掺铒矾酸钇晶体上转换荧光研究

STUDY ON UPCONVERSION FLUORESCENCE OF Er 3+ DOPED YTTRIUM VANADATE

使用波长为８０８和６５８ｎｍ的半导体激光器和染料激光器作为激发源，测量了Ｅｒ３＋：ＹＶＯ４晶体的波长在５５３和４１０ｎｍ附近的上转换荧光．对激发过程的分析表明，贡献于上转换荧光的主要激发机制为激发态吸收．在不同浓度下对上转换荧光的寿命测量结果显示，随Ｅｒ３＋浓度的提高，５５３ｎｍ绿光的荧光寿命随浓度的增加而减小，但４１０ｎｍ的荧光寿命随Ｅｒ３＋浓度无明显变化．结合绿光强度随掺杂浓度增加而减小的结果，认为在所测浓度范围内，绿光发射具有明显的浓度猝灭效应，并且绿光上能级的布居主要来自于蓝光上能级向绿光上能级的无辐射弛豫．

Abstract Upconversion fluorescence near 553 and 410nm was detected when the Er 3+ doped yttrium vanadate (Er 3+ ∶YVO 4) crystal was excited with a 808nm diode laser and a 658nm dye laser. Analysis of excitation mechanism shows that excited state absorption dominantly contributes to the upconversion emissions. Measurement of lifetimes for different Er 3+ concentration indicates that the lifetime of 553nm emission decreases with increasing Er 3+ concentration, but no considerable changes of that of 410nm emission have been observed. With the consideration of the fact that the intensity of 553nm band declines with increasing Er 3+ concentration, we argue that in the concentration range measured there is an appreciable concentration quenching in the 553nm emission, and a dominant population channel of its upper state ( 4 S 3/2 ) is the nonradiative relaxation from the upper state ( 2H 9/2 ) of the 410nm band.