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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studium optických vlastností kovových struktur a jejich využití v nanooptice / Study of Optical Properties of Metallic Structures and Their Applications in Nano-Optics

Neuman, Tomáš January 2014 (has links)
Interaction of metallic structures with electromagnetic radiation is a living topic of near-field optics including plasmonics and nanophotonics. The field-matter interaction treated on the subwavelength scale opens the path to a wide range of applications, among others to different variants of the surface enhanced spectroscopy. In this thesis we theoretically describe how the near-field properties of the metallic structures can be accessed by a probe of near-field scanning optical microscope. Formation of the signal in the near-field microscopy utilizing weakly interacting probes is discussed. Further, we elucidate the mechanism of the surface enhanced infrared spectroscopy. We utilize a model example of linear dipole antennas interacting with sample structures. A close connection is found between the spectroscopic signal and signal of the scattering type near-field optical microscopy.
2

Antenna-coupled Tunnel Diodes For Dual-band Millimeter-wave/infrared F

Abdel Rahman, Mohamed 01 January 2004 (has links)
The infrared and millimeter-wave portions of the spectrum both have their advantages for development of imaging systems. Because of the difference in wavelengths, infrared imagers offer inherently high resolution, while millimeter-wave systems have better penetration through atmospheric aerosols such as fog and smoke. Shared-aperture imaging systems employing a common focal-plane array that responds to both wavebands are desirable from the viewpoint of overall size and weight. We have developed antenna-coupled sensors that respond simultaneously at 30 THz and at 94 GHz, utilizing electron-beam lithography. Slot-antenna designs were found to be particularly suitable for coupling radiation into metal-oxide-metal (MOM) tunnel diodes at both frequencies. The MOM diodes are fabricated in a layered structure of Ni-NiO-Ni, and act as rectifying contacts. With contact areas as low as 120 nm × 120 nm, these diodes have time constants commensurate with rectification at frequencies across the desired millimeter-wave and infrared bands. One challenge in the development of true focal-plane array imagers across this factor-of-300 bandwidth is that the optimum spatial sampling interval on the focal plane is different in both bands. We have demonstrated a focal plane with interleaved infrared and millimeter-wave sensors by fabricating infrared antennas in the ground plane of the millimeter-wave antenna. Measured performance data in both bands are presented for individual antenna-coupled sensors as well as for devices in the dual-band focal-plane-array format.

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