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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. 相似文献
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推导出截断圆对称光束二阶矩的传输方程,它们与无截断光束的二阶矩满足相似的传输定律.因此,基于广义截断二阶矩方法,将直角坐标系中截断二维光束的二阶矩特征参数推广到柱坐标系中的截断圆对称光束,类似方法定义的广义M2因子(M2G因子)是一个传输不变量.对理论的自洽性作了物理解释.推导出柱坐标系中截断超高斯光束的二阶矩参数和M2G因子.对一些有意义的特殊情况作了讨论,并以数值计算例作了说明.
关键词:
光束描述
截断光束
圆对称性
广义截断二阶矩(GTSM)
2因子(M2G因子)')" href="#">广义M2因子(M2G因子) 相似文献
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非傍轴截断平顶光束的质量因子 总被引:1,自引:0,他引:1
使用功率密度的二阶矩方法和Li提出的平顶光束模型,推导出了非傍轴截断平顶光束的束腰宽度、远场发散角和光束质量因子的解析表达式。计算结果表明:非傍轴截断平顶光束的质量因子不仅与截断参数、光束阶数有关,而且与初始束腰宽度和波长之比有关;当截断参数趋近于0时,远场发散角趋于渐近值63.435°;对于光束阶数为1和截断参数趋于无穷大的特例,计算结果分别退化为非傍轴截断高斯光束和非傍轴无截断平顶光束的结果;功率密度的二阶矩方法可用于截断光束,并克服了光束质量因子的发散困难。 相似文献
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《中国物理 B》2020,(6)
Based on the generalized truncated second-order moments, an approximate analytical formula of the beam propagation factor M~2 of high-power laser beams passing through the optical system with multiple hard-edged apertures is deduced. Numerical examples of the beams passing through an aperture-spatial filter are enclosed, and the influences of amplitude modulations(AMs) and phase fluctuations(PFs) on the beam propagation quality of high-power laser beams passing through the multi-apertured ABCD optical system are considered and discussed. It is shown that PFs are able to degrade the beam propagation quality of laser beams more than AMs when the high-power laser beams passing through the aperture-spatial filter, furthermore, one or two aperture-lens optical systems configured appropriate aperture parameters are both able to upgrade the beam propagation quality of high-power laser beams. The M~2 factor of Gaussian beam passing through the multi-aperture optical system is a special case in this paper. 相似文献
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Based on the truncated second-order moments method on the cylindrical coordinate systems and the incomplete gamma function, an analytical expression of the generalized beam propagation factor (MG2 factor) of hard-edged circular apertured diffracted Bessel–Gaussian beams is derived and illustrated numerically. It is shown that the MG2 factor of hard-edged diffracted BGBs mainly depends on the truncation parameter δ and the beam parameters m and η. The results can be reduced to that for the non-truncated Bessel–Gaussian beams case and that for the truncated fundamental Gaussian beams case under certain conditions, respectively. The power fraction is also discussed analytically and numerically. 相似文献
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Continuous-wave green laser with a maximum power of 34 W has been obtained by intracavity frequency doubling with KTP in diode-side-pumped Nd:YAG. The Nd:YAG/KTP green laser has a simple three- mirror V-fold cavity structure. The optical-to-optical conversion efficiency is 9.5%. The instability of the laser is measured when the output powers are near 16, 21, 30, and 34 W after the beam is filtered. At the maximum output power, the M^2 factor is measured to be 8. 相似文献
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有振幅调制和相位畸变光束通过硬边光阑的M2因子 总被引:5,自引:3,他引:2
光束传输M^2因子是表征激光束的有用参量。利用矩形函数的复高斯函数的近似展开方法,给出部分相干光通过硬边光阑后强度二阶矩的近似计算公式,由此可得到部分相干光通过硬边光阑后的推广M^2因子。以有振幅调制和相位畸变光束为例,推导出相应的推广M^2因子的解析表达式,通过数值计算对提出的近似算法的计算精度进行了分析。研究结果表明,使用该近似方法计算得到的推广M^2因子的计算误差小于1%,且通过该方法可直接得到相应的近似解析计算公式,从而使计算得以简化,并有效地提高了计算效率。 相似文献
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部分抽运的板条激光器的热效应分析 总被引:15,自引:5,他引:10
基于热传导方程和高斯赛德尔数值计算方法,对部分抽运板条激光器的温度分布、热应力和热致折射率变化等热效应进行了详细分析,并与单侧抽运及双侧抽运方式进行了比较。结果表明,设计合理的部分抽运板条激光器,可以获得较高的抽运效率,其热效应相比于均匀抽运的情况并没有显著劣化,不论是采用锯齿形传播方式还是直线传播方式的激光器都可以获得较好的光束质量,当一束高斯激光直线经过板条晶体中部时,光束质量因子为1.4,若采用锯齿形传播方式,则光束质量因子可提高到1.1。 相似文献