dc.contributor.advisor | Demir, Hilmi Volkan | |
dc.contributor.author | Tanrıöver, İbrahim | |
dc.date.accessioned | 2019-08-09T08:45:32Z | |
dc.date.available | 2019-08-09T08:45:32Z | |
dc.date.copyright | 2019-07 | |
dc.date.issued | 2019-07 | |
dc.date.submitted | 2019-07-22 | |
dc.identifier.uri | http://hdl.handle.net/11693/52329 | |
dc.description | Cataloged from PDF version of article. | en_US |
dc.description | Thesis (M.S.) : Bilkent University, Department of Electrical and Electronics Engineering, İhsan Doğramacı Bilkent University, 2019. | en_US |
dc.description | Includes bibliographical references (leaves 51-56). | en_US |
dc.description.abstract | Transparent optical components constitute the key elements of modern electro-optical
systems including optical sensors, displays and imaging systems. The working
principle of conventional transparent components rely on gradual phase accumulation.
As a direct result of their working principle, these components suffer from
fundamental limitations on size. Metasurfaces, enabling full wavefront engineering in
subwavelength thicknesses, are promising candidates to replace conventional optics
and overcome the size limitations. Early examples of this concept include plasmonic
metasurfaces containing sub-wavelength metallic structures. However, these
plasmonic structures cannot reach practically sufficient efficiency levels in
transmission mode due to fundamental ohmic losses. This strongly motivates highefficiency
all-dielectric alternatives. These dielectric solutions have thus far been
reported to rely on either the resonance tuning or the geometrical (Pancharatnam–
Berry) phase. Though remedying the efficiency limitation, unfortunately, these
approaches either are impaired with ultra-narrow operation bands or suffer polarization
dependency. In this thesis, we propose and demonstrate two new approaches to address
these problems. In the first approach of ours, universally polarization-insensitive
achromatic wavefront control is achieved using dielectric nanopillars operated as stepindex
cylindrical waveguides intentionally away from the scattering resonances. A
metalens operating in the mid-wave infrared region of electromagnetic spectrum is
shown using these off-resonance waveguiding unit cells as a proof-of-concept
demonstration. Polarization-insensitive diffraction-limited focusing over a broad
spectral band of operation is verified by full electromagnetic simulations. In our
second approach, to further increase the performance and bandwidth of dielectric
metasurfaces, a novel architecture of these phase elements is proposed. Full phase
control of wavefront is achieved using these unit cells. Such metalenses operating in the mid-wave infrared and visible regions are designed as proof-of-concept
demonstrations. Full electromagnetic solutions confirmed entirely polarizationinsensitive
achromatic focusing of the proposed metasurfaces with significantly
increased operation bandwidth. | en_US |
dc.description.statementofresponsibility | by İbrahim Tanrıöver | en_US |
dc.format.extent | xiv, 56 leaves : illustrations (some color), charts (some color) ; 30 cm. | en_US |
dc.language.iso | English | en_US |
dc.rights | info:eu-repo/semantics/openAccess | en_US |
dc.subject | Metasurfaces | en_US |
dc.subject | Waveguides | en_US |
dc.subject | Scatterers | en_US |
dc.title | Universally polarization-insensitive achromatic metasurfaces | en_US |
dc.title.alternative | Evrensel polarizasyon-bağımsız akromatik metayüzeyler | en_US |
dc.type | Thesis | en_US |
dc.department | Department of Electrical and Electronics Engineering | en_US |
dc.publisher | Bilkent University | en_US |
dc.description.degree | M.S. | en_US |
dc.identifier.itemid | B134946 | |
dc.embargo.release | 2020-01-22 | |