Spectral performance and intensive green upconversion luminescence in Er³⁺/Yb³⁺-codoped NaY(WO₄)₂ crystal

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• 作者：Feng Song ; Lin Han ; Hao Tan ; Jing Su ; Jia Yang ; Jian-guo Tian ; Guang-yin Zhang ; Zhen-xiang Cheng and Huan-chu Chen
• 关键词：Er/Yb ; NYW crystal ; Upconversion ; Energy transfer
• 刊名：Optics Communications
• 出版年：2006
• 出版时间：1 March 2006
• 年：2006
• 卷：259
• 期：1
• 页码：179-186
• 全文大小：662 K

文摘

Using Czochralski (CZ) pulling method, an Er³⁺/Yb³⁺-codoped NaY(WO₄)₂ crystal was prepared. Absorption spectra, emission spectra and excitation spectra of this crystal were measured at room temperature. Some optical parameters, such as intensity parameters, spontaneous emission probabilities and lifetimes, were calculated from absorption spectra with Judd–Ofelt (J–O) theory. Upconversion luminescence excited by a 970 nm diode laser was studied. In this crystal, green upconversion luminescence is particularly intensive. Energy transfer mechanisms that play an important role in upconversion processes were analyzed. Two cross-relaxation processes: ⁴G_11/2 + ⁴I_9/2 → ²H_11/2 (or ⁴S_3/2) + ²H_11/2 (or ⁴S_3/2), and ⁴G_11/2 + ⁴I_15/2 → ²H_11/2 (or ⁴S_3/2) + ²I_13/2, which contribute to the intensive green luminescence under 378 nm excitation, were put forward. Background energy transfer ⁴G_11/2(Er³⁺) + ²F_7/2(Yb³⁺) → ⁴F_9/2(Er³⁺) + ²F_5/2(Yb³⁺) was also demonstrated.