对撞增强型YAG相位共轭腔

降低SBS相位共轭腔的启动阈值以及如何提高输出光束的质量一直是人们关心的课题。报道了在YAG激光器上运行一种新型对撞增强型YAG受激布里渊散射相位共轭激光腔的输出特性。该腔具有较低的启动阈值和较高的输出能量;该腔型最高能输出150mJ的能量,输出脉宽最窄为11ns,光束发散角为1.3mrad,输出能量和光束质量都很优良。     

Glass transitions and mixed phases in block SBS

Differential scanning calorimetry (DSC) does not allow for easy determination of the glass‐transition temperature (T_g) of the polystyrene (PS) block in styrene–butadiene–styrene (SBS) block copolymers. Modulated DSC (MDSC), which deconvolutes the standard DSC signal into reversing and nonreversing signals, was used to determine the (T_g) of both the polybutadiene (PB) and PS blocks in SBS. The T_g of the PB block was sharp, at ?92 °C, but that for the PS blocks was extremely broad, from ?60 to 125 °C with a maximum at 68 °C because of blending with PB. PS blocks were found only to exist in a mixed PS–PB phase. This concurred with the results from dynamic mechanical analysis. Annealing did not allow for a segregation of the PS blocks into a pure phase, but allowed for the segregation of the mixed phase into two mixed phases, one that was PB‐rich and the other that was PS‐rich. It is concluded that three phases coexist in SBS: PB, PB‐rich, and PS‐rich phases. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 276–279, 2005     

受激布里渊散射的阈值效应

本文讨论了受激布里渊散射的阈值效应对后向受激散射光（泵浦光的相位共轭波）线宽、发射角、脉宽、能量集中度的影响,利用其阈值效应可以获得一个面积尽量小的共轭光斑。     

多模石英光纤SBS相位共轭实验研究

采用芯径为100μm、长2m的无掺杂多模阶跃石英光纤,在1.06μm波段,研究了不同焦距下,光纤与耦合透镜间的距离以及泵浦能量对反射率和波形的影响。在不同的入射能量下,得到最大反射率为68.95%,脉宽压缩到入射光脉宽的1/3～1/2。     

SBS新介质C4Cl6参数确定及性能研究

 从介质对光的吸收机理出发，研究了吸收系数较小的受激布里渊散射（SBS）新介质六氯-1,3-丁二烯（C4Cl6）。通过基本的物理参数，确定了入射光波长为1 064 nm时C₄Cl₆的SBS参数，其吸收系数约为0.003 cm^-1，声子寿命约为0.25 ns，增益系数约为4.9 cm·GW^-1。分析了入射光波长与介质SBS参数的关系，布里渊频移与入射光波长成反比，声子寿命与入射光波长的平方成正比，增益系数一般与入射光波长无关。在单池SBS系统中，利用Nd:YAG调Q激光器研究了C₄Cl₆的SBS性能。实验结果表明：由于其吸收系数小，与具有相同增益系数的H₂O比较，C₄Cl₆具有较高的能量反射率（饱和能量反射率大于55%）和较宽的SBS脉宽；由于其声子寿命短，与具有相同吸收系数的CS₂比较，C₄Cl₆的SBS波形上升时间较短。吸收系数小和声子寿命短的特点，使C₄Cl₆适合作为放大池介质，这对优化SBS介质选取，提高SBS系统性能具有一定意义。     

Non-isothermal kinetics of styrene-butadiene-styrene asphalt combustion

The combustion characteristics of styrene-butadiene-styrene （SBS） asphalt are studied by thermogravimetric analysis （TG/DTG） at four different heating rates. According to the saturates/aromatics/resins/asphaltenes （SARA） fractionation method, the combustion process of SBS asphalt can be divided by Gaussian peak fitting into three main stages： oil content release, resin pyrolysis, and asphaltene and char combustion. When the heating rate increases, the mass losses of the oil content and resin pyrolysis increase, and less asphaltenes are formed at a higher temperature. The activation energy values are calculated by the Coats-Redfern method to be in the range 61.6 kJ/mol-142.9 kJ/mol. The Popescu method is used for the kinetic analysis, and the result shows that the three stages of asphalt combustion can be explained by the sphere phase boundary reaction model, the second order chemical reaction model, nucleation, and its subsequent growth model, respectively.     

基于高非线性光纤中SBS效应的慢光系统

实验研究了高非线性光纤(HNLF)中受激布里渊散射(SBS)的阈值、增益谱、放大特性及其慢光特性,并与普通单模光纤(SMF)进行了对比分析。测量实验表明,HNLF在线宽100MHz的泵浦激光作用下,SBS的阈值为60mW,增益带宽为150MHz,获得的最大慢光延迟量将近15ns,延迟谱与增益谱较好对应。对基于SBS的未来全光通信系统中的高性能光延迟线或全光缓存器具有重要的参考价值。     

主振-功放系统SBS位相共轭技术研究

利用单池与双池位相共轭池,对SBS位相共轭特性进行了研究,实现MOPA激光系统SBS位相共轭高反射率、高保真度、大能量高光束质量激光输出,为高功率激光器的发展提供了有效技术途径。     

Cr4+:YAG调Q的SBS激光器

对在SBS调Q的YAG激光器中加入Cr4+:YAG的情况进行了计算模拟和实验研究,证明两种被动调Q的适当结合,可明显地提高系统的稳定性。     

双通放大受激布里渊散射脉冲压缩

文章报道了利用双通放大结构进行受激布里渊散射（ＳＢＳ）脉冲压缩，实验获得了近极限压缩的脉冲，压缩率近１０倍。实验中同时观察到脉冲压缩中的相位跃变。相位跃变是受激背散射光与入射激光间的增益与损耗调制的结果。