QUANTITATIVE-ANALYSIS OF ERBIUM LUMINESCENCE IN LIYF4 DOPED WITH LOW (1.41-PERCENT) AND HIGH (38.5-PERCENT) ER+3 CONCENTRATIONS

The luminescent-channel efficiency for Er+3 ions in LiYF4:Er+3 (38.5%) crystal was measured and compared with the case of Er+3 as a low-concentration dopant (1.41%) in crystals of LiYF4. The S-4(3/2) --> I-4(13/2), I-4(15/2) luminescent transitions are strongly quenched in the high concentrated system, by two possible cross-relaxation processes involving one phonon absorption, favoring the population of the I-4(11/2) and I-4(13/2) levels. A strong quenching of the total Er+3 luminescence by approximately 6.8 times was observed in the highly doped system at 300 K. The two middle infrared (mid-IR) I-4(11/2) --> I-4(13/2) and I-4(13/2) --> I-4(15/2) luminescent transitions were quenched by an attributed energy transfer from the Er3+ excited I-4(11/2) and I-4(13/2) levels to Me(++)(OH-)(2) and HCO- molecules that are present in the host material as impurities.