浅议物理实验教学环节改革

为进一步提高大学物理实验的教学质量，本文就实验课的预习、操作、实验报告的撰写及考核方法进行了探讨。     

牛顿环实验中的误差分析

本文对牛顿环测透镜曲率半径实验中引起误差的各种原因进行分析讨论，指出了误差的主要来源及比较完善可行的处理方法。     

乳化炸药密度对其压力减敏的影响

在相同的乳胶基质内分别添加2%、3%、4%、5%的空心玻璃微球,2%、3%、4%、5%的膨胀珍珠岩和0.10%、0.15%、0.20%、0.25%的化学发泡剂制备了3组乳化炸药。测试了各组乳化炸药未受压时和受冲击波动态压缩作用之后的水下爆炸冲击波,以波峰值计算他们的压力减敏度。比较了各组乳化炸药的压力减敏度大小,分析了密度对乳化炸药压力减敏的影响。结果表明:密度较大的乳化炸药压力减敏度较小,膨胀珍珠岩或化学发泡剂的添加量越大,乳化炸药越容易产生压力减敏作用;空心玻璃微球的添加量由2%增加到4%,乳化炸药的压力减敏度增加,但当空心玻璃微球的添加量由4%增加到5%后,乳化炸药的压力减敏度反而减小。密度对乳化炸药压力减敏影响的主要原因在于密度调整剂周围的乳胶基质破乳。     

一种新结构高双折射光子晶体光纤

提出了一种新结构的高双折射光子晶体光纤,通过引入掺氟实心圆的方式形成双折射,而不采用大多数高双折射光子晶体光纤中引入不同孔径空气孔或椭圆空气孔的结构。应用全矢量平面波法对其基模场分布、模式截止以及各种结构参量对模式双折射特性的影响进行了详细的分析和讨论。结果表明,该结构光子晶体光纤可以在较宽波长范围内产生10-3量级的模式双折射,且通过调节孔径,可以灵活地将双折射最高点调整到所需的波长上。另外,该结构高双折射光子晶体光纤在拉制工艺、光纤强度以及光纤熔接等方面也具有一定的优势。     

硅球多层模板溶胶浸渍法制备有序多孔TiO2薄膜

采用垂直沉积法组装了平均球径为188 nm的三维有序二氧化硅微球阵列。以该阵列为模板，通过在TiO₂前驱体溶胶中多次浸渍热处理循环，随后采用超声辅助的NaOH溶液腐蚀去除硅球模板，制备了>20层厚的反转结构的二氧化钛多孔膜。该二氧化钛薄膜在550 ℃下热处理20 h其多孔结构保持不变，表明采用此方法制备的二氧化钛多孔膜具有较好的热稳定性。X射线衍射图表明550 ℃下热处理得到的是具有锐钛矿结构的二氧化钛多孔膜。透光光谱显示了光子带隙出现在～400 nm。通过SEM观察，二氧化钛多孔膜     

光子晶体光纤接续损耗的理论分析

基于超格子构造法,采用全矢量模型计算了光子晶体光纤的模场半径,由此出发理论分析了光子晶体光纤与普通单模光纤之间接续损耗分别受横向偏移、轴向倾斜以及模场不匹配的影响,给出了光子晶体光纤在部分常用结构参量区域{Λ,d/Λ}内与SMF-28接续损耗的理论值,讨论了光子晶体光纤各结构参量与接续损耗之间的关系。并简要分析了不同结构光子晶体光纤之间的接续损耗。结果表明,接续损耗对横向偏移和轴向倾斜都非常敏感;孔距是决定接续损耗大小最主要的因素;与普通单模光纤接续,当光子晶体光纤的孔距比该单模光纤纤芯半径大一些时,接续损耗比较小;两种不同结构光子晶体光纤之间的接续损耗大小最主要取决于它们孔距的差异。     

Analysis on Raman gain coefficients in polarization maintaining photonic crystal fibers

The Raman gain coefficients in polarization maintaining photonic crystal fibers (PM-PCFs) are analyzed in order to design fibers for linearly polarized Raman fiber laser with enhanced performances. The results show that a well designed germanium-doped PM-PCF can attain the value of Raman gain coefficient over 50 W-1·km-1, going with very high birefringence and single mode operation at 1.55-μm signal wavelength and 1.45-μm pump wavelength.     

A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings

A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings is proposed. In this model calculated are only the potential modes of a unit cell, which is a high-index ring in the low-index background for this fibre, rather than the whole cladding periodic structure based on Bloch＇s theorem to find the bandgap. Its accuracy is proved by comparing its results with the results obtained by using the accurate full-vector plane-wave method. High speed in computation is its great advantage over the other exact methods, because it only needs to find the roots of one-dimensional analytical expressions. And the results of this model, mode plots, offer an ideal environment to explore the basic properties of photonie bandgap clearly.     

Design of broadband nearly-zero flattened dispersion highly nonlinear photonic crystal fiber

We propose a new structure of broadband nearly-zero flattened dispersion highly nonlinear photonic crystal fiber （PCF）. Through optimizing the diameters of the first two inner rings of air-holes and the GeO2 doping concentration of the core, the nonlinear coefficient is up to 47 W^-1.km^-1 at the wavelength of 1.55 um and nearly-zero flattened dispersion of ±0.5 ps/（nm·km） is achieved in the telecommunication window （1460 - 1625 nm）. Due to the use of GeO2-doped core, this innovative structure can offer not only a large nonlinear coefficient and broadband nearly-zero flattened dispersion but also low leakage losses.     

二氢苯骈[c]菲啶类生物碱的制备及其抗乙肝病毒的活性

二氢苯骈[c]菲啶类生物碱是自然界中一类重要的生物活性成分,但含量很低.利用硼氢化还原方法,对博落回粗提物中的血根碱和白屈菜红碱混合物进行还原、分离,得到了二氢血根碱和二氢白屈菜红碱;并初步评价了其抗乙肝病毒活性.结果表明,利用硼氢化还原方法制备二氢苯骈[c]菲啶类生物碱的产率较高,还原产物具有一定的抗乙肝病毒活性.