Optical memory storage

Siwick, B.J., Kalinina, O., Kumacheva, E., Miller, R.J.D., and Noolandi, J. (2001) Polymeric nanostructured material for high-density three-dimensional optical memory storage. J. Appl. Phys., 90 (10), 5328-5334. 

Several studies with Yb " or Er " active BaTiOs ceramics have been conducted due to their large number of optical applications such as frequency conversion, light modulation, optical switching, and optical memory storage. In particular, when a matrix is doped with trivalent Er ", green and red infrared emissions at about 1.0 and 1.5 pm are obtained. 

The question as to whether and to what extent and in what area optical mass storage would replace magnetic systems (disk, tape) was controversially being discussed in the 1980s. In spite of all predictions of an imminent substitution, as of late 1994 magnetic hard disks stiU are the system of choice for computer-dedicated mass storage due to their speed (access time, transfer rate), physical size, and energy consumption this is especially tme when memory-intensive appHcations are mn which use the hard disk as virtual memory. 

The acceptance of optical data storage iato the mass storage market, which is as yet exclusively dominated by magnetic systems, will be fundamentally boosted if optical drives and media are subject to uniform standards and become fully compatible, and multiuser drives are offered which enable the user to employ alternatively CD-ROM and EOD disks, and maybe WORM disks as well (and CD-R disks, respectively). A prerequisite, however, will be whether rewritable optical memories will use the MOR or the PCR process. This accord especially will be hard to reach. 

Magnetooptic Materials. The appHcation of magnetooptic effects to optical memory systems, such as for laser beam writing and magnetooptic read, has been the subject of much research. Magnetooptic storage media offer the potential of storing over 120 Mbit/cm of information without contact of the read/write head which would thus be very competitive to floppy disks and tape. 

CD-R was something of a surprise invention as, in the late 1980s, most of the major manufacturers in the optical memory area were commercializing the non-standard and relatively expensive WORM media, while focusing their research and development efforts on erasable optical storage. It was also believed that a writeable CD-Audio/CD-ROM-compatible medium was not feasible, due to the high reflectivity needed to meet the CD standard as defined by the Red and Orange Books.196... 

Photochromic dithienyl- and dibenzothienylethenes, particularly those containing the central 1,2-perfluorocyclopentene fragment, belong to the major group of compounds, which have attracted the attention of researchers in the field of information storage (optical memory) and optical switches because their starting (A) and cyclic (B) forms are, in most cases. 

Photochromism Light Ophthalmic lenses, novelty printing, security printing, cosmetics, optical data storage, memories and switches, sensors... 

Y is then reconverted back to X (erase). Such a write-lock-read-unlock-erase cycle could constitute the basis for an optical memory system with multiple storage and nondestructive readout capacity. 

---