Realization of three-dimensional guiding of photons in photonic crystals

Three-dimensional photonic crystals(1-10) are expected to provide a fundamental building block for the realization of three-dimensional manipulation of photons. However, because of the lack of systematic design principles to precisely control bending and guiding in three dimensions, as well as advancements in the fabrication technology necessary for the realization of large-area, defect-free three-dimensional photonic crystals, the arbitrary three-dimensional manipulation of photons has yet to be demonstrated. Here, we develop a new design concept for three-dimensional waveguides and bends, and realize it experimentally in silicon three-dimensional photonic crystals. We demonstrate clear three-dimensional optical guiding phenomena, in which light is incident on the crystal from one side, is bent vertically and horizontally (and is even split into two or trapped by an intermediate nanocavity), and is finally emitted from the other side of the crystal. These results will open the door to the realization of three-dimensional optical c hips with various functionalities.