Upconversion processes in Er3+:KPb2Cl5 laser crystals

Energy transfer and dynamics of excited levels population were studied in erbium doped potassium-lead chloride crystals Er3+:KPb2Cl5 under direct impurity excitation in UV (at 355 nm) and IR (975-980 nm) spectral ranges. It was shown that emission spectrum of Er3+:KPb2Cl5 crystals strongly depends on excitation spectral range. Under direct UV selective excitation of Er ions the population of lower energy levels goes via cascade schemes. Under upconversion IR continuous-wave or pulsed excitation at 4I11/2 level the population of upper energy levels goes via excited state absorption and upconversion nonradiative energy transfer. The efficiency of upconversion processes at room temperature is demonstrated. The different ways of Er excited level population are discussed.