应用于白光显示的碲酸盐玻璃上转换发光特性

用高温熔融法制备了Tm3+/Er3+/Yb3+共掺碲酸盐玻璃(TeO2-ZnO-La2O3)样品,测试了玻璃样品的吸收光谱和上转换发光光谱,分析了上转换发光机理。结果发现:在975 nm,波长激光二极管(LD)激励下,制备的碲酸盐玻璃样品可以观察到强烈的红光(662 nm)、绿光(525、546 nm)和蓝光(475 nm)三基色上转换发光,分别对应于Er3+的4F9/2→4I15/2,2H11/2→4I15/2、4S3/2→4I15/2和Tm3+的1G4→3H6能级跃迁;随着Yb3+掺杂含量和泵浦功率的增加,样品的上转换发光强度都得到了一定程度的提高;通过调整稀土掺杂的浓度,得到了接近于标准白光(EE)发射。     

共沉淀纳米粉体制备Yb:CaF2激光陶瓷及其性能研究

利用共沉淀法合成的粉体, 通过真空烧结结合热压烧结后处理制备了掺镱的氟化钙透明陶瓷(Yb:CaF₂)。在600 ℃预烧1 h, 700 ℃热压烧结2 h制备的5at%Yb:CaF₂透明陶瓷在1200 nm处的直线透射率达到92.0%。对陶瓷的显微结构、光谱特性和激光性能进行了测试和讨论。研究结果表明, 陶瓷样品的显微结构均匀, 平均晶粒尺寸为360 nm。此外, 计算得到Yb:CaF₂陶瓷在977 nm处的吸收截面和1030 nm处的发射截面分别为0.39×10 ^-20和0.26×10 ^-20cm ²。最后, 对Yb:CaF₂陶瓷激光性能进行了表征, 得到最大输出功率为0.9 W, 最大斜率效率为23.6%。     

Intense continuous-wave laser and mode-locked pulse operation from Yb3+-doped oxyfluoride glass–ceramic fibers

Ultrafast fiber lasers, due to their short pulse duration, excellent beam quality, and high brightness, are extensively used in precision processing, biomedicine, nonlinear optics, and spectroscopy. However, great challenges still exist in improving the optical conversion efficiency in glass-based gain media because of the high non-radiative transition probability. Here, we demonstrate an oxyfluoride glass–ceramic (GC) fiber containing NaYF₄:Yb³⁺ nanocrystal that enables enhanced 1064-nm continuous-wave laser output with an optical signal-to-noise ratio of 60 dB. Compared with the as-prepared glass fiber, the optical conversion efficiency of GC fiber is improved from 24.2% to 30.0%. The improvement of laser action is mainly caused by the preferential incorporation of Yb³⁺ into the NaYF₄ nanocrystal with low phonon energy. Using this well-developed GC fiber, we successfully built a passively mode-locked pulsed fiber laser that deliveries laser pulses with a pulse duration of 8.1 ps and a repetition frequency of 56.92 MHz. These results highlight that the GC strategy may provide a roadmap for the development of ultrafast fiber laser and the application of GC fibers in various optoelectronic fields.     

Synthesis and spectral properties of Yb/Ho co-doped yttria 2 μm transparent ceramics

Yb/Ho co-doped yttria transparent ceramics, Yb/Ho:Y₂O₃, were prepared by vacuum sintering with additional 0.5 wt.% tetraethyl orthosilicate (TEOS) as sintering aid from the Yb/Ho co-doped yttria nanopowders synthesized by co-precipitation method. The optical quality of transparent ceramics was improved significantly, as increasing the sintering temperature from 1800 °C to 1850 °C as well as the holding time from 20 h to 25 h, respectively. The absorption spectrum was measured to find out the advisable emission source wavelength. The 2 μm emission bands were observed under laser diode excitation at 980 nm in the co-doped sample with 5 mol% of Yb³⁺ and 1 mol% of Ho³⁺, and broad emission bandwidth were obtained.     

Yb微合金化Al-2.4Cu-1.3Li合金的均匀化退火工艺及微观组织演变

通过SEM、EDS、DSC、XRD等测试手段研究了Al-2.4Cu-1.3Li-(Yb)合金铸态及均匀化过程中组织及微观结构演变。SEM观察显示,铸态组织中存在明显的枝晶偏析,枝晶间距为45±6μm(Al-Cu-Li合金)与43±7μm(Al-Cu-Li-Yb合金),一次相形貌为块状或条状,面积占比为2.8%(Al-Cu-Li合金)与2.2%(Al-Cu-Li-Yb合金),EDS和XRD结果显示其主要成分为多种AlCu(Li)相,Al-Cu-Li-Yb合金中还存在少量Al₈Cu₄Yb相。根据DSC测试与均匀化动力学计算,制定均匀化退火工艺为500℃×12 h。SEM观察显示退火后样品枝晶偏析已经消除,残留一次相为聚集球状AlCuFe相和/或骨骼状Al₈Cu₄Yb相,面积占比下降到0.93%(Al-Cu-Li合金)和0.76%(Al-Cu-Li-Yb合金)。为了使Yb进一步回溶,针对Al-Cu-Li-Yb合金制定二级均匀化工艺为500℃×12 h+530℃×12 h,残留一次相面积占比下降到0.53%...     

掺Yb3+锂硅酸盐玻璃组分与光谱性质的研究

采用高温熔融工艺制备了Yb3+掺杂锂硅酸盐玻璃,玻璃的组分为SiO2-Li2O-Na2O-MgO-CaO-BaO-Al2O3-Yb2O3。经过理论和实验分析,我们得出该组分的最佳比例为70SiO2-18Li2O-8MgO-2Al2O3-2Yb2O3mol%,它具有较高的发射截面和较长的荧光寿命,并随着修饰体阳离子场强增大,配位体之间位置的有序化降低,即格位的对称性下降,因此吸收截面和发射截面逐渐增大,荧光寿命降低。     

纵向抽运准三能级Yb:YAG激光器的理论模型及实验研究

在激光谐振腔中,边缘冷却的激光晶体中存在着温度梯度分布,从而使激光晶体等效为一个热透镜.热透镜效应对固体激光器的性能影响很大.由于热透镜效应,振荡光光斑半径会随抽运光功率及激光谐振腔腔型结构的变化而变化,这将影响输出光功率的大小.在考虑振荡光光斑半径随抽运光功率及谐振腔变化的情况下给出了速率方程的表达式,并采用数值方法求解.由理论分析可知,输出光功率与抽运光功率及谐振腔腔型结构有关.在相同的抽运功率下,腔型不同输出光功率不同.采用930 nm纵向抽运,发射光波长1030 nm的准三能级Yb∶YAG晶体在三种不同腔型结构下进行实验,实验结果表明腔型结构对激光输出功率影响很大.实验结果与模拟符合较好.     

掺Yb3+光纤放大器的自发辐射噪声分析

为了研究掺Yb3+光纤放大器中自发辐射噪声分布情况,利用离散化的方法求解掺Yb3+)光纤放大器的速率方程,理论研究了不同的抽运方式、端面反射率、抽运功率以及有无滤波等条件下,端面抽运掺Yb3+光纤放大器中自发辐射的功率放大特性.结果表明,不同边界条件下的自发辐射功率差异较大;通过减少光纤端面的菲涅耳反射和利用滤波技术等方法,可有效抑制光纤激光放大器中自发辐射噪声的功率放大.     

掺Yb3+双包层光纤激光器的自脉冲行为分析

为了对掺Yb3+双包层光纤激光器的自脉冲行为进行系统的理论研究,采用数值模拟方法,对光子数密度和反转粒子数密度随时间及抽运功率的变化、阻尼系数与后腔镜的反射率和掺杂粒子浓度的关系,以及光纤本身固有振荡频率随后腔镜反射率的变化进行了理论分析.结果表明,随抽运功率的增加,振荡频率增加,振幅度减小;降低输出端的反馈和粒子的浓度可以抑制自脉冲现象.另外提出了抑制光纤激光器自脉冲的措施,为设计掺Yb3+双包层光纤激光器提供了理论依据.