Abstract

We have developed a dual-layer rewritable HD DVD media having a larger capacity of 40 GB (20 GB per layer) for the optical system with the NA of 0.65 and the wavelength of 405 nm, and achieved the good recording characteristics. For both layers, we used the same track pitch of 0.34 μm as the single layer HD DVD-RAM. For the L1, we optimized the recording layer and the interface layer materials to achieve both good recording performance and sufficient reflectivity. For the L0, we solved the cross-erase that had previously been a problem by carefully choosing the combination of the recording material and the interface layer material, maintaining the disc transmittance at about 50 %. As a result, we have obtained the good recording characteristics for both layers. We combined these two new technologies and have shown the feasibility of the dual-layer rewritable media of 40 GB user data capacity for HD DVD system.

© 2007 Optical Society of America