Anomalous Dispersion Characteristics Of Photonic Crystals And Their Application

A photonic crystal is an artificial structure which has a periodic modulation of dielectric constant on a length scale of wavelength. The photonic band gap and defects in the photonic crystals have been utilized to demonstrate ultrasmall lasers, ultrasmall waveguides and resonant-type narrow-band filters. On the other hand, bulk photonic crystals exhibit unique light propagation phenomena arising from the anomalous dispersion, and applications based on these anomalous dispersion have also been demonstrated, such as an ultralow group velocity, superprisms, negative refractive structures and self-collimating structures.The subject of this thesis is to investigate the unique dispersion characteristics of photonic crystals, and to explore some possible applications in e.g. optical communications.The background of the thesis is introduced in Chapter 1. Numerical simulation methods used in this thesis are introduced in Chapter 2. We also discuss the dispersion, loss and anomalous group velocity of photonic crystal slab structures in this Chapter. We propose two photonic crystal structures of negative refraction in Chapter 3. The proposed 2D metallo-dielectric photonic crystal of negative refraction is based on porous alumina template infiltrated with silver nano-wires. The proposed 3D photonic crystal of negative refraction is based on multiple-beam interference lithography (holographic lithography). Both structures can be realized in the optical region with some well-developed inexpensive technologies. As an application example of negative refraction in photonic crystals, we propose a novel scheme of polarization beam splitters in Chapter 4. Some 2D photonic crystals are designed in which the effective refractive index is negative for one polarization and positive for another polarization. A polarization beam splitter is demonstrated experimentally in the nearinfra-red region based on photonic crystal slab structures. The application of photonic crystals in light-emitting diodes is discussed in Chapter 5. We also introduce a mass-production method to fabricate 2D photonic crystal patterns with interference lithography. Chapter 6 concludes and outlines some future works.