Accession Number : ADP008268

Title :   Temporal Accessing of Frequency-Domain Optical Storage: Specific Approaches and General Considerations,

Corporate Author : OREGON UNIV EUGENE DEPT OF PHYSICS

Personal Author(s) : Mossberg, Thomas W.

Report Date : 22 MAY 1992

Pagination or Media Count : 6

Abstract : The ultimate memory device would be one in which a bit of data is stored in every atom or molecule within a storage material. Such a memory would have an incredible storage capacity of somewhere in the range of 10 to the 22nd power bits/cm3. Traditional optical memories, whether two- or three-dimensional, can never hope to achieve atomic-level storage densities for the simple reason that minimally sized storage cells always have edge dimensions on the order of or larger than the wavelength of light employed. In the case of visible light, cubic wavelength scale storage volumes contain billions of atoms. A new class of optical memories has recently been proposed which holds the promise of making near atomic-level data storage a reality. This approach to storage, generically referred to as frequency-selective optical data storage, works by addressing atoms spectrally as well as spatially. It tums out that the constituent atoms/molecules within many materials display spectrally narrow resonances (with a width referred to as delta fh), and that the resonances of individual atoms/molecules are spread throughout a rather broad frequency range (referred to as delta fi). Thus atoms located within a minimally sized spatial volume can be subdivided and hence addressed on the basis of their frequencies. In some materials, up to delta fi/delta fh approx. 10 to the 7th power frequency subdivisions can be made, making it possible to subdivide the billions of atoms/molecules within a minimally sized spatial storage volume into separately addressable groups containing only a few hundred atoms each. The atoms/molecules belonging to each spectral group are generally positioned randomly throughout the spatially addressed storage volume with which they are associated.

Descriptors :   *FREQUENCY, *MEMORY DEVICES, *OPTICAL DATA, *OPTICAL STORAGE, *ACCESS TIME, ADDRESSING, APPROACH, ATOMS, CELLS, DENSITY, EDGES, LIGHT, MATERIALS, MOLECULES, SCALE, STORAGE, THREE DIMENSIONAL, VOLUME, WIDTH, ACCESS, SPECTRA, RESONANCE, LASERS, READ WRITE MEMORIES, COMPUTERS, TIME.

Subject Categories : Electrooptical and Optoelectronic Devices
      Computer Hardware
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE