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3 results on '"Kenichi Nagata"'

1. Optical characterization of multilayer stacks for phase-change media

Author

Kenichi Nagata, Rongguang Liang, Chubing Peng, Kelly Daly Flynn, and Masud Mansuripur

Subjects
3D optical data storage, Materials science, genetic structures, business.industry, Analytical chemistry, Dielectric, eye diseases, Slot-waveguide, Ellipsometry, Attenuation coefficient, Optical recording, Optoelectronics, sense organs, business, Refractive index, Layer (electronics)
Abstract

We report results of measurements of the optical constants of the dielectric layer, reflecting layer, and phase-change layer used as the media of phase-change optical recording. The refractive index and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.

Published
2002

2. Advanced 4.7-GB DVD-RAM with a 4X data transfer rate

Author

Shigeaki Furukawa, Kenichi Nishiuchi, Noboru Yamada, Rie Kojima, and Kenichi Nagata

Subjects
Constant linear velocity, Optics, Materials science, business.industry, Modulation, Transfer (computing), Recording layer, DVD-RAM, Electrical engineering, business, Optical disc, Jitter, Data rate units
Abstract

We demonstrated the possibility of high data rate recording on a DVD-RAM disk which utilizes Ge-Sb-Te phase-change materials. To ensure high transfer rate overwriting on the DVD, quadruple speed (44Mbps) recording at a linear velocity of 16.4 m/s was tested using a Sn-added Ge-Sn-Sb-Te material as the recording layer. Double speed (22Mbps) recording on the present 4.7GB DVD-RAM at a linear velocity of 8.2 m/s was also tested. A CNR of more than 53 dB and an erasability of more than 30 dB were obtained at each double, triple and quadruple speeds. In addition, by recording via 8-16 random modulation signals, a jitter of 9 percent or less and a direct overwrite performance of 100,000 cycles were confirmed.

Published
2002

3. Accelerated aging studies for phase-change-type disc media

Author

Kenichi Nagata, Kazumi Yoshioka, Suguru Nakamura, Tetsuya Akiyama, Uchida Masami, Takeo Ohta, Shigeaki Furukawa, and Inoue Kazuo

Subjects
Phase change, Materials science, business.industry, Analytical chemistry, Electrical engineering, Dielectric, Plateau (mathematics), business, Accelerated aging, Ferroelectricity, Ternary alloy, Arrhenius plot, Active layer
Abstract

The excellent stability of GeTe-Sb2Te3-Sb phase change disc media was demonstrated in accelerated aging studies. The disc was composed of the pseudo ternary alloy active layer of GeTe-Sb2Te3-Sb, ZnS-SiO2 dielectric layers and Al quadrilayer rapid cooling structure. This structure leads high performance C/N ratio of 55dB and more than 30dB eras ability with wide plateau power dependency. We measured the archival and the shelf characteristics of C/N and bit error rate (BER) as a function of exposure time for discs exposed to 80 degrees C 80% RH, and 90 degrees C 80% RH. From the Arrhenius plot, the life time of the phase change type disc media were expected to be longer than 60 years in 32 degrees C 80% RH environment.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Published
1990

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