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Japan’s National Institute of Information and Communications Technology has unveiled a new handheld, 3D communications tool. The gCubik, developed by the NICT earlier in the year, reproduces 3D images, inside a 10cm-per-side cube, that are viewable without special glasses. Now, the gCubik+i can generate the images in real-time allowing them to be manipulated using touchscreen panels and on-board motion sensors.
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Non-volatile holographic storage in doubly doped lithium niobate crystals

Non-volatile holographic storage in doubly doped lithium niobate crystals 

Nature 393, 665-668 (18 June 1998)
Photorefractive materials are being widely investigated for applications in holographic data storage1. Inhomogeneous illumination of these materials with an optical interference pattern redistributes charge, builds up internal electric fields and so changes the refractive index.

Subsequent homogeneous illumination results in light diffraction and reconstructs the information encoded in the original interference pattern. A range of inorganic and organic photorefractive materials are known2, in which thousands of holograms of high fidelity can be efficiently stored, reconstructed and erased. But there remains a problem with volatility: the read-out process usually erases the stored information and amplifies the scattered light. Several techniques for 'fixing' holograms have been developed3, 4, 5, 6, but they have practical disadvantages and only laboratory demonstrators have been built7, 8, 9, 10. Here we describe a resolution to the problem of volatility that should lead to the realization of a more practical system. We use crystals of lithium niobate — available both in large size and with excellent homogeneity — that have been doped with two different deep electron traps (iron and manganese). Illumination of the crystals with incoherent ultraviolet light during the recording process permits the storage of data (a red-light interference pattern) that can be subsequently read, in the absence of ultraviolet light, without erasure. Our crystals show up to 32 per cent diffraction efficiency, rapid optical erasure of the stored data is possible using ultraviolet light, and light scattering is effectively prevented. PERMALINK

K. Buse1, A. Adibi1 and D. Psaltis1

  1. California Institute of Technology, Department of Electrical Engineering, Pasadena, California 91125, USA

 

 

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