Compact-disc compatible wideband write-once optical disc memories using multilayered ultra-thin silver films

A write-once (WO) optical disc memory with compact disc (CD) compatibility is demonstrated by using a multilayer consisting of a silver reflective layer, thin glass spacing layer, and silver quasi-island recording layer. The reflectance of the multilayer is >70% at a wavelength of 800 nm. The reflectance can be greatly lowered by laser irradiation, since the silver quasi-island layer changes by heating, becoming absorptive and of low reflectivity due to structural change. As a large reflectance change has been observed not only at 800 nm for CD but also at 650 nm for a digital video disc (DVD), a CD-DVD compatible wideband write-once optical disc is realised