Photonic crystals are latticelike structures that can manipulate the flow of light. Materials scientists have now devised a way of making such crystals with complex three-dimensional structures that could serve as the basic elements of optical computers.
The new technique prints 3-D patterns on a surface layer by layer using a specially designed ink. "This allows us to directly write the structures we want," says lead investigator Jennifer Lewis of the University of Illinois at Urbana-Champaign. She and her colleagues describe the process in an upcoming Advanced Materials.
The ink consists of an organic chemical containing titanium mixed with a polymer. A 1-micrometer wide nozzle dispenses filaments of ink as it travels over a silicon wafer. The ink dries rapidly, causing the filaments to solidify. Heating at 600° C burns away the polymer and organic material, leaving behind a structure composed almost entirely of polycrystalline titanium dioxide.