Browsing by Author "Sigalas, M."
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Item Open Access Defect structures in a layer-by-layer photonic band-gap crystal(American Physical Society, 1995) Özbay, Ekmel; Tuttle, G.; Sigalas, M.; Soukoulis, C. M.; Ho, K. M.We have experimentally and theoretically investigated defect structures that are incorporated into a three-dimensional layer-by-layer photonic band-gap crystal. The defects are formed by either adding or removing dielectric material to or from the crystal. For both cases, we observed localized modes with frequencies that lie within the forbidden band gap of the pure crystal. Relatively high peak transmission (10 dB below the incident signal), and high quality factors (2000) have been measured. These measurements were in good agreement with theoretical simulations. Theoretical calculations also predict very high (Q>106) quality factors for certain cavity structures. © 1995 The American Physical Society.Item Open Access Defect structures in metallic photonic crystals(A I P Publishing LLC, 1996-12-16) Özbay, Ekmel; Temelkuran, B.; Sigalas, M.; Tuttle, G.; Soukoulis, C. M.; Ho, K. M.We have investigated metallic photonic crystals built around a layer‐by‐layer geometry. Two different crystal structures (face‐centered‐tetragonal and tetragonal) were built and their properties were compared. We obtained rejection rates of 7–8 dB per layer from both metallic crystals. Defect modes created by removing rods resulted in high peak transmission (80%), and high quality factors (1740). Our measurements were in good agreement with theoretical simulations.Item Open Access Laser-micromachined millimeter-wave photonic band-gap cavity structures(American Institute of Physics, 1995) Özbay, Ekmel; Tuttle, G.; McCalmont, J. S.; Sigalas, M.; Biswas, R.; Soukoulis, C. M.; Ho, K. M.We have used laser-micromachined alumina substrates to build a three-dimensional photonic band-gap crystal. The rod-based structure has a three-dimensional full photonic band gap between 90 and 100 GHz. The high resistivity of alumina results in a typical attenuation rate of 15 dB per unit cell within the band gap. By removing material, we have built defects which can be used as millimeter-wave cavity structures. The resulting quality ~Q! factors of the millimeter-wave cavity structures were as high as 1000 with a peak transmission of 10 dB below the incident signal. © 1995 American Institute of Physics.Item Open Access Reflection properties and defect formation in metallic photonic crystals(IEEE, 1998-05) Özbay, Ekmel; Temelkuran, Burak; Sigalas, M.; Tuttle, G.; Soukoulis, C. M.; Ho, K. M.The reflection properties of layer-by-layer metallic photonic crystals were investigated using metallic photonic crystals with simple-tetragonal (st) structure. The observed properties were used to predict defect formation in these crystals. The reflection and transmission amplitude characteristics were measured by a network analyzer and standard gain horn antennas. Transformation matrix method was employed for the theoretical simulations.Item Open Access Reflection properties of metallic photonic crystals(1998) Temelkuran, B.; Özbay, Ekmel; Sigalas, M.; Tuttle, G.; Soukoulis, C. M.; Ho, K. M.We measured reflection-magnitude and reflection-phase properties of metallic photonic crystals. The experimental results are in good agreement with the theoretical calculations. We converted the reflection-phase information to an effective penetration depth of the electromagnetic waves into the photonic crystal. This information was then used to predict resonance frequencies of defect structures. A symmetric resonant cavity was built, and an experimental set-up limited reflection magnitude of 80 dB below the incident signal was observed at resonance frequency.