Browsing by Subject "Electric network analyzers"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Open Access Enhanced transmission of microwave radiation in one-dimensional metallic gratings with subwavelength aperture(American Institute of Physics, 2004) Akarca-Biyikli, S. S.; Bulu, I.; Özbay, EkmelWe report a theoretical and experimental demonstration of enhanced microwave transmission through subwavelength apertures in metallic structures with double-sided gratings. Three different types of aluminum gratings (sinusoidal, symmetric rectangular, and asymmetric rectangular shaped) are designed and analyzed. Our samples have a periodicity of 16 mm, and a slit width of 2 mm. Transmission measurements are taken in the 10–37.5 GHz frequency spectrum, which corresponds to 8–30 mm wavelength region. All three structures display significantly enhanced transmission around surface plasmon resonance frequencies. The experimental results agree well with finite-difference-time-domain based theoretical simulations. Asymmetric rectangular grating structure exhibits the best results with ,50% transmission at 20.7 mm, enhancement factor of ,25, and ±4° angular divergence.Item Open Access Guiding and bending of photons via hopping in three-dimensional photonic crystals(IEEE, Piscataway, NJ, United States, 2000) Bayındır, Mehmet; Temelkuran, B.; Özbay, EkmelFor the past decade, photonic crystals, also known as photonic bandgap (PBG) materials, have inspired great interest because of their novel scientific and engineering applications such as the inhibition of spontaneous emission, thresholdless lasers, optical circuits, antennas, waveguides, detectors, fibers, and so on. Creating defect states within the PBG are very important for such applications. Recently, we have reported the eigenmode splitting due to coupling of the localized defects and guiding of the electromagnetic (EM) waves through a periodic arrangement of such defects in three-dimensional (3D) photonic crystals. Although the modes of each cavity were tightly confined at the defect sites, overlapping between the nearest-neighbor modes is enough to provide the propagation of photons via hopping. We report on the observation of guiding and bending of EM wave through evanescent defect modes for three different PBG waveguide structures.Item Open Access Reflection properties and defect formation in photonic crystals(A I P Publishing LLC, 1996-08-05) Özbay, Ekmel; Temelkuran, B.We have investigated the surface reflection properties of a layer-by-layer photonic crystal. By using a Fabry-Perot resonant cavity analogy along with the reflection-phase information of the photonic crystal, we predicted defect frequencies of planar defect structures. Our predictions were in good agreement with the measured defect frequencies. Our simple model can also predict and explain double defect formation within the photonic band gap.Item Open Access Resonant cavity-enhanced detectors embedded in photonic crystals(IEEE, 1996) Temelkuran, Burak; Özbay, EkmelSummary form only given. We demonstrate the resonant-cavity-enhanced effect by placing microwave detectors in a layer-by-layer photonic crystal. We used the output of a network analyzer as the microwave source, and fed the output to a horn antenna to obtain EM waves. The crystal was then replaced in the beam-path of the EM wave, and the electric field inside the cavity was measured by a probe that consisted of a monopole antenna. The output of the antenna was measured by use of two different techniques: network analyzer and microwave detector within the cavity. The first cavity structure was similar to a one-dimensional Fabry-Perot resonator made of two mirrors separated by a distance.