共查询到18条相似文献,搜索用时 406 毫秒
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推广T矩阵法来研究二组分颗粒复合介质的非线性交流响应,解析推导出基频、三次及五次谐波频率下的有效线性介电常数及三阶和五阶非线性极化率的解析表达式.当组分颗粒的介电常数为实数时,表达式同以前微扰理论完全一致.进一步数值计算了金属-电介质复合介质的有效非线性交流响应,数值结果表明,体系的三阶、五阶非线性极化率在表面等离子共振频率附近有明显增强,而且,随着体积分数提高,共振峰增强且伴随着共振频率红移现象.还进一步讨论了维度效应对体系非线性交流响应的影响.
关键词:
T矩阵方法
复合介质
非线性交流响应 相似文献
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以菲涅耳-基尔霍夫衍射理论为基础,对通过非线性介质的高斯光束传输行为进行理论分析,分别给出了强吸收、无吸收情况下开孔、闭孔Z扫描曲线公式;对不同条件下非线性介质的归一化透过率进行数值模拟计算,发现Z扫描曲线透射峰和透射谷表现出3种新的特性:随着入射激光峰值光强的增加,Z扫描曲线透射峰的高度受到抑制,而透射谷则加强变得更深;非线性相移的增加对Z扫描曲线透射峰和透射谷均有增高和加深的作用;激光束束腰半径越大,Z扫描曲线的峰谷特征越明显。 相似文献
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基于Drude模型研究了异向介质的色散磁导率对调制不稳定性的影响. 结果表明,在反常色散情形,赝五阶非线性在异向介质的负折射区中增大了调制频谱的范围及增益值,这与常规正折射介质中出现的现象正好相反;自陡峭效应在异向介质中有可能为负值,但无论正负,也无论在正折射区还是负折射区,它都抑制调制不稳定性的产生;二阶非线性色散效应在正、负折射区中分别促进和抑制调制不稳定性的产生. 在正常色散情形,由于二阶非线性色散效应的作用,使本来在常规正折射介质中不可能出现的调制不稳定性现象也能出现,这一特性为在正常色散区形成孤 相似文献
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采用高斯分解法,分析并讨论了非局域非线性介质的Z扫描特性.基于介质的非线性响应函数为高斯型,给出了用于确定非局域非线性介质的非线性折射率系数的透过率表达式,分析了非局域非线性介质的非局域程度对透过率曲线的影响,得到了计算非局域非线性介质的非线性折射率系数以及非局域程度的方法,讨论了由于非局域性条件所带来的对实验上的一些参数的调整,提出了测量介质非局域程度的可行的实验方法并说明了其他注意事项.同时还数值模拟了在介质的响应函数为双曲正割型情况下通过薄样品的远场Z扫描曲线,并与高斯响应情况下的结果进行了比较. 相似文献
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Through analysis of the dispersion relation in a photonic bandgap structure, the effective optical Kerr nonlinearity that determines a Z-scan profile particularly near the stop-band edges, is derived. Near and inside the stop band, the nonlinear optical phase change that originates from an off-resonant response is converted into a change in nonlinear optical intensity through Bragg reflection. The Z-scan measurement of a cholesteric liquid-crystal photonic bandgap structure confirmed that off-resonant Kerr nonlinearity is responsible for the characteristic open-aperture Z-scan profiles near the stop-band edges. 相似文献
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当考虑到五阶非线性对光脉冲传输的影响时, 光纤中类明孤子的传输服从含五阶非线性修正项的非线性Schrdinger方程。利用何氏半反推法建立该类明孤子运动方程的变分形式, 然后应用何氏变分法导出该方程基态孤子解的双曲正割表达式。同时, 受何氏指数函数方法的启发, 建立了一种新的高斯表达式。一方面, 基于得到的显式表达式相关学者可进一步研究五阶非线性对光脉冲传输的影响。另一方面, 该求解过程也进一步显示了用何氏变分法求解数学物理中非线性发展方程的简洁有效性。 相似文献
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Nonlinear responses and optical limiting behavior of Basic Violet 16 dye under CW laser illumination
Nonlinear optical properties of Basic Violet 16 dye solution in water are studied employing different optical techniques. Experiments are performed using the second harmonic of a continuous Nd-Yag laser beam at 532 nm wavelength and 100 mW power. The effect of nonlinearity of Basic Violet 16 dye in broadening the laser beam is observed. The optical limiting behavior is investigated by measuring the transmission of the samples. The third-order nonlinearity, χ3 of Basic Violet 16 dye, is measured using Z-scan data. The nonlinear absorption coefficient is calculated using the open aperture Z-scan data, while its nonlinear refractive index is measured using the closed aperture Z-scan data. All experiments are done for different concentrations and thicknesses of Basic Violet 16 dye solution. The effect of intensity of input laser beam on the nonlinear susceptibility is studied experimentally. Results indicate that Basic Violet 16 dye is a potential candidate for low-power optical limiting applications. 相似文献
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Multiwalled carbon nanotubes and BaTiO3 composite films have been prepared by
pulsed-laser deposition technique at room temperature and high temperature of
600℃, separately. The structures of the composite films are investigated by
using scanning electron microscopy and x-ray diffraction. The optical behaviours of
the samples produced at different temperatures are compared with Raman spectroscopy,
and UV-visible absorption. And the observation by Z-scan technique reveals that
the composite films have a larger optical nonlinearity, and the samples prepared at
high temperatures have better transmittance and opposite sign imaginary part of
optical third-order nonlinearity. 相似文献
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光孤子传输中的高阶色散以及高次非线性效应是光纤通讯发展的重要制约因素。从光孤子在光纤中的一般传输方程出发, 在较大的入纤功率的前提下, 综合考虑了高阶色散、五次非线性和损耗因素, 得到其具体传输方程, 并据此从理论上分析了高阶色散和非线性对光孤子传输性能的影响。本文采用分步傅里叶方法, 以MATLAB为实现工具, 实现高阶色散和非线性对光孤子传输影响的模拟计算, 并深入分析了高阶色散和非线性导致的孤子脉冲频移现象。计算结果表明: 在入射功率较大的时候, 高阶色散效应不可忽略。当五次非线性γ2>0时,孤子脉冲主峰发生微小频移; 而当五次非线性γ2<0时, 孤子脉冲主峰基座产生微小频移; 当高阶色散β3>0时频率出现红移, 而当β3<0时, 频率出现蓝移。 相似文献
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Kartashov D Ališauskas S Pugžlys A Voronin AA Zheltikov AM Baltuška A 《Optics letters》2012,37(12):2268-2270
Third- and fifth-harmonic generation by ultrashort laser pulses in the mid-infrared (mid-IR) reveals nonlinear-optical effects beyond the fifth-order nonlinearity and enables, because of an extraordinarily long coherence length, efficient multiplex frequency upconversion of ultrashort mid-IR pulses. We show that harmonic generation by mid-IR pulses provides an access to the key optical constants of gas media, allowing metrology of linear and nonlinear-optical susceptibilities in the mid-IR and offering a tool for the remote sensing of the atmosphere. 相似文献
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用变分法研究高阶色散和五阶非线性对高斯脉冲在光纤中传输特性的影响 总被引:10,自引:1,他引:9
从修正的非线性薛定谔方程出发,采用变分法,导出了在高阶色散和五阶非线性共同作用情况下高斯型脉冲参量随传输距离的演化方程组;求出了振幅与脉宽、频率与啁啾、脉宽与啁啾之间的三个重要约束关系;并进一步得出了脉宽随传输距离演化的解析解和脉冲中心位置随传输距离的演化规律;描绘了高阶色散和五阶非线性下,脉宽随传输距离演化的图形.结果表明:光纤中的高阶色散和五阶非线性都会影响高斯型脉冲各个参量的演化,但脉宽和振幅间的绝热关系并未改变.高阶色散使高斯型脉冲的脉宽展宽,五阶非线性使高斯型脉冲的脉宽压缩,它们对脉宽或初始啁啾的影响可以在一定程度上抵消,从而有可能使脉冲近似实现保形传输. 相似文献