Room-temperature laser action at 4.38 m in CaGa/sub 2/S/sub 4/:Dy/sup 3+/

Summary form only given. There has recently been a great deal of interest in solid-state mid-IR (3-10 m) lasers. To avoid luminescence quenching, hosts for these lasers must have maximum phonon frequencies below /spl sim/400 wavenumbers, ruling out traditional oxides and fluorides. Identifying a host that incorporates rare earth ions and resists attack by moisture has been difficult. We report 4.38 m lasing on the /sup 6/H/sub 11/2/ /sup 6/H/sub 13/2/ transition of Dy/sup 3+/ in crystalline CaGa/sub 2/S/sub 4/ (calcium thiogallate,) a sulfide host that is not moisture sensitive. To our knowledge, this is the first report of laser action beyond 4 m in any rare-earth-doped sulfide. Spectroscopic data and 1.4 m laser operation in this material were presented previously.