Multilayered multifunctional metasurfaces for the generation and manipulation of highly structured vectorial beams

In recent years, research in optics and photonics produced many forms of structured light for different applications, such as optical trapping, telecommunication, and imaging. Generating such beams usually requires challenging control of phase, amplitude, and polarization, and often more than one phase plate is needed. Mounting such optical elements leads to lengthy alignment procedures, worsened by tight tolerances and complex beam shapes. Here we present a method for fabricating two aligned metalenses on the two surfaces of a substrate, halving therefore the degrees of freedom for alignment. Such method is shown to work for a device capable of multiplying the topological charge of an OAM beam.