الفهرس 
Chapter 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
Photonic Devices Nowadays, developing optical communication systems to achieve high transmission capacity became a strong necessity due to the rapid progress in information exchange and the need to increase the efficiency of current communication technologies. Optical communication systems rely heavily on the integration of different optical devices such as, detectors, couplers, modulators, and multiplexers. To transmit digital signal over an optical traveling wave, the optical wave should be modulated using the digital electronic signal. An electro-optical modulator is responsible for switching the optical wave to pass or block depending on the information digital signal. Such modulators are the key components in any optical communication system, since they convert the digital electronic signals to optical signals to travel over the optical fibers for long distances with minor losses. Recently, photonic crystal fibers (PCFs) based devices attract much attention due to their unprecedented optical properties that cannot be achieved using conventional optical fiber devices. Further, PCFs are commonly used in designing highly tunable and compact optical devices thanks to their high flexibility and unusual light control mechanisms. Phase changing materials (PCMs) such as vanadium dioxide (VO2) are considered as new adaptive materials as their phase can be changed from insulating to conducing by applying an external electric field or by changing temperature. In this thesis a mid-infrared optical modulator based on a silicon D-shaped PCF (SiD-PCF) with vanadium dioxide (VO2) as a PCM is presented in detail. The modulation process can be controlled based on the phase transition of VO2 material between insulating (ON) and conducting (OFF) states. The full vectorial finite element method (FVFEM) is utilized to numerically analyze the proposed design. Whereas, the light propagation through the suggested structure is studied using the 3D finite difference time domain (3D-FDTD) method. The optical loss of the fundamental TM mode supported by Si-D-PCF structure in both ON- and OFF-states is investigated. The extinction ratio (ER) of the reported modulator approaches 236 dB while the insertion loss (IL) is less than 1.3 dB over the studied wavelength range 3 - 7 μm and the device length (LD) is taken as 0.5 mm. The obtained results reveal that the proposed modulator could be utilized in photonic integrated circuits (PICs) that require high ER, low IL, and large bandwidth. Chapter (1) Introduction Chapter (2) summarized the detailed classifications of optical modulators, the major classes of materials used for optical modulation, and a description of the SPPs and how it interacted with other materials. In chapter (3), characteristics of PCFs, their advantages, their applications and their unique and novel characteristics over the conventional fibers are explained. Chapter (4) defines different numerical techniques that are generally utilized for design, analysis and optimize of photonic devices. Chapter (5) reports and explains the results of an optical modulator that operates in the mid-IR region and is based on Silicon D-shaped PCF with VO2 material which acts as a PCM. The transition of VO2 material from the insulating (ON-state) to the conducting (OFF-state) phases can be utilized for modulation process. The suggested design is numerically analyzed using the FVFEM and the 3D-FDTD method is utilized to study the propagation of light within the suggested design. The suggested modulator can be used in PICs with low IL, ultrahigh ER, and wide bandwidth. Finally, chapter (6) summarizes the conclusions and provides suggestions for further work.