Browsing by Subject "Field enhancement"

Now showing 1 - 6 of 6

Open Access
LSPR enhanced MSM UV photodetectors
(IOP Publishing, 2012-10-18) Butun, S.; Cinel, N. A.; Özbay, Ekmel
We fabricated localized surface plasmon resonance enhanced UV photodetectors on MOCVD grown semi-insulating GaN. Plasmonic resonance in the UV region was attained using 36nm diameter Al nanoparticles. Extinction spectra of the nanoparticles were measured through spectral transmission measurements. A resonant extinction peak around 300nm was obtained with Al nanoparticles. These particles gave rise to enhanced absorption in GaN at 340nm. Spectral responsivity measurements revealed an enhancement factor of 1.5. These results provided experimental verification for obtaining field enhancement by using Al nanoparticles on GaN.
Open Access
Nanoplasmonic three-dimensional surfaces with strong surface-normal electric field enhancement
(IEEE, 2013) Güngör, Kıvanç; Ünal, Emre; Demir, Hilmi Volkan
Conventional plasmonic structures provide field enhancement in the plane. The proposed nanoplasmonic three-dimensional surfaces, with unity coverage in the plan-view, enable surface-normal enhancement and achieve 7.2-fold stronger maximum field enhancement compared to the two-dimensional counterparts. © 2013 IEEE.
Open Access
Raman enhancement on a broadband meta-surface
(American Chemical Society, 2012-07-30) Ayas S.; Güner, H.; Türker, B.; Ekiz, O. O.; Dirisaglik, F.; Okyay, Ali Kemal; Dâna, A.
Plasmonic metamaterials allow confinement of light to deep subwavelength dimensions, while allowing for the tailoring of dispersion and electromagnetic mode density to enhance specific photonic properties. Optical resonances of plasmonic molecules have been extensively investigated; however, benefits of strong coupling of dimers have been overlooked. Here, we construct a plasmonic meta-surface through coupling of diatomic plasmonic molecules which contain a heavy and light meta-atom. Presence and coupling of two distinct types of localized modes in the plasmonic molecule allow formation and engineering of a rich band structure in a seemingly simple and common geometry, resulting in a broadband and quasi-omni-directional meta-surface. Surface-enhanced Raman scattering benefits from the simultaneous presence of plasmonic resonances at the excitation and scattering frequencies, and by proper design of the band structure to satisfy this condition, highly repeatable and spatially uniform Raman enhancement is demonstrated. On the basis of calculations of the field enhancement distribution within a unit cell, spatial uniformity of the enhancement at the nanoscale is discussed. Raman scattering constitutes an example of nonlinear optical processes, where the wavelength conversion during scattering may be viewed as a photonic transition between the bands of the meta-material.
Open Access
SILVER nano-cylinders designed by EBL used as label free LSPR nano-biosensors
(SPIE, 2011) Cinel, Neval A.; Bütün, Serkan; Özbay, Ekmel
Localized Surface Plasmon Resonance (LSPR) is based on the electromagnetic-field enhancement of metallic nano-particles. It is observed at the metal-dielectric interface and the resonance wavelength can be tuned by the size, shape, and periodicity of the metallic nanoparticles and the surrounding dielectric environment. This makes LSPR a powerful candidate in bio-sensing. In the present work, the size and period dependency of the LSPR wavelength was studied through simulations and fabrications. The surface functionalization, that transforms the surface into a sensing platform was done and verified. Finally, the concentration dependency of the LSPR shifts was observed. All the measurements were done by a transmission set-up. The study is at an early stage, however results are promising. The detection of specific bacteria species can be made possible with such a detection method. © 2011 SPIE.
Open Access
Three-dimensional nanoplasmonic surfaces with strong out-of-plane electric field enhancement
(IEEE, 2013) Güngör, Kıvanç; Ünal, Emre; Demir, Hilmi Volkan
Conventional 2D plasmonic structures, with surface coverage ~50%, provide field enhancement in the plane. The proposed 3D nanoplasmonic surfaces, with unity coverage, achieve 7.2-fold stronger out-of-plane enhancement compared to the 2D counterparts. © OSA 2013.
Open Access
Universal infrared absorption spectroscopy using uniform electromagnetic enhancement
(American Chemical Society, 2016) Ayas S.; Bakan, G.; Ozgur E.; Celebi, K.; Dana, A.
Infrared absorption spectroscopy has greatly benefited from the electromagnetic field enhancement offered by plasmonic surfaces. However, because of the localized nature of plasmonic fields, such field enhancements are limited to nanometer-scale volumes. Here, we demonstrate that a relatively small, but spatially uniform field enhancement can yield a superior infrared detection performance compared to the plasmonic field enhancement exhibited by optimized infrared nanoantennas. A specifically designed CaF2/Al thin film surface is shown to enable observation of stronger vibrational signals from the probe material, with wider bandwidth and a deeper spatial extent of the field enhancement as compared to such plasmonic surfaces. It is demonstrated that the surface structure presented here can enable chemically specific and label-free detection of organic monolayers using surface-enhanced infrared spectroscopy, indicating a great potential in highly sensitive yet cost-effective biomolecular sensing applications.