Strontium fluorapatite (S-FAP) nano-grained laser ceramics

The use of large-sized, highly transparent polycrystalline strontium fluorapatite (S-FAP) ceramics could be a breakthrough in the high-power laser field due to its excellent laser gain properties. However, its hexagonal crystal structure makes it difficult to obtain laser quality in polycrystalline ceramics owing to birefringence. In this study, fully densified transparent Nd- and Yb-doped S-FAP ceramics with an average grain size of similar to 100 nm can successfully be fabricated via liquid-phase nano-powder synthesis followed by spark plasma sintering, thereby achieving laser oscillation of the Nd:S-FAP ceramics for the first time. Furthermore, we elucidated the discrepancy in the emission properties between single-crystal and ceramics with randomly oriented crystal grains. We believe that these findings can provide important insights into the design and development for efficient non-cubic ceramic laser systems.