Browsing by Subject "Field localization"
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Item Open Access Near-field light localization using subwavelength apertures incorporated with metamaterials(Elsevier, 2012-03-12) Ates, D.; Cakmak, A. O.; Özbay, EkmelWe report strong near-field electromagnetic localization by using subwavelength apertures and metamaterials that operate at microwave frequencies. We designed split ring resonators with distinct configurations in order to obtain extraordinary transmission results. Furthermore, we analyzed the field localization and focusing characteristics of the transmitted evanescent waves. The employed metamaterial configurations yielded an improvement on the transmission efficiency on the order of 27 dB and 50 dB for the deep subwavelength apertures. The metamaterial loaded apertures are considered as a total system that offered spot size conversion ratios as high as 7.12 and 9.11 for the corresponding metamaterial configurations. The proposed system is shown to intensify the electric fields of the source located in the near-field. It also narrows down the electromagnetic waves such that a full width at half maximum value of λ/29 is obtained.Item Open Access Novel optical antenna designs of comb shaped split ring architecture for NIR and MIR enhanced field localization(IEEE, 2014) Kılıç, Veli Tayfun; Ertürk, Vakur B.; Demir, Hilmi VolkanWe demonstrated NIR/MIR resonance behavior in optical antennas of comb-shaped split-ring resonators enabling substantially larger field enhancements than single/array of dipoles with the same side length, despite their simple architecture.Item Open Access Semiconductor-less photovoltaic device(IEEE, 2013) Atar, Fatih B.; Battal, Enes; Aygun, Levent E.; Dağlar, Bihter; Bayındır, Mehmet; Okyay, Ali KemalWe demonstrate a novel semiconductor-less photovoltaic device and investigate the plasmonic effects on this device structure. The device is made of metal and dielectric layers and the operation is based on hot carrier collection. We present the use of surface plasmons to improve energy conversion efficiency. The field localization provided by surface plasmons confine the incident light in the metal layer, increasing the optical absorption and hot electron generation rate inside the metal layer. The device consists of two tandem MIM (metal-insulator-metal) junctions. Bottom MIM junction acts as a rectifying diode and top MIM junction is used to excite surface plasmons. The device operation principle as well as the topology will be discussed in detail. © 2013 IEEE.Item Open Access Volumetric plasmonic resonator architecture for thin-film solar cells(AIP Publishing, 2011-03-04) Sefunc, M.A.; Okyay, Ali Kemal; Demir, Hilmi VolkanWe propose and demonstrate a design concept of volumetric plasmonic resonators that relies on the idea of incorporating coupled layers of plasmonic structures embedded into a solar cell in enhanced optical absorption for surface-normal and off-axis angle configurations, beyond the enhancement limit of individual plasmonic layers. For a proof-of-concept demonstration in a thin-film organic solar cell that uses absorbing materials of copper phthalocyanine/perylene tetracarboxylic bisbenzimidazole, we couple two silver grating layers such that the field localization is further extended within the volume of active layers. Our computational results show a maximum optical absorption enhancement level of ∼67% under air mass 1.5 global illumination considering both polarizations.