Tm^(3+)掺杂CdWO_4单晶的发光特性

Optical Spectra of Tm^(3+)-doped CdWO_4 Crystal

用坩埚下降法生长获得了尺寸为φ25 mm×90 mm、Tm2O3初始掺杂摩尔分数为0.5%的CdWO4单晶。晶体的颜色由上部血红色逐渐加深至下部的黑褐色。对不同部位的晶体薄片进行800℃的氧化处理,测定了处理前后不同部位的吸收光谱和FTIR红外光谱。经氧气退火处理后,由于氧空位缺陷减少,晶体的颜色明显变淡。在吸收光谱中观测到421,684,805 nm的吸收带。其中421 nm的吸收峰随退火温度的升高而逐步减弱,经800℃处理后基本消失。在808 nm激光二极管激发下,观察到中心波长为1.5μm和1.8μm的荧光发射,分别对应于Tm3+的3H4→3F4,3F4→3H6的能级跃迁。

Tm^3 ＋ -doped CdWO4 single crystal with a size of φ25 mm × 90 mm was grown by the Bridgman method. The raw mole fraction of Tm203 in crystal was 0.5%. The upper part of crystal grown at the final stage appears blood-red color, while the lower at the initial stage brown- blackness. The absorption and IR spectra of various parts of crystal before and after O2-annealing were characterized. The color of the crystal becomes weak after the crystal is treated at 02 atmos- phere due to the reducing of oxygen vacant defect. The peaks of 421,684 and 805 nm were observed in the absorption spectra. The peak of 421 nm becomes weak gradually with the increase of annea- ling tempearture, and almost disappears after 800 ℃. The emission spectra of single crystal were also investigated under the excitation of 808 nm at room temperature. A strong emission band at 1.50 μm and a weak band at 1.80 μm were observed, which corresponding to the ^3 H4→^3F4 and ^3F4→^3H6 transitions of Tm^3＋ , respectively.