Hisataka Sugiyama

High Storage Density Optical Recording with a Stable Micro Green Second Harmonic Generation Laser Consisting of Nd:YVO4 and KTP

A stable micro second harmonic generation (SHG) laser consisting of a diode- pumped Nd:YVO4 laser doubled by KTiOPO4 achieves 3 times higher storage density than usual on an erasable optical disk.

High storage density optical disks using pit-edge recording on PbTeSe thin film

Pit-edge recording, where, the leading and trailing edges of the pit correspond to code-data 1, can achieve about one and a half times more bit density than that of pit-position recording. Using pit-edge recording with an effective write-read compensation scheme, we have achieved high linear density of 0.63 microm/bit on a PbTeSe ablative type optical disk. The write compensation is able to cancel pit expansion caused by thermal diffusion and surface tension of the recording film. We also confirmed the possibility of 0.50-microm/bit recording with an advanced compensation scheme on a PbTeSe optical disk. The corresponding user data capacity is ~1 Gbyte/side on a 130-mm diam optical disk.

High-speed large-capacity optical disk using pit-edge recording and MCAV method

A large size optical disk (for example, in 300 mm diameter) has been applied to document files and archived coded data files. Recently, demands for larger capacity and higher speed are growing greatly. Therefore, we developed a write once optical disk (300 mm in diameter), which adopts the pit-edge recording method and the MCAV (modified constant angular velocity) method to achieve higher linear density. On optical disk system combining the above two methods has yet been developed. In addition, new techniques must still be developed to satisfy the requirements of large capacity and high speed using these two methods. In this paper, new techniques were have developed are discussed.

Sn-Sb-Se/Sb-Bi Bilayer Phase-Change Media for High-Density Write-Once Optical Recording

We have developed Sn-Sb-Se/Sb-Bi bi-layer phase-change media for high-density write-once optical disks. Crystallized marks as small as 0.5 ? m are stably recorded without initialization. These phase-change media, compared to ablative type write-once media, have high carrier-to-noise ratio, low jitter, and long life. Mark-edge recording with multi-pulse laser irradiation on the media provides a linear bit density of 0.48 ? m/ bit and track pitch of 1.2 ? m using a 690-nm-wavelength laser diode and 0.55 numerical aperture (NA) objective lens. This corresponds to 1.1 Gbit/in.2, or 14 GB formatted data capacity per both sides for a 12-inch-diameter disk with a zoned constant angular velocity (ZCAV) format.

Analysis of Leading Edge/Trailing Edge Independent Detection Method in Optical Disk

The effects of independent detection of leading edge / trailing edge on edge-shift and jitter are investigated for typical heat-mode recording processes using read-out pulse width, recording timing measurements and thermal simulation. In addition, in order to investigate the edge-shift reduction limit for this new method, a method is proposed to analyze what causes the edge-shifts; it statistically evaluates the relative edge intervals between adjacent edges of a particular worst-case recording pattern. Our results clarify that the new method is effective for reducing edge-shifts and jitter.

Optimized Servo System of DVD Drive for Video Camera

This paper presents the servo system to suppress the influence of vibration for built-in DVD drive inside a video camera. The developed servo system prevents tracking disturbance caused by vibration acceleration and focus disturbance caused by disc trembling due to Coriolis effect.

Sn-Sb-Se phase-change media for high-density write-once optical disk

We have developed Sn-Sb-Se/Sb-Bi bi-layer phase-change media for high- density write-once optical disks. Crystallized marks as small as 0.5 micrometers are stably recorded without initialization. These phase-change media, compared to ablative type write-once media, have high carrier-to- noise ratio, low jitter, and long life. Mark-edge recording with multi- pulse laser irradiation on the media provides a linear bit density of 0.48 micrometers /bit and track pitch of 1.2 micrometers using a 690-nm-wavelength laser diode and 0.55 NA objective lens. This corresponds to 1.1 Gbit/in.2, or 14 GB formatted data capacity per both sides for a 12- inch-diameter disk with a zoned CAV format.

Write System of Blu-ray Disc Drive for Video Camera

This paper presents the write system for a Blu-ray disc (BD) camera drive to write with PCAV (partial constant angular velocity) method. The system controls the write waveform of the power and the pulse timing according to the write speed and the temperature. The power margin and the symbol error rate sufficiently show high performance not depending on the write speed at high temperature.

Consideration of code for multilayer optical disk

Multi-layer recording method has been studied and developed since dual layer disk of DVD-ROM and the studied disk type has expanded from ROM to Rewritable disk. Multi-layer disk has new problems different from a single layer disk. One is an inter-layer cross-talk, which a component of a signal from adjacent layer leaks into a detected signal when the information data is reproduced from a target layer. Second is a recording power fluctuation, which the light power reached a target layer changes by marks on intermediate layers. There were many works that solve this problem. This causes severe problem for signal processing and recording performance. There was work that was proposed to design the structure of a multi-layer disk and an optical head. In this paper, we reported the consideration of a code in order to solve the problems.

High-density recording by two-dimensional signal processing

To make higher density on optical disk, a new recording method- 2D recording-which can increase the track-density rather than the linear density was proposed. The performance of this method on increasing density is estimated by the simulation and confirmed by measuring the read-out signal. Consequently, it is clarified that this method can attain more than twice the areal density independently and realize the density of 2.2Gbit/in2 which is 8 times as large as that of first generation using 680 nm laser diode.