共查询到18条相似文献,搜索用时 265 毫秒
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高功率激光多程放大系统光束传输的计算分析 总被引:6,自引:6,他引:0
报道了高功率激光多程放大系统光束传输的模拟程序, 该程序考虑了放大介质的增益分布、增益饱和、增益恢复系数、介质吸收损耗、B积分以及光阑和空间滤波器等光学元件对激光传输和放大的影响, 并给出了典型的计算实例。 相似文献
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考虑到有限厚介质的表面热对流,利用格林函数方法理论计算了强激光作用下介质材料的3维温度分布,给出了温升与材料尺寸的关系式及其关系曲线。以单晶硅材料为例进行了模拟计算,结果表明:温升不仅与材料本身的性质(热容,热导率,密度)密切相关,而且还与材料的吸收系数,激光加热参数(功率密度,能量分布,光斑大小,作用时间),以及对流换热系数有关。在激光照射的初始阶段,材料表面温度迅速增加;其后,随着激光照射时间的增加,温度增加量逐步变缓。 相似文献
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给出了光谱、时间、空间分辨的激光二极管(LD)抽运动力学模型,包括LD阵列输出的波长啁啾效应、输出功率随时间的瞬态变化,重点研究了不同吸收带宽的激光介质对大功率LD阵列输出的光谱选择吸收特性. 基于该模型,分析了三种典型激光增益介质Yb:YAG,Yb:S-FAP,Nd:YAG在脉冲储能运转方式下的抽运激发性能. 优化了不同增益介质所需的LD阵列的初始中心波长,并对三种介质对LD波长啁啾效应的敏感性进行了详细研究.
关键词:
激光二极管阵列
波长啁啾
抽运动力学
激光材料 相似文献
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激光诱导介质击穿中的脉冲截断问题 总被引:1,自引:0,他引:1
强激光与介质相互促进作用过程中,当自由电子的密度达到介质的损伤阈值时,介质将被击穿,脉冲的后续能量被激光等离子体强烈吸收而引发截断,这个时间点定义为截断时间点.脉冲的截断时间点对激光脉冲能量的传输有很大的影响.理论研究了入射激光脉冲能量对脉冲截断时间点分布的影响.定量分析和模拟了截断时间点对脉冲能量透过率的影响.模拟结果和实验结果符合很好.研究发现:激光脉冲能量透过率由脉冲截断时间点的位置决定.当脉冲截断时间点分布在脉冲前沿、峰值和后沿时,激光脉冲能垦的透过率分别对应小于50%,等于50%和大于50%.在线测量激光脉冲能量的透过率也可作为一种在线检测光学元件是否发生破坏的方法. 相似文献
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Based on computer simulation, we demonstrate the possibility of formation of solitons upon propagation of a femtosecond laser pulse in a medium containing gold nanoparticles in the presence of two-photon light absorption. The solitons are formed when the laser pulse induces a positive phase grating. The speed of solitons substantially exceeds the speed of laser radiation propagating in a linear medium. 相似文献
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A theoretical investigation of the absorption of the pump light at different intensities through a four-level solid-state laser medium is presented. It is found that the variation of the pump intensity inside the laser medium cannot always simply be dominated by Beer's law. Transmission of the pump light through this laser medium is closely related to the pump intensity itself. In fact, when the pump intensity is relatively low, whose values depend on the characteristics of the medium, the variation of the pump light through the laser medium is consistent with Beer's law. However, while the pump intensity is high enough, the relationship between the transmission of the pump light and its propagation distance is demonstrated to be linear. These theoretical results have been confirmed by the experiment with a medium of YAG:Nd. 相似文献
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Emission spectra of multimode lasers are very sensitive to spectrally selective extinction in their cavity. This phenomenon
allows the quantitative measurement of absorption. The sensitivity of measurements of intracavity absorption grows with the
laser pulse duration. The ultimate sensitivity obtained with a cw laser is set by various perturbations of the light coherence,
such as quantum noise, Rayleigh scattering, four-wave mixing by population pulsations, and stimulated Brillouin scattering.
It depends on the particular laser type used, and on its operative parameters, for example pump power, cavity loss, cavity
length, and length of the gain medium. Nonlinear mode-coupling dominates the dynamics of lasers that feature a thin gain medium,
such as dye lasers, whereas Rayleigh scattering is more important in lasers with a long gain medium, such as doped fibre lasers,
or the Ti:sapphire laser. The highest sensitivity so far has been obtained with a cw dye laser. It corresponds to 70000 km
effective length of the absorption path. The ultimate spectral resolution is determined by the spectral width of mode emission,
which is 0.7 Hz in this dye laser. High sensitivity and high temporal and spectral resolution allow various practical applications
of laser intracavity spectroscopy, such as measurements and simulations of atmospheric absorption, molecular and atomic spectroscopy,
process control, isotope separation, study of free radicals and chemical reactions, combustion diagnostics, spectroscopy of
excited states and nonlinear processes, measurements of gain and of spectrally narrow light emission. Intracavity absorption
in single-mode lasers shows enhanced sensitivity as well, although not as high as in multimode lasers.
Received: 10 May 1999 / Published online: 29 July 1999 相似文献
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The aim of the current study is to simulate the laser photon through biological tissue during PDT therapy using Monte Carlo
simulation technique. The model is coded using MATLAB. Interaction of laser light with turbid medium e.g. human tissue depends
on the optical properties of the medium i.e. refractive index n, absorption coefficient μ
a
, scattering coefficient μ
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and anisotropy factor g. Laser light transport through tissue is governed by the radiative transport equations based on absorption and scattering.
Direct sampling is used for step-size generation before interaction via absorption or scattering with the transmitting medium,
for deflection and azimuthal angle (θ and ϕ) when the scattering even occurs. The tissue medium considered is divided into
radial, axial and angular grid elements and an infinite narrow beam with normal incidence on the tissue is considered. The
laser light absorbance inside the tissue, reflectance at the top boundary of the tissue and transmittance at the bottom are
estimated and these quantities are shown varying radially and angularly. Results of reflectance, transmittance and fluence
are compared with the already published results to confirm the authenticity of our coding and these results are found to lie
at only 3–4% error. 相似文献
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D.A. Zimnyakov E.A. Isaeva A.A. Isaeva M.V. Pavlova A.P. Sviridov V.N. Bagratashvili 《Optics Communications》2012,285(9):2377-2381
The effect of competition of laser light absorption and scattering in dispersive media (1 μm polystyrene microspheres in ethylene glycol) with added dye (rhodamine 6G) was studied under the condition of near-resonant absorption of probe light in the host medium (solution of rhodamine 6G in ethylene glycol). The parameters of speckle modulation of transmitted light (the average speckle intensity and the oscillation index) were applied for characterization of light transport in the probed scattering systems as a function of dye concentration. The increase in dye concentration does not cause the expected decay in the transmittance of the examined dispersive systems for 532 nm laser light, but results in the decrease of their turbidity. This effect is accompanied by the rise of the average intensity and the oscillation index of speckle-modulated light, and can be rationalized by partial matching of the real parts of refractive indices for the host medium and embedded scatterers. This interpretation was supported by statistical modeling of light transport through the examined scattering systems. 相似文献
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A. Karabutov N. B. Podymova V. S. Letokhov 《Applied physics. B, Lasers and optics》1996,63(6):545-563
The methods of time-resolved laser optoacoustic tomography of inhomogeneous media and related problems are reviewed. Time-resolved laser optoacoustic tomography allows one to measure the distribution of light absorption in turbid media with depth resolution up to several microns in real time. The theory of laser excitation of acoustic waves by absorbing of light in particles, dispersed in transparent, light-absorbing or scattering media, is developed. The distribution of light absorption can be obtained from the temporal course of acoustic pressure. Two schemes of acoustic wave detection — in the medium under testing (direct detection) and in transparent medium, coupled to the investigated one (indirect detection) — are discussed. In both cases the reconstruction of light absorption can be made by simple calculations. Test experiments with homogeneous and layered media confirm the proposed theoretical models and the possibility of using the proposed experimental schemes. Light absorption in homogeneous, inhomogeneous media and in absorbing particles dispersed in turbid media was investigated. The experimental setup allows one to measure the absorption coefficients over the range 1-500 cm–1 with the depth resolution 10–15 m over the depth 1–1.5 mm. 相似文献
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We extended the range of operation of the CO2 laser pumped spin-flip Raman laser in n-InSb up to magnetic fields of 14 T. The laser at high fields is strongly influenced by optical phonons which interact resonantly with the electron spin system, and by intraband absorption of the Raman scattered light in the scattering medium. 相似文献