Analysis of specular resonance in dielectric bispheres using rigorous and geometrical-optics theories.
Analysis of specular resonance in dielectric bispheres using rigorous and geometrical-optics theories.
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使用严格的几何光学理论分析介电双球中的镜面共振。
DOI：
10.1364/josaa.20.001771
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
K. Miyano
中科院分区：
文献类型：
--
作者：
H. Miyazaki;H. Miyazaki;K. Miyano
我们最近已经确定了从介质双球体在镜面方向上的共振散射，这一直被称为镜面共振，是一种彩虹（焦散）和双球体的一般现象。在系统计算的基础上，我们讨论了镜面共振的细节。除了严格的理论，它精确地描述了散射，即使在共振区，射线跟踪方法，它给出了散射的几何光学限制，使用。镜面共振被明确地定义为从对称轴的双球面的镜面反射的方向上的强散射，其强度超过来自非相互作用的双球面的散射。然后指定用于计算特定镜面共振的参数范围。这种共振在宽范围的折射率（从1.2到2.2）中在宽范围的尺寸参数（从5到无穷大）中以及对于在与对称轴成40度的角度内入射的任意偏振光变得突出。这种特殊的散射即使在球体不接触或球体的大小不同时也可以保持明显。因此，镜面共振是介电双球体中一种常见且稳健的现象。此外，我们证明了从bispheres散射的各种特征可以成功地解释，通过使用直观和简单的表示。除了镜面共振之外，大多数重要的散射也可以理解为几何光学理论中的焦散。镜面共振在这些焦散中的最小尺寸参数处变得引人注目，因为其光学轨迹仅由表面处的折射组成，并且具有异常大的强度。然而，一些特性不能用几何光学来解释。特别是，它们的散射强度的振荡行为很好地描述了简单的两波干涉模型。
We have recently identified the resonant scattering from dielectric bispheres in the specular direction, which has long been known as the specular resonance, to be a type of rainbow (a caustic) and a general phenomenon for bispheres. We discuss the details of the specular resonance on the basis of systematic calculations. In addition to the rigorous theory, which precisely describes the scattering even in the resonance regime, the ray-tracing method, which gives the scattering in the geometrical-optics limit, is used. Specular resonance is explicitly defined as strong scattering in the direction of the specular reflection from the symmetrical axis of the bisphere whose intensity exceeds that of the scattering from noninteracting bispheres. Then the range of parameters for computing a particular specular resonance is specified. This resonance becomes prominent in a wide range of refractive indices (from 1.2 to 2.2) in a wide range of size parameters (from five to infinity) and for an arbitrarily polarized light incident within an angle of 40 degrees to the symmetrical axis. This particular scattering can stay evident even when the spheres are not in contact or the sizes of the spheres are different. Thus specular resonance is a common and robust phenomenon in dielectric bispheres. Furthermore, we demonstrate that various characteristic features in the scattering from bispheres can be explained successfully by using intuitive and simple representations. Most of the significant scatterings other than the specular resonance are also understandable as caustics in geometrical-optics theory. The specular resonance becomes striking at the smallest size parameter among these caustics because its optical trajectory is composed of only the refractions at the surfaces and has an exceptionally large intensity. However, some characteristics are not accounted for by geometrical optics. In particular, the oscillatory behaviors of their scattering intensity are well described by simple two-wave interference models.