Browsing by Subject "Gap"

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    Exceptionally directional sources with photonic-bandgap crystals
    (Optical Society of America, 2001-11) Biswas, R.; Özbay, Ekmel; Temelkuran, B.; Bayındır, Mehmet; Sigalas, M. M.; Ho, K.-M.
    Three-dimensional photonic-bandgap crystals are used to design and fabricate uniquely directional sources and receivers. By utilizing the resonances of a Fabry-Perot cavity formed with photonic-bandgap crystals, we were able to create exceptionally directional sources by placing the sources within such a cavity. Very good agreement between finite-difference time-domain calculations and the experiment is obtained. Radiation patterns with half-power beam widths of less than 12 degrees were obtained. (C) 2001 Optical Society of America.
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    Experimental demonstration of photonic crystal based waveguides
    (A I P Publishing LLC, 1999-01-25) Temelkuran, B.; Özbay, Ekmel
    We report the experimental demonstration of waveguides built around layer-by-layer photonic crystals. An air gap introduced between two photonic crystal walls was used as the waveguide. We observed full (100%) transmission of the electromagnetic (EM) waves through these planar waveguide structures within the frequency range of the photonic band gap. The dispersion relations obtained from the experiment were in good agreement with the predictions of our waveguide model. We also observed 35% transmission for the EM waves traveling through a sharp bend in an L-shaped waveguide carved inside the photonic crystal. (C) 1999 American Institute of Physics.
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    Resonant cavity enhanced detectors embedded in photonic crystals
    (American Institute of Physics, 1998) Temelkuran, B.; Özbay, Ekmel; Kavanaugh, J. P.; Tuttle, G.; Ho, K. M.
    We report a resonant cavity enhanced (RCE) detector built around a three-dimensional photonic band gap crystal. The RCE detector was built by placing a monopole antenna within the localized modes of planar and boxlike defectstructures. The enhanced electric field around these defectstructures were then measured by a microwave detector and a network analyzer. We measured a power enhancement factor of 3450 for planar cavity structures. A Fabry–Perot cavity model was used to understand and predict resonant cavity enhancement in this structure. The tuning bandwidth of the RCE detector extends from 10.5 to 12.8 GHz, which corresponds to the full photonic band gap by the crystal. These RCE detectors have increased sensitivity and efficiency when compared to conventional detectors, and can be used for various applications. © 1998 American Institute of Physics