Upconversion luminescence in Er³⁺ doped Ga₁₀Ge₂₅S₆₅ glass and glass-ceramic excited in the near-infrared Available to Purchase

The infrared-to-visible frequency upconversion was investigated in Er³⁺-doped Ga₁₀Ge₂₅S₆₅ glass and in the transparent glass-ceramic obtained by heat-treatment of the glass above its glass-transition temperature. Continuous-wave and pulsed lasers operating at 980 nm and 1480 nm were used as excitation sources. The green (²H_11/2 → ⁴I_15/2; ⁴S_3/2 → ⁴I_15/2) and red (⁴F_9/2 → ⁴I_15/2) photoluminescence (PL) signals due to the Er³⁺ ions were characterized. The PL decay times were influenced by energy transfer among Er³⁺ ions, by cross-relaxation processes and by energy transfer from the Er³⁺ ions to the host material. The PL from the Er³⁺ ions hosted in the crystalline phase was distinguished only when the glass-ceramic was excited by the 1480 nm pulsed laser. The excitation pathways responsible for the green and red PL bands are discussed to explain the differences between the spectra observed under continuous-wave and pulsed excitation.