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    Photonic band gap engineering in two-dimensional photonic crystals and iso-frequency contours
    (Taylor & Francis Ltd, 2014) Erdiven, U.; Karadag, F.; Karaaslan, M.; Unal, E.; Dincer, F.; Sabah, C.
    We have theoretically investigated photonic band structures of two-dimensional (2D) photonic crystals (PCs) in air background. The lattices consist of the rotated and modified square dielectric rods. The influence of opto-geometric parameters of designed unit-cell structures are analyzed in terms of opening frequency gaps and appearing tilted band graphs by applying plane wave expansion method. Optimum structures with large photonic band gaps are notified. In order to get gap maps, the gaps as a function of the size and the rotation angle of the square rods are calculated. So, the band gaps of transverse magnetic and transverse electric polarization modes indicate symmetry in point of the rotation angle and these band gaps overlap. Thus, the smallest width of the narrow air veins is founded as 0.06a. The results show almost 40nm complete width of the air veins for mid-gap wavelength =1.55m. This result shows the fabrication capability of these optimized PC structures.
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    Planar Photonic Crystals Biosensor Applications of TiO2
    (Polish Acad Sciences Inst Physics, 2012) Erdiven, U.; Karaaslan, M.; Unal, E.; Karadag, F.
    We examine quality factor and sensitivity change depending on the resonant wavelength changing refractive index of surrounding liquid for TiO2 photonic crystal slab structure. Photonic crystal slab structure is used widely for biological materials such as proteins, antigens, DNA, cells, virus particles and bacteria. Mentioned photonic crystal slabs are usable with large-area biosensor designs. They permit direct access to externally incident optical beams in a microfluidic device. Model calculations are based on two-dimensional periodic crystal structure. Photonic crystal slab consists of a square lattice of air holes in a finite-thickness dielectric slab. The time domain simulations were implemented by software MIT Electromagnetic Equation Propagation.