High-order Laguerre-Gauss polychromatic beams from Bragg-Berry flat optics

International audience; We report on the design, fabrication, and experimental characterization of reflective geometric phase optical elements enabling the generation of scalar and vectorial high-order Laguerre-Gauss optical beams over a broad spectral range. This is made possible by combining azimuthal and radial structuring of helix-based liquid-crystal films exhibiting the circular Bragg reflection phenomenon. By extending the previously introduced concept of Bragg-Berry optical elements to the polychromatic shaping of the radial degrees of freedom and showing their combination with azimuthal ones, this work suggests that spectrally broadband spin-orbit processing of optical information over multiple spatial degrees of freedom can be further considered on experimental grounds.