(Color online) Schematic setup of the LCLV single feedback system including external amplitude control. Concept of the external amplitude control (forcing). A digital projector DP images a incoherent intensity distribution, which is used as forcing, onto the LCLV. The polarizers PO2, PO3, and PO4 adjust forcing intensity and polarization state.
(Color online) Exemplary bistability curve of the phase in relation to the pump intensity . In the ranges between (◇) and (엯) patterned system states are observed. Feedback solitons spontaneously form in the region where a uniform lower state coexists with a patterned upper state.
Position control using an external incoherent amplitude control. (a) The uncontrolled system; the feedback solitons experience interaction and are located only in a small part of the aperture due to inhomogeneities. (b) The spatial distribution of the external control consists of a quadratic lattice with Gaussian shaped peaks at the lattice points. (c) The feedback solitons are positioned by the external control. The bottom right corner of the experimental images shows the far field (Fourier transform).
(Color online) Images of a sequence with a complete addressing scheme. Top: signal of the external amplitude control. Bottom: write intensity of the LCLV feedback system. A detailed description can be found in the text.
(Color online) Intensity vs time plot of a repeated complete addressing scheme. The intensity of the external amplitude control in arbitrary units (line). The intensity of a single addressing position (dashed line). The maximum temporal resolution of the CCD camera is .
(Color) Intensity profile of the cone used as external amplitude control for the investigation of gradient dependent drift velocities.
(Color online) Motion of a feedback soliton at a cone-shaped intensity gradient. The background depicts the system response to the cone gradient without a feedback soliton (inverted gray scale). The trajectory of the feedback soliton, which moves from right to left, is denoted by 엯. Additionally the local gradients are marked with arrows.
(Color online) Averaged velocity of a feedback soliton vs variable intensity gradient. For each data point an average over five measurements has been taken. The error bars are the standard deviation of the data points. The gradient is measured in gray scale (gs) per pixel (px) of the forcing master. The dashed line is a guide to the eye.
(Color online) Position-dependent velocity (+) of a single feedback soliton moving at a cone gradient and absolute value of the local gradient .
(Color online) Feedback soliton motion in an hexagonally shaped gradient. Measurements at different wave numbers of the forcing hexagon. (a) . (b) . (c) . Top row: addressing of feedback solitons. Center row: final equilibrium state. Bottom: inverted gray scale image of the pure hexagonal gradient with indication for the addressing position (∗), the final equilibrium position (엯), and the local extrema of the hexagonal grid (+).
Plot of the quality of trapping (엯), (◻) induced by the hexagonal forcing against the wave number of forcing. has been determined from absolute distances in real space, while is derived from a Fourier analysis. The line is a mere guide to the eye.
(Color online) Optical Fourier transform of the center column of Fig. 10 (wave number hexagon forcing: ). (a) Hexagonal gradient only; (b) addressing of optical feedback solitons. The markers indicate the Fourier modes, which are selected for analyzing the system state. For details of the analysis, please refer to the text. (c) Final equilibrium state. The images depict an inverted gray scale.
Sequence with dynamic positioning of optical feedback solitons. A section of the aperture is shown. Left column: signal of the forcing movie. Right column: the response of the feedback solitons. The feedback solitons ignite at the right, while the forcing input, which consists of a chessboard pattern, moves to the left. The feedback solitons follow the motion of the forcing input. The reference lines illustrate the movement. The time interval between the images is .
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