Novel Read-Out Technology for Multi-Layer Disk using Polarization Device

When the multi-layer disc is read by a normal optical pickup, the signal light that is reflected in the read-out layer contains stray light from the adjacent recording layers, which is called the layer cross-talk (LCT). To reduce the LCT, we developed a new optical pickup that has a segmented wave-plate made of an auto-cloned photonic crystal. It has some advantages of perfect removal of LCT, detection of the high efficiency of the signal light, and the miniaturization of the optical pickup. In addition, by using this optical pickup, we confirmed the improvement of the signal performance, using a HD DVD dual-layer disc that has a thin spacer layer thickness, to increase the LCT.