Polarization conversion on nanostructured metallic surfaces fabricated by LIPSS

Casquero, Noemi; Martinez-Calderon, Miguel; Perez, Noemi; Granados, Eduardo; Olaizola, Santiago M.; Rodriguez, Ainara

Fabricating reflective waveplates using nanostructured surfaces has taken great interest in recent years due to their simple structure: a diffractive grating composed of ripples with subwavelength period. The surface ripples act as an artificial birefringent material: the anisotropy of the surface corrugation generates a phase delay between two perpendicular light polarizations. The control of the period, fill factor, depth and orientation of the ripples are crucial to optimize the change of the polarization of the reflected light. Although there are different strategies to fabricate subwavelength diffraction gratings to convert the polarization of light in reflection mode, here we propose the use of Laser Induced Periodic Surface Structures (LIPSS) as a new approach for this purpose. In this work, large area subwavelength reflective gratings have been fabricated via LIPSS with periods of 580 nm and 630 nm. These gratings were able to convert the incident linear polarized laser light at 633 nm into reflected circular polarized light, and vice versa, with ellipticity values lower than 2,7°. This is, to the best of our knowledge, the first report on the use of LIPSS for polarization conversion.

Conference proceeding of the work presented in LPM2018