High-frequency gratings for applications to DVD pickup systems

Binary gratings with feature sizes smaller than the illumination wavelength were designed, fabricated and experimentally tested for operation in transmission at 650 nm. The elements were designed for integration in DVD pickup systems. We used rigorous coupled wave analysis for the design of diffractive optical elements such as polarizing beam splitters (PBSs), phase retardation plates, deflection gratings and beam splitter gratings. Electron-beam-lithography and reactive ion etching techniques were employed to produce the PBSs and the phase retardation plates in quartz glass. For the PBS elements diffraction efficiencies of higher than 75% were measured for TE and TM polarization. Furthermore a phase retardation plate, which showed a phase difference of 44.8° (theoretical, 45°) between TE and TM polarized light, was realized.