Upconversion spectroscopy of Ca3Ga2Ge4O14 doped with trivalent erbium

We report on upconversion spectroscopy of CGGO:5% Er3+ crystals at 10 K. Fl uorescence is observed from the S-4(3/2) and P-2(3/2) multiplets for both r esonant and non-resonant excitation of the F-4(9/2) multiplet with a single DCM dye laser. Due to the frequency of the exciting laser, the S-4(3/2) fl uorescence requires the absorption of two photons, while the P-2(3/2) emiss ion requires the absorption of three photons. Degradations in the expected power dependence of these upconversion fluorescences can be explained in te rms of the cycling of Er3+ ion excitation via cross relaxation energy trans fer.