title: Depth profiling the whispering gallery modes in TiO2:Eu3+ microspheres using cathode luminescence.
abstract: The depth-resolved luminescence of whispering gallery modes (WGMs) was studied in TiO2:Eu3+ microsphere using cathode luminescence. As the penetration depth of the electron beam into the microsphere was increased through the control of the accelerating voltage, periodic structures appeared superimposed over the intrinsic transition lines of Eu3+, which were attributable to the cavity enhancement effect of the spontaneous emission by WGM resonance. The calculated radial intensity distribution of the WGM and the penetration depth explained the observed dependence of the WGM structure's visibility on the accelerating voltage.
authors.affiliation: Department of Physics, Faculty of Science, Shizuoka University, 836, Ohya, Suruga-ku Shizuoka, 422-8529, Japan. spmtomi@ipc.shizouka.ac.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Tomita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ikari
authors.forename: Hidenori
authors.initials: H
authors.lastname: Mimura
authors.forename: Takahiro
authors.initials: T
authors.lastname: Matsumoto