Overview

Photonics plays an important role in modern technological systems, such as telecommunications and sensing systems. Traditionally, the manipulation of optical photons has relied in general on the mechanism of total internal reflection (TIR). ^[1] Since the 1980s, the research in new purpose-built materials has opened up the possibilities of localizing and controlling light in cavities and waveguides by a new physical mechanism, ^[2], ^[3] namely the photonic band-gap (PBG) effect, there has been a growing interests in the realization of photonic crystals or photonic band-gap structures as optical components and circuits. ^[4] Photonic band gap that excludes light transmission in all directions for a specific wavelength range, is analogous to the electronic band structure of semiconductor materials, ^[5] where the periodic arrangement of ions on a lattice gives rise to the energy band structure and the energy bands control the motion of charge carriers through the crystal. The periodic arrangement of refractive index variation in photonic crystal controls how photons are able to move through the crystal. A simple example is a simple-cubic lattice, whose lattice points are occupied by dielectric spheres. The crux of photonic crystals is that the lattice constant lies in the order of an optical wavelength. ^[1] The most striking effect is that for a certain range a frequencies (colors) light can not propagate in the photonic crystal. Natural examples can be found, such as opal. Light of frequency within the photonic band-gap of the opals is reflected, which...