Theory of Optical Information Storage in Solids

G. G. Grigoryan, Y. Pashayan-Leroy, Claude Leroy +1 more

P. J. van Heerden

In photography, information is stored in a medium which is essentially two-dimensional. Three-dimensional optical storage is possible in semitransparent colored materials, like alkali halides with color centers. With the use of coherent light sources, like lasers, large amounts of information can be stored in the volume, and retrieved with little interference. The storage of information is accomplished by the formation of interference patterns between each two plane parallel waves. This paper develops the theory of this form of storage. It turns out that the information storage capacity is as if every little cube with sides equal to the wavelength of light acts as an independent information storage cell, and the essential noise in recovering this information is only the statistical fluctuation in the number of color centers in such a cube. The storage capacity is therefore of the order of 1012–1013 bits per cm3. The main property of this way of information storage is the appearance of a “ghost image,” partly but not completely analogous to the one described previously. This property makes three-dimensional storage very suitable for associative memories. The theory lends support to Beurle’s proposed mechanism of information storage in the brain.

W. J. Firth

Jin-Yue Gao

Atomic coherence is the result of interaction between light and materials,which leads to many important physical phenomenon.Currently,most experimental researches on atomic coherence are reported in atomic gases.Compared with atomic gases,the related experimental researches in solid materials have more practical applications.This paper introduces the recent research progress of atomic coherence in solid-state materials in detail,including the Electromagnetically Induced Transparency(EIT) in solid materials,light velocity reduction and coherent storage,controllable eraser of optical storage information,all-optical route based on optical storage,optical velocity reduction and reversible storage of double light pulses and enhanced four-wave mixing based on atomic coherence,it also discusses its application to relative fields.

M. Gromovyi, V. I. Romanenko, Simon Mieth +2 more

Hai-Hua Wang, Lei Wang, Xiaogang Wei +5 more

We demonstrate storage and selective release of a light pulse in a Pr:YSO crystal, which is based on atomic spin coherence created by fractional stimulated Raman adiabatic passage (STIRAP). The fractional STIRAP gives better storage fidelity compared to STIRAP. Selective release of stored optical information and better storage fidelity have practical applications in information processing and all-optical communication.