Abstracts 2002

Abstract of Publication No. 419

S. Heer, M. Wermuth, K. Krämer and H. U. Güdel
Sharp 2E upconversion luminescence of Cr3+ in Y3Ga5O12 codoped with Cr3+ and Yb3+
Phys. Rev. B 65, 125112/1-10 (2002)      Full Text (PDF)      DOI-Link     

Abstract: We report on upconversion luminescence in Y3Ga5O12 codoped with Cr3+ and Yb3+. This is, to our knowledge, the first upconversion process directly involving Cr3+. At low temperature excitation around 10 314 cm1 leads to relatively strong red luminescence in the title compound. The sharp upconversion luminescence around 14 300 cm1 is identified as the 2E 4A2 transition of Cr3+. The upconversion excitation spectrum follows he Yb3+ 2F7/2 2F5/2 absorptions in the range 11200 - 10315 cm1. From transient measurements the upconversion mechanism is found to be dominated by an energy transfer step: Two excited Yb3+ ions simultaneously transfer their excitation energy to the Cr3+ ion. In Y3Ga5O12:2% Cr3+, 1% Yb3+ the efficiency of the process at 10 K and for 150 mW laser power is 6% and decreases with increasing temperature due to intrinsic loss mechanisms of the system.

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