一种用单模光纤制作亚微米周期光栅的方法

本文报道一种用单模光纤制作亚微米周期光栅的全息方法,并详细分析和讨论了影响光栅质量的各种因素。实践证明这一方法完全适于制作面积不小于10×10mm~2适于集成光学元件需要的高质量光栅。     

Radiation condition and scattering problem for time-harmonic acoustic waves in a stratified medium with a nonstratified inhomogeneity

In this paper, a generalized Sommerfeld radiation conditionis presented for the scattering waves in a stratified mediumwith a nonstratified inhomogeneity. Using integral equationmethods, the uniqueness and existence of the direct scatteringproblem are proved. Relations between the scattered acousticwaves in the far field and the sound profile of the inhomogeneityare obtained. Using these relations, the author proves threereciprocity relations between the free-wave far-field patternsand the guided-wave far-field pattern vectors correspondingto incident distorted plane waves and normal mode waves. Thenconditions under which a set of far-field patterns is completein a Hilbert space are determined using the reciprocity relation.These properties are important in investigating inverse scatteringproblems.     

平面波导偏转光栅特性分析

本文借助由偏转波耦合方程得出的偏转系数R就平面波导偏转光栅的角度特性以及频率特性进行了讨论。分析表明,偏转光栅的这些特性主要决定于入射波与偏转波间耦合系数|K|与光栅长度L的乘积|K|L,而不单独依赖于|K|或L。     

化学液相沉积法调变沸石孔径及异构体择形分离

本文用化学液相沉积方法精细调变NaY沸石孔径, 在适当的溶剂中硅酯与沸石吸附水或表面羟基作用而沉积于沸石外表面, 沸石孔口有效地被缩小。制备了一系列氧化硅沉积量不同的SiNaY沸石, 红外光谱、比表面和孔体积测量结果表明随着沉积量增加沸石孔径逐渐缩小, 但沸石骨架结构、孔容和内表面性质基本不变。测定了SiNaY样品对于对二甲苯/1, 3, 5-三甲苯, β-甲基萘/α-甲基萘, 1, 2, 4-三甲苯/1, 3, 5-三甲苯, 对二甲苯/间二甲苯和对甲酚/间甲酚五类分子尺寸不同的液体混合体系的择形吸附行为, 发现SiNaY沸石对分子尺寸与沸石孔径相近的混合体系具有良好的择形选择吸附分离性能。