Fabrication of Photonic Crystal Cavities for Terahertz Wave Resonations

Photonic crystals with periodic arrangement of dielectric media can exhibit forbidden gaps in electromagnetic wave bands through Bragg diffraction (Ohtaka; 1979, Yablonovitch; 1987, John; 1987, Temelkuran; 2000). The prohibited frequency ranges are especially called photonic band gaps. If the periodicity is changed locally by introducing a defect, localized modes appear in the band gap (Ho; 1990, Soukoulis; 1999, Noda; 1999, Kirihara; 2002a, Kanehira; 2005). Such localization function of electromagnetic waves can be applied to various devices, for example resonators, waveguides, and antennas. Three dimensional photonic crystals with a diamond structure are regarded as the ideal photonic crystal since they can prohibit the propagation of electromagnetic waves for any directions in the band gap (Ho; 1990, Kirihara; 2002b). However, due to the complex structure, they are difficult to fabricate. In our previous investigations, we have succeeded in fabricating micrometer order diamond structures by using stereolithography method of a computer aided design and manufacturing (CAD/CAM) processes (Chen; 2007a, 2007b, 2007c, 2008, Kanaoka; 2008, Miyamoto; 2008). Subsequently, structural modifications of the diamond lattice structures to control the terahertz wave propagations were investigated by using the CAD/CAM process practically (Takano; 2005, Kirihara; 2009, 2008a, 2008b). In near future industries, electromagnetic waves in a terahertz frequency range with micrometer order wavelength will be expected to apply for various types of novel sensors which can detect gun powders, drugs, bacteria in foods, micro cracks in electric devices, cancer cells in human skin and other physical, chemical and living events (Kirihara; 2009b, Exter; 1989, Clery; 2002, Kawase; 2003, Woodward; 2003, Wallace; 2004, Oyama; 2008). In this chapter, the novel stereolithography process to fabricate the micro diamond photonic crystals by using the ceramic slurry with the nanoparticles will be introduced. And, the resonation and localization properties of the terahertz waves into various types of the structural defects introduced according to theoretical electromagnetic simulations will be demonstrated.