Kenjirou Kiyono

Organic Dye 25 GB Write-Once Disk with In-Groove Structure

We have developed a new write-once disk technology, which is applicable to the Blu-ray disc system. An organic dye was adopted for the recording layer, which was optimized for the recording of the laser diode wavelength of 405 nm. We adopted a concave in-groove for the recording tracks to avoid thermal interference with adjacent recording tracks due to undesired and uneven dye pooling between adjacent tracks, considering the advantage of fabrication by spin-coating. We optimized the in-groove structure for low-to-high modulated recording. A sample disk, which was made by the conventional spin-coat process, showed good recording and readout characteristics with remarkably low cross-talk and cross-writing.

Rewritable Multilevel Recording by Mark-Size Modulation on Growth-Dominant Phase-Change Material

Rewritable multilevel recording based on reflectivity modulation, by means of two-level write intensity modulation and duty ratio control of writing and cooling pulses on conventional four-layer stack, was realized using an eutectic growth-dominant phase-change material. Tangential amorphous mark size modulation with the competitive process of amorphization and recrystallization during resolidification was observed.

Application of multi-level recording with growth-dominant material to CD and blue DVR generations

We confirmed that the ML (reflectivity) recording with growth-dominant material can be universally applied to any density of optical disc from CD to DVR blue. The present study is focused on the evaluation from the view point of a removable disc manufacturer, i.e., reliability such as overwrite cyclability and archival and self life and volume production capability.