Kiselev A D, Reshetnyak V Yu, Sluckin T J
Chernigov State Technological University, Shevchenko Street 95, 14027 Chernigov, Ukraine.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 May;65(5 Pt 2):056609. doi: 10.1103/PhysRevE.65.056609. Epub 2002 May 3.
We extend the T-matrix approach to light scattering by spherical particles to some simple cases in which the scatterers are optically anisotropic. Specifically, we consider cases in which the spherical particles include radially and uniformly anisotropic layers. We find that in both cases the T-matrix theory can be formulated using a modified T-matrix ansatz with suitably defined modes. In a uniformly anisotropic medium we derive these modes by relating the wave packet representation and expansions of electromagnetic field over spherical harmonics. The resulting wave functions are deformed spherical harmonics that represent solutions of the Maxwell equations. We present preliminary results of numerical calculations of the scattering by spherical droplets. We concentrate on cases in which the scattering is due only to the local optical anisotropy within the scatterer. For radial anisotropy we find that nonmonotonic dependence of the scattering cross section on the degree of anisotropy can occur in a regime to which both the Rayleigh and semiclassical theories are inapplicable. For uniform anisotropy the cross section is strongly dependent on the angle between the incident light and the optical axis, and for larger droplets this dependence is nonmonotonic.
我们将球形粒子光散射的T矩阵方法扩展到一些简单情形，即散射体具有光学各向异性。具体而言，我们考虑球形粒子包含径向且均匀各向异性层的情形。我们发现，在这两种情形下，T矩阵理论都可以通过使用具有适当定义模式的修正T矩阵假设来构建。在均匀各向异性介质中，我们通过关联波包表示和电磁场在球谐函数上的展开来推导这些模式。所得的波函数是变形的球谐函数，代表麦克斯韦方程组的解。我们给出了球形液滴散射数值计算的初步结果。我们专注于散射仅由散射体内局部光学各向异性引起的情形。对于径向各向异性，我们发现在瑞利理论和半经典理论均不适用的区域，散射截面与各向异性程度之间可能存在非单调依赖关系。对于均匀各向异性，截面强烈依赖于入射光与光轴之间的夹角，对于较大的液滴，这种依赖关系是非单调的。
