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Recent Advances in Moiré Superlattice Structures of Twisted Bilayer and Multilayer Graphene 下载免费PDF全文
Twisted bilayer graphene(TBG), which has drawn much attention in recent years, arises from van der Waals materials gathering each component together via van der Waals force. It is composed of two sheets of graphene rotated relatively to each other. Moiré potential, resulting from misorientation between layers, plays an essential role in determining the band structure of TBG, which directly relies on the twist angle. Once the twist angle approaches a certain critical value, flat bands will show u... 相似文献
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采用高斯分解法(GD)对大非线性相移下的Z扫描特性进行了分析,通过对数值算法的优化,将GD推广到对脉冲入射激光下大非线性相移下的Z扫描理论分析.对不同条件下大非线性相移Z扫描曲线峰谷结构的比较,发现在大非线性相移的情况下,Z扫描曲线的峰和谷随透过光阑或入射光强变化表现出某些新的特性.随着透过光阑孔径的增加,Z扫描曲线峰的变化要明显快于谷的变化,而且在谷明显存在的情况下,峰很快消失.采用皮秒脉冲激光下的纯二硫化碳实验对理论结果加以验证,实验结果和理论分析相一致.我们的分析结果对大非线性相移下Z扫描测量有一定的指导性意义,避免在大非线性相移下对Z扫描结果产生错误的分析.
关键词:
大非线性相移
高斯分解法
Z扫描 相似文献
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Optical nonlinearities of new organophosphorus fullerene derivative were determined by the Z-scan method with a pulsed Q-switch Nd:YAG laser at 532nm. The experimental results demonstrated that the derivative has much larger excited-states nonlinear absorption and nonlinear refraction than C60. A five-level model was utilized to fit the experimental data, and a good agreement is reached. Some parameters such as excited-state absorption cross and refraction cross were obtained. To our knowledge, the excited-state cross section of new organophosphorus fullerene derivative and its effective ratio to the ground-state cross section are the largest values among the fullerene derivatives reported to date. 相似文献
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采用高斯分解法(GD)对大非线性相移下的Z扫描特性进行了分析,通过对数值算法的优化,将GD推广到对脉冲入射激光下大非线性相移下的Z扫描理论分析.对不同条件下大非线性相移Z扫描曲线峰谷结构的比较,发现在大非线性相移的情况下,Z扫描曲线的峰和谷随透过光阑或入射光强变化表现出某些新的特性.随着透过光阑孔径的增加,Z扫描曲线峰的变化要明显快于谷的变化,而且在谷明显存在的情况下,峰很快消失.采用皮秒脉冲激光下的纯二硫化碳实验对理论结果加以验证,实验结果和理论分析相一致.我们的分析结果对大非线性相移下Z扫描测量有一定的指导性意义,避免在大非线性相移下对Z扫描结果产生错误的分析. 相似文献
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合成了meso-四(4-二茂铁甲酰氧基苯基)卟啉及其锌配合物.采用紫外-可见吸收光谱、稳态和时间分辨荧光光谱以及开孔Z-扫描等实验方法对其线性与非线性光学性质进行研究.结果表明二茂铁的引入对卟啉的吸收几乎未产生影响,但是却使卟啉的荧光发生了强烈的猝灭,荧光寿命缩短.说明在基态二茂铁与卟啉之间未发生作用,而在激发态发生了较强的电子和能量的传递.与相应的meso-四(4-苯甲酰氧基苯基)卟啉及其锌配合物相比,meso-四(4-二茂铁甲酰氧基苯基)卟啉及其锌配合物的反饱和吸收性能降低,但是非线性光学性质仍然优于性能优良的富勒烯C60. 相似文献
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Effect of coupling between linear absorption and nonlinear absorption on Z-scan measurements 下载免费PDF全文
The contribution of multiphoton absorption to open-aperture Z-scan measurements is analysed by coordinate transformation. The approximate closed-form solution is obtained, which is suitable for application in higher-optical power regime. As an example, the coupling between linear absorption and two-photon absorption is discussed in detail. 相似文献
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在纳秒时域,研究了激光脉冲宽度变化对克尔介质中瞬态热光非 线性效应的影响.通过不同脉冲宽度τp下得到的二硫化碳 苯胺黑溶液的Z_scan实验结果,对瞬态热光非线性效应和光克尔效应的共存过程进行了分析 .随着脉冲宽度的增加,观察到了热光非线性效应从瞬态到稳态变化过程和Z_scan峰谷特性 的转变.同时,从声波的传播方程和光波的非线性传播方程出发,用数值计算方法模拟了这 一非线性过程,结果表明数值模拟结果和实验结果是相符的.
关键词:
瞬态热光非线性效应
脉冲宽度
Z_scan
克尔效应 相似文献