White Light Upconversion Emissions from
Tm3+?+ Ho3+?+ Yb?3+?Codoped Tellurite and Germanate Glasses on Excitation with 798 nm Radiation
?
[Giri et. al., Journal of Applied Physics 104, 113107 (2008)]

MSE 576 Thin Films & Analysis Presentation
Deepak Rajput
Graduate Research Assistant
Center for Laser Applications
University of Tennessee Space Institute
Tullahoma, Tennessee 37388-9700
Email: drajput@utsi.edu Web: http://drajput.com

Outline

* Introduction
* Experimental
* Results & Discussion
* Absorption
* Fluorescence
* Emission
* Upconversion studies / mechanism
* Summary
Introduction: General

* Radiative emission from rare earth doped glasses.
* One of the mechanisms: Upconversion !!
* White: Red + Green + Blue
* RGB successfully obtained from Upconversion luminescence of rare earth (RE) doped glasses.
* White light generation: Control the intensities of RGB.
* Host glass matrix: Very Important !! (because of QE)
* Tellurium oxide and germanium oxide glasses have: high solubility for RE ions, low phonon energies, and high glass stability , and are suitable for this purpose.

Introduction: Inspiration

* Generation of RGB fluorescence in Tm3++Er3++Pr3+ triple doped fluoride glasses excited by two near-infrared lasers emitting at different wavelengths (Downing et al*).

Introduction: contd..

Objective:
Up- and downconversion emission studies of Tm3+?+ Ho3+?+ Yb?3+ codoped tellurite and germanate glasses.

* The upconversion multicolor emissions were tuned to yield white light for both tellurite and germinate triple doped glasses.
* Discuss the possible mechanisms.

Experimental

* The host glasses used:
* 75 TeO2 + 25 Li2O (Tellurite glass)
* 65 GeO2 + 10 TeO2 + 25 Li2O (Germanate glass)
* Preparation method: Melt-quench
* Raw materials:
* GeO2 (99.9% pure)
* TeO2 (99.9% pure)
* Li2CO3 (99.0% pure)
* Tm2O3, Yb2O3, and Ho2O3 (99.99% pure)

Experimental ..contd

* Triple doping level:
* Tm3+: 0.5 mol %
* Yb3+: 2.0 mol %
* Ho3+: 0.6, 0.8, 1.0, and 1.2 mol%
* Germanate glass: the melting temperature was 1100oC.
* Good optical quality, stable against atmospheric pressure, and suitable for absorption and luminescence measurements.

Experimental ..contd

Thank You !!