Silicon dual-functional metasurfaces for the compact generation of multi-ring, azimuthally-variant, and helico-conical perfect vector beams

The ability to generate structured light with arbitrarily controlled polarization in a compact optical path has been a challenge over the last few years in the fields of optics and photonics. In this regard, our work proposes the design, fabrication, and characterization of new dielectric dual-functional meta-optics that generate orbital angular momentum beams with on-demand different vectorial behaviors acting only on the input polarization. The metaoptics are designed as an array of periodic subwavelength metastructures (so-called meta-atoms) composed of silicon nanofins on a silicon substrate, acting like half-wave plates that exploit both the geometric and dynamic phases. We prove the generation of dual-ring perfect vector beams and novel complex vectorial configurations: azimuthally-variant perfect vector beams and helico-conical vector beams. This design solution offers both compactness of the optical path and easy integration with other optical elements, suggesting intriguing applications in telecommunications, imaging, particle manipulation, and quantum information.