the others. Recent progresses on them and their engineering in our lab are reported, and some new phenomena such as Fermi pockets in superconductor are discovered with them.