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Abstract: Photonic crystals have many potential applications because of their ability to control light-wave propagation. We report on the fabrication and properties of quasi-two-dimensional photonic crystals with triangular lattices of dielectric rods in air. Rod-type photonic crystal structures were fabricated in silicon by electron beam lithography and dry-etching techniques. Mach–Zehnder interferometers were fabricated from two-dimensional photonic crystal waveguides. Transmission spectra were measured and device operation was shown to be in agreement with theoretical calculations. The interferometers can be used in the visible light region. Such an approach to photonic element systems should enable new applications for designing components in photonic integrated circuits. [Copyright &y& Elsevier]

Abstract: Photonic crystals (PCs) have many potential applications because of their ability to control light-wave propagation. We have investigated the tunable bandgap in a three-dimensional anisotropic photonic crystal structures modulated by a nematic liquid crystal. The PC structure composed of an anisotropic dielectric sphere in the liquid crystal medium is studied by solving Maxwell''s equations using the plane wave expansion method. The photonic band structures are found to exhibit partial bandgaps for the simple-cubic lattices. Numerical simulations show that the bandgaps can be continuously tuned in simple-cubic lattices consisting of anisotropic dielectric spheres by infiltrating nematic liquid crystals. We analyzed the variations of bandgap by considering various modulation of electric field. Such a mechanism of bandgap adjustment should open up a new application for designing components in photonic integrated circuits. [Copyright &y& Elsevier]

Abstract: Photonic crystals (PCs) have many potential applications because of their ability to control light-wave propagation. In this paper, the influence of interaction region of elliptical pillars on a directional photonic crystal waveguide coupler is studied by solving Maxwell''s equations with use of finite-difference time-domain method. The PC waveguide coupler introduced two rows of elliptical pillars in the interaction region. Introducing elliptical pillars in the interaction region can reduce the coupling length of PC waveguide coupler. The coupling length of PC waveguide coupler was changed by rotating the rotation angle of elliptical pillars. These results may provide novel application in photonic integrated circuits. [Copyright &y& Elsevier]