Blu-ray discs

As blue diode lasers became available on a large scale [10], a new generation of storage disks with further increased storage capacity was developed by the Blu-ray Disc Association and by Toshiba and NEC within the DVD Forum [4j. As can be seen in Table 12.1, a HD-DVD holds 15 GB and BDs hold 25 GB (singlelayer DB) or 50 GB (dual-layer BD). Figure 12.3 shows, as a typical example, the cross-section of a novel disk type having a triple-layer structure one BD layer and a dual DVD layer to be read by a blue and a red laser, respectively. 

Blu-Ray Disc (BD) Disc commonly used for storage of high-definition video and audio that can hold twenty-five to fifty gigabytes of information. BDs can also contain other forms of information, such as computer programs or data backup. 

Optical media is more durable than electromagnetic tape and is less vulnerable to environmental conditions. With the exception of Blu-ray Discs, the speed of data retrieval is considerably slower than that of a computer hard drive. The storage capacity of optical disks is significantly less than that of hard drives. Another, less common form of optical storage is optical tape, which consists of a long, narrow strip of plastic upon which patterns can be written and fi-om which the patterns can be read back. 

Taylor, Jim, et al. Blu-ray Disc Demystified. New York McGraw-Hill, 2009. Provides a detailed overview of Blu-ray technology, its uses, and its shortcomings. 

Optical media 32 Compact Discs, CDs and DVDs, Blu-Ray discs, digital and holography discs, innovative data storage technology (e.g., near-field recording discs)... 

Recording bits on Blu-ray discs are less than 150 nanometers long, allowing more than 50 Gb of data to be stored on a 12-cm disc ... 

Chalcogenide alloys such as GeSbTe-based compounds are of interest for applications in rewritable optical media (Digital Versatile Disc, Blu-ray disc) and in non-volatile electronic memory devices [1-5]. Both applications rest on a fast and reversible transformation between the crystalline and amorphous phases which represent the two states of the memory. The phase change is induced by heating, either... 

Phase change materials based on chalcogenide alloys are of widespread use in rewritable optical media (Digital Versatile Disc, Blu-ray disc) because of the strong optical contrast between the amorphous and crystalline phase (see inset of Fig. 15.9). Such a strong optical contrast is rather unusual since in typical semiconductors (e.g. GaAs in [91]) the amorphous and the crystalline phases have a similar... 

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