A spring disk clamp is provided for securing one or more data storage disks to a disk drive without the need for screws. The shaft journal andor the intermediate portion areis provided with a material thickness reduction within a distance a from the contact surfaces which is less than substantially half the material thickness at the contact surfaces, in order to guide the force flow thorough the weld seam. of at least one rubber-free andor rubber-modified vinyl polymer, the rubber-modified vinyl polymers being prepared in the bulk, solution or suspension polymerization process,C) 0. A dielectric structure is formed over the upper DBR and surrounds the optical guide.