CHAPTER 1Introduction to Photonic CrystalsMotivationIn recent decades, a new frontier has opened up due to the tremendous advancements in semiconductor technology that have brought incredible changes to our society and to people's lives. The goal became to control the optical properties of materials. A vast range of technological developments become possible through the engineering of materials capable of responding to light waves over a desired frequency range. They can perfectly reflect light waves, or allow them to propagate only in certain directions, or even confine them to a specified volume [1]. The introduction of components such as optical fibers or integrated peaked waveguides, based on the principle of total internal reflection for light guiding, has brought revolutionary changes in the telecommunications and communications industry. optical. Apart from this, another light control method based on Bragg diffraction has already been used in many devices such as dielectric mirrors. The principle of dielectric mirrors based on one-dimensional (1D) light reflection was generalized to two and three dimensions in 1987 [2, 3] which led to a new class of materials: photonic crystals. Photonic crystals result from the cooperation of periodic scatterers, which is why they are called crystals because of their periodicity and photonic because they interact with light. In the 21st century, there is a vision that photonic devices could take over from electronic devices. Through the use of strikingly analogous theoretical and manufacturing approaches, photonic crystals allow us to control the flow of photons and, through their ability to interact with light on a wavelength scale, they have the potential ... middle of paper. .....the width is obtained. To test the applicability of the proposed designs, we calculated various parameters to analyze the buffer capacity of the proposed PC waveguide. Chapter 2 gives a theoretical introduction to the properties of photonic crystals starting with Maxwell's equations. These equations are presented as a linear Hermitian eigenvalue problem, a form in which many useful properties become apparent. The properties of photonic crystals are then described by the characteristic structure of the photonic band or the scatter diagram representing the eigensolutions of the eigenvalue problem for a periodic dielectric structure. Chapter 3 provides a brief overview of published research on photonic crystal waveguides. Chapter 4 discusses the design and results of line-defect photonic crystal waveguide structure by moving the position of rows of holes adjacent to the defect waveguide.