推广的高斯光束远场发散角理论

本文定义了光腔高斯光束的外发散角和内发散角。利用ABCD矩阵,g-、g~*-参数表示和为实验所支持的多模远场发散角的定义推导出了简单两镜腔和多元件谐振腔基模和多模外发散角和内发散角的一般公式,得出了(1)一般固体激光腔;(2)输出镜为平面反射镜;(3)激     

圆环孔径衍射高斯光束远场发散角研究

基于夫琅禾费衍射理论,通过对衍射积分的核函数进行近似,推导并得出了简洁的经圆环形孔径衍射的高斯光束远场发散角的近似解析式。在不同衍射孔径外径和不同遮拦比的条件下,将该解析式与严格的夫琅禾费衍射积分进行比较,发现二者求出的远场发散角接近一致,最大误差不超过2.7%。与传统数值积分求取光束发散角相比,该近似解析式在避免繁琐的积分运算同时保持了较高的精度。该解析式成立条件为高斯光束的束腰直径大于等于3.5倍中心遮拦直径,且小于等于孔径直径;在实际工程应用中,特别是具有大口径、小遮拦比特点的空间激光通信光学天线这一应用场景,该条件一般能够被满足。     

高斯光束光学

我们想分二次来阐述这个课题,本讲先介绍有关高斯光束光学的基本理论和公式。与普通光源相比,激光在单色性、相干性和亮度等方面都具有许多可贵的特性,这是众所周知的。另外,在垂直于激光束传播方向的截平面内,光波的电矢量振幅具有高斯分布规律的光束(称之为高斯光束)在介质中传播时也有一些有别于普通光源的独特规律和特点,这对于激光束应用及变换来说,也是不容忽视的。     

基模高斯光束远场发散角的近场测量方法

本文提出了一个在近场测量基模高斯激光束远场发散角的方法和计算公式,理论误差极小。     

基于Delphi的高斯光束发散角测量数据实时处理软件开发

在高斯光束参数测量实验中,实验数据的实时性处理是一个难题。文中开发的实验数据处理软件主要包括测量数据曲线的拟合、判断曲线是否符合高斯分布、光斑大小的计算、发散角和腰斑大小的计算。该软件操作方便、界面简单、精度高、运行结果直观易懂,很好地解决了实时处理问题,具有一定实用价值。     

光束发散度低、输出能量高的稳定YAG谐振腔

本文叙述一种稳定的谐振腔结构,由3×1/4YAG棒产生200毫焦耳的输出能量,光束高度准直,发散度小于1毫弧度(全角包括90％能量),准高斯波幅分布,能在达20赫的任意重复频率下工作,而不需要对反射镜再准直。这种新型结构一般适用于其它激光系统。     

利用光栅测量高斯光束发散度的理论计算

提出了利用不同参数Q值光栅测量单模TEM_(00)激光高斯光束发散角的方法.由大量的理论计算和一元线性回归方程误差分析得到了若干组理论误差低于1%的能用于测量的线性关系式.     

基于楔板剪切干涉的高斯光束远场发散角测量

为准确、方便地测量高斯光束远场发散角,提出了一种基于楔板剪切干涉的方法:将传统的双向剪切干涉仪进行改装,使能同时测出激光传输路径上两个不同位置处的波前曲率半径,并由曲率半径求出发散角.该方法解决了传统剪切干涉法只能定性判断光束准直状态而不能定量测量发散角的问题,实现了剪切干涉对基模高斯光束发散角的定量测量.实验测量误差和理论分析结果相符.误差分析表明影响发散角测量精度的主要因素为干涉条纹宽度测量误差.     

高阶横模光束的发散角

本文对高阶横模光束发散角进行了讨论,并提出发散角的一种新的定义方法。     

内腔连续波光学参量振荡器:高斯光束理论

建立了描述内腔连续波单共振光学参量振荡器(ICCWSRO)的功率特性的高斯光束理论。     

用于连续高功率YAG激光器的高斯镜稳定腔的设计

本文通过对高斯镜热透镜稳定腔(GRMSR)内光束特征的分析,提出了设计该类激光谐振腔的一般原则,并设计了平平腔型高斯镜稳定腔。实验结果与理论分析相符,并得到高输出功率、高光束质量的连续YAG激光输出。     

Diffraction loss of stable optical resonators with internal limiting apertures

In many stable laser resonators, the diffraction loss is principally or entirely due to internal occluding elements with two or more limiting apertures, rather than to any mirror size limitations. Such resonators, with any number of arbitrarily located circular or rectangular limiting apertures, can be decomposed into a set of equivalent empty symmetric cavities with finite size mirrors. When the end mirrors are convex, with radii of curvature greater than the distance to the nearest aperture, the equivalent symmetric cavities are stable, and their diffraction losses are given by graphs published by Fox and Li [6]-[8] and reproduced here for the reader's convenience. The method is illustrated by examples with circular and rectangular limiting apertures.     

Excitation of self-focusing optical fibre by Gaussian beam

The launching efficiencies of the HE1m modes and the overall launching efficiency are calculated when a self-focusing optical fibre is irradiated axially by a Gaussian beam. If the spot size of a Gaussian beam is matched to the characteristic spot size of the fibre, the overall launching efficiency is nearly 100%.     

高斯光束空间传输小光斑可调系统的设计

针对空间远距离光通信、精确制导武器以及卫星导航等领域中高斯光束远场小发散角的严格要求和固定的光电检测平面,提出了高斯光束光斑半径大小可调系统的算法.当天线主镜上发射的光斑和光电检测平面接收点的光斑大小相同时,就相当于高斯光束零发散角.主副镜焦距确定的条件下,根据所要求光斑的大小以及光斑监测点的位置,采用移动失调的卡塞格伦天线的主副镜的位置关系来达到接收光斑半径大小可调的目的.当目标距离为10 km范围内,光斑半径在40～60 mm,通过理论计算、设计和分析,发现调节失调的卡塞格伦天线可以增加天线的性能,灵敏度很高,并验证了其可行性.     

Nonparaxial eigenmodes of stable resonators

A method to determine the nonparaxial eigenmodes of stable resonators is presented. The method is based on the perturbation theory of Lax et al. For calculating nonparaxial components of the electric field. A matrix formalism which uses a mode expansion into paraxial Hermite-Gaussian modes is applied to describe the nonparaxial propagation and the phase shift at a parabolic and a spherical mirror. Expressions for these matrices are derived analytically. Multiplying all matrices corresponding to a round trip, a matrix for the resonator is obtained. Eigenmodes of the resonator are numerically found by solving the eigenvalue problem. In the special case of paraxial propagation and parabolic mirror profiles, the standard Hermite-Gaussian modes result analytically. Nonparaxial modes of a given resonator are compared for different mirror profiles. It is found that, in the nonparaxial domain, spherical mirrors do not change the mode profile and the frequencies of the transverse modes, in contrast to parabolic mirrors which aberrate the beam profile and cause frequency shifts     

Matrix algebra for all-fiber optical resonators

A method for calculating the output intensities of passive optical resonators including fiber couplers is presented. The method is based on matrix algebra and is sufficiently general to consider cavities using several couplers. A 4×4 format is used which incorporates matrices for the action on the fields of both the coupler and the geometry developed around the coupler. The validity of this method is first tested on two well-known optical fiber devices. Then a double Fox-Smith resonator is investigated, and the results exhibit both high-frequency selectivity and high finesse. A potential application to single-longitudinal-mode operation of rare-earth-doped fiber lasers is also discussed     

多元件光学谐振腔的公式化分析方法

本文使用“混合”等价腔的变换技巧,将含热透镜的望远镜腔最后化为[1]、[2]中的两种基本类型,从而可对光腔的模参数,包括两腔镜处的光斑半径、各腰斑的大小和位置给出公式化的解析结果.解决了一般多元件腔模参数的公式化表述问题.数值计算不仅证实了解析结果的正确性.而且给出了整个腔内的光束分布图,光斑尺寸随热焦距的变化关系等数据.     

Unstable optical resonators for laser applications

A simple geometrical analysis has been developed which describes the lowest-order transverse mode of any large-Fresnel-number optical resonator located in the unstable or high-loss region of the resonator mode chart. Such resonators include, for example, resonators in which one or both of the mirrors are divergent spherical surfaces. The lowest mode in such a resonator is assumed to consist of two oppositely traveling divergent spherical waves which uniformly illuminate the end mirrors. The centers of curvature of these spherical waves do not, in general, coincide with the mirror centers of curvature, but are found by requiring that each center be the image of the other upon reflection from the appropriate mirror. The resonator losses are found from purely geometrical considerations, and are given by simple analytical expressions. These losses turn out to be independent of the mirror sizes, so that hyperbolic universal equiloss contours can be drawn on the resonator mode chart. The losses agree well with more exact results obtained by Fox and Li for a few specific cases. Experimental results in good agreement with the analysis have been obtained using a ruby laser rod having a divergent spherical surface ground directly onto one end of the laser rod. Unstable resonators, particularly the "Cassegrainian" unstable configuration used in the experiments, appear potentially useful for diffraction output coupling applications, and possibly also for transverse mode control, in ruby and other high-gain lasers.