Controlling smectic focal conic domains by substrate patterning

We describe a simple method to control the generation and the dimensions of focal conic domains in smectic liquid-crystal films. The surface of silicon substrates is structured in a way that areas with homeotropic anchoring conditions alternate with areas possessing random planar anchoring conditions. In smectic films on such substrates, the anchoring pattern translates into a presence-and-absence pattern of focal conic domains. The lateral dimensions of the planar anchoring areas determine an upper limit of the diameter of the focal conic domains. Thus, an almost arbitrary two-dimensional arrangement of focal conic domains can be achieved by controlling the size and position of individual domains.