Analysis of the Substrate Effect on the Zero-Backward Scattering Condition of a Cu₂O Nanoparticle under Non-Normal Illumination

Substrate-Modulated Electric and Magnetic Resonances of Lithium Niobite Nanoparticles Illuminated by White Light

The manipulation of light at the nanoscale is important for nanophotonic research. Lithium niobite (LiNbO₃), as an ideal building block for metamaterials, has attracted great interest for its unique properties in the field of nonlinear optics. In this paper, we numerically studied the effect of different substrates on the optical resonances of a LiNbO₃ nanoparticle. The results show that the electric and magnetic resonances of such a system can be effectively adjusted by changing the substrate. Compared to the impact of dielectric substrate, the interaction between the LiNbO₃ nanoparticle and the Au film shows a fascinating phenomenon that a sharp resonance peak appears. The multipole decomposition of the scattering spectrum shows that the size, shape of the LiNbO₃ nanoparticle, and the thickness of the SiO₂ film between the particle and the Au film have a significant impact on the electromagnetic resonance of the LiNbO₃ nanoparticle. This work provides a new insight into LiNbO₃ nanoparticles, which may have potential use in the design of dielectric nanomaterials and devices.

Scattering by a chiral sphere above a half-space

Scattering from a chiral sphere above a lossy half-space, which could be of interest in remote sensing and optics, is analytically examined. The proposed method combines the vector Mie solution and the field transformations between vector spherical functions (VSFs) and plane waves (PWs). Using the reflection coefficients of the half-space and vector Mie solution for the chiral sphere, the first-order Mie field together with a relation between the Mie fields of successive orders are derived. The total Mie field is obtained as a series solution which is next converted to a non-recursive formulation. The scattered field is written as the sum of the total Mie field and its reflection from the half-space. The derived expressions are numerically validated. Some explanations based on the series solution are given and numerical results for different cases are presented and briefly discussed.

Kerker Conditions upon Lossless, Absorption, and Optical Gain Regimes

The directionality and polarization of light show peculiar properties when the scattering by a dielectric sphere can be described exclusively by electric and magnetic dipolar modes. Particularly, when these modes oscillate in phase with equal amplitude, at the so-called first Kerker condition, the zero optical backscattering condition emerges for nondissipating spheres. However, the role of absorption and optical gain in the first Kerker condition remains unexplored. In this work, we demonstrate that either absorption or optical gain precludes the first Kerker condition and, hence, the absence of backscattered radiation light, regardless of the particle's size, incident wavelength, and incoming polarization. Finally, we derive the necessary prerequisites of the second Kerker condition of the zero forward light scattering, finding that optical gain is a compulsory requirement.