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Three-dimensional (3D) photonic crystals with a diamond structure made from 40 vol% TiO2–acrylate dielectric composites were formed by means of a CAD/CAM micro-stereolithography system. The lattice constant of the diamond unit cell was 500 μm and the forming accuracy was 10 μm. The photonic band gap in the Γ–X 〈100〉 direction measured by terahertz-time-domain spectroscopy appeared at 280–360 GHz, which agreed fairly well with the band gap calculated by the plane wave expansion method. [ABSTRACT FROM AUTHOR]

Ceramic photonic crystals with diamond structure were fabricated using stereolithography and successive sintering. The green body of an epoxy resin incorporating 10 vol% TiO2–SiO2 was formed by stereolithography and then heated in air at 1100°–1400°C for 2 h. The sintered products maintained the diamond structure with a linear shrinkage ratio of about 57% and a porosity of 38%. The ceramic photonic crystal with eight unit cells showed a photonic band gap at the center frequency of 23.5 GHz. This fabrication method of three-dimensional (3D) ceramic photonic crystals is applicable to other 3D structural ceramics and does not require any molding techniques. [ABSTRACT FROM AUTHOR]

Millimeter-order photonic crystals with the periodic arrangement of the dielectric constant were fabricated by infiltrating the mixed slurry of ceramics and polyester into the epoxy molds with an inverse form of a diamond structure. The epoxy molds are designed and processed by using a CAD/CAM process of stereolithography. The photonic crystals were prepared to have the diamond structure of the ceramic/polyester composite lattice, which is embedded in the epoxy matrix. The ceramic powders mixed with polyester are TiO2, SrTiO3, and BaTiO3 with high dielectric constant. It is possible to control more freely and widely the dielectric constant of the photonic crystals by this method. These ceramic/resin photonic crystals formed the complete photonic band gaps in the microwave band of 7–11 GHz, which can totally reflect the electromagnetic wave for all crystal directions. Attenuation profiles of the transmission amplitude in the band gaps were controlled with the dielectric constant of the composite lattice. The obtained results fairly agreed with the theoretical simulation of the electromagnetic wave propagation through photonic crystals. [Copyright &y& Elsevier]

Photonic crystals with a diamond structure of epoxy lattices in which TiO[sub 2]-based ceramic particles are dispersed were fabricated by stereolithography. The periodicity of the lattice was designed to reflect electromagnetic waves in the gigahertz range. The volume fraction (β) of the dielectric lattice medium was modified from 14% to 33% by changing the rod diameter of the lattice. The photonic band gap was observed along Γ-L 〈111〉, Γ-X 〈100〉, and Γ-K 〈110〉 directions and the complete photonic band gap was formed at over β = 20%. The width of the forbidden gap increased gradually when the β increased over 14%, and reached 2.4 GHz at β = 33%. These results agreed with the band calculation using the plane wave expansion method. [ABSTRACT FROM AUTHOR]

Presents a study which investigated the electromagnetic properties of photonic crystals with diamond structure containing defects. Types of lattice defects in a diamond structure; Calculation of resonant frequencies in the defects; Properties of photonic crystals.

This letter reports an approach, based on microstereolithography, to create three-dimensional photonic crystals of microscale structure made of ceramic-resin composite (before sintering) and dense ceramics (after sintering). For ZrO2 toughened Al2O3 ceramic-resin photonic crystals (with a lattice constant of 500 μm), the forming resolution was around 10 μm and the measured band gap appeared between 350 and 400 GHz in the Γ-X <100> direction, 350 and 400 GHz in the Γ-K <110> direction, and 270 and 360 GHz in the Γ-L <111> direction. After sintering, the lattice constant shrunk to 380 μm and the band gap was between 320 and 420 GHz in the Γ-X <100> direction, 330 and 400 GHz in the Γ-K <110> direction, and 260 and 355 GHz in the Γ-L <111> direction. [ABSTRACT FROM AUTHOR]

Fabricates the three-dimensional photonic crystals with periodic variations in the dielectric constant using stereolithographic rapid prototyping method. Formation of photonic band gaps in a gigahertz range; Attenuation of transmission amplitude; Composition of structures of millimeter-scale ordered epoxy lattices.

Abstract: Fabrication process for three-dimensional ceramic photonic crystals with a diamond structure was investigated. A diamond structure composed of epoxy lattice including SiO2–TiO2 ceramic particles at 10vol.% was fabricated as a precursor by stereolithography. After burning off the epoxy resin in air, the diamond structure of SiO2–TiO2 was successfully sintered at 1400°C for 2.5h. The linear shrinkage ratio was 50%. Cracks were not found in the sintered diamond structure. Photonic bandgap was observed at around 19GHz. [Copyright &y& Elsevier]

Abstract: Photonic fractal with self-similar structure of dielectric medium can strongly localize the electromagnetic wave energy in the three-dimensional fractal structure. We have fabricated Menger-sponge fractal structures of epoxy by using stereolithography. Titania–silica particles were dispersed into the epoxy to increase the dielectric constant and decrease the dielectric loss. The samples have square holes of 1, 3, 9 and 27mm in edge length through the cubic body of 81mm. Four types of Menger-sponge samples with fractal stages 1–4 were subjected for measurement of microwave responses. The both reflection and transmission amplitudes were attenuated simultaneously at frequencies of 9.5, 10.5, 12.0 and 13.5GHz for each sample with fractal stages 1, 2, 3 and 4, respectively. The electromagnetic field amplitudes in the air holes measured by inserting a mono-pole antenna probe confirmed the strong localization of the electromagnetic wave in the central air cavity. The localized mode frequency can be calculated using the sample size, number of stage, and the effective dielectric constant. The localization efficiency increased according to the fractal stage number. [Copyright &y& Elsevier]