O. Jakoby’s research while affiliated with Technical University of Darmstadt and other places

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Publications (3)


Experimental synchronization of periodic patterns and spatiotemporal chaos
  • Conference Paper

July 2003

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6 Reads

B. Gutlich

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O. Jakoby

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T. Tschudi

Spatial synchronization effects are found in a nonlinear optical single-feedback system. If perfect hexagonal patterns are injected, several synchronization regimes are observed. For the coupling of spatiotemporally disordered structures, also indication for synchronization is found.


Spatial synchronization of regular optical patterns

July 2003

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7 Reads

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13 Citations

Physical Review E

We investigate an extended, nonlinear optical experiment, exhibiting the spontaneous formation of hexagonal patterns out of a stationary bifurcation. The system is exposed to a two-dimensional spatially periodic forcing, namely, static hexagonal patterns, under variation of their spatial periodicity. Parameters are the strength of the forcing and the distance to pattern forming threshold. The system response is quantitatively characterized with different methods. We observe several locking regimes, where the system is entrained by the forcing. Most of the locking regimes can be related to resonances between the different critical wave numbers and the forcing wave number or its spatial harmonics. One particular locking appears to result from two of these simple resonances in a kind of generalized order m:n synchronization. The width of the locking regimes increases with forcing strength, apparently representing a spatial analog of Arnold tongues.


Utilizing nonlinear optical pattern formation for a simple image-processing task

April 2003

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5 Reads

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3 Citations

Applied Physics B

A novel scheme for all-optical image processing is suggested, which is based on spontaneous pattern-formation processes. The spatiotemporal instabilities, connected with these self-organization effects, appear in many nonlinear optical systems and mostly obstruct the intended application. We propose to utilize the particular features of pattern formation for parallel image processing, namely the sensitivity to external influences, the selection of well-defined final states, and the rotational and translational invariance. We report here on a single-feedback experiment with a liquid crystal light valve as the optical nonlinearity. In this experiment, the recognition of hexagonal structures is realized. We characterize the response dynamics and study associative properties of this scheme. The extension to square patterns is discussed, and first steps towards a practical implementation are undertaken in providing a simple post-processing scheme and testing the concept on realistic input images.

Citations (2)


... An investigation of the temporal evolution of spontaneously formed optical patterns from an initial seed pattern is also interesting in the context of optical parallel image processing, but only a few studies have been reported. Recently, the formation of such patterns from seed optical patterns, which are continuously supplied by an external source, has been investigated in some nonlinear optical systems, and a spatial frequency filtering effect, spatial locking, and spatial synchronization were observed [19,20]. ...

Reference:

Optical image processing using an optoelectronic feedback system with electronic distortion correction
Utilizing nonlinear optical pattern formation for a simple image-processing task
  • Citing Article
  • April 2003

Applied Physics B

... These outcomes may have important implications for practical applications of spatial forcing in various fields of science including nonlinear optics [24,25] and restoration ecology. An interesting example of the latter field is rehabilitation of banded vegetation on hill slopes by water harvesting [26]. ...

Spatial synchronization of regular optical patterns
  • Citing Article
  • July 2003

Physical Review E