Browsing by Subject "Optical surface waves"
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Item Open Access Acoustic microscopy with mechanical scanning—A review(IEEE, 1979-08) Quate, C. F.; Atalar, Abdullah; Wickramasinghe, H. K.Acoustic waves in liquids are known to have wavelengths comparable to that of visible light if the frequency is in the gigahertz range. The phenomena of Brillouin scattering in liquids is based on such waves. In helium near 2 K acoustic waves with a wavelength of 2000 Å were studied some ten years ago at UCLA. It follows from these observations that an imaging system based on acoustic radiation with a resolving power competitive with the optical microscope is within reach if an ideal lens free from aberrations could be found. Such a lens, which was so elusive at the beginning, is now a simple device and it is the basic component in the acoustic microscope that forms the basis for this review. In this article we will establish the characteristic properties of this new instrument. We will review some of the simple properties of acoustic waves and show how a single spherical surface formed at a solid liquid interface can serve as this ideal lens free from aberrations and capable of producing diffraction limited beams. When this is incorporated into a mechanical scanning system and excited with acoustic frequencies in the microwave range images can be recorded with acoustic wavelengths equal to the wavelength of visible light. We will present images that show the elastic properties of specimens selected from the fields of material science, integrated circuits, and cell biology. The information content in these images will often exceed that of the optical micrographs. In the reflection mode we illuminate the smooth surface of a crystalline material with a highly convergent acoustic beam. The reflected field is perturbed in a unique way that is determined by the elastic properties of the reflecting surface and it shows up in the phase of the reflected acoustic field. There is a distinct and characteristic response at the output when the spacing between the object and the lens is varied. This behavior in the acoustic ieflection microscope provides a rather simple and direct means for monitoring the elastic parameters of a solid surface. It is easy to distinguish between different materials, to determine the layer thickness, and to display variations in the elastic constants on a microscopic scale. These features lead us to believe there is a promising future for the field of acoustic microscopy.Item Open Access Multi-material specific, targeted self-assembly of nanocrystal emitters using genetically engineered peptides on optoelectronic microchips(IEEE, 2008-11) Zengin, Güliş; Şeker, U. O. S.; Koç, Aslı; Mutlugün, Evren; Akyüz, Özgün; Sarı, Emre; Sarıkaya, M.; Tamerler, C.; Demir, Hilmi VolkanWe demonstrated material-specific binding of the quantum dot emitters hybridized with GEPI on multi-material patterned microchips. These proof-of-concept results open up new opportunities in nanophotonics, allowing for more specific and controlled assembly of quantum dots in optoelectronic devices and building of novel molecular organic-inorganic hybrid devicesItem Open Access Multilevel physical optics algorithm for fast solution of scattering problems involving nonuniform triangulations(IEEE, 2007) Gürel, Levent; Manyas, AlpThis paper shows the computational efficiency of the multilevel physical optics (MLPO) algorithm can be further increased by employing nonuniform triangulations of the target surface so that the triangle size is not nearly uniform, but instead, is determined by the surface curvature.Item Open Access A novel approach to 3-dimensional holographic television display: principles and simulations(IEEE, 1992-03) Bozdağı, Gözde; Onural, Levent; Atalar, AbdullahThe authors present a new technique for the display end of a holographic three-dimensional television system and describe the computer simulations. The technique is based on the reproduction of the desired pattern, in this case the hologram, using traveling surface waves. The proposed method is simpler and more efficient than the methods available in the literature and it solves the display resolution and refreshing rate problems completely. Simulations show that the proposed system will work as desired when implemented in real time.Item Open Access Penetration depth of the scanning acoustic microscope(IEEE, 1985-03) Atalar, AbdullahA definition for the penetration depth of the scanning reflection acoustic microscope is given. With this definition it is possible to calculate the penetration depth of a given lens geometry for a given material. The penetration depth depends on the elastic parameters of the object, the signal-to-noise ratio, and the operation frequency of the acoustic microscope. Calculations show that for high-impedance materials, the penetration depthis limited by the wavelength of the surface waves and hence by frequency. For low-impedance materials the opening angle of the lens can be properly selected to make the longitudinal or shear wave penetration dominant, effectively increasing the penetration well above the wavelength limit of the surface wave.Item Open Access Slow surface plasmons on Moiré surfaces(IEEE, 2009) Şenlik, S. Seçkin; Kocabaş, A.; Aydınlı, AtillaIn this report, the authors present the design, fabrication and realization of coupled plasmonic cavities using metallic Moire structures. The phase shifts at the nodes of Moire pattern enable localization of SPPs resulting in a mini band in the band gap region. The authors find group velocities around V g =0.44c at the center of the mini band and approaches to zero at the edges of mini band.Item Open Access Surface-state emission enhancement in white-luminophor CdS nanocrystals using localized plasmon coupling(IEEE, 2008-11) Özel, Tuncay; Soğancı, İbrahim Murat; Nizamoğlu, Sedat; Huyal, İlkem Özge; Mutlugün, Evren; Sapra, S.; Gaponik, N.; Eychmüller, A.; Demir, Hilmi VolkanTo make surface-state emission stronger than band-edge emission for the first time, we proposed and demonstrated plasmon coupling of the surface-state emission from the traps in these CdS nano-luminophors using localized plasmons.