Hiroharu Satoh

Experimental Study of High-Density Rewritable Optical Disk Using a Blue-Laser Diode

The read-write characteristics of an optical disk utilizing a blue-laser diode are examined, applying land and groove recording and partial response and maximum likelihood (PRML) to two optical disk systems: 1) 0.85 numerical aperture (NA) optical disk system consisting of an objective lens with NA of 0.85 and a thin cover layer on a disk with a thickness of 0.1 mm and 2) 0.65 NA optical disk system consisting of an objective lens with NA of 0.65 and a 0.6-mm-thick disk substrate. In the 0.85 NA optical disk system, the track pitch and the data bit length employed for the experiment are 0.29 µm and 0.0987 µm, respectively. These parameters correspond to a capacity of 30 GB/side. In the 0.65 NA optical disk system, they are 0.37 µm and 0.155 µm, respectively, corresponding to a capacity of 15 GB/side. A bottom channel bit error rate (ch.bER) of less than 5.0×10-5 can be obtained in these systems, and it is confirmed experimentally that the ch.bER remains below 1.0×10-4 up to 1000 cross-write cycles.

Digital Versatile Rewritable Disc (DVD-RAM) Complementary Allocated Pit Address (CAPA) Signal and Tracking Error Signal Detection Method; Improving Objective Lens Radial Shift Immunity

The complementary allocated pit address (CAPA) signal in a digital versatile rewritable disc (DVD-RAM) is susceptible to an objective lens radial shift; the reduction of its signal amplitude occurs and the S/N ratio decreases. To alleviate this situation, we propose a new readout signal processing scheme, the center separate detection method (CSD) of discarding a large amount of the 0-th diffracted light beam from the disc. We confirmed the expected results by numerical simulation.

Computational analysis of electric field distribution in dual-layered phase-change disc

We developed a Finite-Difference Time Domain (FDTD) Method based simulator that can analyze Dual-Layered phase-change disc structure. Because of a substrate thickness error, it is necessary to consider spherical aberration. The electric field distributions have been calcuated on Single-Layered and Dual-Layered phase-change discs. We found differences between the electic distributions focused on a groove and on a land. These calculation results can explain the corresponding experimental results clearly.

Experimental study of 30 GB/side rewritable optical disk using a blue-laser diode

The read-write characteristics of a land and groove disk have been examined using a blue-laser diode, high NA objective lens and the PRML method. The wide tilt and defocus margins have been obtained and no deterioration by CW has been observed at a data bit length of 0.0987 /spl mu/m and a track pitch of 0.29 /spl mu/m. These experimental results certify the feasibility of a rewritable optical disk with a capacity of 30 GB/side.

30 GB/side rewritable optical disk for HDTV utilizing a blue laser diode

This paper presents a rewritable optical disk with a capacity of 30 GB/side intended for the next generation of rewritable optical disks. The experimental results have shown that this optical disk has wide tilt margin and is a prospective candidate for supplanting VCR in the HDTV era.