Browsing by Subject "Photon"

Now showing 1 - 7 of 7

Open Access
Guiding, bending, and splitting of electromagnetic waves in highly confined photonic crystal waveguides
(American Physical Society, 2001) Bayındır, Mehmet; Özbay, Ekmel; Temelkuran, B.; Sigalas, M. M.; Soukoulis, C. M.; Biswas, R.; Ho, K. M.
We have experimentally demonstrated the guiding, bending, and splitting of electromagnetic (EM) waves in highly confined waveguides built around three-dimensional layer-by-layer photonic crystals by removing a single rod. Full transmission of the EM waves was observed for straight and bended waveguides. We also investigated the power splitter structures in which the input EM power could be efficiently divided into the output waveguide ports. The experimental results, dispersion relation and photon lifetime, were analyzed with a theory based on the tight-binding photon picture. Our results provide an important tool for designing photonic crystal based optoelectronic components.
Open Access
Negative refraction and superlens behavior in a two-dimensional photonic crystal
(American Physical Society, 2005) Moussa, R.; Foteinopoulou, S.; Zhang, L.; Tuttle, G.; Guven, K.; Özbay, Ekmel; Soukoulis, C. M.
We experimentally and theoretically studied a left-handed structure based on a photonic crystal (PC) with a negative refractive index. The structure consists of triangular array of rectangular dielectric bars with dielectric constant 9.61. Experimental and theoretical results demonstrate the negative refraction and the superlensing phenomena in the microwave regime. The results show high transmission for our structure for a wide range of incident angles. Furthermore, surface termination within a specific cut of the structure excite surface waves at the interface between air and PC and allow the reconstruction of evanescent waves for a better focus and better transmission. The normalized average field intensity calculated in both the source and image planes shows almost the same full width at half maximum for the source and the focused beam.
Open Access
Photonic band gaps, defect characteristics, and waveguiding in two-dimensional disordered dielectric and metallic photonic crystals
(American Physical Society, 2001) Bayındır, Mehmet; Cubukcu, E.; Bulu, I.; Tut, T.; Özbay, Ekmel; Soukoulis, C. M.
We experimentally investigated the influence of positional disorder on the photonic band gap, defect characteristics, and waveguiding in two-dimensional dielectric and metallic photonic crystals. Transmission measurements performed on the dielectric photonic crystals have shown a stop band even if a large amount of disorder was introduced to these structures. On the other hand, the photonic band gap of the metallic crystals was found to be very sensitive to disorder, while the metallicity gap was not affected significantly. We addressed how the transmission characteristics of a cavity were affected in the presence of weak disorder. Since the translational symmetry was broken by disorders, we measured different cavity frequencies when we generated defects at various locations. We also demonstrated the propagation of photons by hopping through coupled-cavity structures in both dielectric and metallic two-dimensional photonic crystals. Effects of weak disorder on guiding and bending of electromagnetic waves through the coupled-cavity waveguides were also investigated.
Open Access
Photonic band-gap effect, localization, and waveguiding in the two-dimensional Penrose lattice
(American Physical Society, 2001) Bayındır, Mehmet; Cubukcu, E.; Bulu, I.; Özbay, Ekmel
We report experimental observation of a full photonic band gap in a two-dimensional Penrose lattice made of dielectric rods. Tightly confined defect modes having high quality factors were observed. Absence of the translational symmetry in Penrose lattice was used to change the defect frequency within the stop band. We also achieved the guiding and bending of electromagnetic waves through a row of missing rods. Propagation of photons along highly localized coupled-cavity modes was experimentally demonstrated and analyzed within the tight-binding approximation.
Open Access
Plasmonics: merging photonics and electronics at nanoscale dimensions
((AAAS) American Association for the Advancement of Science, 2006) Özbay, Ekmel
Electronic circuits provide us with the ability to control the transport and storage of electrons. However, the performance of electronic circuits is now becoming rather limited when digital information needs to be sent from one point to another. Photonics offers an effective solution to this problem by implementing optical communication systems based on optical fibers and photonic circuits. Unfortunately, the micrometer-scale bulky components of photonics have limited the integration of these components into electronic chips, which are now measured in nanometers. Surface plasmon-based circuits, which merge electronics and photonics at the nanoscale, may offer a solution to this size-compatibility problem. Here we review the current status and future prospects of plasmonics in various applications including plasmonic chips, light generation, and nanolithography.
Open Access
Radiation properties of sources inside photonic crystals
(2003) Bulu, I.; Caglayan, H.; Özbay, Ekmel
In this work, we have experimentally studied the emission of radiation from a monopole source embedded in a photonic crystal. We have demonstrated the enhancement of radiation at the band edges and at the cavity modes including coupled cavity modes. Moreover, we have shown that the emission of radiation from a source depends on the group velocities of the modes and on the electric field intensities of the modes at the source location.
Open Access
Spectral negative refraction and focusing analysis of a two-dimensional left-handed photonic crystal lens
(American Physical Society, 2004-11) Güven, Kaan; Aydın, Koray; Alıcı, Kamil Boratay; Soukoulis, C. M.; Özbay, Ekmel
We report the spectral refraction analysis and focusing properties of a two-dimensional, dielectric photonic crystal (PC) slab in freespace. A transverse electric polarized upper band of the crystal is used. The measured refraction spectra indicates that a highly isotropic negative index of refraction is present in the measured frequency range of the band. We demonstrate experimentally and numerically the focusing of the field emitted from an omnidirectional source placed in front of the crystal. Both the source and the focus pattern are away from the PC interfaces of the order of several wavelengths. The focus pattern mimics the arbitrary lateral and longitudinal shifts of the source, which is a manifestation of true flat lens behavior.