Lanthanide-doped glasses as frequency-converter for high-power LED applications

• Published in: Optical materials 2019-02, Vol.88, p.74-79
• Main Authors: Schweizer, Stefan, Rimbach, A. Charlotte, Mungra, Mreedula, Ahrens, Bernd, Steudel, Franziska, Nolte, Peter W.
• Format: Article
• Language: English
• Subjects: Borate glass; Glass ceramic; Lanthanide doping; Lock-in thermography; Thermal diffusivity; White light generation
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2018.11.007

Lanthanide-doped borate glasses represent an attractive alternative as frequency-converter for white-light generation. The CIE colour coordinates of Tm3+, Tb3+, and Eu3+ double- and triple-doped glasses can be tuned over a broad spectral range by varying the lanthanide doping concentrations and ratios accordingly. In addition, double- and triple-doping allow for a change in colour coordinates by using different excitation wavelengths. To overcome the problem of poor optical absorption of the doped lanthanide ions and to increase the optical path length for the excitation light, the as-made glass is successfully processed to a glass ceramic. The amount of crystallites grown in the glass is controlled by appropriate choice of annealing time and temperature. The glass ceramics do not only offer enhanced optical properties, but also improved thermal properties. The thermal diffusivity of the glass ceramic is one order of magnitude higher than that of the glass. •Lanthanide-doped borate glasses as frequency-converter for white light generation.•Enhanced optical properties through thermal processing from glass to glass ceramic.•Controlled crystallization by appropriate choice of annealing time and temperature.•Thermal diffusivity of glass ceramic one order of magnitude higher than that of glass.