Under the framework of generalized Lorenz-Mie theory, we calculate the radiation force and torque exerted on a chiral sphere by a Gaussian beam. The theory and codes for axial radiation force are verified when the chiral sphere degenerates into an isotropic sphere. We discuss the influence of a chirality parameter on the radiation force and torque. Linearly and circularly polarized incident Gaussian beams are considered, and the corresponding radiation forces and torques are compared and analyzed. The polarization of the incident beam considerably influences radiation force of a chiral sphere. In trapping a chiral sphere, therefore, the polarization of incident beams should be chosen in accordance with the chirality. Unlike polarization, variation of chirality slightly affects radiation torque, except when the imaginary part of the chirality parameter is considered.

No abstract

Based on the scattering theory of a chiral sphere, rainbow phenomenon of a chiral sphere is numerically analyzed in this paper. For chiral spheres illuminated by a linearly polarized wave, there are three first-order rainbows, with whose rainbow angles varying with the chirality parameter. The spectrum of each rainbow structure is presented and the ripple frequencies are found associated with the size and refractive indices of the chiral sphere. Only two rainbow structures remain when the chiral sphere is illuminated by a circularly polarized plane wave. Finally, the rainbows of chiral spheres with slight chirality parameters are found appearing alternately in E-plane and H-plane with the variation of the chirality.

This paper considers the reflection and transmission characteristics of a Laguerre-Gaussian (LG) beam in a dielectric slab. The fields of the reflected and transmitted beams are described based on plane-wave angular spectrum representation. Using the generalized Fresnel amplitude reflectance and transmittance, the reflected and transmitted fields in each region are expressed. With the Taylor series approximation of reflectance and transmittance, the analytical expressions of the total reflected and transmitted fields in the input and output regions are derived. The effects of the beam-waist radius and topological charge on the reflected and transmitted field intensities are simulated and discussed in detail. The centroid shifts of the reflected beam are also presented. It is concluded that the distortion of the intensity distribution including the size of the intensity contour, is influenced by the beam-waist radius and the topological charge of the incident beam. The total intensity of the slab, in particular for the case of the transmitted field, is found to be distinguishable from the case of the single interface.

No abstract