ABSTRACT
High-quality three-dimensional photonic crystals were fabricated by use of the vertical deposition method, the laser direct writing method, and the laser holographic lithography method [26,27]. The novel phenomena of negative refraction effect and slow light effect in photonic crystals were also confirmed during this period [28-30]. Various integrated photonic devices based on photonic crystals, such as photonic crystal filter, photonic crystal optical switching, and photonic crystal laser, were realized experimentally [31-33]. In recent years, great attention has been paid to the realization of integrated photonic devices based on the new physical effects and phenomena in photonic crystals [34-36]. Moreover, photonic metamaterials, propagation and localization properties of surface plasmon polariton in metal photonic crystals, and the quantum electrodynamics of high-quality photonic crystal microcavity coupled with quantum dots have been studied extensively [37-40].From the brief discussion of the research history, we can see that the fabrication of high-quality photonic crystal samples and the applications of photonic crystal in micro/nano-scale integrated photonic devices have been always the most pursued research topics, which will be discussed in detail in the following chapters. 1. Fundamental Principles of Photonic CrystalPhotonic crystals are a kind of microstructure photonic materials with a spatially periodic distribution of dielectric constant. The unique properties of photonic crystal are its photonic bandgap effect, which originates from the modulation of light by the spatially periodic distribution of dielectric constant. The photonic bandgap, also called the stop band, corresponds to the frequency range where the density of states of photons is zero in the photonic band structures. An incident electromagnetic wave with a resonant frequency dropping into the photonic bandgap will be reflected completely by the photonic crystal. The reason lies in that there do not exist corresponding Bloch modes that can propagate through the photonic crystal [1,2].When a lattice defect is introduced in a perfect photonic crystal structure, the lattice defect will support an electromagnetic wave mode with a certain resonant frequency. Accordingly, defect
states will appear in the photonic bandgap. The electric-field distribution of the defect mode will be confined in the defect site [41]. By use of the lattice defect, high-quality microcavity can be formed in photonic crystals. There is a drastic increase of the density of states of photons in the center of the defect mode compared with that of the stop band. Owing to the strong photon confinement effect of photonic crystal microcavity, the interactions of light and matter is enhanced greatly in the photonic crystal microcavity. So, not only novel nonlinear optical phenomena can be observed in the photonic crystal microcavity, but also the thresholdless laser emission is promising to be reached in highquality photonic crystal microcavity structure [42,43].
