Field and time thresholds for the electrical fixation of holograms recorded in (Sr0.75Ba0.25)Nb2O6 crystals

Micheron, F.; Bismuth, G.

doi:10.1063/1.1654811

Cited by 79 publications

(15 citation statements)

References 5 publications

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“…We were able to reproduce some of the effects that Micheron and Bismuth reported in Ref. 5, but our observations were different in several important respects. In addition, we report two novel ways of electrically fixing holograms in SBN:75 that give improved performance and demonstrated that holograms of images can be fixed and faithfully reproduced.…”

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confidence: 58%

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Electrical fixing of photorefractive holograms in Sr_075Ba_025Nb_2O_6

1993

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Photorefractive holograms stored in SrO 7 MBaO.2 5 Nb 2 0 6 crystals are electrically fixed at room temperature. The fixed holograms can be read out directly or after a positive-voltage pulse is applied that can dramatically enhance the diffraction efficiency. Single gratings as well as images are recorded and fixed.Volume holograms recorded in photorefractive materials can find important applications in optical memories and optical computing systems. One problem with a photorefractive hologram is that it gets erased by the readout light. Nondestructive readout can be achieved by hologram fixing, and several fixing methods have been reported. by cooling the exposed crystal under an applied field through the ferroelectric phase transition. 8 In general, electrical fixing is preferable from a practical point of view because of its relative simplicity.In this Letter we report the results of our investigation on electrical fixing of photorefractive holograms recorded in SBN:75. We were able to reproduce some of the effects that Micheron and Bismuth reported in Ref. 5, but our observations were different in several important respects. In addition, we report two novel ways of electrically fixing holograms in SBN:75 that give improved performance and demonstrated that holograms of images can be fixed and faithfully reproduced.The crystal sample used in the experiment was grown and poled at Rockwell International Science Center. It has dimensions of 6 mm X 6 mm x 6 mm, with its c axis parallel to the edges. An eternal electric field can be applied along the c axis, and it is called positive (negative) if its direction is same as (opposite) that of the initial poling filed. In our experimental setup (Fig. 1), an ordinary-polarized plane wave from an argon laser (A = 488 nm) is split into three beams, two of which are used for recording a grating in the crystal, with the third used as a nonBragg-matched erasing beam. The grating vectors are approximately parallel to the c axis and the total recording intensity is -10 mW/cm 2 . The diffraction efficiency 9 is monitored with a low-intensity, extraordinary-polarized He-Ne laser beam incident at the Bragg angle. The diffraction efficiency is calculated by subtracting the background noise level from the measured diffracted light and dividing the difference by the transmitted light power.In the first experiment, a holographic grating with a grating spacing A = 11.6 1 ttm was recorded in the completely poled crystal without any applied field. After the diffraction efficiency Y7 reached its saturation value (-q = 11%), the recording beams were blocked, and a negative-voltage pulse with amplitude V = -1 kV and duration t = 0.5 s was applied to the crystal, which caused 77 to fall quickly. After the voltage pulse was removed, 77 recovered a portion of its initial value before the pulse. Then the crystal was illuminated with the non-Bragg-matched erasing beam, and q, decreased further until it reached a steady-state value of 'i 0.06%. This fixed grating could not be erased by the er...

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confidence: 58%

“…2 with Ref. 5, we see that we were "able to achieve electrical fixing, but the fixed grating obtained in our experiment is much weaker than that in Ref. 5.…”

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confidence: 64%

Electrical fixing of photorefractive holograms in Sr_075Ba_025Nb_2O_6

1993

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“…The hologram diffraction comprises a dynamic component, with a characteristically fast response time, and a fixed component, with a much slower response and a lifetime that is several orders of magnitude larger than that of the dynamic grating. This dependence of relaxation rate on exposure level was first reported by Thaxter and Kestigian,1 4 who measured a fixed component with a lifetime of several minutes. We obtain a significant fixed component by simply writing holograms with an incident intensity greater than 1 W/cm 2 for a duration of 2 min or more, or an exposure level of 100 J/cm 2 .…”

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confidence: 80%

Selective page-addressable fixing of volume holograms in Sr_075Ba_025Nb_2O_6 crystals

et al. 1993

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“…Replication of photorefractive space-charge density is achieved through spontaneous polarization modulation in strontium barium niobate (SBN : 75) [98] and barium titanate BaTiO [99]. Thus, the hologram grating exists in the variations in the local spontaneous polarization of a noncentrosymmetic crystal in the form of microdomains whose parameters (density and average length) are correlated with the original electronic space charge [100].…”

Section: Other Techniques For Nondestructive Readoutmentioning

confidence: 99%

Holographic Data Storage Systems

Hesselink

1993

[1993] Digests of International Magnetics Conference

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Field and time thresholds for the electrical fixation of holograms recorded in (Sr0.75Ba0.25)Nb2O6 crystals

Cited by 79 publications

References 5 publications

Electrical fixing of photorefractive holograms in Sr_075Ba_025Nb_2O_6

Electrical fixing of photorefractive holograms in Sr_075Ba_025Nb_2O_6

Selective page-addressable fixing of volume holograms in Sr_075Ba_025Nb_2O_6 crystals

Holographic Data Storage Systems

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