共查询到15条相似文献,搜索用时 62 毫秒
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研究非稀释极限下带壳的球形颗粒复合介质体系光学双稳的温度效应.其中带壳颗粒是由具有线性响应的核和非线性响应的壳层组成.由于复合体系中的空间局域场是不均匀的,所以应用自洽平均场理论,解析推导核内电场平方的空间平均值与外电场的关系表达式,并对不同温度及不同结构参数下的光学双稳进行了数值计算.结果表明,双稳与温度T、结构参数k和体积分数f有关.在k和f一定时,随温度的升高,双稳效应因上阈值减小、下阈值增大而逐渐减弱,直至双稳消失;在T和f一定时,随结构参数的增大,上、下阈值都增大,而上阈值的增速较大从而导致双稳区域宽度加大.
关键词:
带壳颗粒
复合介质
光学双稳
温度效应 相似文献
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重点研究了组分的梯度构形对带壳球形颗粒复合介质的光学双稳特性的影响.其中球形颗粒是由非线性核和介电函数具有梯度分布的线性壳组成.对于壳层介电函数具有幂指数分布的情况,通过求解麦克斯韦方程,得到各区域的势能分布函数,从而求得核内电场的数学表达式.数值研究发现,该复合介质的光学双稳阈值和区域与壳层的厚度及壳层的介电幂指数有关,随着壳层厚度增大或幂指数增大,双稳阈值将变宽.此外,还研究了正入射情况下复合材料体系的反射系数随外电场的变化情况, 发现其关系曲线是一条回线.
关键词:
梯度颗粒
复合介质
光学双稳 相似文献
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利用Maxwell-Garnett近似,并结合谱表示方法,理论研究了具有一般非线性的绝缘颗粒,无规则浸入液体主体基质复合体系的非线性光学性质-在弱非线性条件下,数值研究了体系的有效线性介电函数和光学非线性随体积分数的变化,并发现体系的线性介电函数比光学非线性更依赖于绝缘颗粒组分的体积分数-在一般非线性条件下,研究体系的有效介电函数随入射光强度的依赖关系,还研究了s方向和p方向极化的总反射率的行为-
关键词:
复合介质
谱表示
非线性光学性质 相似文献
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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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本文简述光学双稳性理论和光学非线性机制的研究情况,介绍探索高速度、低功耗和集成化光双稳器件的新进展。重点介绍砷化镓量子阱双稳器件的新发展。 相似文献
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推拉型偶氮化合物的三阶非线性和光学双稳效应 总被引:9,自引:0,他引:9
本文报道从推拉型偶氮化合物中测得了非常高的三阶非线性极化率,X~(3)~6×10~(→3)esu.这对于引起光学双稳现象是至关重要的.利用波长为488nm的氩离子激光为光源,从这类材料掺杂的玻璃态聚合物薄膜的Kretschmann型态中,进一步观察到了光学双稳现象.与此同时,联系这类材料的顺反异构化反应历程,从电子吸收机制或光诱导的折射率变化机制对有关问题进行了讨论. 相似文献
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It is shown that the local field in metal spherical particles with a dielectric core in an external varying electric field has two maxima at two different frequencies. The second maximum becomes more important with an increment in the metal fraction. Due to the nonlinear dielectric function of the core, the composite of these inclusions may have two optically induced bistability domains at different frequencies. At rather high metal fraction, two bistability domains merge and form one entire bistability domain. The parameters of these domains are studied numerically. The paper focuses on the second bistability domain, which has not been discussed in the literature so far. This domain exists in a comparatively narrow frequency range and its onset fields are lower than those of the first bistability domain. The lowest bistability onset fields are obtained in the entire domain. This peculiarity of the optical induced bistability in the metal composite with small dielectric cores can be attractive for possible applications. 相似文献
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We study theoretically a nonlinear response of the planar metal/dielectric nanostructures constituted from periodical array
of ultra thin silver layers and the layers of Kerr-like nonlinear dielectric. We predict hysteresis-type dependences of the
components of the tensor of effective dielectric permittivity on the field intensity allowing the change in material transmission
properties from transparent to opaque and back at extremely low intensities of the light. It makes possible to control the
light by light in all-optical nanoscale devices and circuits. 相似文献
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非线性介质光波导中的传输功率和光学双稳态 总被引:1,自引:0,他引:1
本文对结构为非线性包层/线性芯层/非线性衬底的非线性介质光波导的传输特性进行了深入的分析,给出了模场分布函数,色散关系和传输功率的一组形式统一的公式,并对其传输功率的光学双稳态特性进行了讨论. 相似文献
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We study third harmonic generation in layered configuration when the fundamental exhibits bistable response. We consider two
geometries, namely, a Fabry-Perot cavity with reflection coatings and a distributed feedback structure with alternate nonlinear
layers. In both the cases for suitable choice of frequency, the power response at the fundamental frequency is bistable. We
show that bistability of the fundamental leads to a multivalued character of the generated third harmonic in both the forward
and backward directions. Moreover, we study frequency response in the case of the Fabry-Perot cavity and show that additional
structures arise in the generated third harmonic due to frequency bistability of the fundamental. Our calculations suggest
the possibility of an all optical switch at third harmonic frequency controlled by the parameters (like intensity, frequency)
of the fundamental. 相似文献