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The creation of large-area, unintentional-defect-free three-dimensional (3D) photonic crystals in the optical regime is a key challenge toward the realization of the arbitrary 3D manipulation of photons. In this article, we discuss an advanced fabrication method of 3D silicon photonic crystals based on the highly accurate alignment and wafer bonding of silicon-on-insulator (SOI) wafers. We introduce an advanced alignment system, in which the alignment process is automated by image recognition and feed-back control of stages, and show that it achieves an alignment accuracy better than ~50 nm. The bonding of SOI wafers is also investigated to obtain 3D crystals composed of highly pure crystalline silicon. We show the fabrication results of large-area 3D photonic crystals based on such considerations and demonstrate the successful introduction of artificial defects as functional components, such as coupled waveguide pairs or waveguides/nanocavities. We expect that these will be pioneering results toward the arbitrary 3D control of photons using 3D photonic crystals.

We investigate the transmission of light through three-dimensional structures in opal-like plasmonic-photonic crystals with an Au surface layer of different geometries. We study how the inclusion of buffer layers of various forms affects the spectral characteristics of the structures. Three-dimensional photonic crystals have significant advantages over one-dimensional ones since they display a complete photonic bandgap and porosity. Controlling the spectral characteristics of the hybrid plasmonic-photonic mode is an important task that offers the possibility of creating tunable devices based on such structures. In this work we show that the optical properties of structures with different shapes of the surface layer do not depend on light polarization, except for structures with a corrugated Au layer and a corrugated buffer layer. The bandwidth of a structure with a corrugated Au layer is smaller and shows polarization sensitivity in contrast to a structure with a smooth Au layer. The optical characteristics of hybrid structures undergo significant changes when buffer layers of various shapes are introduced between the photonic crystal and the Au layer. The width of the peak in the transmission spectra changes and its intensity increases against the background after the improvement of the structure of the plasmonic-photonic crystal. Thus, opal-like plasmonic-photonic crystals with different structure of the surface layer have spectral features that can be used in integrated circuits, biosensors, and resonators. • The inclusion of buffer layers of various forms affects the spectral characteristics of the plasmonic-photonic crystal. • The optical properties of different structures do not depend on light polarization. • As an exception, the bandwidth of a structure with a corrugated Au&buffer layers shows polarization sensitivity. • The width and intensity of the peak changes after the improvement of the plasmonic-photonic crystal. [ABSTRACT FROM AUTHOR]