Rewritable Dual-Layer Phase-Change Optical Disk with a Balanced Transmittance Structure

Abstract

A rewritable dual-layer phase-change optical disk with a balanced transmittance structure for the layer located at the laser beam incident side (Layer 0) was developed. In this disk structure, transmittance of the Layer 0 is almost constant whether the layer is recorded or not. This structure was realized by adopting Ge-Sb-Te film-that has appropriate optical constants, and optimizing the thickness of dielectric layers. It is proved that this disk structure is effective for suppressing influence of recording state of the Layer 0 on the layer beneath (Layer 1). Practical performances of the disk with this structure were confirmed for both layers. The feasibility of up to 55GB-capacity was examined for this rewritable dual-layer phase-change optical disk.