Development of thermally fixed photorefractive holograms without light |
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Authors: | I Nee M Müller K Buse |
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Institution: | Fachbereich Physik, Universit?t Osnabrück, 49069 Osnabrück, Germany, DE
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Abstract: | Holographic gratings are recorded and thermally fixed in iron-doped photorefractive lithium-niobate crystals. A spatially
modulated concentration of filled and empty electron traps (Fe2+ and Fe3+) yields a modulated dark conductivity. As a consequence, dark diffusion currents and dark drift currents arise. Space–charge
fields and electro-optic refractive-index changes build up. An additional refractive-index grating, which may originate from
a modulated proton concentration, as well as a pronounced absorption grating arising from the modulated Fe2+ concentration are also observed. The dark development has practical advantages: thermally fixed holograms can be used in
devices without the need to develop them freshly from time to time by illumination. Although with dark development diffraction
efficiencies up to 50% are demonstrated, in general the efficiencies are smaller compared to those achieved by development
with light.
Received: 28 June 2000 / Published online: 8 November 2000 |
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Keywords: | PACS: 42 70LN 61 72 -y 72 20 Jv 42 40 Ht |
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