掺铒碲酸盐玻璃中的浓度猝灭机理研究

测试了掺铒碲酸盐玻璃在不同掺杂浓度下的荧光特性.根据Dexter能量转移理论计算了Er3+在碲酸盐玻璃中发生浓度猝灭的临界距离R₀及Er³⁺间相 互作用参 数C_Er-Er，并与其他基质玻璃中C_Er-Er数值进行了比较.最后建立 了Er³⁺基于OH^-作为猝灭中心下碲酸盐玻璃中的浓度猝灭模型. 关键词： 浓度猝灭模型 能量转移 碲酸盐玻璃 3+')" href="#">Er³⁺     

2 μm mode-locking laser performances of sol-gel-fabricated large-core Tm-doped silica fiber

High-power ultrafast fiber lasers operating at the 2 μm wavelength are extremely desirable for material processing, laser surgery, and nonlinear optics. Here we fabricated large-core(LC) double-cladding Tm-doped silica fiber via the sol-gel method. The sol-gel-fabricated Tm-doped silica(SGTS) fiber had a large core diameter of 30 μm with a high refractive index homogeneity(Δn=2 × 10~(-4)). With the newly developed LC SGTS fiber as the gain fiber, high-power mode-locking was realized. By using a semiconductor saturable absorber mirror(SESAM) as a mode locker, the LC SGTS fiber oscillator generated mode-locked pulses with an average output power as high as 1.0 W and a pulse duration of 23.9 ps at the wavelength of 1955.0 nm. Our research results show that the self-developed LC Tm-doped silica fiber via the sol-gel method is a promising gain fiber for generating high-power ultrafast lasers in the 2 μm spectral region.     

Bi掺杂高磷石英基光纤实现E波段放大

采用改进的化学气相沉积技术结合液相掺杂工艺制备了低损耗Bi掺杂高磷石英基光纤,P2 O5摩尔分数高达7.2％,光纤的背景损耗为18 dB/km@1550 nm.进一步采用1240 nm的可调谐拉曼激光器泵浦自制Bi掺杂高磷石英基光纤,在1355～1380 nm波段实现净增益,在1355 nm波长处的最高增益为5.14 ...     

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.     

Large-mode-area neodymium-doped all-solid double-cladding silicate photonic bandgap fiber with an index step of ～0.5%

A large-mode-area neodymium-doped silicate photonic bandgap fiber was theoretically designed and experimentally demonstrated. The relative index step between the high-index rods and the background glass was ～0.5%,which is the lowest cladding index difference reported on rare-earth-doped all-solid photonic bandgap fibers to our knowledge. An output power of 3.6 W with a slope efficiency of 31% was obtained for a 100-cm-long fiber.     

氟氧化物纳米相玻璃陶瓷Tb(0.7)Yb(5)∶FOV的合作下转换发光

报道了氟氧化物纳米相玻璃陶瓷Tb(0.7)Yb(5)∶FOV的红外量子剪裁研究,测量了从可见到红外的荧光发光光谱、激发谱、和荧光寿命,分析了{1([5 D4→7 F6](Tb3+),2([2 F7/2→2 F5/2] (Yb3+)}的红外量子剪裁现象,发现了487.0nm光激发5 D4能级和378.0nm光激发(5 D3,5 G6)能级的理论量子剪裁效率ηx％Yb依次分别为121.35％和136.27％.首次发现了一种新颖的合作(共协)下转换发光现象{2([(5 D3,5 G6)→5 D4](Tb3+),1([2 F7/2→2 F/2](Yb+)},即首次发现施主Tb3+离子释放两个小能量光子[(5 D3,5 G6)→5 D4]的能量,导致出现一个受主Yb3+的[2 F5/2→2 F7/2]的中等能量的光子.     

Brillouin gain spectrum characterization in Ge-doped large-mode-area fibers

The dependence of Brillouin gain spectrum (BGS) characteristics, including the Brillouin frequency shift (BFS) and the BGS bandwidth, on germanium concentration in large-mode-area Ge-doped passive fibers is investigated theoretically and experimentally. The simulation results show that the BFS is inversely proportional to GeO₂ concentration, and the BGS bandwidth initially increases with the augment of GeO₂ concentration, and then decreases. The BGSs of four fibers with core diameters of 10 μm and 20 μm for different GeO₂ concentrations are compared experimentally. Experimental results demonstrate that with the same core diameter, the variations of BFS and BGS bandwidths with GeO₂ concentration accord with the simulation results. Additionally, the BGS characteristics of three large-mode-area passive fibers with diameters of 10 μm, 25 μm, and 30 μm are measured, which confirm that the increasing of the fiber diameters will cause the BGS bandwidth to broaden. We believe that these results can provide valuable references for modulating the high-power narrow-linewidth fiber lasers and Brillouin fiber amplifiers.     

Nd3+-doped silica glass and fiber prepared by modified sol-gel method

Large-size Al³⁺/Nd³⁺co-doped silica glass with 5000 ppm Nd³⁺and 50,000 ppm Al³⁺doping concentrations was prepared by the modified sol-gel method combined with high-temperature melting and molding technology. Electron probe microanalyzer tests indicated that high doping homogeneity was achieved with this sample preparation method. The spectral properties of the Nd³⁺ions were evaluated. Nd³⁺-doped silica fiber(NDF) with a core-to-cl...     

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。