Nobuhisa Yoshida

Dual-layer rewritable phase-change recording media for HD DVD system

We have investigated the recording characteristics of the dual-layer phase-change recording media for a system that uses the blue-violet laser (wavelength of 405 nm), with the numerical aperture of 0.65 and light incidence on 0.6-mm-thick substrate having the land and groove format (HD DVD). In order to achieve higher storage density for its beam spot size, a number of technologies have been incorporated into the media, such as the bismuth-substituted pseudobinary GeSbTe alloy recording film and hafnium oxide-based interface layer material. The feasibility of the user capacity of 36 GB has been successfully demonstrated.

Dual-layer phase-change recording media for system with NA of 0.65 and light incidence on 0.6-mm-thick substrate

We have investigated the recording characteristics of the dual-layer phase change recording media for the sysetm with the NA of 0.65, the wavelength of 405 nm, and the light incidence on 0.6-mm-thick substrate having the land and groove format. For both L0 and L1 of the dual-layer disc, we have adopted bismuth substituted pseudo-binary GeSbTe alloy film as the recording layer and a novel interface layer material in order to improve overwriting characteristics. Bit error rate measurements have successfully demonstrated the feasibility of the user capacity of 36GB and confirmed 30GB with tilt margins.