Date of Award

4-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering

Department

Electrical and Communication Engineering

First Advisor

Amine El Moutaouakil

Second Advisor

Adel Najar

Abstract

THz technology is a promising field that has various applications in communication, medical imaging and diseases’ detection, scanning, and the food industry. Since THz technology is still in its early stages, there is a lot of work to be done to obtain devices that work efficiently in the THz range. One of these devices is THz absorbers that are the basic building blocks for the next generation THz systems whether in communication systems, imaging or shielding. THz absorbers are structures that can absorb electromagnetic waves in the THz range (0.1-10 THz). THz absorbers can be wideband (absorb a wide range of THz frequencies) or selective frequency absorbers (absorb a specified THz frequency). The aim of this study is to reach a nearly perfect selective THz absorber with near unity absorption based on 2D materials. 2D materials are known to have low cost, and they are abundant, and easy to fabricate through typical techniques like chemical vapor deposition (CVD) and dry transfer. The focus of the work is to study the characteristics of recently reviewed materials like MoS2 and phosphorene and their heterostructures characteristics with graphene then utilizing these properties to design an absorber. This study is a theoretical based one, where the finite element method (FEM) is used to simulate the final design that was based on the previous experimental and theoretical calculations. The simulation was verified by applying the transmission circuit theory that verifies the high absorption of the structure. The proposed structure is the first to have a high absorption above 90% and that reaches 95% for some frequencies that is based on 2D materials without including noble materials like gold and silver to increase its absorption. The device is electrically tunable through most of the THz spectrum (1.3 THz -10 THz) that surpasses previous metamaterial absorbers which have limited range tunability. These characteristics enable easy fabrication and low-cost preparation that is considered an advancement in the THz absorbers.

Arabic Abstract


ﺗﻄﺒﯿﻘﺎت اﻟﺘﯿﺮاھﯿﺮﺗﺰ ﻟﺒُﻨﻰ اﻟﺠﺮاﻓﯿﻦ اﻟﻤﺘﻐﺎﯾﺮة

ﺗﻌﺘﺒﺮ ﺗﻘﻨﯿﺔ اﻟﺘﯿﺮاھﯿﺮﺗﺰ أﺣﺪ أھﻢ اﻟﺘﻘﻨﯿﺎت اﻟﻮاﻋﺪة ذات اﻟﺘﻄﺒﯿﻘﺎت ﻓﻲ ﻣﺠﺎﻻت ﻣﺨﺘﻠﻔﺔ ﻣﺜﻞ أﺟﮭﺰة اﻻﺗﺼﺎﻻت واﻟﻤﺠﺎل اﻟﻄﺒﻲ ﺳﻮاء ﻓﻲ اﻟﺘﺼﻮﯾﺮ اﻟﻄﺒﻲ أو ﻟﻠﻜﺸﻒ ﻋﻦ ﺑﻌﺾ اﻷﻣﺮاض وﻛﺬا ﻓﻲ اﻟﺼﻨﺎﻋﺎت اﻟﻐﺬاﺋﯿﺔ. و ﺑﻤﺎ أن ﺗﻘﻨﯿﺔ اﻟﺘﯿﺮاھﯿﺮﺗﺰ ﻣﺎزﻻت ﺗﺨﻄﻮ ﺧﻄﻮاﺗﮭﺎ اﻷوﻟﻰ ﻓﺄﻣﺎﻣﻨﺎ اﻟﻌﺪﯾﺪ ﻣﻦ اﻟﺠﮭﻮد ﺣﺘﻰ ﻧﺘﻤﻜﻦ ﻣﻦ اﻟﺤﺼﻮل ﻋﻠﻰ ﻧﺒﺎﺋﻂ ﺗﻌﻤﻞ ﺑﻜﻔﺎءة ﻓﻲ ھﺬا اﻟﻄﯿﻒ ﻣﻦ اﻟﺘﺮددات. و ﺗﻌﺪ ﻣﺎﺻﺎت اﻟﺘﯿﺮاھﯿﺮﺗﺰ أﺣﺪ اﻟﻤﻜﻮﻧﺎت اﻷﺳﺎﺳﯿﺔ ﻷﻧﻈﻤﺔ اﻟﺘﯿﺮاھﯿﺮﺗﺰ اﻟﻤﺴﺘﻘﺒﻠﯿﺔ ﺣﯿﺚ ﺗﺘﻮاﺟﺪ ﻓﻲ أﻧﻈﻤﺔ اﻻﺗﺼﺎﻻت و اﻟﻔﺤﺺ اﻟﻄﺒﻲ و اﻟﺘﺼﻮﯾﺮ ﺑﻮﺟﮫ ﻋﺎم وﻛﺬا ﺣﺠﺐ اﻷﺷﻌﺔ اﻟﻐﯿﺮ ﻣﺮﻏﻮب ﻓﯿﮭﺎ. إن ﻣﺎﺻﺎت اﻟﺘﯿﺮاھﯿﺮﺗﺰ ھﻲ أﺟﮭﺰة ﻗﺎدرة ﻋﻠﻰ اﻣﺘﺼﺎص ﻣﻮﺟﺎت اﻟﺘﯿﺮاھﯿﺘﺰ وﻗﺪ ﺗﻜﻮن واﺳﻌﺔ اﻟﻨﻄﺎق ﺑﺤﯿﺚ ﺗﻤﺘﺺ ﺣﯿﺰ ﺗﺮددات ﺗﯿﺮاھﯿﺮﺗﺰ ﻛﺒﯿﺮ أو ﺻﻐﯿﺮة اﻟﻤﺪى ﺑﺤﯿﺚ ﺗﻤﺘﺺ ﺗﺮدد ﻣﺤﺪد ﺑﻌﯿﻨﮫ. إن ھﺪف ھﺬة اﻟﺪراﺳﺔ ھﻮ ﺗﺼﻤﯿﻢ ﻣﺎص ﺷﺒﮫ ﻣﺜﺎﻟﻲ ذو ﻗﺪرة ﻋﻠﻰ اﻻﻣﺘﺼﺎص ﺗﻘﺮب ﻣﻦ الـ100% ﻷﺷﻌﺔ اﻟﺘﯿﺮاھﯿﺮﺗﺰ وﯾﻌﺘﻤﺪ ﻋﻠﻰ اﻟﻤﻮاد ﺛﻨﺎﺋﯿﺔ اﻷﺑﻌﺎد اﻟﺘﻲ ﺗﻌﺪ ﻗﻠﯿﻠﺔ اﻟﺘﻜﻠﻔﺔ وﻣﺘﻮﻓﺮة وﺳﮭﻠﺔ اﻟﺘﺤﻀﯿﺮ ﻣﻦ ﺧﻼل اﻟﻄﺮق اﻟﺘﻘﻠﯿﺪﯾﺔ ﻣﺜﻞ اﻟﺘﺮﺳﯿﺐ اﻟﻜﯿﻤﯿﺎﺋﻲ. إن ھﺬا اﻟﺒﺤﺚ ﯾﻨﺎﻗﺶ ﺧﺼﺎﺋﺺ اﻟﻤﻮاد اﻟﺮاﺋﺠﺔ ﻣﺆﺧﺮا ﻣﺜﻞ ﺛﺎﻧﻲ ﻛﺒﺮﯾﺘﯿﺪ اﻟﻤﻮﻟﯿﺒﺪﯾﻨﻮم MoS2 واﻟﻔﺴﻔﻮرﯾﻦ وﺧﺼﺎﺋﺺ ھﺬه اﻟﻤﻮاد ﻓﻲ اﻟﺒُﻨﻰ اﻟﻐﯿﺮ ﻣﺘﺠﺎﻧﺴﺔ ﻟﻠﺠﺮاﻓﯿﻦ وﺗﻮظﯿﻒ ھﺬه اﻟﺨﺼﺎﺋﺺ ﻟﻌﻤﻞ اﻟﻤﺎص اﻟﻤﺜﺎﻟﻲ. إن ھﺬا اﻟﺒﺤﺚ ھﻮ دراﺳﺔ ﻧﻈﺮﯾﺔ ﺗﻢ ﻓﯿﮭﺎ اﺳﺘﺨﺪام "طﺮﯾﻘﺔ اﻟﻌﻨﺎﺻﺮ اﻟﻤﺤﺪودة" ﻟﻤﺤﺎﻛﺎة اﻟﺘﺼﻤﯿﻢ اﻟﻤﻘﺘﺮح ﻣﻌﺘﻤﺪﯾﻦ ﻓﻲ ذﻟﻚ ﻋﻠﻰ اﻷﺑﺤﺎث اﻟﺘﺠﺮﯾﺒﯿﺔ واﻟﻨﻈﺮﯾﺔ اﻟﺴﺎﺑﻘﺔ. وﻗﺪ ﺗﻢ اﻟﺘﺤﻘﻖ ﻣﻦ اﻟﻨﺘﺎﺋﺞ ﺑﺘﻄﺒﯿﻖ "ﻧﻈﺮﯾﺔ دواﺋﺮ اﻟﻨﻘﻞ" اﻟﺘﻲ أﻛﺪت اﻟﻘﺪرة اﻟﻌﺎﻟﯿﺔ ﻟﮭﺬا اﻟﺘﺼﻤﯿﻢ ﻋﻠﻰ اﻣﺘﺼﺎص أﺷﻌﺔ اﻟﺘﯿﺮاھﯿﺮﺗﺰ. إن اﻟﺘﺼﻤﯿﻢ اﻟﻤﻘﺘﺮح ھﻮ اﻷول ﻣﻦ ﻧﻮعه اﻟﺬي ﻟﮫ اﻟﻘﺪرة ﻋﻠﻰ اﻣﺘﺼﺎص أﻛﺜﺮ ﻣﻦ 90% ﻣﻦ اﻷﺷﻌﺔ اﻟﺴﺎﻗﻄﺔ ﻋﻠﯿﮫ واﻟﺘﻲ ﺗﺼﻞ إﻟﻰ 95% أو أﻛﺜﺮ ﻋﻨﺪ ﺑﻌﺾ اﻟﺘﺮددات واﻟﺬي ﻓﻲ ﻧﻔﺲ اﻟﻮﻗﺖ ﻻ ﯾﺴﺘﺨﺪم أي ﻣﻦ اﻟﻤﻌﺎدن اﻟﻨﻔﯿﺴﺔ ﻣﺜﻞ اﻟﺬھﺐ أو اﻟﻔﻀﺔ ﻟﻠﻮﺻﻮل ﻟﮭﺬا اﻻﻣﺘﺼﺎص اﻟﻌﺎﻟﻲ. ﻛﻤﺎ ﯾﻤﻜﻨﻨﺎ ﺿﺒﻂ اﻟﺘﺮدد اﻟﻤﺮاد اﻣﺘﺼﺎﺻﮫ اﻟﻜﺘﺮوﻧﯿﺎ ﻋﻦ طﺮﯾﻖ ﺗﺤﺪﯾﺪ ﻗﯿﻤﺔ ﻓﺮق اﻟﺠﮭﺪ اﻟﻤﻄﺒﻖ ﻋﻠﯿﮫ واﻟﺬي ﺑﺪورة ﯾﻤﻜﻨﮫ ﻣﺴﺢ أﻏﻠﺐ ﺗﺮددات اﻟﺘﯿﺮاھﯿﺮﺗﺰ (1.3-10 تيتراهيرتز) وھﻜﺬا ﺗﻔﻮق اﻟﻤﺎﺻﺎت اﻟﺴﺎﺑﻘﺔ اﻟﺘﻲ ﺗﺘﻤﯿﺰ ﺑﻘﺪرﺗﮭﺎ اﻟﻌﺎﻟﯿﺔ ﻟﻼﻣﺘﺼﺎص ﻟﺘﺮددات محددة فقط. إن هذه الخصائص ﺗﺘﯿﺢ ﺳﮭﻮﻟﺔ اﻟﺘﺼﻨﯿﻊ ﺑﺘﻜﻠﻔﺔ ﻣﻨﺨﻔﻀﺔ واﻟﺬي ﯾﻌﺪ ﺳﺒﻘﺎ ﻓﻲ ھﺬا اﻟﻤﺠﺎل.

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