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Controlling Properties of Optical Pulses by Using Photonic Crystal Based Structures
Miri, Mehdi | 2013
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- Type of Document: Ph.D. Dissertation
- Language: Farsi
- Document No: 44452 (05)
- University: Sharif University of Technology
- Department: Electrical Engineering
- Advisor(s): Rashidian, Bizhan; Mehrany, Khashayar
- Abstract:
- Because of widespread use of optical communication systems, analysis of optical wavepacket behavior during propagation in optical devices is of great importance. On the other hand, constant demand for improving the quality of data transmission and increasing data processing speed raises the necessity of studying novel electromagnetic structures for the purpose of designing new optical devices. Therefore, Photonic Crystal (PC) based structures, for their unique optical properties, have been subject of vast investigation in last two decades. Control of optical wavepacket behavior in photonic crystal based structures is considered in the present dissertation. Depending on the structure under study, optical beams or pulsed plane waves (as two special cases of wavepackets) will be studied with more details. The structure of this dissertation is as follows. Basic concepts of optical wavepacket propagation in free space will be reviewed and organization and goals of the thesis will be demonstrated in the Introduction section. In the first chapter, total reflection of optical waves from boundary of photonic crystal and homogeneous media is considered. Based on definition of expected photonic skin depth, a geometrical approach will be used to describe the spatial shift of the center of gravity of reflected beams. Then, resonance between incident wave and modes of the PC based structure will be used to amplify and control spatial displacement and temporal delay of optical wavepackets during the total reflection from the boundary. Chapter II is devoted to propagation of optical beams and pulsed plane waves in photonic crystals. Because of the importance of light coupling into photonic crystals, this concept is discussed in the first section of Chapter II. A transmission line model will be proposed for two-dimensional PCs. This model then will be used to design wideband matching stages for efficient coupling light into PCs. Then unique diffraction and dispersion properties of photonic crystals and its effects on waves propagating inside photonic crystal will be demonstrated through examples. Photonic crystal NanoBeam resonators (PCBNRs) are considered in Chapter III. In first section, a transmission line model will be developed for one-dimensional periodic waveguide. By using this model an algorithm will be proposed for designing NanoBeam resonators with desired properties (resonance frequency, quality factor, and mode volume). Fabrication and characterization results show accuracy of the transmission line model and efficiency of the proposed algorithm. In the second section of Chapter III, NanoBeam resonators will be designed for specific application to control behavior of optical pulses. These applications include optical modulators, wideband tunable resonators, Coupled Resonators Optical Waveguides (CROWs), and optical filters
- Keywords:
- Photonic Crystal ; Transmission-line Model ; Time Delay ; Optical Wavepacket ; Impedance Matching ; Nanobeam Resonator
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