We report on a simple and novel method to induce Si-related oxygen-deficient defects in CaO-Al_2O_3-SiO_2 glasses by using Al metal instead of part Al_2O_3.Blue emission is observed from the glass samples.Moreover,the quantities of the oxygen-deficient defects can be controlled by adjusting Al content. We also prepare glass samples using Al instead of part Al_2O_3 and doped with Eu^(3+) ions.Addition of Al results in reduction of Eu^(3+) ions to Eu^(2+) ions and change of the luminescence property.The investigation made on to control and characterize the defects could lead to the development of more efficient economical materials with improved properties.
In Ag^+ and Au^(3+) co-doped silicate glass sample,we realized controllable precipitation and dissolution of Ag and Au nanoparticles.A new method was proposed for separate precipitation of Ag and Au nanoparticles in different areas of the same sample through femtosecond laser irradiation and further annealing;different colors were obtained in the same glass.We also studied the laser dissolution of Ag and Au nanoparticles in the Ag^+ and Au^(3+) co-doped silicate glass.The mechanism of the phenomena we observed was discussed briefly.
Infrared to visible upconversion luminescence was demonstrated in trivalent Europium doped Ca_2Al_2SiO_7 crystal (Eu^(3+):Ca_2Al_2SiO_7) irradiated by focused infrared femtosecond laser.The upconversion luminescence originated from ~5D_0 to ~7F_j (j=1,2) transitions of Eu^(3+).The relationship between the upconversion luminescence intensity and the pump power indicated that the upconversion from near-infrared to red is dominated by a two-photon absorption process of Eu^(3+).Analysis suggested that two-photon simultaneous absorption induced population inversion should be the predominant frequency upconversion mechanism.
We reported effect of various alkaline oxides on the broadband infrared luminescence from bismuth-doped aluminophosphate glasses.The samples of (99-x)P_2O_5-17Al_2O_3-xR_2O-1Bi_2O_3 (R=Li,Na and K, x=0 and 10 in mol%) were prepared under reducing condition controlled by additional carbon powders.The fluorescent intensity decreased with increasing content of alkaline oxides and basicity of host glasses.The 1/e fluorescence lifetime of the 72P_2O_5-17Al_2O_3-10R_2O-1Bi_2O_3 (R=Li,Na and K) glasses decreased from 461 to 316μs,as alkaline ions changed from Li^+ to K^+.
A femtosecond laser with 800 nm,250 kHz and 150 fs was used to irradiate Sm^(3+)-doped Li_2O- Nb_2O_5-SiO_2 glass.At the initial stage of the laser irradiation,a white emission was observed near the focal point of the laser beam inside the glass.After 20 second irradiation,a red and blue emission began to emerge.From the micro-Raman spectra,we found that the crystal spot has formed at the focal point of the femtosecond laser beam in the glass.The mechanism of the observed phenomena is discussed.
We report on broadband infrared emission of bismuth-doped RO-B_2O_3(R=Ca,Sr,Ba) glasses. Glass samples are prepared under various conditions by a conventional melting-quenching method and the luminescence properties in infrared wavelength region are investigated,No apparent infrared luminescence is observed in the SrO-B_2O_3 and BaO-B_2O_3 prepared in air,while glasses prepared in reducing atmosphere exhibit a broadband infrared luminescence peaking at 1300 nm with a full width at half maximum(FWHM) of about 200 nm when excited by an 800 nm laser diode.A mechanism was proposed to explain the observed phenomena. The presence of low valence bismuth,probably Bi^+,is responsible for the broadband infrared emission.
