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1.
In this paper we present calculations of the three-dimensional mode structure and output beam characteristics of unstable resonator with turbulent active medium. The calculations of the output beam are carried out in the Fresnel approximation using the well-known iterative method [1]. The active medium is modeled as a series of phase screens with Kolmogorov statistics. The dependence of output radiation parameters of the gas flow laser with unstable resonator on the strength of turbulence in active medium and parameters of resonator is under consideration. 相似文献
2.
E. F. Yelden H. J. J. Seguin C. E. Capjack S. K. Nikumb H. Reshef 《Optical and Quantum Electronics》1992,24(9):S889-S902
The output characteristics of several large-area multichannel unstable resonators are presented. The conventional unstable resonator and a novel toric unstable resonator, in both confocal and nonconfocal configurations, have been studied. Output beam profiles, optical energy extraction, beam focusability, resonator alignment properties and polarization states of the various resonators have been analysed in depth. 相似文献
3.
本文从菲涅耳衍射积分公式出发研究了激光器非稳腔输出环状光束在空间的传输规律.由轴上光强的极值点位置给出了划分非稳腔传输空间的近场、中场和远场区域公式.理论计算结果表明,非稳腔输出端环状光束在中场区域激光能量逐渐向轴心方向转移,而在远场变为爱里型圆盘状光束的过程.在非稳腔脉冲TEA CO_2激光器上测得的实验结果与理论计算结果很好地符合. 相似文献
4.
M.H. Mahdieh 《Optics Communications》2008,281(1):121-128
Field characteristics and beam quality of confocal positive branch unstable resonator under some practical imperfections has been investigated. Based on Fresnel-Kirchhoff integral, the near and far field intensity of the resonator was calculated numerically. Using the second order moment method, the beam quality factor, M2 of the resonator was also calculated. Variety of practical distorting affects, mainly misalignment, off-axis, and thermal deflection of the mirrors, as well as gain non-uniformity were considered in these calculations. The results show that the beam quality factor is more sensitive to the off-axis and misalignment distortions while the non-uniform gain has significant effect only for unusual conditions. The effects of geometrical parameters, i.e. Fresnel number as well as magnification factor on the beam quality were also investigated. 相似文献
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The properties of unstable resonators in on-axis and off-axis geometry were investigated both theoretically and experimentally. Diffraction loss, mode structure, beam quality and misalignment sensitivity were measured in single-shot operation with a gas-cooled Nd: YAG slab laser (4×12×100 mm3) and compared with theoretical results obtained by solving the Fresnel integral equation numerically. The excellent agreement allowed detailed resonator optimization. Furthermore, the resonator performance in high-power operation was investigated with two water-cooled Nd: YAG slab lasers (6×25×163 mm3 and 7×26×191 mm3) capable of 670 W of output power. Beam quality near the diffraction limit and a maximum output power of 475 W was achieved with an on-axis unstable resonator with variable-reflectivity mirror. 相似文献
7.
Output beam analysis of high power COIL 总被引:1,自引:0,他引:1
As the output power of a chemical oxygen iodine laser (COIL) increases, the output laser beam instability appears as the far-field beam spot drift and deformation for the large Presnel number unstable resonator. In order to interpret this phenomenon, an output beam mode simulation code was developed with the fast Fourier transform method. The calculation results show that the presence of the nonuniform gain in COIL produces a skewed output intensity distribution, which causes the mirror tilt and bulge due to the thermal expansion. With the output power of COIL increases, the mirror surfaces, especially the back surface of the scraper mirror, absorb more and more heat, which causes the drift and deformation of far field beam spot seriously. The initial misalignment direction is an important factor for the far field beam spot drifting and deformation. 相似文献
8.
Output beam drift and deformation in high-power COIL 总被引:1,自引:0,他引:1
During the operation of a chemical oxygen iodine laser (COIL) with an unstable resonator of a large Fresnel number, as the output power increases, an instability of the output laser beam will appear, behaving mainly as far-field beam spot drift and deformation. In order to interpret this phenomenon, thermal expansion analysis on the scraper with finite element analysis method and a simulation of the output beam mode of this kind of laser by the method of Fast Fourier Transform were developed. From the experimental measurement and the calculation, we proposed that the presence of the nonuniform temperature distribution of scraper causes the front surface of the scraper to tilt and bulge due to thermal expansion. As the output power is increasing, all the mirror surfaces, especially the scraper's, will absorb more and more heat, causing thermal expansion of the mirror front surface to occur more seriously, thus resulting in the tilting and deformation of the far-field beam spot. The initial misalignment of the direction is also an important factor leading to the far-field beam spot drift and deformation. 相似文献
9.
CO2泵浦源是光泵气体太赫兹激光器的核心器件之一,其性能直接关系到太赫兹激光器的工作稳定性。CO2泵浦源一般由闪耀光栅作为全反射尾镜,构成特殊的光栅腔实现波长的选支输出。采用传输矩阵的特征向量法对光栅谐振腔的腔内光场模式进行了理论分析与数值模拟,计算了光栅腔的一系列本征模式及相应的衍射损耗。结果表明光栅腔的腔内模式特性等效于一个平凹腔,而对于大菲涅尔数的光栅腔, Littrow波长的附近支线也可能具有衍射损耗较低的低阶模,可能优先于Littrow波长的高阶模起振,导致光栅腔的波长选择性降低。 相似文献
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为了将虚共焦非稳腔输出光束质量高和角锥棱镜谐振腔具有免调试的优点结合到一起,提出了用球面角锥棱镜构成虚共焦非稳腔的方案。利用已有虚共焦非稳腔钕玻璃激光器,设计加工了一球面角锥棱镜非稳腔钕玻璃激光器。模拟计算了两谐振腔输出光束的模式分布,然后对两钕玻璃激光器进行了实验对比研究。结果表明:实验得到的模式分布与模拟计算结果相吻合,球面角锥棱镜非稳腔钕玻璃激光器与虚共焦非稳腔钕玻璃激光器分别获得了最大2 176.9 J和2 340.6 J的能量输出,二者的电光效率与束散基本相同,分别为4.3%,0.30 mrad和4.6%,0.26 mrad。 相似文献
12.
为了将虚共焦非稳腔输出光束质量高和角锥棱镜谐振腔具有免调试的优点结合到一起,提出了用球面角锥棱镜构成虚共焦非稳腔的方案。利用已有虚共焦非稳腔钕玻璃激光器,设计加工了一球面角锥棱镜非稳腔钕玻璃激光器。模拟计算了两谐振腔输出光束的模式分布,然后对两钕玻璃激光器进行了实验对比研究。结果表明:实验得到的模式分布与模拟计算结果相吻合,球面角锥棱镜非稳腔钕玻璃激光器与虚共焦非稳腔钕玻璃激光器分别获得了最大2176.9J和2340.6J的能量输出,二者的电光效率与束散基本相同,分别为4.3%,0.30mrad和4.6%,0.26mrad。 相似文献
13.
CO2泵浦源是光泵气体太赫兹激光器的核心器件之一,其性能直接关系到太赫兹激光器的工作稳定性。CO2泵浦源一般由闪耀光栅作为全反射尾镜,构成特殊的光栅腔实现波长的选支输出。采用传输矩阵的特征向量法对光栅谐振腔的腔内光场模式进行了理论分析与数值模拟,计算了光栅腔的一系列本征模式及相应的衍射损耗。结果表明光栅腔的腔内模式特性等效于一个平凹腔,而对于大菲涅尔数的光栅腔, Littrow波长的附近支线也可能具有衍射损耗较低的低阶模,可能优先于Littrow波长的高阶模起振,导致光栅腔的波长选择性降低。 相似文献
14.
为了提高光束质量、压缩光束发散角,利用现有高功率稳定腔TEA CO2激光器进行了非稳谐振腔的技术改造及激光输出试验,非稳谐振腔采用正分支虚共焦型非稳腔方案。为充分研究谐振腔结构参数及激光振荡模体积对输出能量和光束发散角的影响,共设计加工了包含4种放大率、5种模体积的20组非稳腔腔镜组合。在其它参数都相同的试验条件下,进行了非稳腔镜的单脉冲输出对比试验,得到的最大输出能量为14 J,是原平凹稳定腔的70%,而光束发散角只是原平凹稳定腔的1/4。 相似文献
15.
对Du Fort-Frankel差分格式用于谐振腔模式计算进行简要分析,以该差分格式为基础,提出基于移动矩阵法的非稳腔模式数值计算快速算法.对空腔共焦非稳腔模式进行数值模拟,将计算结果与参考文献进行对比,两者吻合较好.对有源共焦非稳谐振腔内增益区位置对谐振腔输出功率的影响进行数值计算,结果表明:对于采用共焦非稳腔的大功率激光器,当增益体积一定、小信号增益曲线相同时,随着谐振腔内增益区与凹面镜之间的距离的减小,激光器输出功率会有较为明显的提高.数值算例证明了本文方法的正确性和有效性. 相似文献
16.
为保持器件结构紧凑型的同时获得稳定的高功率、高光束质量激光输出,将相移光学阵列谐振腔技术用于射频激励扩散型冷却板条波导CO2激光器.实验发现,该设计方案虽然波导结构为矩形宽波导,但是由于采用了具有相移阵列结构的全反射镜,获得的激光束输出空间分布具有阵列输出光束的基本特征.在波导截面为1mm×20mm、增益介质长度为20cm的波导结构条件下,获得了46W的激光功率输出和11.3%的电光转换效率.激光束输出的远场空间分布呈空间压缩的极锐单峰.由于该结构具有的选模特性,远场为单峰空间分布特
关键词: 相似文献
17.
《物理学报》1999,48(7):4
In this
paper, an optical array resonator with phase-shifting end mirror has been combined with
the RF-excited diffusively cooled slab waveguide CO2 lasers to obtain a
desirable output laser beam with single-peaked far-field intensity distribution, which is
highly spatially suppressed with the merits of high brightness and good characteristics of
propagation. In the experiments, a maximum output power of 46 W and highest conversion
efficiency of 11.3% have been obtained from a 200-mm-gain-length device. The laser beam
intensity distribution acquired has similar characteristics to the ouptut beam from laser
arrays due to the periodical structure of the phase-shifting total reflector, and has an
excellent stability due to the mode-selection capability of this type of resonator. In
this paper, theoretical analysis is also given, based on which corresponding theoretical
model is established, the practical feasibility is shown, and the laser beam output with
characteristics of in-phase array mode is predicted. The systematical experimental
investigation indicates the prominent influence of the parameters of the phase-shifting
array end mirror on the property of the output beam. Furthermore, the manufacturing errors
of the phase-shifted array resonator are analyzed and the analysis provides a theoretical
guide to the design of this type of lasers. 相似文献
18.
《中国物理 B》2019,(2)
The vectorial eigenvector method was applied to compute the cylindrical vector(CV) modes of polarization-dependent resonators and multiple modes in the CV mode selected resonator were tracked. Then, the mode characteristics of CV mode selected resonator depending on the Fresnel number, geometry parameters, and polarization parameters were simulated.When the difference in reflection coefficient between radial and azimuthal polarization is greater than 0.021 for spherical semi-confocal cavity, the radially polarized TM01*mode most probably appears in the resonator due to its lowest loss,which is consistent with an azimuthal polarization-selective resonant cavity. Moreover, the appropriate phase shift factor contributes to suppress non-rotationally symmetrical modes, which promotes the selection of CV modes. The Fresnel number between 2 and 2.5 are the appropriate range of values when the value of geometry parameters g2 is 0.5, both of which decide the effective Fresnel number. 相似文献
19.