Browsing by Author "Caglayan, H."
Now showing items 1-20 of 46
-
Beaming and enhanced transmission through a subwavelength aperture via epsilon-near-zero media
Hajian, H.; Özbay, Ekmel; Caglayan, H. (Nature Publishing Group, 2017)We numerically validate and experimentally realize considerable funneling of electromagnetic energy through a subwavelength aperture that is covered with an epsilon-near-zero metamaterial (ENZ). The epsilon-near-zero ... -
Beaming of electromagnetic waves emitted through a subwavelength annular aperture
Caglayan, H.; Bulu, I.; Özbay, Ekmel (Optical Society of American (OSA), 2006)We study the diffraction of electromagnetic waves from subwavelength metallic circular apertures in the microwave spectrum. The theoretical and experimental demonstration of the near- and far-field electromagnetic distributions ... -
Beaming of light and enhanced transmission via surface modes of photonic crystals
Bulu, I.; Caglayan, H.; Özbay, Ekmel (Optical Society of America, 2005-11-15)We report beaming and enhanced transmission of electromagnetic waves by use of surface corrugated photonic crystals. The modes of a finite-size photonic crystal composed of dielectric rods in free space have been analyzed ... -
Bright off-axis directional emission with plasmonic corrugations
Sattari, H.; Rashed, A. R.; Özbay, Ekmel; Caglayan, H. (OSA - The Optical Society, 2017)In this work, a new plasmonic bulls-eye structure is introduced to efficiently harvest the emitted light from diamond nitrogen vacancy (NV) centers. We show that the presence of a simple metal sub-layer underneath of a ... -
Cavity formation in split ring resonators
Caglayan, H.; Bulu, I.; Loncar, M.; Özbay, Ekmel (Elsevier BV, 2008-12)We report that it is possible to obtain a cavity structure by the deformation of a unit cell of an split ring resonator (SRR) structure. We presented the Q-factor of the cavity resonance as 192 for an SRR-based single ... -
Chiral metamaterials with negative refractive index based on four "U" split ring resonators
Li, Z.; Zhao, R.; Koschny, T.; Kafesaki, M.; Alici, K. B.; Colak, E.; Caglayan, H.; Özbay, Ekmel; Soukoulis, C. M. (American Institute of Physics, 2010-08-23)A uniaxial chiral metamaterial is constructed by double-layered four "U" split ring resonators mutually twisted by 90°. It shows a giant optical activity and circular dichroism. The retrieval results reveal that a negative ... -
Compact size highly directive antennas based on the SRR metamaterial medium
Bulu, I.; Caglayan, H.; Aydin, K.; Özbay, Ekmel (Institute of Physics Publishing, 2005)In this work, we studied the far-field properties of the microwave radiation from sources embedded inside the split-ring resonator (SRR) metamaterial medium. Our results showed that the emitted power near the resonance ... -
Comparison of back and top gating schemes with tunable graphene fractal metasurfaces
Aygar, A. M.; Balci, O.; Cakmakyapan, S.; Kocabas, C.; Caglayan, H.; Özbay, Ekmel (American Chemical Society, 2016)In this work, fractal metasurfaces that consist of periodic gold squares on graphene are used to increase light-graphene interaction. We show by simulations and experiments that higher level fractal structures result in ... -
Composite chiral metamaterials with negative refractive index and high values of the figure of merit
Li, Z.; Caglayan, H.; Alici, K. B.; Kafesaki, M.; Soukoulis, C. M.; Özbay, Ekmel (Optical Society of America, 2012)A composite chiral metamaterial (CCMM) is designed and studied both numerically and experimentally. The CCMM is constructed by the combination of a continuous metallic wires structure and a purely chiral metamaterial (CMM) ... -
Coupling effect between two adjacent chiral structure layers
Li, Z.; Caglayan, H.; Colak, E.; Zhou, J.; Soukoulis, C. M.; Özbay, Ekmel (Optical Society of America, 2010-03-01)A pair of mutually twisted metallic cross-wires can produce giant optical activity. When this single chiral layer is stacked layer by layer in order to build a thick chiral metamaterial, strong coupling effects are ... -
Coupling enhancement of split ring resonators on graphene
Cakmakyapan, S.; Caglayan, H.; Özbay, Ekmel (Pergamon Press, 2014-12)Metallic split ring resonator (SRR) structures are used in nanophotonics applications in order to localize and enhance incident electromagnetic field. Electrically controllable sheet carrier concentration of graphene ... -
Enhanced transmission and beaming via a zero-index photonic crystal
Hajian, H.; Özbay, Ekmel; Caglayan, H. (American Institute of Physics Inc., 2016)Certain types of photonic crystals with Dirac cones at the Γ point of their band structure have a zero effective index of refraction at Dirac cone frequency. Here, by an appropriate design of the photonic structure, we ... -
Enhanced transmission and directivity from metallic subwavelength apertures with nonuniform and nonperiodic grooves
Li, Z.; Caglayan, H.; Colak, E.; Özbay, Ekmel (AIP Publishing LLC, 2008)Nonuniform and nonperiodic grooves are used to enhance the transmission and directivity of emissions from a single metallic subwavelength aperture. By using nonuniform and nonperiodic grooves, the amplitude and phase of ... -
Enhanced tunability of V-shaped plasmonic structures using ionic liquid gating and graphene
Ozdemir, O.; Aygar, A. M.; Balci, O.; Kocabas, C.; Caglayan, H.; Özbay, Ekmel (Elsevier Ltd, 2016)Graphene is a strong candidate for active optoelectronic devices because of its electrostatically tunable optical response. Current substrate back-gating methods are unable to sustain high fields through graphene unless a ... -
Experimental demonstration of labyrinth-based left-handed metamaterials
Bulu, I.; Caglayan, H.; Özbay, Ekmel (Optical Society of America, 2005-12-12)In this present work, we propose and demonstrate a resonant structure that solves two major problems related to the split-ring resonator structure. One of the problems related to the split-ring resonator structure is the ... -
Experimental observation of subwavelength localization using metamaterial-based cavities
Caglayan, H.; Bulu, I.; Loncar, M.; Özbay, Ekmel (Optical Society of America, 2009-01-01)We report subwavelength localization of electromagnetic fields within cavities based on metamaterials. Cavity resonances are observed in the transmission spectrum of a split-ring resonator and composite metamaterials cavity ... -
Experimental validation of strong directional selectivity in nonsymmetric metallic gratings with a subwavelength slit
Cakmakyapan, S.; Caglayan, H.; Serebryannikov, A. E.; Özbay, Ekmel (American Institute of Physics, 2011-02-02)Strong directional selectivity is theoretically predicted and experimentally validated at the microwave frequencies in the beaming regime for a single subwavelength slit in nonsymmetric metallic gratings with double-side ... -
Extraordinary grating-coupled microwave transmission through a subwavelength annular aperture
Caglayan, H.; Bulu, I.; Özbay, Ekmel (Optical Society of America, 2005-03-07)We studied coupling phenomena between surface plasmons and electromagnetic waves in the microwave spectrum using circular apertures surrounded by array of grooves. We first present experimental and theoretical results of ... -
The focusing effect of graded index photonic crystals
Kurt, H.; Colak, E.; Cakmak, O.; Caglayan, H.; Özbay, Ekmel (AIP Publishing LLC, 2008)We describe an approach to implement graded index (GRIN) structures using two-dimensional photonic crystals (PCs). The lattice spacing along the transverse direction to propagation is altered and we show, both theoretically ... -
Focusing surface plasmons via changing the incident angle
Caglayan, H.; Bulu, I.; Özbay, Ekmel (AIP Publishing LLC, 2008)We report a circular metallic aperture with a subwavelength circular slit in the microwave regime, in which we experimentally demonstrate that this aperture can excite and focus surface plasmons. Under normal illumination, ...