Upconversion Mechanisms in <TEX>$Tm^{3+}$</TEX>-doped Glasses under 800 nm Excitation

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J. Korean Ceram. Soc. > Volume 37(2); 2000 > Article

Journal of the Korean Ceramic Society 2000;37(2): 111.

800nm 파장 여기관에 의한 $Tm^{3+}$첨가 유리내 상향 전이 현상 기구

정훈, 정운진¹, 허종¹

광주과학기술원 정보통신공학과
¹포항공과대학교 재료금속공학과 광전자 유리재료 연구실

Upconversion Mechanisms in $Tm^{3+}$-doped Glasses under 800 nm Excitation

ABSTRACT

700nm red emission(3F3longrightarrow3H6) in Tm3+ ion with 800 nm(3H6longrightarrow3H4) excitation via upconversion process has been reported only in host materials which have low phonon energies such as halide crystals. However, we observed 700nm and 480nm(1G4longrightarrow3H6) upconverted emission with 800nm excitation in several oxide glasses which has never reported. With spectroscopic analyses and lifetime measurements of each nergy level of Tm3+ ion doped in various oxide glasses, following mechanisms are suggested. For red upconversion, upconversion mechanism changed with Tm3+ concentration. While direct excitation up to 3F3 level via anti-Stokes excitation was dominated at low concentration, two-step excitation via 3H6longrightarrow3H4 and 3F4longrightarrow3F3 transitions was dominated at high concentration. For blue upconversion, two step excitation mechanism up to 1G4 level was suggested as follows : electrons are exciated up to 3H5 with direct excitation with pumping light up to 3H4 followed by multiphonon relaxation, and then additional reabsorption of pumping light excites electrons up to 1G4.

Key words: Upconversion, $Tm^{3+}$, Oxide glass, Phonon energy, Rate equation