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Proceedings Paper

Noise reduction in photorefractive memory by double mutually pumped phase conjugate mirrors
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Paper Abstract

In this report, we demonstrate a noise reduction recording in a photorefractive memory with a dynamic refreshing technique by mutually pumped phase conjugate mirrors (MPPCMs). The dynamic refreshing, that means the continuous rewriting of an original hologram with the optical feedback in synchronism with the readout, largely contributes to the maintenance of the recorded hologram by all-optical process. Two MPPCMs are used in the dynamic refreshing technique; one is built for the optical feedback, the other is used as the storage. The nondestructive readout without any fixing technique can be achieved by the continuous rewriting with the beam resonance between the phase conjugate mirrors. Our technique additionally offers the noise reduction of an input image in the recording process without any external image processing systems. The noise reduction is caused by the characteristics of the MPPCM that the incident intensity ratio required for the MPPCM generation is determined by the coupling strength of the crystal. Moreover, the application of the MPPCM to the photorefractive memory brings great advantages of the high quality image retrieving and the simple optical configuration because the illumination of two incoherent beams into a PR crystal can generate the mutual phase conjugate beams in the MPPCM. We show the noise reduction effect is controllable by the appropriate adjustment of the incident beam intensities. We also experiment on the photorefractive memory with this technique using barium titanate crystals and show the high-quality noise-reduced image can be read out over 10 times longer than the conventional readout technique.

Paper Details

Date Published: 17 June 2004
PDF: 8 pages
Proc. SPIE 5362, Advanced Optical and Quantum Memories and Computing, (17 June 2004); doi: 10.1117/12.528224
Show Author Affiliations
Hisatoshi Funakoshi, Hokkaido Univ. (Japan)
Atsushi Okamoto, Hokkaido Univ. (Japan)

Published in SPIE Proceedings Vol. 5362:
Advanced Optical and Quantum Memories and Computing
Hans J. Coufal; Zameer U. Hasan, Editor(s)

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