Additive Manufacturing and Strategic Technologies in Advanced Ceramics: Ceramic Transactions

Stereolithographic additive manufacturing was customized successfully to create micro ceramics components. Photo sensitive acrylic resin with alumina of 170 nm in diameters was spread on a glass substrate with 5 to 10 m in layer thickness by using a mechanical knife edge. Cross sectional layers patterned by ultraviolet laser scanning of 10 to 100 m in variable diameter were laminated to create composite precursors. Dense components could be obtained through dewaxing and sintering heat treatments. Photonic crystals with periodic arrangements in magnetic permeability were created to control electromagnetic waves in terahertz frequency range by Bragg diffraction. The terahertz waves can synchronize with vibration modes of various biochemical molecules. Efficient terahertz wave resonators to excite the molecule vibrations will be specifically applied for novel analyzers and reactors. The photonic crystals including micro cavities were designed and fabricated successfully to resonate with microwaves in terahertz frequency range. The wave transmittances through the photonic crystals including the liquid cells were measured by using a terahertz time domain spectroscopy, and cross sectional profiles of electric field intensities were calculated by a transmission line modeling method. INTRODUCTION Periodic arrangements in dielectric constants can reflect electromagnetic waves through Bragg diffraction. Especially called photonic crystals theoretically exhibits forbidden gaps prohibiting wave transmissions1. The diffraction wavelengths are comparable to the lattice constants. Diamond type micro lattices with isotropic periodicities were processed as the perfect structure to open the photonic band gaps for all crystal directions2. However, special lattice propagations were difficult to create by conventional machining of molding processes. In our investigation group, ceramics photonic crystals with diamond structures were created by stereolithographic additive manufacturing and nanoparticles sintering. The band gap formation in the terahertz frequency ranges had been observed3. In this investigation, single and double cavities were introduced into the diamond photonic crystals in order to study the characteristic resonance modes by using computer aided design, manufacture and evaluation. These structural misfits can localize the electromagnetic waves strongly through multiple reflections, and wave amplification can realize transmission peak formations in the photonic band gaps according to the defect size3.