Plane-wave scattering by asymmetric mesoscale semicylinder: controllable formation of multiple interrelated photonic nanojets

This work reveals new possibilities for creating controllable photonic nanojets (PNJs) and their complexes, “photonic multijets” (PMJs), characterized by the specific morphological and energy-concentrating properties. These specific light structures can be generated upon scattering a monochromatic plane wave by a mesoscale dielectric semicylinder (SC) with geometric asymmetry (its flat surface is inclined with respect to the incident wave). An output field in the form of PMJ unites several interrelated PNJs of comparable intensities. The main spatial features of the separate PNJs, produced in this process, and their interrelations, are investigated via computer modeling based on the COMSOL Multiphysics environment and finite-difference time-domain (FDTD) method. The number, positions, orientations and intensities of the PNJs depend on the SC size, orientation and dielectric parameters as well as on the exciting-light wavelength. The modeling results show the possibilities for purposeful creation and control of the PMJs with desirable characteristics. In particular, excitation by bi-chromatic light with two different wavelengths enables realization of a passive switching element capable of dynamically altering the electromagnetic field distribution depending on the irradiation spectrum. This can be used for creation of optical splitters and switching devices. Their potential characteristics are discussed as well as the prospects for experimental implementation and applications in optical signal-processing systems.