Hongpeng You

Three-photon-excited fluorescence of Al2O3-SiO2 glass containing Eu3+ ions by femtosecond laser irradiation

Near-infrared to visible upconverted fluorescence was observed in the Al2O3–SiO2 glass containing Eu3+ ions during femtosecond laser irradiation. The dependence of the intensity of the Eu3+ emission on the pump power reveals that the three-photon excitation is dominant in the upconversion process from near-infrared into the visible fluorescence. The analysis of the upconversion mechanism indicates that upconversion fluorescence comes from the three-photon simultaneous absorption that leads to the population of the 4f levels via the excitation of the charge transfer state of the Eu3+ ions.

Upconversion luminescence of Al2O3–SiO2:Ce3+ glass by femtosecond laser irradiation

Near-infrared to visible upconversion luminescence was observed in a sol-gel processed Al2O3–SiO2 glass containing Ce3+ ions under femtosecond laser irradiation. The optical properties of the glasses reveal that the upconversion luminescence comes from the 5d→4f transition of the Ce3+ ions. The relationship between the intensity of the Ce3+ emission and the pump power reveals that a three-photon absorption predominates in the conversion process from the near-infrared into the blue luminescence. The analysis of the upconversion mechanism suggests that the upconversion luminescence may come from a three-photon simultaneous absorption that leads to a population of the 5d level in which the characteristic luminescence occurs.

Local structure and persistent spectral hole burning of the Eu3+ ion in SnO2-SiO2 glass containing SnO2 nanocrystals

The local structure and persistent spectral hole burning (PSHB) of the Eu3+ ion in SnO2–SiO2 glass containing SnO2 nanocrystals were investigated. The excitation and emission spectra of the Eu3+ ions indicate that the Eu3+ ions are doped into the SnO2 nanocrystals and glass phases. The variation in the site symmetry of Eu3+ ions in the nanocrystal from D2h or C2h symmetry may be due to oxygen vacancies. Fluorescence line-narrowing spectra reveal that the Eu3+ ions in the glass phase have two sites, one of which exhibits a unique feature. The calculated second crystal-field parameters show that the coordinating oxygen ions of site I are closer to the Eu3+ ions with increasing excitation energy, while those of site II are farther away from the Eu3+ ions. This result leads to the opposite behavior of the fluorescence lines of the Eu3+ ions at the two sites. PSHB was also observed and multiholes with a narrow width can be burned in the SnO2–SiO2 glass containing SnO2 nanocrystals.

Photon-excited fluorescence of rare-earth ions-doped gasses by femtosecond laser irradiation

Local modification of Eu3+ ions doped in SnO2- and Al2O3-SiO2 glasses was investigated using a femtosecond laser pulse. SnO2 nanocrystals were successfully precipitated in transparent glasses by irradiation with an 800-nm femtosecond laser. Upon laser irradiation, the Sn atoms were activated to react with oxygen, resulting in the formation of SnO2 nanocrystals. The precipitated SnO2 crystals grew up to ca. 5 nm size by the Joule-heating effect of the laser. The fluorescence intensities of the codoped-Eu3+ ions were enhanced higher than 100 times that of the glass without nanocrystals by exciting with the energy corresponding to the absorption edge of the SnO2 nanocrystals, the energy of which is effectively transferred to the Eu3+ ions. Near-infrared to visible up-converted fluorescence was observed in the Eu+3 ions doped in the Al2O3-SiO2 glasses during femtosecond laser irradiation. The dependence of the intensity of the Eu3+-emission on the pump power reveals that the three-photon excitation is dominant in the up-conversion process. These glasses can provide a bright prospect for their optical applications.