In this thesis we consider telecom applications of line defect waveguides in PCS that should act as ‘light pipes’ for directional transmission of signals.What is the motivation of using PCS-based waveguides instead of conventional waveguides? In conventional slab-based waveguides the energy distribution has a tail extending into the claddings and waveguiding relies on ‘total internal reflection’ (TIR). When the waveguide turns a bend the TIR condition is broken and energy leaks away. On the other hand, in a PCS-based waveguide the lateral ‘walls’ are ‘metallic-like’ because the wave is strongly attenuated inside these walls for frequencies in the photonic bandgap (PBG). Consequently, sharp bends in PCS-based waveguides are, in principle possible, because in-plane radiation losses are suppressed. Being the first PhD thesis on photonic crystals in the Integrated Optical Microsystems Group, the focus of this research is on design and fabrication of PCS-based integrated optical components in silicon-on-insulator substrates. In Chapter 1 the basic physical concepts of photonic crystals are introduced, in order to aid understanding and interpretation of computational results and design rules. Chapter 2 presents an overview of the most common computational methods and modeling tools applicable to the analysis and design of photonic crystals. The emphasis is put on strengths and weaknesses of each method. The calculation results and the design rules derived from them are presented in the following two chapters. Chapter 3 contains applications of the theoretical framework and computational techniques from the previous two chapters. The representative results presented are interpreted in terms of design and optimization criteria of photonic crystals with 2D periodicity as function of geometrical parameters (e.g. filling factor, slab thickness). We introduce a new class of photonic crystals (called “hexagon-type‿) that offers flexibility in adjusting the lattice configuration and provides a large PBG. Chapter 4 contains a study of propagation phenomena in line defect waveguides and their impact on the device performance. After comparing different engineering solutions, we opted for a hybrid design (hexagonal holes plus triangular inclusions) in which the PhC waveguide resembles closely a ridge waveguide. Chapter 5 contains fabrication results obtained using available technologies: laser interference lithography, reactive ion etching and focused ion beam. Chapter 6 contains preliminary measurement results using end-fire coupling. Five appendices, containing mathematical and technological details, complement the main chapters.
|Award date||25 Feb 2005|
|Place of Publication||Enschede, Netherlands|
|Publication status||Published - 25 Feb 2005|
- IOMS-PCS: PHOTONIC CRYSTAL STRUCTURES