الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 132 |  |  |
| | | from | 132 | | |
Abstract
This thesis aims at introducing different optical metasurfaces specifically de-signed to achieve subwavelength focusing in the infrared range. Most of the plas-monic research in the literature has been directed towards the visible range and little attention was given to infrared metasurfaces and their applications. In this thesis, we have presented three different metasurfaces that can achieve sub-wavelength focusing in the infrared domain. The structures presented achieve either high focusing resolu-tion or high transmission efficiency or extended mid-infrared bandwidth so they can satisfy the different critical requirements of different infrared applications. We study and compare their performance parameters across the wavelength and we also study the influence of the used metal’s permittivity on the transmission performance. Those studies and comparison are meant to provide future designers an insight on how to design the metasurfaces that suit their performance requirements in the infrared range. They are also meant to make the design process easier.
Our aim was also to design those metasurfaces such that they would be easily and cheaply fabricated and integrated in infrared applications. We did this by using CMOS compatible and inexpensive materials such as copper and silicon. This is in contrast to the materials that were commonly used in visible plasmonics such as gold and silver or metamaterials.
The other goal of this thesis was to design a dielectric axicon zone plate metalens to be used in high sensitivity optical sensing as an example application. The axicon zone plate is compact, more efficient and easier to fabricate in comparison to the traditional bulky axicon. We made our designs specifically at the wavelength of 3.3 microns at which the absorption of CH4 gas is maximum. We developed an ana-lytical formulation for the intensity variation with the refractive index and concluded the condition to achieve maximum sensitivity.