Browsing by Subject "Cavity mode"

Now showing 1 - 5 of 5

Open Access
All-chalcogenide variable infrared filter
(SPIE, 2009) Kondakcı, H. Esat; Köyle, Özlem; Yaman, Mecit; Dana, Aykutlu; Bayındır, Mehmet
We present the design, fabrication, characterization of spatially variable infrared filter and a demonstration of the filter as a simple infrared spectrometer. A varying photonic band gap filter which consists of thermally evaporated, high refractive index contrast amorphous chalcogenide glass multilayers, makes the structure suitable to be used as spectrometer. Due to graded thickness structure, the filter exhibits a position dependent stop band and a cavity mode ranging from 2 to 8 μm wavelengths. It is demonstrated that the filter can be used to detect absorption peaks of common gases in the cavity mode range of the filter. © 2009 SPIE.
Open Access
Direct imaging of localized surface plasmon polaritons
(Optical Society of America, 2011-08) Balcı, Sinan; Karademir, Ertuğrul; Kocabaş, Coşkun; Aydınlı, Atilla
In this Letter, we report on dark field imaging of localized surface plasmon polaritons (SPPs) in plasmonic waveguiding bands formed by plasmonic coupled cavities. We image the light scattered from SPPs in the plasmonic cavities excited by a tunable light source. Tuning the excitation wavelength, we measure the localization and dispersion of the plasmonic cavity mode. Dark field imaging has been achieved in the Kretschmann configuration using a supercontinuum white-light laser equipped with an acoustooptic tunable filter. Polarization dependent spectroscopic reflection and dark field imaging measurements are correlated and found to be in agreement with finite-difference time-domain calculations.
Open Access
Grating based plasmonic band gap cavities
(Optical Society of American (OSA), 2009-08) Şenlik, S. Seçkin; Kocabaş, Aşkın; Aydınlı, Atilla
We report on a comparative study of grating based plasmonic band gap cavities. Numerically, we calculate the quality factors of the cavities based on three types of grating surfaces; uniform, biharmonic and Moiré surfaces. We show that for biharmonic band gap cavities, the radiation loss can be suppressed by removing the additional grating component in the cavity region. Due to the gradual change of the surface profile in the cavity region, Moiré type surfaces support cavity modes with higher quality factors. Experimentally, we demonstrate the existence of plasmonic cavities based on uniform gratings. Effective index perturbation and cavity geometries are obtained by additional dielectric loading. Quality factor of 85 is obtained from the measured band structure of the cavity. © 2009 Optical Society of America.
Open Access
Photonic bandgap infrared spectrometer
(Optical Society of America, 2010) Kondakci, H.E.; Yaman, M.; Dana, A.; Bayındır, Mehmet
We propose and demonstrate an infrared (IR) absorption spectrometer, made with a spatially variable photonic bandgap (PBG) structure, a blackbody source, and a simple IR detector, to identify the IR molecular fingerprints of analyte molecules. The PBG-based structure consists of thermally evaporated, IR transparent, high-refractive-index chalcogenide quarter-wave stacks (QWS) with a cavity layer. Spatial variation of the very sharp transmission peak due to the QWS cavity mode allows the structure to be used as a variable IR filter. Our proposed IR-PBG spectrometer can be used for detection and identification of volatile organic compounds.
Open Access
Physics and applications of defect structures in photonic crystals
(Springer, 2003) Özbay, Ekmel; Bayındır, Mehmet; Shumovsky, Alexander S.; Rupasov, V. I.
We propose and demonstrate a new type of propagation mechanism for electromagnetic waves in photonic band gap materials. Photons propagate through coupled cavities due to interaction between the highly localized neighboring cavity modes. We report a novel waveguide, which we called coupled-cavity waveguide (CCW), in three-dimensional photonic structures. By using CCWs, we demonstrate lossless and reflectionless waveguide bends, efficient power splitters, and photonic switches. We also experimentally observe the splitting of eigenmodes in coupled-cavities and formation of defect band due to interaction between the cavity modes. The tight-binding (TB) approach, which is originally develop for the electronic structures, is applied to the photonic structures, and compared to the experimental results. Our achievements open a new research area, namely physics and applications of coupled-cavities, in photonic structures. We think that our results are very important for constructing future all-optical components on a single chip.