摘要:
基于广义截断二阶矩法,推导出了截断部分相干厄米-高斯(H-G)光束的广义M2G因子的解析表达式.截断完全相干H-G光束、截断高斯谢尔模型(GSM)光束以及截断高斯光束可以做为本文结果的特例给出.研究表明:截断部分相干H-G光束的广义M2G因子与截断参数δ,模阶数m以及相干参数α有关.当δ非常小时,M2G因子出现奇偶分群现象,即m为奇数的M2G因子互相非常接近,m为偶数的M2G因子互相非常接近,但当δ增大时这种现象逐渐消失.对于截断GSM光束,任意具有不同δ值的M2G因子随α变化的两曲线之间一定存在交叉现象.但是,对于截断部分相干H-G光束的M2G因子,则不一定会发生这种交叉现象.此外,m越大,M2G因子受参数δ的影响越大,可以忽略光阑效应的δ也越大.
Abstract:
Based on the method of generalized truncated second-order moment, the analytical formula of the generalized beam propagation factor (M2G factor) of truncated partially coherent Hermite-Gaussian(H-G) beams is derived. The analytical results obtained from truncated fully coherent H-G beam, truncated Gaussian Shell Model (GSM) beam and truncated Gaussian beam are given as particular examples in this paper. It is shown that the M2G factor of truncated partially coherent H-G beam depends on truncated parameter δ, beam order m, and beam coherence parameter α. When the value of δ is very small, the odd-even groups happen to the M2G factor, i.e., the values of M2G factor with different values of the odd m are nearly the same, and so are they for the even m case. However, this phenomenon disappears as δ increases. For the truncated GSM beams with different values of δ, there exist the cross points between the curves of the M2G factor versus α. However, this phenomenon may disappear for truncated partially coherent H-G beams. In addition, the larger the m is, the more the M2G factor is affected by the δ, and the effect of aperture on M2G factor may be neglected when the δ is larger.