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结合环形腔理论,运用蒙特卡罗法模拟了光子在介质中的随机行走。研究了倍频Nd:YAG(脉宽6 ns,频率20 Hz)脉冲激光器作为泵浦光,在TiO2 / 若丹明 B有机增益介质中,散射微粒的颗粒密度和泵浦光面积对随机激光器阈值强度的影响。模拟结果表明:随机激光阈值和光子在增益介质中的随机行走路程长度和光子通过边界返回增益区和非增益区的几率有关。随着泵浦光面积的增加,随机激光器阈值降低;增益介质中散射颗粒密度的增加降低了随机激光器的阈值。 相似文献
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基于非相干反馈随机激光器的扩散方程理论,将扩散方程中的增益项改写为饱和形式,并利用有限差分方法,研究了双光子抽运随机激光器中辐射光能量随时间演化特性.对扩散方程的数值求解给出了系统辐射光能量由自发辐射开始,经历小信号增益状态得到放大,再到由于增益饱和形成稳态输出的整个演化过程.表明介质的无序导致了在较低能量情况下也能获得饱和增益这样的非线性效应.结果为研究获得双光子抽运随机激光器的稳态输出提供了理论依据.
关键词:
随机激光器
双光子抽运
饱和效应
无序介质中的光学效应 相似文献
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实验观测了短腔染普激光器输出的多纵模激光及其经一级染料放大的激光光谱,比较了光谱特性。在一定情况下,短腔染料激光器的多纵模激光经放大器放大可产生一个至几个新纵模,新纵模与短腔染料激光器输出的纵模有相似的频率间隔、线宽及频率牵引等特征。新纵模产生属于三阶四光子混频(即四波混频)为主导的非线性光学效应。存在频率牵引表明,增益介质中的多波混频存在频率失配,在这一四波混凝中光子能量并不守恒。 相似文献
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实验观测了短腔染料激光器输出的多纵模激光及其经一级染料放大的激光光谱,比较了光谱特性。在一定情况下,短腔染料激光器的多纵模激光经放大器放大可产生一个至几个新纵模,新纵模与短腔染料激光器输出的纵模有相似的频率间隔、线宽及频率牵引等特征。新纵模产生属于三阶四光子混频(即四波混频)为主导的非线性光学效应。存在频率牵引表明,增益介质中的多波混频存在频率失配,在这一四波混频中光子能量并不守恒 相似文献
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激光器型全光波长转换器的小信号分析 总被引:2,自引:1,他引:1
当外部光子注入到激光器有源腔中时 ,载流子把被注入光子消耗的一部分放大 ,进而激光器自身的输出功率将降低。基于此 ,可以实现全光波长转换。理论上基于载流子消耗机制 ,对激光器型波长转换器进行了小信号分析 ,给出了频率响应函数。理论分析表明 ,激光器型全光波长转换器的转换速度取决于激光器光子寿命以及激光器腔内的光子密度。 相似文献
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利用有限元分析法结合Fox-Li迭代法,考虑腔内本征模式与腔镜热形变的相互耦合作用,计算模拟了正支共焦非稳腔的本征模式分布,定量分析了高功率激光器腔镜热变形对输出光束质量的影响,重点讨论了腔镜热变形所引起的腔内本征模式相位特性的变化,并从波前功率谱密度、Zernike像差系数及光束质量值等角度对腔镜发生热形变前后的激光器输出光束的光束特性进行比较分析。研究结果表明:高功率激光器腔镜热形变对输出光束的光束质量会产生一定的影响,且随着激光输出功率的增大,镜面热形变引起的输出光束波前相位高频比例及Zernike高阶像差均会有所增大,波前畸变程度也明显变大,光束质量逐渐变差。 相似文献
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Continuous wave operation of a dye laser pumped at 633 nm by a HeNe laser is reported. A jet of a cooled solution of Oxazine 1 in ethanol was used as the laser medium in an asymmetric spherical cavity. With mirrors of high reflectivity a threshold as low as 10 mW could be achieved. 相似文献
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报道了平面镜和自泵浦相位共轭镜反馈He-Ne激光器的非稳特性,观测了反馈镜位置对激光光强起伏及波动频率的影响,即在半腔长的整数倍附近,激光光强具有较大的起伏和秒量级的准周期振荡,并对其产生机理进行了分析。 相似文献
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N. N. Rosanov 《Optics and Spectroscopy》2008,105(3):466-477
Gaussian modes and pumping threshold values are found for a laser with spherical mirrors and angular selector. It is shown that, compared to the case of plane-parallel mirrors, the threshold overshoot is proportional to the square root of the mirror curvature. In the absence of the Kerr nonlinearity of the medium, exceeding the oscillation threshold of a stable cavity causes steady-state regimes to be established, whereas, for unstable cavities, pulsation regimes arise in a wide range of parameters. Calculations confirm the formation of moving localized structures in a laser with misaligned plane mirrors. 相似文献
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V. L. Kasyutich 《Applied physics. B, Lasers and optics》2009,96(1):141-148
Propagation of an elliptical Gaussian beam in a multiple-pass optical cell formed by two twisted cylindrical mirrors has been
described by means of complex curvature tensors. Using the ABCD tensor approach various light patterns were computed for the use in tunable laser absorption spectroscopy with a multiple-pass
optical cell. Light patterns with high beam-spot density can be also defined for a cavity formed by two twisted cylindrical
high-reflectivity mirrors. In order to achieve higher cavity output intensity, a high-reflectivity cylindrical mirror cavity
with at least one mirror that has a central transparent spot for laser beam injection has been described for applications
in non-resonant cavity enhanced absorption spectroscopy.
The author was with TDL Sensors Ltd., when the experimental part of this work was performed. 相似文献
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Random lasing in fully disordered systems having organic and inorganic nature has been the subject of extensive studies since the beginning of the past decade. The interest mainly emerges from the unexpected role played by disorder in the laser action. The disorder was considered detrimental for the optical feedback in cavity laser, until it was demonstrated that multiple-scattering materials including a gain medium act as random laser. Here, a completely new approach is reported, where freely suspended complex fluid films doped with fluorescent molecules under optical excitation generate narrowband lasing peaks. The constellation of localized modes is selected by properly choosing the gain profile. The idea to have laser action in absence of mirrors and boundaries realizes an unparalleled tunable and moldable laser source. 相似文献
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V. A. Lisinetskii D. N. Bus’ko R. V. Chulkov A. S. Grabchikov P. A. Apanasevich V. A. Orlovich 《Journal of Applied Spectroscopy》2008,75(2):300-307
We have studied the conditions resulting in maximum lowering of the excitation threshold for pulsed stimulated Raman (SRS)
lasers. It has been shown theoretically that in order to achieve the lowest possible values of laser radiation pulse energy
needed to excite lasing in SRS lasers, we need high reflection of the cavity mirrors and low losses at the wavelength of the
1st Stokes component, high reflection of the output mirror at the wavelength of the pump radiation, and also matching of the
confocal parameters for the exciting laser radiation and the cavity with each other and with the length of the Raman-active
medium. The experimentally achieved excitation threshold for an SRS laser based on a barium nitrate crystal was 6 μJ, which
quantitatively corresponds well to the calculation results. Lasing of up to five Stokes components simultaneously occurred.
The efficiency for conversion of the laser radiation to one component was as high as 39%.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 284–290, March–April, 2008. 相似文献