20 February 2007 Quasi in situ microscopic study of hologram build-up in LiNbO3 crystals
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Abstract
Interference microscopy was applied to direct microscopic observation of temporal evolution of phase holograms in LiNbO3:Fe photorefractive crystals. First a hologram was recorded in the sample, and diffraction efficiency was monitored during hologram build-up using inactinic laser light. Thus kinetics of hologram build-up could be determined. The initial hologram was erased using white light. Then a series of write-erase cycles were performed with increasing exposure times. Holograms were observed by interference microscope after each exposure. The time elapsed between the exposure and the microscopic observation was negligible compared to the relaxation time of the hologram. The obtained temporal evolution of grating profile gives a deeper insight into the physical mechanism of hologram formation in photorefractive materials than simple diffraction efficiency measurements. A congruently grown sample of LiNbO3 doped with 10-3 mol/mol Fe in melting was studied by the method above. Sample thickness was set to 300 &mgr;m to allow correct microscopic observation. Plane-wave holograms were recorded in the samples using an Ar-ion laser at &lgr; = 514 nm of grating constants of 3, 6.5 and 8.8&mgr;m.
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István Bányász, István Bányász, Gábor Mandula, Gábor Mandula, "Quasi in situ microscopic study of hologram build-up in LiNbO3 crystals", Proc. SPIE 6488, Practical Holography XXI: Materials and Applications, 648808 (20 February 2007); doi: 10.1117/12.701887; https://doi.org/10.1117/12.701887
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