Upconversion spectroscopy of Ca₃Ga₂Ge₄O₁₄ doped with trivalent erbium

Abstract

We report on upconversion spectroscopy of CGGO:5% Er³⁺ crystals at 10 K. Fluorescence is observed from the ⁴S_3/2 and ⁴S_3/2 multiplets for both resonant and non-resonant excitation of the ⁴F_9/2 multiplet with a single DCM dye laser. Due to the frequency of the exciting laser, the ⁴S_3/2 fluorescence requires the absorption of two photons, while the ²P_3/2 emission requires the absorption of three photons. Degradations in the expected power dependence of these upconversion fluorescences can be explained in terms of the cycling of Er³⁺ ion excitation via cross relaxation energy transfer.

Key Words:

• Er³⁺
• Clacium gallogermanate
• Upconversion
• Energy transfer