Dynamic control of light scattering in a single particle enabled by time modulation

Abstract

The interaction of light with time-varying materials offers intriguing opportunities for controlling light scattering and wavefront manipulation, thereby unlocking fascinating applications in the realm of optics and photonics. In this study, we present an analytical solution for the scattering from a particle made of a material with time-varying permittivity by exploiting the T-matrix approach. Through the manipulation of the active medium's eigenvalues, we demonstrate the pivotal ability to regulate the elements of a dynamically controlled T-matrix, thus enabling precise control over the scattering characteristics of the particle. Crucially, this dynamic control is achieved without resorting to modifying the particle's inherent physical parameters, such as shape, size, and dispersion. We demonstrate that the eigenvalues of the dynamic material can be skillfully manipulated through the adequate choice of the particle's modulation function, resulting in either in-phase or out-of-phase interactions between the magnetic and electric dipole modes, allowing us to satisfy the Kerker conditions at diverse harmonics. The results of the optimal modulation functions are presented in both the near-field and far-field regions, revealing time modulation as a dynamic means of achieving unidirectional scattering. Our findings pave the way for developing time-varying structures comprising dynamic meta-atoms, offering valuable insight into advanced light–matter interactions, and providing lucrative guidance for future research in the realm of dynamic photonic systems.