Modelling of Photonic Crystal (PhC) Cavities: Theory and Applications

Abstract

In recent years, many researchers have shown their interest in producing a compact high-performance optical chip that is useful for most telecommunication applications. One of the solutions is by realising photonic crystal (PhC) structures that exhibit high-quality factors in a small mode volume, V. Silicon on insulator (SOI) is one of the main contenders due to its high-index contrast between the silicon (Si) core waveguide with silica (SiO 2) cladding surrounding it. The maturity of silicon photonic can also be incorporated with CMOS chips making it a desired material. A strong optical confinement provided by PhC structures makes it possible to realise the compact device on a single chip. In this chapter, we will discuss a fundamental background of photonic crystal cavities mainly on one-dimensional (1D) structures, which are the simplest as compared to their counterparts, 2D and 3D PhC device structures. We have modelled a photonic crystal cavity using finite-difference time-domain (FDTD) approach. This approach uses time-dependent Maxwell equation to cover wide frequency range in a single simulation. The results are then compared with the actual measured results showing a significant agreement between them. The design will be used as basic building block for designing a more complex PhC structures that exhibit high-quality factors for applications such as filtering, DWDM and sensors.