【摘要】 介绍了一种基于介观反射光谱分析的纳米尺度折射率波动表征的方法,揭示了介观反射光谱用于纳米尺度折射率波动表征的机理。采用时域有限差分方法,分析了光在一维折射率分布介质中的传播情况和光谱特征,并通过精确控制一维通道内部折射率波动的标准差和空间相关长度,定量分析了混乱度的仿真计算值及其与理论设置值的关系。结果表明,反射光谱对混乱度的变化是高度敏感的,一维光传输通道内纳米尺度上的折射率波动可以通过反射光谱来感知,且混乱度在一定近似条件下,随着折射率波动方差及其相关长度的增大而线性增大。该方法避开了远场光学衍射极限的限制,有望获得以往无法觉察的纳米尺度变化的统计信息。更多还原

【Abstract】 A method based on reflective mesoscopic spectroscopy for characterization of refractive-index fluctuations at nano-scale is introduced.Mechanism of mesoscopic spectroscopy for perceiving reflective-index fluctuations at length scale of nanometers is revealed.Based on simulation by finite difference time domain method,light propagation in one-dimensional refractive-index variable medium and resulting reflective spectral characteristics are analyzed.Through precise control of standard deviation and spatial correlation length of refractive-index fluctuations along one-dimensional channel,simulated disorder strengths and their relation to theoretical settings are quantitatively analyzed.Results show that reflective spectrum is highly sensitive to disorder strength and thus it is feasible for the refractive index fluctuations at nano-scale within one-dimensional channel to be perceived through reflective spectrum.Under certain approximating conditions,disorder strength is proportionally enlarged with increasing variance and spatial correlation length describing refractive-index fluctuations.The proposed method might be useful in probing statistical structural changes at nano-scale which are unperceivable up to now,and hence avoiding the limitation due to optical diffraction in far field.更多还原