Investigation of Population Dynamics in 1.54-μm Telecom Transitions of Epitaxial (ErxSc1-x)2O3 Thin Layers for Coherent Population Manipulation: Weak Excitation Regime

We have investigated the energy transfers in the 1.54-mu m region of (Er,Sc)(2)O-3 epitaxial thin films grown on Si(111). The interplay of the energy transfers between Er ions in the different and the same symmetry sites makes the dynamics complicated. To suppress the energy transfer upconversion, low power and resonant excitation of the third crystal-field level (I-4(13/2) : Y-3') of the Er3+ site with C-3i symmetry was employed. The time-resolved photoluminescence measurements of the Y-1'-Z(1)' transition indicate the existence of two decay components having fast (10-100 mu s) and slow (0.1-1 ms) relaxation times in the range of 4-60 K. The model calculation including the inter-site energy transfers, the temperature-sensitive and -insensitive non-radiative relaxations fits the experimental results well. Moreover, the long averaged inter-Er3+ distance obtained by decreasing Er concentration was found to reduce two kinds of non-radiative relaxation rates and the energy transfer rates between Er ions very effectively.