Embedded cavities and waveguides in three-dimensional silicon photonic crystals

To fulfil the promise that complete-photonic-bandgap materials hold for optoelectronics applications, the incorporation of three-dimensionally engineered defects must be realized. Previous attempts to create and characterize such defects were limited because of fabrication challenges. Here we report the optical and structural characterization of complex submicrometre features of unprecedented quality within silicon inverse opals. High-resolution three-dimensional features are first formed within a silica colloidal crystal by means of two-photon polymerization, followed by a high-index replication step and removal of the opal template to yield embedded defects in three-dimensional silicon photonic crystals. We demonstrate the coupling of bandgap frequencies to resonant modes in planar optical cavities and the first waveguiding of near-infrared light around sharp bends in a complete-photonic-bandgap material.