Dual-layer Blu-ray Disc based on fast-growth phase-change materials

Blu-ray Discs are recorded and read with a blue-violet 405 nm laser through a high numerical aperture 0.85 objective lens. The main application of Blu-ray Discs will be high definition television (HDTV) recording. Future demand for a major capacity increase within the Blu-ray Disc family is anticipated by development of multi-layer technology. However, the optical and thermal characteristics of the currently used phase-change materials restrict the number of layers to two. Such a dual-layer re-writable disc still allows for design choices, which affect system performance. First we describe the spacer technology we have used for making of our dual-layer disc. The two recording layers are based on stack designs with fast-growth materials.