COMPACT-DISC COMPATIBLE WIDE-BAND WRITE-ONCE OPTICAL DISC MEMORIES USING MULTILAYERED ULTRA-THIN SILVER FILMS

A write-once (WO) optical disc memory with compact disc (CD)-compatibi lity is demonstrated by using a multilayer consisting of a silver refl ective layer, thin glass spacing layer: and silver quasi-island record ing layer. The reflectance of the multilayer is >70% at a wavelength o f 800nm. The reflectance can be greatly lowered by laser irradiation, since the silver quasi-island layer changes by heating, becoming absor ptive and of low reflectivity due to structural change. As a large ref lectance change has been observed not only at 800nm for CD but also at 650nm for a digital video disc (DVD), a CD-DVD compatible wideband wr ite-once optical disc is realised.