Nanostructured holograms for broadband manipulation of vector beams

We report a new type of holographic interface, which is able to manipulate the three fundamental properties of light (phase, amplitude, and polarization) over a broad wavelength range. The design strategy relies on replacing the large openings of conventional holograms by arrays of subwavelength apertures, oriented to locally select a particular state of polarization. The resulting optical element can therefore be viewed as the superposition of two independent structures with very different length scales, that is, a hologram with each of its apertures filled with nanoscale openings to only transmit a desired state of polarization. As an implementation, we fabricated a nanostructured holographic plate that can generate radially polarized optical beams from circularly polarized incident light, and we demonstrated that it can operate over a broad range of wavelengths. The ability of a single holographic interface to simultaneously shape the amplitude, phase, and polarization of light can find widespread applications in photonics.