Abstract: An optical device (34, 66, 76) includes an electro-optical layer (48), having an effective local index of refraction at any given location within an active area of the electro-optical layer that is determined by a voltage waveform applied across the electro-optical layer at the location. Conductive electrodes (44, 64, 74, 82, 84) extend over opposing first and second sides of the electro-optical layer. The electrodes include an array of excitation electrodes, which extend along respective, mutually-parallel axes in a predefined direction across the first side of the electro-optical layer, and which includes at least first and second electrodes having different, respective widths in a transverse direction, perpendicular to the axes. Control circuitry (38) is coupled to apply respective control voltage waveforms to the excitation electrodes so as to generate a specified phase modulation profile in the electro-optical layer.

Abstract: A method for encoding information includes specifying a digital value and providing a symbol (28, 70, 80, 90, 100) comprising a plurality of polygons (72, 82, 92, 94, 102) meeting at a common vertex (74, 84, 96, 98, 104) and having different, respective colors selected so as to encode the specified digital value.

Abstract: A method for encoding information includes specifying a digital value and providing a symbol (28, 70, 80, 90, 100) comprising a plurality of polygons (72, 82, 92, 94, 102) meeting at a common vertex (74, 84, 96, 98, 104) and having different, respective colors selected so as to encode the specified digital value.

Abstract: An optical device (24, 60) includes an electro-optical layer (40, 62), having an effective local index of refraction at any given location within an active area of the electro-optical layer that is determined by a voltage waveform applied across the electro-optical layer at the location. An array of excitation electrodes (46, 68, 72), including parallel conductive stripes extending over the active area is disposed over one or both sides of the electro-optical layer. Control circuitry (48, 70, 74) is coupled to apply respective control voltage waveforms to the excitation electrodes and is configured to concurrently modify the respective control voltage waveforms applied to excitation electrodes so as to generate a specified phase modulation profile in the electro-optical layer.

Abstract: A method for encoding information includes specifying a digital value and providing a symbol (28, 70, 80, 90, 100) comprising a plurality of polygons (72, 82, 92, 94, 102) meeting at a common vertex (74, 84, 96, 98, 104) and having different, respective colors selected so as to encode the specified digital value.