Before 2005

E DelRe, B Crosignani, M Tamburrini, M Segev, M Mitchell, E Refaeli, and AJ Agranat. 1998. “One-dimensional steady-state photorefractive spatial solitons in centrosymmetric paraelectric potassium lithium tantalate niobate.” Optics Letters 23 (6), Pp. 421 - 423. Publisher's Version Abstract

We report the first observation of spatial one-dimensional photorefractive screening solitons in centrosymmetric media and compare the experimental results with recent theoretical predictions. We find good qualitative agreement with theory. (C) 1998 Optical Society of America.

Eugenio DelRe, Mario Tamburrini, Mordechai Segev, Eli Refaeli, and Aharon J Agranat. 1998. “Two-dimensional photorefractive spatial solitons in centrosymmetric paraelectric potassium–lithium–tantalate–niobate..” Applied Physics Letters, 73, 1. Publisher's Version Abstract

We report the observation of steady-state two-dimensional photorefractive self-trapping and screening spatial soliton formation in a sample of potassium–lithium–tantalate–niobate in the centrosymmetric paraelectric phase. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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M Balberg, M Razvag, E Refaeli, and AJ Agranat. 1998. “Electric field multiplexing of volume hologram in paraelectric crystals.” Applied Optics , 37, Pp. 841-847. Abstract
Electric-field multiplexing (EFM) results from the tuning of the effective wavelength of the light beam inside a photorefractive crystal. This tuning results from the application of an external electric field to the crystal during holographic recording. We demonstrate the high Bragg selectivity of this multiplexing technique in paraelectric crystals and compare it with the selectivity obtained in the ferroelectric phase. The effects of the two major physical parameters of working in the paraelectric phase, the temperature and the external electric field applied during the writing stage, are investigated. Experimental results of the EFM of three image-bearing holograms recorded in reflection geometry are presented along with a qualitative analysis of the Bragg selectivity in paraelectric crystals.
O Levi, G Perepelitsa, D Davidov, AJ Agranat, I Benjamin, S Shalom, R Neumann, and Y Avny. 1998. “Holographic Storage in Conjugated Polymers Composites.” Phys. Rev. B Rapid Comm., 57, Pp. 12647-12650. Abstract
We report here on the fabrication and optimization of composites of conjugated polymer in Sol-Gel and PVA matrices. FTIR spectroscopy as well as other observations show that efficient phase and absorption holograms can be created in the material upon illumination, via the photochromic effect. The main contribution to the absorption change is chain scission and photo-oxidation mechanism. Optimized holographic composites with diffraction efficiencies as high as 26% are shown. Beam interaction between the writing beams is observed for these composites, while the diffraction efficiencies was improved by an order of magnitude.
AJ Agranat, M Razvag, M Balberg, and V Leyva. 1997. “Dipolar holographic gratings induced by the photorefractive process in potassium lithium tantalate niobate at the paraelectric phase.” J. Opt. Soc. Am. B 14 (8), Pp. 2043 - 2048. Publisher's Version Abstract
We present experimental evidence indicating the formation of dipolar holographic gratings in potassium lithium tantalate niobate at the paraelectric phase slightly above the phase transition, These gratings are formed in the dark, following the writing of space-charge-based photorefractive gratings, under an external electric field. The dipolar gratings create a spatial modulation of the low-frequency dielectric constant, and the latter induces a spatially correlated modulation of the polarization, which is transformed into birefringence gratings through the quadratic electro-optic effect. (C) 1997 Optical Society of America.
M Balberg, M Razvag, S Vidro, E Refaeli, and AJ Agranat. 1996. “Electroholographic neurons implemented on potassium lithium tantalate niobate crystals.” Optics Letters , 21, 19, Pp. 1435-1439. Abstract
We describe a new approach for constructing large-scale artificial neural networks. The novelty of our approach is based on the concept of electroholography (EH), which permits interconnecting of electronic neurons by minute-volume holograms, using the voltage-controlled photorefractive effect in paraelectric crystals. Crystals of potassium lithium tantalate niobate (KLTN) in the paraelectric phase are shown to be suitable for implementing this concept. A small network composed of two KLTN crystals on which holographic connections are recorded is presented to demonstrate the EH approach.
AJ Agranat, O Schwartzglass, and J Shappir. 1996. “The charge controlled analog synapse.” Solid State Electronics 39 (10), Pp. 1435 - 1439. Publisher's Version Abstract
A generic circuit, the charge controlled analog synapse (CCAS) is presented. The CCAS is designed to be the basic building block in microelectronic realizations of large scale artificial neural networks. It is based on representing the synaptic strength as a charge packet which controls the junction capacitance of a reverse biased diode. The CCAS is a synapse with three main features: (i) a small cell with few components per cell; (ii) a short term dynamic memory, and (iii) a variable accuracy which depends on the cell size. The principle of operation of the CCAS is explained. Details of the design of a first prototype are given. Experimental results which substantiate the theoretical predictions are presented. Finally, the basic properties of the CCAS are discussed. Copyright (C) 1996 Elsevier Science Ltd
Offer Schwartzglass and Aharon J Agranat. 1996. “Letter: VLSI implementation of pulsating neural networks.” Neurocomputing, 10, Financial Applications, Pp. 405 - 413. Publisher's Version Abstract
We describe a generic approach for realizing networks of pulsating neurons based on charge pumping of interface states situated in the channel of MOS transistors. Two basic building blocks will be described: the pulse activated charge pumping (PSCP) synapse, and the charge sensitive oscillator (CSO). The PSCP synapse which operates as either a short or a long term memory device which produces a charge packet proportional to the number of pulses applied to its input, will be described in detail together with experimental results demonstrating its capability. The CSO circuit which is a charge controlled oscillator will be described together with simulations of its output frequency dependence on its input voltage, and the relation between the temporal dependence of output waveform on its input charge.
Accession Number: 0925231296001385; Author: Schwartzglass, Offer (a); Author: Agranat, Aharon J. (∗, a); Affiliation: Division of Applied Physics and the Interdisciplinary Center for Neural Computation, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; Number of Pages: 9; Language: English;
Aharon J Agranat. 1993. “Electro-holographic artificial neural networks.” Physica A: Statistical Mechanics and its Applications, 200, Pp. 608 - 612. Publisher's Version Abstract
A new approach for implementing artificial neural networks (ANNs), based ona novel concept in volume holographic storage-electroholography (EH)-is described. EH is based on the use of paraelectric photorefractive crystals in which the photorefractive mechanism is created in the paraelectric phase. Thus the quadratic electrooptic effect is used to transform the information carrying space charge fields into birefringence gratings, and therefore the diffraction efficiency is governed by an external electric field. This principle enables the construction of a page oriented architecture in which each neuron is implemented as a local electronic circuit, governing the diffraction efficiency of a small volume hologram representing the axon of the neuron. The EH approach is expected to enable the construction of networks with 105−106 neurons, each with 103−104 synapses.
Accession Number: 037843719390566M; Author: Agranat, Aharon J.; Affiliation: Division of Applied Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; Number of Pages: 5; Language: English;

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