Michiharu Abe

Organic dye materials for optical recording media

This paper describes optical memory disks which utilize organic dye material for the recording layer. Optical memory disks with cyanine as the organic dye can be fabricated with relative ease by the wet-coating method and are expected to have the possibility of high-density recording. The currently developed dye material exhibits high metallic reflection and absorption capabilities at the laser diode wavelength region. Single-layer-type optical memory disks with the coated dye material were examined. Excellent stability and read–write characteristics have been found satisfactory for practical use.

Potentiality of the Ag-In-Sb-Te phase change recording material for high density erasable optical discs

The feasibility of using Ag-In-Sb-Te phase change material for high density of directly overwritable optical discs has been studied. A linear density of 0.34 μm /bit with a track pitch of 0.74 μm is confirmed to be achievable with a light source wavelength of 680 nm, with an objective lens NA of 0.60 and the criteria of data-to-data jitter of less than 14% of the channel bit length. The recording characteristics are also studied using an optical system with a 635 nm red laser diode in order to investigate the attainment of a linear density of 0.267 μm/bit which is equivalent to the DVD-ROM (read only memory) specification.

Semi transparent Recording Stack with Fast-Crystallization Phase-Change Material for Dual-Layer Optical Disk

We report the experimental results of a semi transparent recording stack with a fast-crystallization (FC) phase-change material for a dual-layer optical disk, using a pickup with a blue laser diode at 405 nm and a lens numerical aperture (NA) of 0.85 to achieve the highest capacity. The transmittance of 47% and the clock-to-data jitter of approximately 9% were obtained from the semi transparent recording stack. We confirmed that the FC phase-change material could be applied to a high-capacity dual-layer recording system.

High-speed blue-laser recording on the double-decker phase change disk with high-reliability

In this paper, we report the feasibility of 100 Mbps data transfer-rate with high reliability and wide-power margin that media can apply to double-deck high density recording of 42 GB capacity corresponding to an optical recording disk system (K. Schep et al, ISOM Tech. Dig., p. 210, 2000) using a blue laser diode at 405 nm, and NA (numerical aperture) of 0.85.

100-Mbps high-speed phase-change recording with blue laser

We have studied a phase-change recording with a blue laser diode wavelength (405nm), an objective lens (NA 0.85) and Ag-In-Sb-Te system phase change material. We report land and groove recording on a 0.1mm thin cover disk structure, and 120mm-diameter polycarbonate substrate. Finally we confirmed the possibility of high data transfer-rate 100Mbps and high-density 20.9GB corresponding to those of a new optical recording system (DVR) (1) at the condition of recording velocity 17m/s, linear density of 0.130 micrometers /bit and 0.35 micrometers track-pitch.

CD-erasable (CD-E) disk technology

CD-ROM has established itself as the preferred medium for the cost-effective distribution of software and various types of multimedia information. The ongoing price reductions of write- once CD-R media and drives are broadening the application range of CD-R from CD- prototyping and small-scale data distribution towards data archiving and bck-up at the desktop. The addition of erasability would increase the attractiveness of recordable CD technology and enable its wide-spread use for personal recording of all types of data files with convenient data interchange. A CD-erasable system (CD-E) with the following characteristics would be very desirable: 1) compatible with existing computer systems and software, 2) erasable with direct overwrite (DOW), 3) recordable using CD-R recorders with minimum modification, 4) readable on CD-ROM players with minimum modification, and 5) reliable. The potential of Ag-In-Sb-Te phase-change materials for CD-E discs and some basic studies have been previously reported by Ricoh. In this paper, we present detailed results of DOW recording on Ricohs CD-E discs at 2.4-2.8 m/s (CD double speed). We conclude that reliable writing and reading as outlined in the concept above can be achieved with this CD-E system.