3-D Light Channels
Miniature waveguides can steer light through solid materials in three dimensions.
Source: “Embedding cavities and waveguides in three-dimensional silicon photonic crystals”
Paul V. Braun et al.
Nature Photonics 2: 52-56
Results: Researchers at the University of Illinois, Urbana-Champaign, have developed a laser technique that can carve detailed, three-dimensional waveguides into silicon photonic crystals, materials with regularly spaced holes that can control the motion of photons.
Why it matters: Optical chips, which use photons instead of electrons to carry information, could speed up computers, because photons travel faster than electrons. They could also cheaply increase bandwidth in telecommunications equipment. Previously, researchers made flat, two-dimensional waveguides using lithography, a common chip-making technique. But a way to make three-dimensional waveguides gives researchers more freedom in designing optical circuits: light can be bent around corners, and optical materials can be layered.
Methods: To build their photonic crystal, the researchers began by packing silica beads together to form a three-dimensional matrix. They immersed the beads in a light-sensitive monomer, which flowed into the spaces between the beads. A precise laser beam solidified some of the monomer into “paths” of polymer. Then the researchers rinsed the structure, removing the excess monomer, and filled the remaining spaces between beads with silicon. Finally, they used an acid to dissolve the beads and the polymer, leaving a silicon structure with periodic holes where the beads had been and channels–waveguides–where the polymer paths had been.
Next steps: The researchers are creating waveguide designs that are more complex. They will also explore ways to build functional optical circuits.