Light can focus atoms into simple patterns for etching carbon-coated gold layers. Sending the atoms through holographically generated light can create periodic designs and may help grow precisely designed crystals. Image courtesy of Phys. Rev. Lett. 88, 083601 (2002)
Above: Microbeads immersed in liquid floated freely at first (left) but gradually formed small crystals (right, 10 days later) in an experiment aboard the Space Shuttle. Larger crystallites devour smaller ones, even early on, when they are far apart, according to work that aims to elucidate the details of crystallization. Image courtesy of NASA and Princeton University.
Researchers dream of building crystals from the ground up to achieve tight control of their periodic structure. One approach to 3D patterning envisions steering atomic beams with a maze of laser light, but creating complicated light patterns isn't easy. Now a team reports that a so-called holographic crystal can efficiently generate more complex stencils for atoms. With a single incoming laser, the researchers generated a three-beam interference pattern and etched a periodic design onto a gold surface. The method could theoretically accommodate 1000 beams and make intricate structures, such as photonic crystals--a new technology that may lead to "circuits of light."