(Y1-XYbX)3Al5O12晶體生長及其綠光現象研究

Abstract

近年來由於 InGaAs 的發展，由半導體雷射激發摻鐿離子雷射材料的發展，在應用於高功率、高效率的固態雷射引起了極大的研究熱潮。其是因Yb3＋離子具有最簡單的能階：2F7/2基態和2F5/2激發態，且僅相距約10,000 cm－1，因此諸如激態吸收等不良的效應在摻鐿離子的固態雷射中是不易見到的。 此外，Yb：YAG 雷射晶體更具有高的熱傳導率，以及優良的物理和化學性質等，而且鐿離子和釔離子在單位晶包中僅相差1.5﹪，因此由柴式提拉法（Cz）可以生長出摻雜高濃度Yb3＋離子的Yb：YAG晶體，誠因如此，Yb：YAG單晶已成為半導體雷射激發固態雷射（DPSSL）中的重要元件。 我們已成功的生長了摻雜Yb3＋離子濃度由 0 到 100 at.﹪的Yb：YAG大尺寸、高品質單晶，並以920 nm以及973 nm 兩種不同波長的InGaAs LD激發，觀察到了炫爛耀眼的綠光，這是所有關於Yb：YAG晶體文獻中所不曾提及的新現象。在光譜的實驗及分析探討後，我們認為InGaAs LD泵浦Yb:YAG所見到的綠光（green light），是由於摻雜Yb3＋離子所引起，且可能是由雙光子躍遷而產生的。

Due to recent development of InGaAs diode laser, Yb3＋ doped solid state materials to be used as gain for high-power and high-efficiency diode-pumped solid-state lasers have attracted a great deal of interest. The Yb3＋ ion has the simplest energy level：only two multiplet manifolds－the 2F7/2 ground state and the 2F5/2 excited state. Among rare-earth ions, only Yb3＋ion has excited state within approximately 10,000 cm－1. Because of this, deleterious effects such as excited absorption and up-conversion are absent in Yb3＋ lasers. Besides, Yb：YAG crystals have many other attractive characteristics such as high thermal conductivity, excellent physical and chemical properties of the host materials. Moreover, because yttrium and ytterbium garnet are isostructural with only about 1.5﹪difference in unit-cell size, doping concentration of Yb3＋ can be very high in YAG crystal grown by Czochralski（Cz）method. Yb：YAG crystal has become an important component in diode-pumped high-power laser systems. Yb：YAG crystals were successfully grown using the Czochralski technique with Yb concentration,【Yb】, varying from 0 to 100 at.﹪. During the study of the spectral performance on the crystals, a shining green emission light（centered at around 550nm）generated from the crystal was observed after being excited by the 920 or 973 nm InGaAs LD source. This greenish light emission is a new phenomenon which is not been reported before in Yb：YAG crystals. The result was ascribed to the presence of the Yb3＋ dopant and the effect of two-photon transition.