5.3.2. Traps and Grating Dark Decay 3288 5.3.3. Other Concerns 3288 6. New Photorefractive Materials 3289 6.1. Polymer Composites 3289 6.2. Organic Amorphous Glasses 3292 6.3. Fully Functionalized Polymers 3294 6.4. Polymer-Dispersed Liquid Crystals 3295 6.5. Other Liquid Crystal-Containing Materials 3296 6.6. Near-Infrared-Sensitive Materials 3297 6.7. Other Materials Directions 3298 6.7.1. Hybrid Organic−Inorganic Composites and Glasses 3298

Organic photorefractives: mechanisms, materials, and applications.

The present invention provides methods and apparatuses for writing information to, reading information from, and erasing information on a luminescent data storage medium comprising Al 2 O 3 . The method includes writing and erasing of the information using photoionization via sequential two-photon absorption and non-destructive reading the information using fluorescent detection. The apparatuses for writing and reading the information incorporate confocal detection and spherical aberration correction for multilayer volumetric fluorescent data storage. The methods also allow multilevel recording and readout of information for increased storage capacity.

Optical single-bit recording and fluorescent readout utilizing aluminum oxide single crystals

The present invention provides aluminum oxide crystalline materials including dopants and oxygen vacancy defects and methods of making such crystalline materials. The crystalline materials of the present invention have particular utility in optical data storage applications.

Aluminum oxide material for optical data storage

Unfettered and near-instantaneous access to massive amounts of information has become so commonplace that we are all starting to take it for granted. But the decreasing cost of storing data and the increasing storage capacities of ever smaller devices have been key enablers of this revolution. Current storage needs are being met because improvements in conventional technologies---such as magnetic hard disk drives, optical disks, and semiconductor memories---have been able to keep pace with the demand for greater and
faster storage.
However, there is strong evidence that these surface-storage technologies are approaching fundamental limits that may be difficult to overcome, as ever-smaller bits become less thermally stable and harder to access. Exactly when this limit will be reached remains an open question: some experts predict these barriers will be encountered in a few years, while others believe that conventional technologies can
continue to improve for at least five or perhaps even ten more years. In either case, however, one or more successors to current data storage technologies will be
needed in the near future. An intriguing approach for next generation data-storage is to use light to store information throughout the three-dimensional volume of a material. By distributing data within the volume of the recording medium, it should be possible to achieve far greater storage densities than current technologies can offer.
In this talk, I review progress to date in these various volumetric storage technologies, describe the open engineering challenges, and speculate wildly on their prospects for the near future.

http://geoffreyburr.org/papers/SPIE2003_3Dstorage_proceedings.pdf

Three-dimensional optical storage

The present invention provides methods and apparatuses for writing information to, reading information from, and erasing information on a luminescent data storage medium comprising Al2O3. The method includes writing and erasing of the information using photoionization via sequential two-photon absorption and non-destructive reading the information using one-photon absorption and confocal fluorescent detection. The apparatuses for writing and reading the information incorporate confocal detection and spherical aberration correction for multilayer volumetric fluorescent data storage. The methods also allow multilevel recording and readout of information for increased storage capacity.

Bit-wise optical data storage utilizing aluminum oxide single crystal medium

In three-dimensional optical bit data storage, data bits can be recorded as a result of the change in refractive index in photorefractive and photochromic materials under single-photon and two-photon excitation by a high numerical-aperture objective. In principle, these recorded data bits can be read out using reflection confocal microscopy because such a microscope exhibits an optical sectioning property for three-dimensional imaging. In this article, the conditions are described under which three-dimensional data bits recorded by the photorefractive effect under single-photon and two-photon excitation in these materials can be read in reflection confocal microscopy. The effect of the refractive-index mismatch between a volume recording medium and its immersion medium on these conditions is also considered.

http://ieeexplore.ieee.org/iel5/5/17462/00805918.pdf

Min Gu

Papers

Confocal readout of three-dimensional data bits recorded by the photorefractive effect under single-photon and two-photon excitation