Beam Parameters for End Diffraction of TE0 Mode of Planar Waveguide

The relation between diffractive beam parameters and normalized frequency is analyzed that leads to two improved Tormulas for two kinds of mode-field halT-widths and several formulas for divergence angle as well as beam propagation factor. The numerical calculation indicates that the maximal relative error is less than 0.5% within a reasonable parameter range.     

矩形光波导E_(00)~y模衍射特性分析

基于Marcatili近似理论,给出了一种矩形光波导Ey00模模场的近似表达,根据平面波角谱理论,推导出了矩形光波导Ey00模衍射场的空间频谱表达式,探讨了其x轴方向上的空间频谱分布特性,分析了矩形光波导Ey00模在x,y轴方向上的光传输因子M2,并采用方形桶桶中功率对矩形波导Ey00模空间频率半宽度进行数值分析,得到了由方形桶桶中功率定义的矩形光波导Ey00模空间频率半宽度随归一化频率变化的关系曲线。     

高斯光束经环形光栅的衍射特性分析

基于傅里叶-贝塞尔变换计算高斯光束垂直入射环形光栅时的衍射远场分布,分析了其衍射远场光强分布的一般规律,并与平面波入射时的情况进行了比较.计算结果表明：当光栅半径为1.5倍高斯光束束腰半径时, 随着光栅环数的增加,中央亮斑半值全宽先减小后增大、中央亮斑所包含的功率占总功率的比值减小、中央主极大光强值减小,三者的变化趋势与平面波入射时的趋势一致;中央亮斑半径、次极大光强值变化趋势与平面波入射时的变化趋势不同.当环数小于5时,高斯光束经过环形光栅的衍射场光强变化无规律;当环数大于10后两种情况下衍射场光强变化都不明显;当环数趋于无穷时中央亮斑半径、中央亮斑半值全宽、次极大光强值趋于圆孔衍射(环数等于1)时的值,中央亮斑所包含的功率占总功率的比值约等于圆孔衍射时的1/2,中央主极大光强值约等于圆孔衍射时的1/4.     

高斯光束经环形光栅的衍射特性分析

基于傅里叶-贝塞尔变换计算高斯光束垂直入射环形光栅时的衍射远场分布,分析了其衍射远场光强分布的一般规律,并与平面波入射时的情况进行了比较.计算结果表明:当光栅半径为1.5倍高斯光束束腰半径时,随着光栅环数的增加,中央亮斑半值全宽先减小后增大、中央亮斑所包含的功率占总功率的比值减小、中央主极大光强值减小,三者的变化趋势与平面波入射时的趋势一致;中央亮斑半径、次极大光强值变化趋势与平面波入射时的变化趋势不同.当环数小于5时,高斯光束经过环形光栅的衍射场光强变化无规律;当环数大于10后两种情况下衍射场光强变化都不明显;当环数趋于无穷时中央亮斑半径、中央亮斑半值全宽、次极大光强值趋于圆孔衍射(环数等于1)时的值,中央亮斑所包含的功率占总功率的比值约等于圆孔衍射时的1/2,中央主极大光强值约等于圆孔衍射时的1/4.     

Diffractive beam parameters of LP01 mode of fiber

The diffractive beam parameters of LP01 mode of fiber are analyzed in detail. Based on solving linear equations, two formulas for two kinds of mode-field radii as functions of normalized frequency are presented, and relations between angular radius of far-field divergence, beam propagation factor, and normalized frequency are given. Numerical calculation indicates that the maximal relative error is smaller than 1% within a reasonable parameter range.     

Analysis on Far-Field of Slab Waveguide and Its Gaussian Approximation

This paper researches end diffraction of slab waveguide and then matching efficiency between the far-field and its Gaussian approximate field is analyzed leads to a new definition of divergence half-angle. Finally, why the far-field can be approximated by a Gaussian function is presented according to characteristic of beam propagation factor.     

Mode-field half widths of Gaussian approximation for fundamental mode of two kinds of optical waveguides

This paper analyzes the characteristic of matching effciency between the fundamental mode of two kinds of optical waveguides and its Gaussian approximate field.Then, it presents a new method where the mode-field half-width of Gaussian approximation for the fundamental mode should be defined according to the maximal matching effciency method. The relationship between the mode-field half-width of the Gaussian approximate field obtained from the maximal matching effciency and normalized frequency is studied; furthermore, two formulas of mode-field half-widths as a function of normalized frequency are proposed.     

单模光纤端面衍射光束参量与其结构参数关系研究

本文采用指数函数拟合光纤基模端面衍射场光束参量与光纤基本参数的关系，分别得到了各个光束参量与光纤归一化频率V和光纤芯层半径a关系的解析表达式。把曲线拟合得到的基于V和a表达的解析函数的计算结果，与基于光纤芯层参量U、包层衰减参量W和光纤芯层半径a表达的解析函数的计算结果相比，当1.5 相似文献   

激光束受限衍射对扫描系统分辨本领的影响

基于菲涅耳衍射积分公式推导出激光束经扫描元件衍射后场分布表达式,数值分析了激光束经扫描元件后衍射场振幅分布、激光束在扫描面上的光斑半径和激光扫描系统光学分辨本领的大小.结果表明,改变入射光束的束腰半径对激光扫描系统线分辨率、可分辨光点数和分辨容积产生不同的衍射影响.采用近似和拟合方法,分段给出不同衍射情况下激光扫描系统的线分辨率的函数表达式,并通过误差分析证明了近似和拟合函数表达式的精确性.