Radial Polarization Converters (S-waveplates) are space-variant retarders designed to convert linear polarization to radial or azimuthal polarization to reduce laser beam spot size. Alternatively, they can be used to convert circularly polarized light to an optical vortex (donut-shaped beam). The converters are manufactured by inscribing self-organized nanogratings inside fused silica using a femtosecond laser. Radial Polarization Converters (S-waveplates) are beneficial for a variety of polarization-sensitive applications. Radially polarized beams are highly efficient at micro-drilling high aspect-ratio features in metal, while vortex (donut-shaped) beams are ideal for STED or two-photon excitation fluorescence microscopy, laser micromachining, and optical tweezer applications (multiple particle trapping).
Higher Order Radial Polarization Converters can generate vortices with increased topological charge or vector Bessel beams when used in combination with axicons. These types of beams are used in micromachining applications, such as microhole drilling of transparent materials.