Sept. 26, 2017

Polycrystalline ceramic materials offer advantages including robustness over conventional glass as gain media for solid state lasers: devices that find many applications such as laser processing and medical surgery.

Recently, there has been renewed interest in fluoride ceramics lasers for ultrashort pulse laser oscillators/amplifiers. Here, Shotaro Kitajima at the University of Electro-Communications, Tokyo, Hitoshi Ishizawa at Nikon Corporation, and colleagues report on the development of the first Yb³⁺-doped CaF₂-LaF₃ ceramic laser with a maximum power output of 4.36 W and slope efficiency of 69.5%.

Kitajima and colleagues fabricated CaF₂ ceramics doped with two rare earth ions of La and Yb from 1 at. % La³⁺, 1 at. % Yb³⁺to 6 at. % La³⁺, 6 at. % Yb³⁺. The doping was carried out using a wet process to mix CaF₂ with two kinds rare-earth fluorides with average diameters of 200 nm. This was followed by sintering first between 750°-900° in air followed by the hot isostatic pressing method between 700°-1000° in an inert atmosphere.

Notably, the random orientation of the axes of grains in ceramics improves their mechanical robustness, which is one of the main motivations for producing CaF₂ ceramics for gain media.

The findings described in this paper show that it may be possible to significantly improve the physical properties of Yb: CaF₂-ceramic materials for high performance laser gain media.

Reference

Shotaro Kitajima, Kentaro Yamakodo, Akira Shirakawa, Ken-Ichi Ueda, Yoshinobu Ezura and Hitoshi Ishizawa "Yb³⁺-doped CaF₂-LaF₃ ceramics laser" Optics Letters, Published online (31st March 2017); doi: 10.1364/OL.42.001724

https://doi.org/10.1364/OL.42.001724