title: Improved infrared emissions of Er(3+)-Tm3+ co-doped Al2O3 thin films: the role of cross relaxation among rare earth ions.
abstract: We report the infrared emissions of Er(3+)-Tm3+ co-doped amorphous Al2O3 thin films pumped at 791 nm by a Ti:sapphire laser. The as-deposited films were annealed to improve the photoluminescence performance. Three cross relaxation channels among Er(3+)-Tm3+ and Tm(3+)-Tm3+ ions incorporated in the films were investigated as annealing temperature increases especially from 800 to 850 degrees C. In order to understand the Stark effect and cross relaxations, the photoluminescence spectra were deconvoluted by Gaussian fittings. Our results indicate that the luminescence intensity of 1.62 microm in comparison to 1.5 microm can be enhanced by the cross relaxation process [Er3+ (4I13/2) + Tm3+ (3H6) --> Er3+ (4I15/2) + Tm3+ (3F4)], and the longer-wavelength side of Er3+ emission can be improved by the CR process [Er3+ (4I15/2) + Tm3+ (3H4) --> Er3+ (4I3/2) + Tm3+ (3F4) at expense of the Tm3+ 1.47 microm emission which is also maybe quenched by the CR effect between themselves. These results suggest one possible approach to achieve broadband infrared emissions at the wavelength region of 1.45-1.65 microm from the Er(3+)-Tm3+ co-doped systems.
authors.affiliation: School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.forename: Zhisong
authors.initials: Z
authors.lastname: Xiao
authors.forename: Lu
authors.initials: L
authors.lastname: Yan
authors.forename: Fang
authors.initials: F
authors.lastname: Zhu
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Anping
authors.initials: A
authors.lastname: Huang
authors.forename: Jinliang
authors.initials: J
authors.lastname: Wang