Reflective Metastructure Q-plate for Ultrashort Laser Pulses

The orbital angular momentum of light is an intriguing property for developing light driven applications. It emerged as an independent degree of freedom by which to manipulate light and, consequently, the interaction of light with matter. Several methods exist for the generation of light carrying orbital angular momentum, mostly employing transmitting or reflecting optical components, which radially modulate the phase profile of the light. As one of such components, transmissive q-plates established themselves as standard elements due to their usability over a broad wavelength range. Here, we present our approach to build a highly reflective q-plate based on a plasmonic metasurface capable of converting orbital angular momentum from the nanostructure to ultrashort laser pulses without temporal broadening. We highlight its working principle over a wide range of wavelengths for reflection under normal and gracing incidence.