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基于强度二阶矩定义, 导出了高斯涡旋光束光束传输因子即M2 因子的解析表达式, 高斯涡旋光束的M2 因子唯一取决于拓扑电荷数n. 数值计算表明, 高斯涡旋光束的M2 因子随着拓扑电荷数n的增大而增大. 基于强度高阶矩, 还导出了高斯涡旋光束经傍轴ABCD光学系统传输时峭度参数的解析表达式, 高斯涡旋光束的峭度参数取决于拓扑电荷数n、参数δ、矩阵元A和矩阵元D. 在自由空间传输时, 高斯涡旋光束的峭度参数仅取决于拓扑电荷数n和参数δ. 自由空间传输时, 高斯涡旋光束峭度参数的变化规律为: 峭度参数随参数δ的增大先减小而后趋向于一最小值, 随拓扑电荷数n的增大而减小. 这一研究有助于高斯涡旋光束的实际应用. 相似文献
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激光光束传输因子M2的一些问题 总被引:7,自引:4,他引:3
本文讨论与M2因子有关的一些问题,指出在近轴近似条件下由光束的二阶强度矩定义的M2因子满足M2≥1,其中只有对基模高斯光束等式才成立.由光束的功率通量值定义的M2因子(Mpc2)有可能小于1,Mpc2的大小取决于所定义的光斑半径内包含的光功率的百分数.通过计算光场的二阶矩,我们获得了轴向相干叠加的高斯光束的M2因子的解析解. 相似文献
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基于广义惠更斯-菲涅尔原理和非Kolmogorov(非K)谱,推导出了厄米-高斯光束在非K大气湍流中传输的束宽、角扩展以及M2因子的解析表达式.数值计算表明,在传输距离比较远(如z≥3 km)时,厄米-高斯光束的束宽、角扩展和M2因子随广义指数参量α的增大而增加直到α=3.11时达到最大值后再随α的增大而减小;随湍流的内尺度l0的减小而增大;随外尺度l0的增加而增大(3.6<α<4).但是当广义指数参量α在3<α<3.6区间取值时,束宽和M2因子几乎不随外尺度的增加而变化. 相似文献
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双共价因子在半磁半导体HgS:Co2+光谱中的应用 总被引:1,自引:1,他引:0
本文采用一种适用于共价晶体的含双共价因子(Nt≠Ne)的能量矩阵计算方法,研究了Co2+离子在HgS中的光学吸收谱,并对结果进行了讨论.研究结果表明,对于共价性强的晶体,Racah参量A对能级跃迁的贡献不能忽略. 相似文献
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本文从理论上研究了主克尔型介质中非束缚态空间亮孤子的传输行为。数值计算结果表明:在主克尔型χ(3)+χ(5)介质中可以传输非束缚态空间亮孤子。传输稳定性与其背景平面波的横向渐近传播常数q和χ(3),χ(5)系数有关,非平凡相位因子在三、五阶效应竞争中的平衡作用,是获得非束缚态空间亮孤子稳定传输的关键。 相似文献
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利用传统的固相反应法制备了BiFe1-xMnxO3 (x= 0-0.20)陶瓷样品, 研究了不同Mn4+掺杂量对BiFeO3陶瓷密度、物相结构、显微形貌、 介电性能和铁电性能的影响.实验结果表明:所制备的BiFe1-xMnxO3 陶瓷样品的钙钛矿主相均已形成,具有良好的晶体结构, 且在掺杂量x=0.05附近开始出现结构相变.随着Mn4+添加量的增加, 体系的相结构有从菱方钙钛矿向斜方转变的趋势,且样品电容率大幅度增大, 而介电损耗也略有增加;在测试频率为104 Hz条件下, BiFe0.85Mn0.15O3 (εr=1065)的 εr是纯BiFeO3 (εr=50.6)的22倍; 掺杂后样品的铁电极化性能均有不同程度的提高,可能是由于Mn4+稳定性优于 Fe3+,高价位Mn4+进行B位替代改性BiFeO3陶瓷, 能减少Bi3+挥发,抑制Fe3+价态波动,从而降低氧空位浓度,减小样品的电导和漏电流. 相似文献
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光子消灭算符高次幂本征态的振幅N次方压缩 总被引:4,自引:0,他引:4
本文研究了光子消灭算符高次幂ak(k≥3)的k个正交归一本征态的振幅N次方压缩特性,结果表明,当k为偶数时,这些本征态均可存在振幅N次方(N=(m+1/2)k,m=0,1,2,…)压缩。 相似文献
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Beam quality changes of Gaussian Schell-model (GSM) beams propagating through axicons are investigated in detail. The expressions showing beam quality changes of GSM beams are derived in terms of Wigner distribution function. It is shown that, when a GSM beam passes through a divergent or convergent axicon, the beam quality factor (M2 factor) becomes larger. The increment of the M2 factor is dependent on the incident beam size, wave number, refractive index of the axicon material and the angle of the axicon; but it is independent of the coherence of the beam. The explanation for the increment of the M2 factor is also given. 相似文献
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It has been shown that the temporal coherence of a non-mode-locked laser is periodic in 2L/c. It has also been demonstrated that the limitations imposed on the depth of field in holography by the laser coherence properties may easily be overcome by illuminating the object with multiple beams. In such a system each object beam should travel the same distance to the holographic plate as the reference beam, or a multiple of 2L farther. For large objects (which would have large depths of field) multiple beam illumination is necessary anyway, to ensure uniform illumination of the object. In fact the limiting factor with regard to the size of an object and the depth of field should be the laser's power and not its coherence length. An advantage in this method of overcoming conventional limitations is that there is no reduction in the laser's output power as is involved in some other methods of coherence length improvement. 相似文献
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Study on the Beam Quality of Uncoupled Laser Diode Arrays 总被引:5,自引:0,他引:5
GAO Chunqing WEI Guanghui 《Chinese Journal of Lasers》2001,10(4):241-245
1 Introduction Laserdiodesystemswithoutputpowersofseveraltenswattsorseveralhundredswattsareavailableinrecent years.Theyhavebeenwidelyusedinpumpingsolid statelasersandlasermedicine .Comparedwithsolid statelasersandCO2 lasers,thehigh powerlaserdiodehasdiff… 相似文献
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The beam quality of uncoupled laser diode array is studied theoretically and experimentally. By calculating the second order moments of the beam emitted from the laser diode array, the dependence of the M2-factor of the laser diode array on the M2-factor of the single emitter, the ratio of the emitting region to the non-emitting space, and the number of emitters, has been deduced. From the measurement of the beam propagation the M2-factor of a laser diode bar is experimentally determined. The measured M2-factor of the laser diode bar agrees with the theoretical prediction. 相似文献
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报道了高功率、高光束质量的垂直腔面发射半导体激光器(VCSEL)侧泵的Nd:YAG激光振荡器。从VCSEL泵浦源的主动冷却的热沉结构出发,设计了5个227 W的VCSEL线阵,并且通过优化侧面泵浦大口径激光棒的结构,研制成了具备480 W输出能力的棒状激光模块,相应的光-光效率为49.7%。在此基础上,设计了一种高功率、高光束质量的VCSEL侧面泵浦棒状Nd:YAG激光振荡器。腔内插入望远镜光学元件,并通过优化各光学元件的参数使其工作在热近非稳区域,以达到增大基横模体积和抑制高阶横模目的。最终,获得114 W的输出功率,相应的平均光束质量因子M2为1.42。由于VCSEL具备优秀的波长-温度稳定性,这种高功率、高光束质量的VCSEL泵浦的固体激光器在工业、空间等领域,具有极为广阔的应用前景。 相似文献
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We demonstrate a novel method for improvement of spatial beam quality by use of the angular selectivity of a thick phase grating inserted into various laser cavities. Preliminary experiments with an intentionally degraded beam from a Nd:YVO4 laser have enhanced beam propagation factor M2 by a factor of 4.5. Operation with a broad-area laser diode in an external cavity with a thick grating was achieved. We obtained 100 mW of cw power in a beam with an M2 of 1.3. Moreover, a reduction of the output spectrum by as much as a factor of 3.8 was obtained. 相似文献
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The experimental results of self-injection locking of an antireflection-coated broad-area diode laser with a 1000-microm-wide emitting area are presented. To our knowledge, it is the broadest single-element diode laser that has been used in an external-feedback cavity until now. Usually, wide diode lasers suffer from filamentation, which leads to poor spatial beam quality. We show, however, that the beam quality of the diode laser is improved significantly when we use asymmetric self-injection locking. An output power of 2.05 W is obtained with a beam quality factor M2 of 2.7. The self-injection locking technique improves the beam quality by a factor of 107. By comparing the results with those obtained with an ordinarily coated diode laser with a 1000-microm-wide emitter we show that antireflection coating on the front facet is decisive for this improvement in the beam quality. 相似文献