Beaming and localization of electromagnetic waves in periodic structures
Author
Çağlayan, Hümeyra
Advisor
Özbay, Ekmel
Date
2010Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
We want to manipulate light for several applications: microscopy, data
storage, leds, lasers, modulators, sensor and solarcells to make our life healthier,
easier or more comfortable. However, especially in small scales manipulating light
have many difficulties. We could not focus or localize light into subwavelength
dimensions easily, which is the key solution to beat today’s devices both in
performance and cost. Achievements in three key research fields may provide the
answer to these problems. These emerging research fields are metamaterials,
photonic crystals and surface plasmons. In this thesis, we investigated beaming and
localization of electromagnetic waves in periodic structures such as:
subwavelength metallic gratings, photonic crystals and metamaterials. We studied
off-axis beaming from both a metallic subwavelength aperture and photonic crystal
waveguide at microwave regime. The output surfaces are designed asymmetrically
to change the beaming angle. Furthermore, we studied frequency dependent beam
steering with a photonic crystal with a surface defect layer made of dimmers. The
dispersion diagram reveals that the dimer-layer supports a surface mode with
negative slope. Thus, a photonic crystal based surface wave structure that acts as a
frequency dependent leaky wave antenna was presented. Additionally, we
investigated metamaterial based cavity systems. Since the unit cells of metamaterials are much smaller than the operation wavelength, we observed
subwavelength localization within these metamaterial cavity structures. Moreover,
we introduced coupled-cavity structures and presented the transmission spectrum
of metamaterial based coupled-cavity structures. Finally, we demonstrated an
ultrafast bioassay preparation method that overcomes the today’s bioassay
limitations using a combination of low power microwave heating and split ring
resonator structures.
Keywords
Surface PlasmonsUltrafast Bioassay
Subwavelength Localization
Metamaterial based Cavity
Negative Permeability
Negative Permittivity
Composite Metamaterial
Split Ring Resonator
Metamaterial
Backward Leaky Wave
Beam Steering
Surface Mode
Photonic Crystal
Off-Axis Beaming