Dielectric metalenses with off-axis and multi-focal spots based on converging Airy beams with different initial velocities or accelerations

Abstract

In the context of light focusing, converging Airy beams play an essential role. The two Airy beams that are commonly used in the literature for autofocusing of the Airy beams are mirror-symmetric. In this paper, we consider the two converging Airy beams to have different values of accelerations or initial velocities, the subject that up to our knowledge has not been studied before. To explore the effect of applying Airy beams with different initial velocities or accelerations, we apply the required phase and amplitude of the two launched Airy beams to a one-dimensional arrangement of dielectric c-shaped metaatoms. Silicon c-shaped metaatoms give us the opportunity of having full control of the phase and amplitude of the incident 700 nm light. Simulation results demonstrate that convergence of the two Airy beams with various values of initial velocities or accelerations causes the focal spot to deviate from the optical axis. The extent to which the focal spot deviates from the main axis depends strongly on the initial parameters of the included Airy beams. The focal spot coordinates that are achieved from the simulation results are well agreed with the analytical calculations that we also provided. Using the inutile space between the two launched Airy beams as an independent hyperbolic metalens, gives us the opportunity of designing a multi-focal metadevice with different off-axis and on-axis focal spot arrangements.