Inorganic Write-once Disc Research Articles

New Inorganic Write-Once Disc Using Low-Cost and Environmentally Friendly Oxynitride Materials for Multilayer Disc System

We have developed a new inorganic write-once disc using low-cost and environmentally friendly recording materials of Si oxynitride and Al oxynitride with high transmittance. Data-to-clock jitters of 5.6% for Layer 1, 5.5% for Layer 2, and 6.3% for Layer 3 of the individual single-layer discs were obtained using a limit equalizer. This newly developed recording material is immensely promising for a multilayer disc system.

A New Inorganic Write-Once Disc using Hydrogen-Containing Dielectric Recording Material for Multi-Layered Blu-ray Disc System

We have developed a completely novel inorganic write-once disc using a hydrogen-containing dielectric recording material. We demonstrate the recording characteristics of a newly developed write-once disc on the basis of the Blu-ray disc format (dual-layered, 4× speed).

Dual-Speed Inorganic Write-Once Disk with Low-to-High Polarity

We have developed a new inorganic write-once optical disk for an optical recording system with a numerical aperture of 0.85 and a 405 nm blue-violet laser diode. The recording layer is composed of multi-layered structure of alternating Mg-based alloy layer and Si layer. Our experimental results showed that the recording sensitivity of the optical disk is strongly dependent on the stack structure of the recording layer, which can be optimized through adjusting the number of the component layers. Dynamic experiment results showed that the write-once optical disk has a low-to-high polarity and jitter value below 7.5% can be achieved at both 1× and 2× speeds. Effects of the multi-layered recording layer structure and the low-to-high polarity on recording performance are discussed.

Inorganic Write-Once Disk by Complete DC Sputtering Process for Blue Laser System

We studied an inorganic write-once disk using an objective lens with a numerical aperture of 0.85 and a 405 nm blue-violet laser diode. We confirmed that the reflectivity of the disk was controllable by adjusting the nitrogen flow rate during sputtering of a Bi–Ge nitride recording layer and disk structure. The disk that had been adjusted to high reflectivity showed a large modulated amplitude. We confirmed that complete DC sputtering process is a practicable process to make inorganic recording stacks. This means that the structure of the equipment for the production of the disks will be simple and operation of it will be easy. We made the high-reflectivity disk by the DC sputtering deposition process. The reflectivity of the disk was 34%, the modulated amplitude was 60%, and the jitter was 5.8%.

BD-Type Write-Once Disk with Pollutant-Free Material and Starch Substrate

We realized an inorganic write-once disk for an optical recording system of the Blu-ray disk format. We developed a new Al alloy for the reflective layer and a Nb-compound oxide nitride material for the dielectric layer. By adopting these materials for the reflective layer and the dielectric layer of our write-once disk, we achieved complete exclusion of toxic substances specified in the pollutant release and transfer register (PRTR) law. That is, this disk did not contain any substances specified in the PRTR law. We confirmed this disk to be compatible with 1× to 2× recording at the user capacity of 25.0 GB. The bottom jitter values of both 1× and 2× were less than 6.0%. In addition, we developed another kind of substrate, which was made of a natural polymer derived from corn starch. The bottom jitter value was 6.0% at the user capacity of 25.0 GB with the limit equalizer.

Recording Mechanism of High-Density Write-Once Disks Using Inorganic Recording Material

We realized an inorganic write-once disk using a Bi-Ge nitride alloy recording layer for an optical recording system for the Blu-ray disc format. We developed a recording system, which is composed of two types of metal nitride as a recording material. One metal nitride is decomposed easily by the heat of the laser beam during recording. The other metal nitride is not decomposed at that temperature. The recording signal modulation depends mainly on the reflectivity change of the recording layer caused by the decomposition of nitride. The non-decomposing nitride controlled the reaction and prevented deformation of the layer. Thus we could obtain a well-formed minute mark. We confirmed the reliability of our hypothesis on the recording mechanism by using another material, which is composed of Sn-N and Ti-N. By this method, we confirmed that this recording mechanism can be widely applied to any inorganic recording material.

Inorganic Write-Once Disc for High Speed Recording

We have developed an inorganic write-once disc based of the Blu-ray disc format. Our write-once disc has a double layer recording stack of a Cu alloy layer and a Si layer. These materials are environmentally friendly and low in cost. We designed a new write pulse strategy for high-speed recording while maintaining low recording peak power. As a result of using our write strategy, we obtained a jitter value of less than 8% with optimum recording power of 5 mW in the range of 36 Mbps to 144 Mbps.

Inorganic Recordable Disk with More Eco-Friendly Material for Blue

We realized an inorganic write-once disk using a high numerical aperture (NA) objective lens and a blue-violet laser diode. Its recording layer was Bi–Ge nitride alloy which was more environmentally friendly than that of the rewritable disk. The data-to-clock jitter of 5.7% was obtained at 25 GB capacity, using the limit equalizer. In addition, we confirmed that this disk had potential for application as a 1X-2X recordable disk.