One SIL Head Recording/Reading on a Rewritable Dual-Layer Optical Disk Having High-index Cover and Separation Layers

Abstract

We have developed a dual-layer rewritable optical disk with high-index (n=1.8) cover and separation layers and first demonstrated near-field recording/reading for both L0 and L1 layers with single SIL (Solid Immersion Lens) optical head. The surface smoothness of the disk and the stability of a gap servo were improved by applying a new forming process of the high-index cover layer of the disk. A beam expander composed of three lenses enabled focusing both L0 and L1 recording layers without exchanging SIL head. The recording characteristics at the capacity of 150GB were confirmed.