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dc.contributor.advisor Swillam, Mohamed Elsayed, Mohamed 2017-09-13T07:40:04Z Fall 2017 en_US 2017-09-13
dc.description.abstract Adding more functionality to chips is an important trend in the advancement of technology. During the past couple of decades, integrated circuit developments have focused on keeping Moore’s Law alive – “More of Moore”. Moore’s law predicts the doubling of the number of transistors on an integrated circuit every year. My research objectives revolve around “More than Moore”, where different functionalities are sought to be integrated on chip. Sensing in particular is becoming of paramount importance in a variety of applications. Booming healthcare costs can be reduced with early diagnosis, which requires improved sensitivity and lower cost. To halt global warming, environmental monitoring requires miniature gas sensors that are cheap enough to be deployed at mass scale. First, we explore a novel silicon waveguide platform that is expected to perform well as a sensor in comparison to the conventional 220 nm thick waveguide. 50 and 70 nm shallow silicon waveguides have the advantage of easier lithography than conventional 220 nm thick waveguides due to the large minimum feature size required of 1 µm. 1 µm wide waveguides in these shallow platforms are single mode. A multi-mode interference device is designed in this platform to function as the smallest MMI sensor, giving sensitivity of 427 nm / refractive index unit (RIU) at a length of 4 mm. The silicon photonic MMI sensor is based on detecting refractive index changes. Refractometric techniques such as the MMI sensor require surface functionalization to achieve selectivity or specificity. Spectroscopic methods, usually reserved for material characterization in a research setting, can be adapted for highly specific label-free sensing. Chapter 4 explores the use of a highly doped III-V semiconductor for on chip infrared spectroscopy. Finite element method and finite different time domain were both used to design a plasmonic slot waveguide for gas sensing. On chip lasers and detectors have been designed using InAs. While InAs is still considered more expensive than silicon, the electronics industry expects to start incorporating more materials in standard fabrication processes, including III-V semiconductors for their superior properties including mobility. Thus, experimental realization of this sensor is feasible. A drawback with infrared spectroscopy is that it is difficult to use with biological fluids. Chapter 5 explores the use of Raman spectroscopy as a sensing method. To adapt Raman spectroscopy for sensing, the most important task is to enhance the Raman signal. The way the Raman signal is generated means that the number of photons is generally very low and usually bulk material or concentrated fluids are used as samples. To measure low concentrations of a probe molecule, the probe molecule is placed on a surface enhanced Raman spectroscopy (SERS) substrate. A typical SERS substrate is composed of metal nanostructures for their surface plasmon resonance property, which causes a large amplification in the electric field in particular hot spots. By decorated silicon nanowires with silver nanoparticles, an enhancement factor of 1011 was realized and picomolar concentrations of pyridine were detected using Raman spectroscopy. In conclusion, this thesis provides new concepts and foundations in three directions that are all important for on chip optical sensing. First, silicon photonics is the technology of choice that is nearest to the market and a multi-mode interference sensor based on shallow silicon waveguides was designed. Further work can explore how to cascade such MMIs to increase sensitivity without sacrificing the free spectral range. Second, infrared plasmonics is a promising technology. Before semiconductor plasmonics, on chip devices operated in the visible or near IR and then microwave region of the electromagnetic spectrum. By using highly doped semiconductors, it is possible to bridge the gap and operate with mid-infrared wavelengths. The implications are highlighted by designing a waveguide platform that can be used for next generation on chip infrared spectroscopy. Third, Raman spectroscopy was exploited as a sensing technique by experimental realization of a SERS substrate using equipment-free fabrication methods. en_US
dc.description.sponsorship First, I would like to thank Professors Mohamed Swillam and Yehea Ismail for their guidance and motivation and for having me a part of the nanophotonics research lab (NRL) and the center of nanoelectronics and devices (CND). They both have spent tremendous efforts in creating and maintaining a healthy research environment and for that I am deeply grateful. I would like to extend many thanks to members of the NRL and CND, for their help and friendship that will definitely continue for several years to come. Special thanks to my coauthors Aya Zaki and Abdelaziz Gouda. Special thanks to Raghi Samir for helping me learn the simulation tools in my first few weeks. Special thanks to Ahmad Bassam for help with scanning electron microscope images and Raman measurements and for helpful discussions. Special thanks to Hosam Mekawey and Hani Mostafa for their assistance in setting up the simulation environment. I would like to thank the examiners, Dr. Salah Obayya and Dr. Karim Addas for their time and effort. I would like to acknowledge the STRC team for their help. Thanks to Asmaa Gamal for training me to use the Raman. Thanks to Ahmed Nour, Ahmed Beltagy and Ahmed Ghazaly for their skills and dedication that definitely enhanced my learning experience. Thanks to Saleh for his continuous help. The American University in Cairo is acknowledged for providing me a fellowship to fund this Master of Science degree. I would like to especially thank the course instructors: Dr. Mohamed Swillam, Dr. Tarek Ghanem, Dr. Nageh Allam, Dr. Wael Mamdouh, Dr. Yehea Ismail, Dr. Hassan Azzazy, Dr. Adham Ramadan, Dr. Mohab Anis. Every course I took was useful and helped shape this thesis and definitely enriched the educational experience at the AUC. The Optical Society of America (OSA) is acknowledged for providing a travel grant to present at the international OSA network of students (IONS) conference 2016. AUC’s Graduate Student Association is acknowledged for providing a grant to present at Photonics North conference 2016 through AUC’s Office of Student Development (OSD). The AUC is acknowledged for providing a conference grant to present at META’16. The international society for optics and photonics (SPIE) is acknowledged for providing a travel grant to present at Photonics West 2017. Lumerical is acknowledged for providing licenses for their software for some periods of time. To my family, especially my father, mother and my closest friend, I say thank you for your endless unwavering support, patience and love during this period. Special thanks to my closest friend, Sara, my wife. en_US
dc.format.extent 106 p. en_US
dc.format.medium theses en_US
dc.language.iso en en_US
dc.rights Author retains all rights with regard to copyright. en
dc.subject integrated en_US
dc.subject silicon en_US
dc.subject photonics en_US
dc.subject waveguides en_US
dc.subject raman en_US
dc.subject nanowires en_US
dc.subject silver en_US
dc.subject nanoparticles en_US
dc.subject mid-infrared en_US
dc.subject plasmonic en_US
dc.subject slot waveguide en_US
dc.subject semiconductor en_US
dc.subject.lcsh Thesis (M.S.)--American University in Cairo en_US
dc.title On-chip optical sensors en_US
dc.type Text en_US
dc.subject.discipline Nanotechnology en_US
dc.rights.access This item is restricted for 2 years from the date issued en_US
dc.contributor.department American University in Cairo. School of Engineering Interdisciplinary Program en_US
dc.embargo.lift 2019-09-13T07:40:04Z
dc.description.irb American University in Cairo Institutional Review Board approval is not necessary for this item, since the research is not concerned with living human beings or bodily tissue samples. en_US
dc.contributor.committeeMember Ismail, Yehea
dc.contributor.committeeMember Obayya, Salah
dc.contributor.committeeMember Addas, Karim

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    This collection includes theses and dissertations authored by American University in Cairo graduate students.

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