Optical implementation of the Hopfield model

Farhat, Nabil H.; Psaltis, Demetri; Prata, A.; Paek, Eung Gi

doi:10.1364/ao.24.001469

Cited by 547 publications

(153 citation statements)

References 7 publications

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“…If q T min is the minimal acceptable diffraction efficiency when f3,, = 1/R, then the number of exposures that can be recorded and detected is Ao/Vmi,, or {1 + [91(a)/c(a)]2}l/2A/2V-2n. Under the assumption that Tlmin 10-4, Ao/ 2 ?lmin has been shown to reach 10 3 in BaTiO 3 . 3 1 Even more promising results have been obtained in photo-organics.…”

Section: E Practical Implicationsmentioning

confidence: 98%

“…This approach was taken by Mok et al, who recorded more than 1000 expo- At 1-,um resolution, N 1 is 10 4 /cm of aperture. Since the maximum rank is approximately Nl, a 1-cm 3 hologram formed of -10,000 exposures would be nearing its maximum information capacity. Even without taking advantage of complex time constants, the state of the art is not far off this pace.…”

Section: E Practical Implicationsmentioning

confidence: 99%

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Control of volume holograms

Brady

1992

J. Opt. Soc. Am. A

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The mismatch in the number of degrees of freedom supported by volume holograms and the boundary fields that control them limits the dynamic range of recorded holograms. For holograms controlled by using fractal sampling grids, the maximum dynamic range falls inversely with the minimum number of exposures needed to record the hologram, the rank of the hologram. In adaptive holography, feedback between coupled holograms prevents the dynamic range from decreasing faster than the fundamental limit. If the control problem is overcome, the maximum dynamic range that a hologram can support falls inversely with the square root of the rank. In principle, holograms in which the dynamic range falls inversely with the square root of the rank can be recorded by using cross-spectrally coherent polychromatic pulses.

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Section: E Practical Implicationsmentioning

confidence: 98%

Section: E Practical Implicationsmentioning

confidence: 99%

Control of volume holograms

Brady

1992

J. Opt. Soc. Am. A

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“…There are many possible ways to use this mode of real-time control of array response, but the most interesting possibility is the use of control signals derived from internal feedback to effectuate epigenetic development of the complete system response. As research in neural networks elegantly demonstrates, 33,34 control by suitably convolved feedback signals affords a mechanism for learning and adaptive behavior. Figure 6 suggests in a highly idealized way some aspects of visual perception which might be well addressed in such a photoneural system.…”

Section: Photoneural Systemsmentioning

confidence: 99%

Photoneural systems: an introduction

Jones

1987

Appl. Opt.

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Recent developments in technology make feasible the implementation of hybrid optoelectronic processors designed to mimic directly neurological processes of cognition. This paper discusses the practicability and potential utility of a particular class of photoneural device and architecture which is based on neural models of sensory perception. Perception is mediated by a vastly complex hierarchy of processes, but each step in the hierarchy seems to involve relatively simple antagonistic responses which remain topographic coherent when mapped to various subsystems of the brain. The topographic invariance of cognitive data transmission is suggestive of optical imaging operations and is the essential rationale for the design strategy discussed here.

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“…Theoretical calculations have shown that the basic origin of these properties resides in highly chage correlated excited states of the w -electron distribution comprising these structuresX' . Thesog striking properties together with demonstrations of 8 phase conjugate wave generation , optical bistability , and associative memory networks have stimulated considerable growth in research and development activities in centers throughout the world.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Optical Processes In Organic Media: Large Non-Resonant Third Order Electronic Responses In High Performance Liquid Crystal Polymer Structures

Garito

Teng

1986

SPIE Proceedings

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SAbstract. A,,sỸ E..rganic and polymer structures exhibit unusuelw arge, ultrafast second and third ( order nonlinear optical properties in a large number of structures, phase., and states. Rapid advances in the field can be achieved through further development of stable, high performance polymer structures having outstanding secondary properties as demonstrated, for example, by high performance liquid crltal polymers. For two such polymer systems, PBX and PST, third harmonic generation n~asurements show that they possess large nonresonant third order optical susceptibilLties whose origin resides in ultrafast, lossless excitations of highly charge correlated Y-electron states IntroductionPhysical studies have demonstrated that organic and polymer structures possess unusually large, ultrafast second and third order nonlinear optical properties in a large number of material structures, phases, and states that include organic crystas, monomolecular films, polymer structures, liquid crystals and liquid crystal polymersi -. Theoretical calculations have shown that the basic origin of these properties resides in highly chage correlated excited states of the w -electron distribution comprising these structuresX' . Thesog striking properties together with demonstrations of 8 phase conjugate wave generation , optical bistability , and associative memory networks have stimulated considerable growth in research and development activities in centers throughout the world.A wide variety of potential applications in advanced optical technologies are being actively pursued that include optical signal processing and computing, image reconstruction, data storage and telecommuications.The intrinsic response time for electron excitations is ultrafast (10-14 -16-15 sec). In general, a nonlinear optical polarization in a medium involves either resonant absorptive, or non-resonant reactive, nonlinear responses. A reactive nonlinear response is due to lossless virtual optical excitations in the nonlinear medium with no net population changes or any material transformations which do occur in an absorptive response. Examples include non-resonant harmonic generation, frequency mixing, and optical Kerr effects. By far the fastest response times occur in reactive nonlinear media since reactive responses do not involve relatively slow material changes of the nonlinear medium. Moreover, among the possible virtual excitations of reactive responses, electron excitations of order 1-seconds (1 fs) are intrinsically faster than phono 2 excitations -which involve much slower nuclear displacements and vibrations of order W1 2 seconds (1 ps).For large classes of conjugated molecules and polymer structures, the remarkable property is that the nonlinear optical responses are dominated by lgles. virtual excitations of the v-electron states, especially those possessing large charge correlations. LThis property was first demonstrated in second order responses. For example, in crystal--line solids only electronic excitations contribute to second harmonic g...

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Optical implementation of the Hopfield model

Cited by 547 publications

References 7 publications

Control of volume holograms

Control of volume holograms

Photoneural systems: an introduction

Nonlinear Optical Processes In Organic Media: Large Non-Resonant Third Order Electronic Responses In High Performance Liquid Crystal Polymer Structures

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