|Ph.D Student||Biener Gabriel|
|Subject||Light Manipulation by Use of Subwavelength Structures|
|Department||Department of Mechanical Engineering||Supervisor||Professor Hasman Erez|
|Full Thesis text|
Micro and nanostructure have opened new scopes of methods for the formation of beams with sophisticated phase and polarization distributions. Such structures are usually used to form homogeneous space-invariant polarizers or wave plates. We recently, developed a novel method for designing and realizing nonuniformly polarized beams using inhomogeneous anisotropic subwavelength structures. In this research we have investigated spatial-polarization state scrambling for image encryption obtained with subwavelength structures as well as manipulation of polarization-dependent multi-vortices.
We also present a method to control the absorption of a resonator by using a subwavelength structure consisting of thin metallic plates that behaves as a metamaterial film. We demonstrate the ability to tailor the conductivity of such a metallic subwavelength structure to achieve a resonator with the desired impedance matching for the mid-infrared range. This approach provides for broadband, as well as a broad angle, enhanced absorption.
Finally, we demonstrate an extraordinary quasi-monochromatic thermal emission with high spatial coherence length (lc=2414l) and a quality factor of Q=2320, applied for radiation frequencies that are much smaller than the plasma frequency of metal (w<<wp). This emission was achieved by forming a plasmonic bandgap, which was obtained by a periodic structure upon a metallic surface. Such a structure modifies the dynamics of the surface wave, which results in enhancement of the density of states while maintaining a large coherent length.