CCD高斯光束监测仪

CCD高斯光束监测仪是测定激光束和其他光束截面某一方向上光能量分布的设备。 它可以测定激光束近光场和远光场能量分布、光束发散角,通过示波器显示,能获得较直观的激光束模式分布曲线。并且对于光束瞬态光能量分布,小截面弱光强的光束能量分布也能得到很好的测量效果。 仪器由探测头和电源驱动器组成,探测头能用手旋转,因此,通过测定其他方向的光强,能观察整个截面的能量分布。     

强激光的计算模拟:平顶高斯光束模型

基于广义惠更斯－菲涅耳衍射积分,将平顶高斯光束作为一个整体光束,对其基本性质和变换特性作了统一研究。推导出了平顶高斯光束通过有线性增益（损耗）的近轴ABCD光学系统、无光阑和有光阑ABCD光学系统后解析形式的传输方程。对平顶高斯光束的相似变换以及与超高斯光束的一致性也作了分析。所得结果对强激光的模拟提供了一个有用的计算模型。     

聚焦余弦平方高斯光束的梯度力

利用Collins公式推导了余弦平方高斯光束（CSGB）通过无光阑透镜光学系统聚焦后的光强分布及梯度力表达式。通过数值模拟讨论了光束参数、光束入射距离及系统菲涅耳数的变化对梯度力分布及光阱的数量、位置及尺度的影响。结果表明,光束相关参数越大光阱的数量越多,光阱的位置随光束入射距离而改变,系统菲涅耳数增加光阱尺度减小,而位置不变。     

高斯光束通过位相板后的变化

对基模和高阶高斯光束通过位相板后的变化作了详细的计算分析.研究表明,位相板可以改变光场分布和用功率含量百分比定义的Me2 因子,甚至使Me22.     

大气湍流中受限高斯光束的轴向光强分布

利用扩展Huygens-Fresnel原理分析了大气湍流中圆形孔径限制下高斯光束的传播特性,得到了轴上平均光强的解析表达式,运用数值模拟方法计算了不同湍流强度、孔径大小和波长下的轴上平均光强.结果表明,轴上平均光强在近场发生振荡,其振荡幅度随湍流强度增强和发射孔径的增大而降低,振荡的周期随传播距离的增大而增加;在远场随传播距离的增大,振荡逐渐消失,平均光强平滑下降,最后一个平均光强极大值的位置与湍流强度和波长成反比,与发射孔径成正比.     

Astigmatic Gaussian beams produced by axially asymmetric laser cavities

Gaussian beams generated within astigmatic resonators are themselves astigmatic, having wavefront curvatures and spot sizes that are different when measured in two orthogonal directions. Expressions are derived for the confocal parameters, spot sizes, waist positions, and stability conditions of beams formed within spherical mirror resonators that contain one or more inclined plates (or Brewster-ended laser rods). An expression is also derived for the resonant frequencies of the TEMmnmode in such a resonator. It is shown that the frequency degeneracy between modes of the samem + nis lifted and the frequency splittings are calculated. The astigmatism produced by prisms used for dispersion is also considered and precautions are described for avoiding serious astigmatism in resonators containing such prisms.     

湍流大气中部分相干空心聚焦束的光强分布

基于广义惠更斯-菲涅耳原理和相位结构函数的平方近似,研究了湍流大气中聚焦部分相于空心光束传输特性,用张量积分的方法导出了接收面上平均光强分布的解析表达式。研究结果表明：对于给定的传输距离,焦面上的光强分布均为高斯分布。高斯分布的峰值和腰宽与空心光束的初始相干长度、焦距的长度以及大气湍流起伏强度和湍流外尺度密切相关,而且在强湍流情况下,湍流外尺度严重影响峰值强度。     

非傍轴高斯光束通过小孔光阑衍射的轴上光强

基于瑞利衍射积分,不使用通常的近似Rλ(λ为波长),推导出非傍轴高斯光束通过小孔光阑衍射的轴上光强的精确解析表达式。并对传统的光强定义和光强的精确表述进行了比较研究。结果表明,两种定义之间的差异与f参数,截断参数δ和传输距离z有关。     

Gain-coupled distributed-feedback GaInAs-GaAs laser structuresdefined by maskless patterning with focused ion beams

First-order periodic gain modulation in GaInAs-GaAs laser structures has been realized by maskless focused ion-beam implantation. The structures were implanted with Ga⁺-ions at an ion energy of 130 keV and a line dose of 1*10⁷ 1/cm. The periodicity of the gratings was designed for laser operation at 77 K and room temperature. With optical pumping we have observed single-mode laser operation due to the distributed feedback effect at wavelengths between 849 mn and 944 mn at 77 K (grating periods between 124 and 140 nm) and between 954 nm and 1005 mn at room temperature (grating periods between 140 and 148 nm)     

高强度激光对光学薄膜的破坏

在薄膜破坏中起主要作用的是个别的脉冲尖峰。分析了薄膜结构对薄膜受破坏的影响,以及SiO_2保护膜在提高ZrO_2/SiO_2膜的抗激光强度中的作用。     

Gaussian beams in anisotropic media

The letter presents a simplified analysis which enables a calculation of the behaviour of Gaussian beams in anisotropic media starting from Maxwell's equations. This method is applicable to uniaxially and biaxially anisotropic media as well as to gyrotropic media.     

非圆对称高斯分布激光散斑积分光强统计分布

由于某些应用中,如光学通信的误差概率计算,需要知道接收端光束强度起伏的概率分布。所以,目前对激光散斑积分光强起伏的统计分布规律的量子和经典理论的研究十分活跃,而激光大气闪烁统计分布方面的研究尤为活跃。然而,至今为止,这些研究工作皆局限于圆对称高斯分布大气散射场的闪烁分布并且忽略了接收检测有限孔径和时间累积效应。实际上,在气溶胶湍流大气(如雾、云)中传输的激光散斑的光场一般说来不再满足圆对称高斯分布。为了客观满足描述光束在实际大气中传输散斑积分光强起伏分布规律,十分必要研究描述云、雾大气中传输激光散斑光场的闪烁统计规律。本文将研究并给出非圆对称高斯分布散射场的积分光强起伏概率密度函数。     

高斯光束低阶模焦点能量的相对分布

本文给出了高斯光束低阶横模聚焦后的焦点能量相对分布的解析解,并与不同放大倍率M值情况下的非稳腔单模远场聚焦特性进行比较。若以聚焦平面含激光总能量的80％作为光束发散角的统一基准,计算表明,在某些情况下,利用稳腔选模,可得到接近甚至优于非稳腔选模的良好光学质量,而且光腔结构简化,输出稳定性好及光电转换效率高。     

双束聚焦强红外激光引起可见荧光的光-声-光相互作用的研究

在强红外激光脉冲激发下引起BCl_3分子可见荧光,同时产生脉冲声,当这种声再进入振动激发态分子气体时,引起分子的再激发并再度引起分子分解,并发出可见荧光,即光-声-光现象。由于这种光-声-光现象对于研究激光化学及激光分离同位素的能量转移过程以及激光引起的气体动力学过程是极为重要的,所以,在本工作中使用二个同时的不重迭的强CO_2脉冲聚焦光束对此现象作了进一步的研究,得到了令人鼓舞的结果。将一束激光能量密度降至不足以引起光-声-光致荧光,然后单独加入另一束不重迭聚焦光束,在第一束激光辐照区域亦未     

A neural network based technique for vibration characterization using Gaussian laser beams

This paper presents a neural network technique combined with an optical measurement system for the characterization of mechanical vibrations in industrial machinery. In the proposed system, the Gaussian beam of a laser source illuminates on an array of photodetectors. If either the laser source or the photodetector array is coupled with a vibrating system, then the optical powers detected by the photodetectors will vary accordingly, and are expected to reflect the magnitude and frequency of the X–Y planar vibrations of the monitored system. The time-varying optical powers are input to an artificial neural network-based vibration monitoring system which maps the power distributions to the X–Y position of the laser beam center. An experimental setup of the system is built and used for training and testing purposes. The obtained experimental results demonstrate the adequacy of combining optical techniques with neural networks to estimate the vibration frequency and magnitude. Estimated frequencies were within 1% of the actual ones, and the estimated magnitudes were within 29% of the actual magnitudes when using a chirp signal in the training phase. The magnitude estimation percentage error was further reduced below 12% when the neural network was trained with a decaying chirp signal.     

高斯光束的判别和测量

提出一种判别和测量高斯光束的新方法。在截面内对任意等距四点采光测量,就可判别和测量此高斯光束。     

平顶多高斯光束与平顶高斯光束的一致性研究

对描述平顶光束的两种数学物理模型,即平顶多高斯光束(FMGB)和平顶高斯光束(FGB)作了比较,给出了数值计算结果并作了物理分析。研究表明,具有相同M2因子的两个平顶多高斯光束和平顶高斯光束,无论其束腰宽度是否相等,在广义菲涅耳数相等处都具有相似的光强分布。这一结论对实际工作有应用意义。     

有振幅调制和位相畸变光束的非线性传输

从广义惠更斯-菲涅耳衍射积分和B积分定义出发,并利用统计光学方法,对有振幅调制和位相畸变光束的非线性传输特性作了详细研究.     

Propagation of Gaussian beams in dielectric waveguides

The propagation of Gaussian beams in both a homogeneous medium and a lenslike medium is treated. The correct Helmholz equation derived by the author is used to obtain the analytic solutions, taking into account the diffraction effect. Based on this, the beamwidth and the form of the wavefront are considered. The beamwidth will increase monotonically in the homogeneous medium and will be sinusoidal in the lenslike medium; that is, in the lenslike medium, the width will alternately increase and decrease