الفهرس 
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Abstract
Optical communication represents the recent technology that can be used to process large amounts of data and transmit them. Optical logic gates are considered as key elements in optical processing and communication systems which make the important functions at the nodes of network such as data encoding and decoding, pattern matching, recognition and various switching operations. Most of previous designs suffer from certain limitations such as big size, difficult to perform chip scale integration, high power consumption, low speed and the spontaneous emission noise. Photonic crystals are periodic dielectric structures that formed naturally or artificially. Their devices are applicable to optical logic gates because of their compact size, high speed and versatile functions. There are many numerical techniques used to investigate the characteristics of the photonic crystals structures such as finite difference time domain (FDTD) method and finite element method (FEM). In this thesis, two and three optical controlled AND gates built in 2D photonic crystal (PhC) platform have been proposed. The first proposed AND gate can handle two inputs and support two operating wavelengths, λ =1.5 µm and 1.55 µm. However, the second proposed AND gate can handle three inputs at λ =1.5 µm. Further, the suggested AND gates operation can be switched off by using the NLC layer. The suggested two input AND gate can be switched on to function as an AND gate with no less than 10 dB contrast ratio and 0.35 Tbits/s data rate near the wavelength λ = 1.5 µm. The operation of the two input AND gate is also investigated at λ = 1.55 µm with ON to OFF logic level contrast ratio of not less than 6 dB. Additionally, reconfigurable three-input AND gate near the 1.5 lm window with bit rate (BR) of 0.325 Tbits/s has been proposed and numerically simulated using 2D FEM based on COMSOL multiphysics software package. The use of the proposed reconfigurable optical logic gate instead of traditional PhC logic gate within the PhC platform can be employed for designing programmable compact photonic circuit.