Broadband multifunctional metasurfaces for concentric perfect vortex beam generation via trigonometric functions

Metasurfaces are engineered structures that offer an unprecedented nanoscale solution for precisely manipulating light’s magnitude, phase, and polarization, exhibiting the potential to reduce the size of optical configurations significantly. However, these structures often encounter performance limitations and are typically operational for a single design wavelength. Integrating multiple optical functionalities into a single-layered structure and achieving a highly efficient broadband response is an active metasurface research topic. In this study, we showcased a single-cell driven broadband metasurface capable of generating concentric perfect vortex (PV) beams, where each PV beam is realized by multiplexing the phase profiles of multiple optical components and trigonometric phase features to achieve infinite topological charges. The proposed all-silicon metasurface demonstrates broadband functionality in “E” and “S” optical communication bands spanning from 1460 nm to 1565 nm, covering critical telecom wavelengths, and this characteristic facilitates seamless integration of our work with the existing ecosystem. Our multifunctional approach prioritizes simplicity that yields maximum polarization conversion efficiency and produces different outcomes for different handedness of incident light without introducing complexity. To prove the concept, we numerically simulated multiple metasurfaces for different trigonometric functions, with periods of axicon of 4 µm and 6 µm. The results indicate that this work will pave the way for diverse applications like optical trapping, particle manipulation, quantum processing, optical communication, and high-capacity information processing.