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稠环芳烃有机物的三阶非线性光学性能研究 总被引:1,自引:0,他引:1
采用Nd:YAG皮秒锁模脉冲激光λ=532.0nm,运用3D前向简并四波混频(DFWM)的方法,测量了稠环芳烃中的1.2.5.6二苯并蒽(C22H14),1.2.8.9.二苯并五苯(C30H18)的三阶非线性极化率X^(3),非线性折射系数n2以及三阶非线性的时间响应。发现该类材料具有较大的非线性效应,文中分析了非线性形成机制以及相关的影响因素。 相似文献
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分布反馈激光器中剩余法布里-珀罗腔模对非简并四波混频特性的影响 总被引:2,自引:0,他引:2
基于四波混频(FWM)的全光波长转换技术是未来多波长通信系统的核心技术之一。除半导体光放大器(SOA)外,半导体激光器也是进行波长变换的器件。实验研究了小频率失谐到大频率失谐下分布反馈(DFB)激光器中剩余法布里珀罗腔模对非简并四波混频(NDFWM)的影响,并对其四波混频转换效率进行了分析。结果表明:当探测光波长与法布里珀罗腔的某一谐振波长一致时,分布反馈激光器中的四波混频转换效率将得到显著的增强;当频率失谐为太赫兹时,仍可得到较高的四波混频转换效率。 相似文献
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采用可以减小纤芯面积的小气孔设计方案巧妙设计并成功拉制了一根高非线性的单零色散微结构光纤.利用有限元法模拟并计算得到了该光纤的基模有效折射率、色散系数和非线性系数等基本属性随波长的变化关系,然后利用四波混频的有效相位失配方程模拟了其相位失配曲线.模拟表明,在该光纤中可以同时发生两组四波混频.在位于微结构光纤的正常色散区的0.800,0.810和0.820μm三个波长处,分别采用不同的功率抽运,在实验上都非常明显地观察到了分列于抽运波长两侧的四个增益波带的产生.经与相位失配曲线比较,发现它们满足相位匹配条件,从而证明了两组四波混频过程的同时发生.实验结果与理论预言符合得很好.发生在正常色散区的四波混频效应的产生可归结于负的四阶色散对相位匹配过程的贡献.本文研究可对微结构光纤的结构设计和基于四波混频的多波长转移技术的发展提供经验与借鉴,同时也对非常见波段激光器和宽带光源的开发具有参考意义. 相似文献
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利用高非线性光纤中的交叉相位调制和四波混频分别在仿真中实现了时间透镜. 对基于交叉相位调制的时间透镜中的高非线性光纤中的非线性过程进行了仿真分析. 仿真结果表明, 该时间透镜的主要影响因素为色散、自相位调制与四波混频; 通过采用带有一定色散斜率的高非线性光纤可同时消除色散、自相位调制和四波混频的影响; 另外, 该高非线性光纤的色散零点最好选在信号脉冲和抽运脉冲波长的中心附近. 然后对基于四波混频的时间透镜的实现进行了仿真分析. 仿真结果表明, 该时间透镜的主要影响因素为色散、 自相位调制和其他的四波混频; 通过设定合适大小的信号脉冲和抽运脉冲的功率可消除自相位调制和其他的四波混频的影响; 另外, 通过在高非线性光纤中引入一定的色散可进一步提高信号脉冲和抽运脉冲的功率, 从而获得更高功率的输出脉冲. 最后对两种时间透镜系统做出了比较.
关键词:
光脉冲压缩
时间透镜
交叉相位调制
四波混频 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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In this work, the split-step Fourier method for beam propagation is used to investigate the interaction of ultra-short pulses with epsilon-near-zero materials. The propagation of pulses is governed by the nonlinear Schrödinger equation (NLSE) containing dispersion, gain-bandwidth, self-phase modulation, self-steepening, and absorption parameters. It is found that the intensity profile of the pulse is broadened and the phase of the pulse is shifted by dispersion phenomena. The gain/loss related to the imaginary part of the refractive index causes an increase or decrease in intensity and pulse edge effects. These effects do not favor the steady propagation of the pulse. The self-phase modulation is not noted to appreciably affect the intensity pulse profile. The self-steepening modifies the phase and energy of the pulse during propagation, as well as absorption, which influences the losses by both the linear and nonlinear effects. 相似文献
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P. A. Apanasevich A. A. Afanas'ev V. V. Dritz B. A. Samson 《Optical and Quantum Electronics》1986,18(2):129-135
Forward four-wave mixing (FFWM) of ultrashort light pulses is considered theoretically under their coherent propagation in a resonant-absorbing medium. Nonlinear equations describing FFWM are obtained and studied and it is shown that the energy exchange between pulses of exact resonance may lead to the enhancement of weak radiation. The influence of input radiation parameters and interaction geometry on the FFWM characteristics has been studied. 相似文献
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In this paper, we have analyzed the influences of non-linear refractive index on the four-wave mixing (FWM) characteristics in semiconductor optical amplifiers (SOAs). It has been shown that the generated FWM signal characteristics can be modified due to the variation of non-linear refractive index of the SOA's medium. The wave propagation in the SOA has been modeled using the nonlinear propagation equation taking into account gain spectrum dynamics, gain saturation, which depends on carrier depletion, carrier heating, spectral hole-burning, group velocity dispersion, self-phase modulation and two photon absorption. Simulation of optical wave evolution in the SOA has been carried out using the finite-difference beam propagation method (FD-BPM) both in time and spectral domains. Our simulation results confirm that higher FWM conversion efficiency and lower time bandwidth product are achieved for higher absolute values of non-linear refractive index. Moreover, non-linear refractive index is more efficacious for high power propagated waves in SOAs. Finally, we have studied the modification of waveguide refractive index due to the propagation of optical pulses. We have also shown that when |n2|=1 cm2/TW, refractive index variation is in the order of 10?4 to 10?7 for high and low power input pulses, respectively. 相似文献
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Based on the coupled-mode theory, the propagation of light pulses is studied analytically for a system of an infinite number of tunnel-coupled parallel equidistant waveguides of optically nonlinear materials; in the considered system, waveguides with a positive refractive index alternate with waveguides with a negative refractive index. Partial solutions to a system of nonlinear equations describing the evolution of these pulses are found in the case in which fields in adjacent waveguides differ only in the phase factor. For a solitary wave formed by coupled wave packets localized each in its own waveguide, these solutions describe the stationary propagation in a definite direction. It is shown that the coupling strength between waveguides has an effect on the propagation rate of the obtained stationary pulses. 相似文献
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G. Brida M. Genovese M. G. A. Paris F. Piacentini E. Predazzi E. Vallauri 《Optics and Spectroscopy》2007,102(1):90-97
The propagation of pulses of the pump and its second harmonic in a quadratically nonlinear medium whose linear properties are characterized by a negative refractive index at the pump frequency and by a positive refractive index at the harmonic frequency is considered theoretically. In the case of a low intensity of the interacting waves, the pump and second-harmonic pulses propagate in the opposite directions, but sufficiently powerful pulses can form a simulton—a solitary two-frequency wave propagating in a certain direction as a single whole. Solutions to a set of equations are found which describe the steady-state propagation of a solitary wave and of a nonlinear periodic (cnoidal) wave. 相似文献
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An analysis is presented of passive locking of modes in lasers with an additional intracavity element that limits the spectral width of a laser emission due to frequency dispersion of an order higher than quadratic. It is found that spectral limitation of this type may give rise to a multiple-pulse regime of passive mode-locking. The laser mode of operation established after a transient process, in this case, appears to be multistable, with the number of pulses per axial period being dependent on the initial conditions of the lasing. It is shown that the dependence of the number of pulses on the pump power is of hysteretic character. The theoretical analysis and numerical simulation are carried out using an equation close to the Ginzburg-Landau equation. Specifically, the nonlinear losses and nonlinear refractive index are supposed to be inertia-less and proportional to the light intensity; the frequency dispersion of the gain and the refractive index are approximated by a quadratic dependence; and the frequency-dependent losses related to the additional spectral limitation of the laser emission are determined by fourth-order frequency dispersion. The possibility of using the characteristic features of mode-locking predicted for control of regimes of formation and propagation of ultrashort light pulses is discussed. 相似文献
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《Optics Communications》1987,62(6):374-379
We experimentally observed transmission of “negative pulses” through a single mode optical fiber in conditions where self-phase modulation, due to self induced variations of silica refractive index, may be balanced by the positive group velocity dispersion (dVg/dδ#62;0). Soliton propagation could be expected at power levels where exact compensation of these two distorsions arises. The duration of the output dark pulses, determined by SHG correlation techniques, decreases when the launched power is increased, as predicted by computer simulation. For an input peak power of 0.2 W, corresponding to the theoretical soliton peak power, the emerging dark pulse looks like the input one. 相似文献
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高功率脉冲在大模场掺Yb3+光纤中的自相似传输放大特性 总被引:1,自引:1,他引:0
分析了高功率脉冲在增益光纤中传输放大时非线性薛定谔方程的自相似解,得出注入光的脉宽和能量满足一定关系时,优化增益光纤的长度,才能满足种子光脉冲在增益光纤中的自相似传输放大.揭示了高功率种子光脉冲在光纤中自相似演化的特征参量.此外,模拟了注入能量为400 pJ,脉宽为200 fs,波形分别为正割、高斯以及3阶超高斯的种子光脉冲在纤芯为30μm的大模场增益光纤中的传输放大特性.结果表明3种波形的种子光脉冲的时间波形与光谱均演化为抛物形,时间波形与光谱均发生展宽,但光谱两侧均发生抖动.自相似传输放大后,脉冲为线性啁啾,易于压缩,对实现全光纤高功率超短脉冲产生系统具有重要意义. 相似文献
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Streak formation as side effect of optical breakdown during processing the bulk of transparent Kerr media with ultra-short laser pulses 总被引:2,自引:0,他引:2
C.L. Arnold A. Heisterkamp W. Ertmer H. Lubatschowski 《Applied physics. B, Lasers and optics》2005,80(2):247-253
Femtosecond lasers have been successfully used to perform refractive surgery, by cutting within the bulk of the corneal tissue. As a side effect to the laser cutting there, a streak-like discoloration is observed in histological sections above and below the cutting plane, incident with the direction of laser propagation. These streak-shaped alterations of tissue are believed to originate from low free-electron densities not sufficient to cause optical breakdown. To understand the generation of the streaks, the nonlinear interaction of ultra-short laser pulses with water, as an approximation to corneal tissue, is simulated numerically using a model that simultaneously describes both the nonlinear pulse propagation and the generation of free electrons. The model is used to calculate spatial free electron density distributions generated by ultra-short pulses. Areas of high free-electron density correspond to optical breakdown, whereas areas of low density can be related to streaks. The numerical code can be adapted to practically any transparent dielectric Kerr medium, whose nonlinear optical parameters are known. PACS 72.20.Jv; 42.65.Jx; 42.65.Sf; 42.62.Be 相似文献