Dynamics of the Up-Conversion Emission in Holmium Doped Zblan Fiber

The dynamics of up-conversion, green emission under excitation at different infra-red wavelength in Ho^3? doped ZBLAN fiber is reported. Under infrared, 890 nm quasi cw pumping the complicated temporal behavior of the up-conversion signal is strongly influenced by the intermediate ⁵I₅ state cross relaxation. The mechanisms of the observed up-conversion processes are proposed and the time evolution of the ⁵S₂ population is described by the rate equation model. Parameters of the model are determined and numerical simulations of the excited state dynamics are performed.     

A novel 2-μm pulsed fiber laser based on a supercontinuum source and its application to mid-infrared supercontinuum generation

A new method to achieve 2-μm pulsed fiber lasers based on a supercontinuum(SC) is demonstrated. The incident pump light is a pulsed SC which contains a pump light and a signal light at the same time. The initial signal of the seed laser is provided by the incident pump light and amplified in the cavity. Based on this, we obtain a 2-μm pulsed laser with pulse repetition rate of 50 kHz and pulse width of 2 ns from the Tm-doped fiber laser. This 2-μm pulsed laser is amplified by two stages of fiber amplifiers, then the amplified laser is used for mid-infrared(mid-IR) SC generation in a 10-m length of ZrF4–BaF2–LaF3–AlF3–NaF(ZBLAN) fiber. An all-fiber-integrated mid-IR SC with spectrum ranging from 1.8 μm to4.3 μm is achieved. The maximal average output power of the mid-IR SC from the ZBLAN fiber is 1.24 W(average output power beyond 2.5 μm is 340 mW), corresponding to an output efficiency of 6.6% with respect to the 790-nm pump power.     

Highly birefringent ZBLAN photonic quasi-crystal fiber with four circular air holes in the core

A highly birefringent ZBLAN photonic quasi-crystal fiber with a rectangular array of four relatively small circular air holes in the core region is proposed. Through optimizing fiber structure parameters using a full-vector finite-element method combined with perfectly matched layers boundary condition, its birefringence is up to 2.88 × 10⁻² and the confinement losses of both polarized modes are less than 4.95 × 10⁻⁴ dB/m at 2 μm. To our knowledge, this is the first simulation study showing that a birefringence can be achieved with the order of 10⁻² by all-circular-hole PQFs around 2 μm.     

基于ZBLANⅩⅣPr,Yb频率上转换发光的三维立体显示

本文对利用ZBLANⅩⅣPr,Yb频率上转换发光的三维立体显示做了研究,探讨了其中的一些物理问题.在实验中,我们利用Yb³⁺离子敏化的方法提高Pr³⁺的上转换发光效率;通过降低能引起单频上转换发光的激光强度来提高寻址点和非寻址点在显示过程中的对比度.     

Pr(0.5):ZBLAN的双频激发上转换发光的研究

报道了Pr(0.5):ZBLAN玻璃在双频双光束光源激发下的激发态上转换现象.发现上转换发射谱的荧光与常规荧光发射谱的荧光一致，还发现双频激发下的上转换激发谱有3个明显的谱峰，它们依此对应于788.5nm 1G4→3P2,850.5nm 1G4→1I6和805.0nm 3H6→1D2的激发态吸收跃迁，而大的850.5nm上转换激发谱峰是由大的1G4(Pr3+ )→1I6(Pr3+)跃迁的振子强度f=23.04×10-6所致.这说明起源于1G4能级的激发态吸收上转换尤其1G4(Pr3+)→1I6(Pr3+)     

XPS Study of the Corrosion Protection of Fluorozirconate Glasses Dip-Coated with SnO2 Transparent Thin Films

Tin oxide nanoparticles prepared by an aqueous sol–gel method were deposited by dip-coating on fluorozirconate glass, ZBLAN (53%ZrF₄-20%BaF₂-4%LaF₃-3%AlF₃-20%NaF) to improve its resistance against wet corrosion. The aqueous leaching of uncoated and SnO₂-coated fluorozirconate glass was studied by X-ray photoemission spectroscopy (XPS) and it was shown that even an ultra thin tin dioxide film provides good protection of the glass surface against the bulk propagation of the hydrolytic attack.     

一种带葡萄柚空气孔的高双折射ZrF_4-BaF_2-LaF_3-AlF_3-NaF光子准晶光纤

提出了一种具有二重对称性的ZrF4-BaF2-LaF3-AlF3-NaF(ZBLAN)氟化物玻璃基的光子准晶光纤.光纤结构是以ZBLAN氟化物玻璃为背景材料,外包层由圆形空气孔以正方形与正三角形分布组成的基本单元构成,在芯区两侧引入两个对称的葡萄柚空气孔,以增加光纤的双折射.应用全矢量有限元法,研究了光纤的双折射和限制损耗特性与结构参数的关系.通过优化光纤结构参数,在1800—2200 nm的波长范围内获得了具有单模传输特性的高双折射光纤,其模式双折射高达10-2,比普通保偏光纤高出两个数量级,与目前报道的采用椭圆空气孔微结构光纤获得的高双折射具有同样的量级.但与具有椭圆空气孔微结构光纤相比,提出的光纤结构更易于制作.研究结果为开辟2μm波段光器件的研究做出了有益的探索.     

Er:ZBLAN玻璃的一光束上转换立体显示的初步研究

本文研究了一光束上转换三维立体显示 ,所用材料为Er:ZBLAN氟化物玻璃 ;利用 96 6nm的连续波半导体激光研究了一光束上转换三维立体显示的尺寸效应 ,且得到了它的上转换发光谱 ;尤其是发现了基于 15 2 0nm的半导体激光激发的多光子上转换一光束三维立体显示的性能有大幅度提高 ,这在国际上还未见报道。     

(Er3+,Yb3+)共掺ZBLAN玻璃的一种新颖的类雪崩上转换发光现象

研究了Er3 vZBLAN 和(Yb3 , Er3 )vZBLAN玻璃在966 nm 半导体激光激发下的上转换发光现象, 发现在(Yb3 , Er3 )vZBLAN 玻璃样品上存在由Er3 离子间交叉弛豫导致的上转换发光随激光功率二次攀升的类雪崩上转换发光现象; 并且由稳态速率方程的数值计算得出与实验测量相吻合的结果: 当Er3 离子间的交叉弛豫P很小时, 上转换发光是随抽运激光功率的增强而逐渐趋向饱和的; 当P 较大时, (Yb3 , Er3 vZBLAN 玻璃由于Yb3 和Er3 离子间的交叉能量传递速率很大, 致使Er3 离子的上转换激发速率R很大, 造成上转换发光在达到饱和之前出现一个陡升, 这就是实验观察到的由类雪崩效应导致的上转换发光随激光功率二次攀升的现象。     

Fe-doped ZnS film fabricated by electron beam evaporation and its application as saturable absorber for Er:ZBLAN fiber laser

High-quality Fe-doped Zn S films have been fabricated by electron beam evaporation. After the doping, the fabricated films still maintain the preferential crystalline orientation and phase purity of the host Zn S. According to the observation of surface morphology, the root mean-square roughness of the samples increases slightly with the increase of doping content.All of the prepared samples are in cubic zinc blende structure of Zn S. Transmission spectrum confirms a more obvious dip near 3 μm with higher dopant concentration and it can be attributed to the typical ~5E→~5T_2 transition of Fe~(2+). Fe-doped Zn S film is also successfully used for Q-switched Er:ZBLAN fiber laser.