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为了研究厄米-拉盖尔-高斯(HLG)光束在分数傅里叶变换(FRFT)面上的变换特性,利用柯林斯(Collins)公式,导出了其通过分数傅里叶变换系统后,在分数傅里叶变换面上的光强分布解析式.并利用此解析式作数值计算,研究了其在分数傅里叶变换面上的光强分布特性.研究表明,厄米-拉盖尔-高斯光束在分数傅里叶变换面上的光强分布受参量α,模指数m,n和分数傅里叶变换阶数p的影响.光强分布随p和α周期性变化,周期分别为2,2π.此外,厄米-拉盖尔-高斯光束通过分数傅里叶变换系统后,光束形状保持不变. 相似文献
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洛伦兹-高斯光束的传输特性 总被引:1,自引:0,他引:1
洛伦兹-高斯光束是用于描述某些发散程度较大的激光光源而引入的,在源平面上的q参数趋向于无穷的条件下,洛伦兹-高斯光束退化为洛伦兹光束.基于柯林斯积分公式,导出了洛伦兹一高斯光束经傍轴abcd光学系统的解析传输公式,进行了相关的数值计箅以揭示其傍轴传输特性.基于矢量瑞利-索末菲衍射积分公式,导出了矢量洛伦兹-高斯光束非傍轴条件下的解析传输公式,进行了相应的数值计算;作为一般公式的特例,给出了相应的远场表达式和傍轴结果. 相似文献
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采用广义惠更斯-菲涅耳衍射积分公式推导出厄米-余弦-高斯光束通过负折射率平板材料的传输公式,并利用其解析式进行数值计算和分析。研究结果表明:负折射率平板材料中的负折射率只影响光束的两次聚焦位置;光束参数不仅会改变厄米-余弦-高斯光束的轴上光强分布,还会改变横向光强的分布,但对厄米-余弦-高斯光束轴上最大光强和横向最大光强的位置均没有影响。 相似文献
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基于广义惠更斯-菲涅尔原理,推导了部分相干拉盖尔-高斯(partially coherent Laguerre-Gaussian,PCLG)光束在生物组织传输中交叉谱密度函数的解析表达式,并研究了光束在小鼠真皮组织传输中归一化光强和相位演化受传输距离z、拓扑荷m和径向指数n、空间相干长度σ变化的影响。结果表明,随传输距离增大,光束光强逐渐减弱的同时,光强分布轮廓也由多峰状逐渐演变为单峰状;初始的m阶相干涡旋和n个圆刃型位错先演化成m+2n个相干涡旋,再新生m+2n个相干涡旋。此外,拓扑荷、径向指数、空间相干长度越大,光束的光强分布变化和相位演化越慢。 相似文献
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基于硬边孔函数能拓展成一组有限复高斯函数的和,研究厄米- 高斯光束通过双矩孔
的传输特性,用Collins公式分析,用Matlab进行一些数值模拟。表明:传输特性与光束的参数、光学系统的参数、孔的大小和孔的间距密切相关。其结果可推广到其他孔、光束和多光束,本研究对控制光束和光学系统设计是十分有用的。 相似文献
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Ajay K. Srivastava Ashutosh Bhardwaj Kirti Ranjan Namrata Sudeep Chatterji R. K. Shivpuri 《Materials Science in Semiconductor Processing》2003,6(5-6):555-559
The influence of crystal damage on the electrical properties and the doping profile of the implanted p+–n junction has been studied at different annealing temperatures using process simulator TMA-SUPREM4. This was done by carrying out two different implantations; one with implantation dose of 1015 BF2+ ions/cm2 at an energy of 80 keV and other with 1015 B+ ions/cm2 at 17.93 keV. Substrate orientation 1 1 1 of phosphorus-doped n-type Si wafers of resistivity 4 kΩ cm and tilt 7° was used, and isochronally annealing was performed in N2 ambient for 180 min in temperature range between 400°C and 1350°C. The diode properties were analysed in terms of junction depth, sheet resistance. It has been found that for low thermal budget annealing, boron diffusion depth is insensitive to the variation in annealing temperature for BF2+-implanted devices, whereas, boron diffusion depth increases continuously for B+-implanted devices. In BF2+-implanted devices, fluorine diffusion improves the breakdown voltage of the silicon microstrip detector for annealing temperature upto 900°C.For high thermal budget annealing, it has been shown that the electrical characteristics of BF2+-implanted devices is similar to that obtained in B+-implanted devices. 相似文献
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根据广义惠更斯菲涅尔原理与维格纳分布函数相 结合的方法,导出了电磁高斯谢尔模型阵列光 束(EGSMA Beams)在大气湍流中传输的均方根空间扩展、角扩展以及M2因子的解析式。(分析了其传输特 性与光束宽度、初始相干长度、阵列光束数量、初始偏振度、湍流内尺度以及折射率结构常 数的关系。)研 究结果表明相对M2因子随初始偏振度、初始相干长度和折射率结构常数的减 小,以及阵列光束数量、光束 宽度、和湍流内尺度的增大而减小,此时相对M2因子受大气湍流影响更小。当经过大约5km的传输距离 后,初始相干长度对相对M2因子的影响开始明显加大,且随传输距离增大而 增大。同时研究结果表明当阵 列光束数量增加越多时,相对M2因子越接近1。并且分析得出初始偏振度以及折射率结构 常数对相对M2因子的影响大于相对均方根空间扩展和角扩展。 相似文献
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Mohamed B. El_Mashade 《电子科学学刊(英文版)》2006,23(6):853-863
The χ^2 family of signal fluctuation distributions represents the main fluctuation models which most radar targets follow it in their reflections. This family can be categorized as fluctuation distribution with two degrees of freedom and those with four degrees of freedom. The first category represents all important class of fluctuation models which when illuminated by a coherent pulse train, return a train of fully correlated pulses (Swerling Ⅰ model) or fully decorrelated pulses (Swerling Ⅱ model). The detection of this type of fluctuating targets is therefore of great importance. This paper is devoted to the analysis of Cell-Averaging (CA) based detectors for the case where the radar receiver noncoherently integrates M square-law detected pulses and the signal fluctuation obeys 2 statistics with two degrees of freedom. These detectors include the Mean-Of (MO), the Greatest-Of (GO) and the Smallest-Of(SO) schemes. In these processors, the estimation of the noise power levels from the leading and the trailing reference windows is based on the CA technique. Exact formulas for the detection probabilities are derived, in the absence as well as in the presence of spurious targets. The primary and the secondary interfering targets are assumed to be fluctuating in accordance with the χ^2 fluctuation model with two degrees of freedom (SWI & SWII). The numerical results show that the MO version has the best homogeneous performance, the SO scheme has the best multiple-target performance, while the GO procedure does not offer any merits, neither in the absence nor in the presence of outlying targets. 相似文献
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M. PéRotin A. Sabir L. Gouskov H. Luquet A. Pérez B. Canut B. Lambert 《Journal of Electronic Materials》1991,20(8):517-522
Implantation of Be+ ions into GaAISb epilayers is used to realize thep
+ layer of the Ga0.96Al0.04Sb p+/Ga0.96Al0.04Sbn
− /GaSbn
+ (1.55 /Μm) avalanche photodetector whose performances are detailed in Ref. (1). The GaAISb layers are grown using liquid
phase epitaxy (LPE); the quality of these as-grown layers is shown through photoluminescence and channeling measurements.
The last part of this paper is devoted to the damaging level in the Be+-implanted layers. Some annealing techniques are presented as a mean of restoration of the implanted layers. It is clear from
the results that the Be+ ion implantation leads to a low damage level in this III-V compound. 相似文献
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为了研究空心光束通过硬边光阑透镜傍轴ABCD光学系统后的传输特性,利用柯林斯衍射积分公式,推导出了空心高斯光束通过受圆孔硬边光阑限制的傍轴ABCD光学系统的传输公式,所得公式可用来描述空心高斯光束通过任意傍轴ABCD光学系统的传输.研究了光阑、透镜以及光阑透镜系统对空心高斯光束传输特性的影响,并用数值例做了详细说明.结果表明,光阑和透镜均会使光束的光场分布向源平面前移,光阑会破坏空心高斯光束的空心性,而单纯的透镜只改变光场分布,不会破坏光束的空心性.这一结果对于空心光束的产生和应用有理论指导意义. 相似文献
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高斯光束通过非线性梯度折射率透镜的传输特性 总被引:2,自引:0,他引:2
基于无像差自聚焦理论,使用ABCD定律导出了高斯光束在非线性梯度折射率介质中的解析传输公式。采用矩阵光学方法研究了高斯光束通过非线性梯度折射率透镜的传输特性。结果表明,介质的非线性性和非均匀性、激光功率及入射光束参数影响其传输特性。 相似文献