Optical properties of GGG thin films doped with Ni2+ and Co2+ ions

In the last years it has been observed an increase of interest in transition-metal (TM) doped materials for applications in tunable mid-infrared (MIR) lasers [1], passive Q-switches for near-infrared lasers [2,3] and even as sensitizers for rare-earth ions supporting up-conversion processes [4]. The lasing capability of chromium and titanium ions is definitely the most widely known and repeatedly proven, nevertheless the other ions, like cobalt and nickel could also show promising optical properties [5], indicating their applications in solid state laser systems. Although typical applications of cobalt-doped materials are limited to Q-switching modules, an increasing number of reports also points at their interesting laser properties [6], which result from broad absorption and emission lines enabling widely tunable operation in the IR spectral range.