Modeling and characterization of tunable photonic crystal waveguides based on two-dimensional periodic arrays of silicon pillars

Abstract

Highly dense two-dimensional periodic arrays of nano-scaled silicon pillars present the capacity for acting as photonic crystals which can mould, manipulate and guide light. We demonstrate finite element modelling of silicon pillars based photonic crystals and their effective use in applications like waveguides, multiplexers and switches. The optical wave propagation through these structures was thoroughly simulated and analysed, confirming their high efficiency. Later the fabrication of highly periodic two-dimensional arrays of silicon pillars through the process of etching is also explained. High quality of fabricated silicon pillars is displayed in various scanning electron microscope images. The arrays with pillar radius of 50 nm and lattice constant of 400 nm were successfully utilised as optical waveguides with sharp turns. The experimental results are presented showing a good match with the simulation band gap results. Finally we also present the concept of utilising liquid crystals as an anisotropic medium around the silicon nano-pillars to establish tuneable photonic crystals waveguides. The cell geometry for such a hybrid device is suggested in which by application of voltage the dielectric constant of liquid crystals can be controlled and essentially the waveguides can be tuned.