碲化物发光玻璃中银纳米颗粒表面等离激元增强铒离子发光的研究（英文）

有趣的贵金属表面等离激元的光学性质,尤其是在发光增强领域的表现,使得它已经成为全球的一个研究热点。表面等离激元就是光与贵金属中的自由电子相互作用时,自由电子和光波电磁场由于共振频率相同而形成的一种集体振荡态。该文研究了碲化物玻璃中银纳米颗粒的表面等离激元共振增强铒离子的发光。我们测量了吸收谱、激发谱、发光谱以及荧光寿命。首先,我们挑选365.5和379.0 nm吸收峰作为激发波长测量了385～780 nm波长范围的可见发光光谱,发现有4个发光峰,依次位于408.0, 525.0, 546.0和658.5 nm,容易指认出它们依次为铒离子的~2H_(9/2)→~4I_(15/2),~2H_(11/2)→~4I_(15/2),~4S_(3/2)→~4I_(15/2)和~4F_(9/2)→~4I_(15/2)的荧光跃迁;可以计算出[80 nm平均粒径纳米银的Er~(3+)(0.5%)Ag(0.2%):碲化物玻璃的样品A]的上述4个可见发光的峰值强度是[Er~(3+)(0.5%):碲化物玻璃的样品C]的大约1.44～2.52倍。同时,[50 nm平均粒径纳米银的Er~(3+)(0.5%)Ag(0.2%):碲化物玻璃的样品B]的上述4个可见发光的峰值强度是样品C的大约1.08～1.55倍。随后,我们挑选365.5和379.0 nm吸收峰作为激发波长测量了928～1 680 nm波长范围的近红外发光光谱,发现近红外波段有两个发光峰,位于979.0和1 530.0 nm,容易指认出它们依次为铒离子的~4I_(11/2)→~4I_(15/2)和~4I_(13/2)→~4I_(15/2)的荧光跃迁;同样可以计算出样品A的上述2个近红外发光的峰值强度是样品C的大约1.43～2.14倍。同时,样品B的上述2个近红外发光的峰值强度是样品C的大约1.28～1.82倍。因此,发光的最大增强大约是2.52倍。从荧光寿命动力学实验,我们发现样品A的荧光寿命为τ_A(550)=43.5μs,样品B的荧光寿命为τ_B(550)=43.2μs,样品C的荧光寿命为τ_C(550)=48.6μs。这些实验结果证实了τ_A≈τ_Bτ_C。它意味着样品(B)相对于样品(C)的发光增强是源于自发辐射增强效应。然而,它也意味着样品(A)相对于样品(B)的发光增强是源于纳米银颗粒的粒径尺寸r效应。也就是说当粒径尺寸r增大的时候,散射截面C_s和r~6成正比,而吸收截面C_a和r~3成正比,因此散射截面C_s增大的速度会远大于吸收截面C_a增大的速度,而散射截面C_s是荧光增强的原因,吸收截面C_a是荧光减弱的原因,所以随着银纳米颗粒尺寸的增大,其散射截面占主要部分,当发光材料和金属表面等离子体SP发生耦合时,能量快速的转移到金属表面等离子体SP上,而后被散射到远场,这有利于增强荧光。其综合的结果就导致了发光强度会随r的增大而增强。上述实验的结果对太阳能电池的光伏发电和生物物理应用等领域都有着很好的应用前景。     

Nd~(3+)/Yb~(3+)共掺磷酸盐玻璃光纤的发光与激光特性研究

以970 nm和808 nm半导体激光器作为抽运源,从光纤长度和抽运功率两个方面,探讨了Nd~(3+)/Yb~(3+)摩尔浓度比约为4:1的共掺磷酸盐玻璃光纤的发光与激光特性.在970 nm抽运下,光纤光谱以Yb~(3+)离子的发光为主,但Yb~(3+)→Nd~(3+)能量传递会对光纤光谱(激光和受激放大自发辐射)产生调制作用,调制作用随970 nm抽运功率或光纤长度的增加而显著,甚至出现显著的双波长激光现象.尽管玻璃样品中Nd~(3+)→Yb~(3+)的能量传递效率ηNd→Yb高达64%,但在808 nm抽运下,激光峰始终在1053 nm附近产生,且与808 nm抽运功率大小和光纤长度无关.为解释这一现象,推导了考虑Nd~(3+)离子受激辐射的能量传递模型.从理论模型来看,Nd~(3+)→Yb~(3+)能量传递作用随Nd~(3+)离子受激辐射信号光强度的增加而迅速减弱,这与该光纤实际测试的荧光光谱随808 nm抽运功率的变化规律相符合.因此,当采用Nd~(3+)离子来敏化Yb~(3+)离子时,需要考虑Nd~(3+)离子的受激辐射对Nd~(3+)→Yb~(3+)能量传递的抑制作用.     

国产25/400μm掺镱双包层光纤实现2.2kW窄线宽单模激光输出

基于自主研制的均匀掺杂低热光系数25/400μm掺镱双包层光纤,开展了全光纤高功率窄线宽光纤激光放大实验。激光系统实现了中心波长为1060.3 nm、线宽为25 GHz、最高功率为2.2 kW的单模激光输出,其斜率效率达78%,光束质量因子M~2≈1.2,其功率是目前报道的基于国产25/400μm掺镱双包层光纤窄线宽放大器单模激光输出的最高功率。     

Effect of power scale of 974 and 633 nm lasers on the induced loss at 633 nm of Yb~(3+)/Al~(3+) co-doped silica fiber

Induced loss at 633 nm is tested in Yb~(3+)∕Al~(3+)co-doped silica fiber by a core pumped with a 974 nm laser and probed with a 633 nm laser. The fiber is prepared by the modified chemical vapor deposition method combined with solution doping. Different power scales of pump light and probe light are used in the tests. It is found that there is a dynamic equilibrium between photobleaching induced by 633 nm probe light and photodarkening(PD)induced by 974 nm pump light. For the first time to our knowledge, the effect of 633 nm probe laser power on an induced loss test of Yb~(3+)∕Al~(3+)co-doped silica fiber is studied quantitatively. It suggests that as long as the633 nm probe light power is less than 0.2 m W, the induced loss is mainly contributed by the PD effect of pumping light, and the deviation of induced loss is less than 5%.     

2-um emission performance of Tm^3＋-Ho^3＋ co-doped tellurite glasses

The emission properties of 2-um region fluorescence of Tm^3＋-Ho^3＋ co-doped tellurite glasses are investigated. Introducing F- ions to the composition of tellurite glasses plays a positive effect on the 2-#m emission. A maximum intensity of 2-um emission is achieved when 1.5-mol% Tm2O3 and 1-mol% Ho203 concentration are doped in the glasses. The emission cross section and gain coefficient of the ^5I8-^5I7 transition of Ho^3＋ are calculated. The emission cross section has a maximum of 1.29×10-20 cm^2 at 2048 nm wavelength. The results indicate that Tm＆3＋-Ho^3＋ co-doped tellurite glasses are suitable for 2-um application.     

纳米相氟氧化物玻璃陶瓷中Er~(3+)Yb~(3+)离子对的量子剪裁发光造成的强的光谱调制（英文）

研究了纳米相氟氧化物玻璃陶瓷中Er~(3+)Yb~(3+)离子对的量子剪裁发光造成的强的光谱调制现象。测量了Er~(3+)Yb~(3+)双掺纳米相氟氧化物玻璃陶瓷的X射线衍射谱、表面形貌、激发光谱、吸收光谱、和发光光谱;而且也与Tb~(3+)Yb~(3+)双掺纳米相氟氧化物玻璃陶瓷的相对应的光谱参数进行了比较。发现378nm光激发样品(A)Er(1%)Yb(8.0%)∶FOV和样品(B)Er(0.5%)Yb(3.0%)∶FOV所导致的652.0nm红色发光强度为522nm光激发时的680.85倍和303.80倍;我们还发现378nm光激发所导致的样品(A)Er(1%)Yb(8.0%)∶FOV和样品(B)Er(0.5%)Yb(3.0%)∶FOV的652.0nm红色发光强度为样品(C)Er(0.5%)∶FOV的491.05和184.12倍。我们还发现在378nm光激发时的样品(A)Er(1%)Yb(8.0%)∶FOV和样品(B)Er(0.5%)Yb(3.0%)∶FOV的{978.0和1 012.0nm}红外发光强度依次分别为样品(C)Er(0.5%)∶FOV的{58.00和293.62}倍和{25.11和67.50}倍。更进一步,对于652.0nm波长发光的激发谱,发现(A)Er(1%)Yb(8.0%)∶FOV和(B)Er(0.5%)Yb(3.0%)∶FOV的378.5nm激发谱峰强度是(C)Er(0.5%)∶FOV的大约606.02和199.83倍。同时,也发现样品(A)Er(1%)Yb(8.0%)∶FOV和样品(B)Er(0.5%)Yb(3.0%)∶FOV的一级量子剪裁红外1 012或978nm发光强度为样品(D)Tb(0.7%)Yb(5.0%)∶FOV的二级量子剪裁红外976nm发光强度的101.38和29.19倍。发现的该量子剪裁是目前所报道的最强的量子剪裁。因此,相信所发现的氟氧化物纳米玻璃陶瓷中Er~(3+)Yb~(3+)离子对的一级量子剪裁发光是强的可以作为量子剪裁层应用到提高晶硅太阳能电池的发电效率。研究结果也能加速对目前国际热点的下一代环保的光谱调制太阳能电池的探索。     

Amplified spontaneous emission properties of a single mode Er~(3+)-doped tellurite fiber

Spectral characteristics of the amplified spontaneous emission (ASE) from a novel single mode Er~(3+) doped tellurite fiber with D-type cladding is reported in this letter. When pumped at 980 nm, an ASE source that has nearly a 100-nm flat FWHM bandwidth is obtained with a fiber length of 30-60 cm. Variation of ASE spectra with pump powers and fiber lengths are measured. Output power up to 2.0 mW is obtained with a launched pump power of 660 mW.     

Er3+单掺及Er3+/Yb3+共掺SiO2-Al2O3-La2O3玻璃光谱性质研究

研究了单掺Er³⁺及Er³⁺/Yb³⁺共掺SiO₂-Al₂O₃-La₂O₃玻璃的光谱性质随稀土离子浓度变化规律,应用McCumber理论计算了玻璃在1.53 μm的发射截面及积分吸收截面.结果表明:在Er³⁺离子掺杂浓度相同时,玻璃在980 nm吸收截面与Yb³⁺掺杂浓度成反比;当样品中Yb³⁺离子掺杂浓度为3.94×10²⁰ cm^-3时,玻璃在1.53 μm的吸收截面和发射截面最大,在1.40～1.60 μm积分吸收截面也最大;Er³⁺/Yb³⁺共掺SiO₂-Al₂O₃-La₂O₃玻璃在1.53 μm的荧光半高宽随Er³⁺掺杂浓度升高而增加,当Er³⁺离子掺杂浓度为2.41×10²⁰ cm^-3时,玻璃的荧光半高宽(FWHM)达到52.5 nm.     

Cr3+,Yb3+,Er3+共掺磷酸盐铒玻璃转镜调Q激光性质研究

研究了Cr3+,Yb3+,Er3+共掺磷酸盐铒玻璃转镜调Q激光性质.三种Er2O3掺杂浓度的激光实验结果表明,在Er2O3名义掺杂浓度为0.5wt%时,玻璃的综合激光性质最好,重复频率为0.1Hz时,它的激光阈值功率为14.5mJ,最大输出能量为9.6mJ,斜率效率为0.55%.在同种实验条件下,比较了Cr14和Kigre公司生产的QE-7S激光性质参数,实验表明,前者激光阈值功率稍低,而后者的斜率效率和最大输出功率略高.