title: Fluorescence investigation of Ho3+ in Yb3+ sensitized mixed-alkali bismuth gallate glasses.
abstract: Efficient 2.0 microm infrared and visible upconversion emissions have been observed in Ho3+/Yb3+ co-doped mixed-alkali bismuth gallate (LKBBG) glasses having a maximum-phonon energy of 673 cm(-1). The Judd-Ofelt parameters Omega2, Omega4 and Omega6 of Ho3+ indicate that there is a high asymmetry and strong covalent environment in LKBBG glasses. The large absorption and emission cross-sections of Yb3+ confirm that it is a suitable sensitizer for capturing and transferring pump energy to Ho3+. The emission cross-section profile for the 5I7-->5I8 transition is derived using the reciprocity method and the peak value is 5.54 x 10(-21)cm2, which is much larger than the value in fluorozircoaluminate glasses. LKBBG glasses exhibit low maximum-phonon energy and large refractive index, and it is possible to achieve an effective 1.66 microm U-band emission of Ho3+ under 900 nm laser radiation.
authors.affiliation: Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, PR China. lhai8686@yahoo.com
authors.forename: H
authors.initials: H
authors.lastname: Lin
authors.forename: Y Y
authors.initials: YY
authors.lastname: Zhang
authors.forename: E Y B
authors.initials: EY
authors.lastname: Pun
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D005708:Gallium / Q000737:chemistry*; D005898:Glass; D006695:Holmium / Q000737:chemistry*; D007834:Lasers; D009942:Organometallic Compounds / Q000737:chemistry*; D010087:Oxides; D011336:Probability; D012031:Refractometry; D013050:Spectrometry, Fluorescence / Q000379:methods; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D010087:Oxides; D005707:Gallic Acid; D005708:Gallium; D015018:Ytterbium; D001729:Bismuth; D006695:Holmium