New materials for tunable lasers in the near infrared

There has been considerable recent effort aimed at realising tunable near-infrared laser action in solid-state media. Beyond 1 μm Ni²⁺ and Co²⁺ emissions have been mainly studied, and laser action has been achieved in several materials doped with these ions although usually only at low temperatures. Luminescence from C o²⁺ and Ni²⁺ in the host material LiGa₅O₈ is described and evidence is presented for a high quantum efficiency, even up to room temperature. We describe also the results of our lifetime and luminescence measurements on the various active centres in the Mg₂SiO₄: Cr laser system.