Study on Spectral Properties and Mid-Infrared Laser Performance of Er, La:CaF 2 Crystals.

Er³⁺-doped fluorite crystals, including CaF₂ and SrF₂, are considered as attractive laser gain materials in the mid-infrared (MIR) region with merits of high laser efficiency as well as low doping concentration. In this work, a series of Er, La:CaF₂ crystals were grown and the modulation effect of co-doping La³⁺ ions on the spectral properties and mid-infrared laser performance was investigated. It was found that introducing La³⁺ ions can effectively manipulate the coordination environment of Er³⁺ ions embedded in CaF₂ crystal, thus modulating the shape and intensity of absorption and emission bands. On the other hand, La³⁺ ions can partially substitute Er³⁺ sites in the clusters to form mixed clusters, which affects the energy transfer processes between Er³⁺ ions as well as ~3 μm laser performance, which is dominated by energy transfer up-conversion (ETU) processes between Er³⁺ ions. By co-doping La³⁺ ions into Er:CaF₂ crystal at an appropriate concentration, the spectral parameter modulation can be achieved while maintaining a high MIR laser efficiency. [ABSTRACT FROM AUTHOR]