Analysis of the optical properties of Er~(3+)-doped strontium barium niobate nanocrystals using time-resolved laser spectroscopy

摘要

This paper reports the results obtained in strontium barium niobate (SBN) nanocrystals in glasses doped with 1, 2.5 and 5 mol% of Er~(3+) ions. The melt-quenching method was applied to fabricate the glasses with composition SrO-BaO-Nb_2O_5-B_2O_3 and further thermal treatment was used to obtain glass ceramic samples from the glass precursor. X-ray diffraction patterns confirmed the formation of SBN nanocrystals with an average size of about 50 nm in diameter. Time-resolved fluorescence spectra for the emission of Er~(3+) ions at 1550 nm have been analyzed in order to confirm the incorporation of the Er~(3+) ions into the nanocrystals. Green frequency upconversion emission under excitation at 975 nm coming from the ions in the nanocrystals has been obtained. This intense upconversion is about a factor of 500 higher than that obtained from the ions which reside in the glassy phase. Moreover, temporal evolution studies have been carried out with the purpose of determining the involved upconversion mechanism and the importance of these processes as a source of losses for the optical amplification at 1550 nm.