Metal-Insulator-Metal metasurfaces encompassing polar dielectrics and phase-change materials
| dc.contributor.committeeChair | Bernussi, Ayrton | |
| dc.contributor.committeeChair | Kim, Myoung-Hwan | |
| dc.contributor.committeeMember | de Peralta, Luis Grave | |
| dc.contributor.committeeMember | Saed, Mohammed | |
| dc.contributor.committeeMember | Sanati, Mahdi | |
| dc.creator | Jafari, Ahmad Khayyat | |
| dc.creator.orcid | 0000-0003-2947-7913 | |
| dc.date.accessioned | 2022-09-12T19:47:38Z | |
| dc.date.available | 2022-09-12T19:47:38Z | |
| dc.date.created | 2022-08 | |
| dc.date.issued | 2022-08 | |
| dc.date.submitted | August 2022 | |
| dc.date.updated | 2022-09-12T19:47:39Z | |
| dc.description.abstract | Planar metamaterials with subwavelength thickness, or metasurfaces, consisting of a few layers of planar structures, can be readily fabricated using lithography and nanoprinting techniques. It is predicted that the first generation of metamaterial-based devices will most probably arise from metasurfaces. Metasurfaces enable spatially varying optical responses such as scattering amplitude, phase, and polarization. Metal-Insulator-Metal (MIM) geometry is an important type of metasurfaces which consists of a uniform metallic backplane layer, an intermediate uniform insulating spacer layer, and an array of periodic thin metallic layer lithographically patterned atop. MIM has been proposed to be utilized as smart surface, wide-angle perfect absorber, and impedance-matching surface in almost all the electromagnetic spectral range. Its absorption spectrum can be engineered by making variations in the geometry of the unit cell and/or by including materials with specific optical properties. Embedding a polar dielectric in this structure is another approach for manipulating its absorption spectrum. In the first part of this dissertation, the effect of using Silicon Dioxide (SiO2) as a polar dielectric on the absorption spectrum of a Nickel (Ni)-based MIM structure (tri-layer of Ni-SiO2-Ni) was investigated. The numerical and experimental results have revealed the presence of absorption peaks attributed to the excitation of the optical phonons in the SiO2 spacer layer. Particularly, the focus in this part is to study the absorption due to the excitation of the Berreman (BE) and Epsilon-Near-Zero (ENZ) modes in the SiO2 spacer layer. The effects of the dimensions of the top patterned Ni layer, the radiation incident angle, the thickness of the SiO2 layer, and the polarization of the incident light have been studied in detail. In the second part of this dissertation, planar structures including Vanadium Dioxide (VO2) as a phase-change material have been explored. VO2 by itself is considered as a homogeneous metamaterial and its reversible insulator-metal phase transition makes it an ideal candidate for tunable photonic and optoelectronic devices. As a step towards this goal, the temperature-dependent absorption spectrum of structures consisting of a thin layer of VO2 deposited on different metallic films (Air/VO2/Metal) was studied in the near-infrared (NIR) spectral range particularly near wavelength of 1.5 µm which is significant for telecommunication-related applications. It has been shown that this structure can be considered as an asymmetric Fabry-Perot (FP) resonant cavity in the insulating phase of the VO2 and in the metallic phase of VO2, this structure becomes almost a mirror where its absorption spectrum is independent of bottom metallic layer. The unique temperature-dependent tunability characteristics of the Air/VO2/Metal structure investigated here can be prospectively utilized in the realization of the tunable photonic or optoelectronic devices or for aerospace applications. | |
| dc.description.abstract | Embargo status: Restricted until 09/2027. To request the author grant access, click on the PDF link to the left. | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.uri | https://hdl.handle.net/2346/90218 | |
| dc.language.iso | eng | |
| dc.rights.availability | Restricted until 09/2027. | |
| dc.subject | Metal-Insulator-Metal Metasurafces | |
| dc.subject | Mid-Infrared | |
| dc.subject | Polar Dielectrics | |
| dc.subject | Berreman Mode | |
| dc.subject | Epsilon-Near-Zero Mode | |
| dc.subject | Vanadium Dioxide | |
| dc.subject | Tunable Photonic Devices | |
| dc.title | Metal-Insulator-Metal metasurfaces encompassing polar dielectrics and phase-change materials | |
| dc.type | Dissertation | |
| dc.type.material | text | |
| local.embargo.lift | 2027-08-01 | |
| local.embargo.terms | 2027-08-01 | |
| thesis.degree.department | Physics | |
| thesis.degree.discipline | Applied Physics | |
| thesis.degree.grantor | Texas Tech University | |
| thesis.degree.level | Doctoral | |
| thesis.degree.name | Doctor of Philosophy |