Vol. 53, No. 5
November 1999
pp. 903-910

The kinetic limitation of anti-Stokes luminescence of Er ^{3 +} and Yb ^{3 +} doped infrared upconversion materials

SACHIN K MAHAJAN*, P K KHARE and B P CHANDRA

Department of Post-Graduate Studies and Research in Physics and Electronics, Rani Durgavati University, Jabalpur 482 001, India
* Present address: Department of Applied Physics, Samrat Ashok Technological Institute,Vidisha 464 001, India
MS received 4 June 1999

Abstract.

Infrared-to-visible wave-length conversion in the Yb³⁺-Er³⁺doped phosphors system has been described by a simple three level model based on two ions mechanism. The excitation in the range of 900-1000 nm of an IR-photon is first absorbed by Yb ³⁺ ion as a sensitizer attributed to the resonant energy transition in Er³⁺ ion from ⁴S_{3/ 2} ® ⁴I_{15 / 2} and ⁴F_{9 / 2} ® ⁴ I_{15/ 2}, respectively for green and red emission. The essential energy transfer processes in this system i.e. upconversion from ⁴I_{11 / 2} and ⁴I_{13 / 2}, cross-relaxation from ⁴S_{3 / 2} and ⁴F_{9 / 2} are taken into account. The limitations of the rate-equation approach are examined with a focus on the underlying dynamics of this rare-earth system.

Keywords. Anti-Stokes luminescence; upconversion; cross-relaxation; sequential excitation.

PACS Nos 78.60; 78.55Hx

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