טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentBiener Gabriel
SubjectLight Manipulation by Use of Subwavelength Structures
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Erez Hasman
Full Thesis textFull thesis text - English Version


Abstract

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.