Study of photonic crystal structures by THz-TDS

Abstract

Scope and Method of Study: The purpose of this study was to examine the behavior of dielectric and metallic photonic crystal structures embedded in single mode metal parallel plate waveguide (PPWG). The terahertz (THz) pulse was coupled in and out by two plano-cylindrical silicon lenses. The photonic crystals were fabricated by using Micro-Electro-Mechanical-Systems (MEMS) technology, which constructed very high aspect ratio structures. The transmission properties of the THz radiation of these structures were investigated using terahertz time-domain spectroscopy (THz-TDS).

Findings and Conclusions: We demonstrated the transmitted THz bandgaps in the 2D polymer (SU-8) photonic crystal structures, 2D metallic photonic crystal structures and 2D metallic photonic crystal defect structures. The experimental results matched the transfer matrix method (TMM) and the finite difference time domain (FDTD) simulation results very well. A very important conclusion is that the advantages of single mode PPWG and the coupling method give us a powerful tool to simulate infinite 2D ideal photonic crystal structures. This method can be used to do the farther research of THz photonic crystal structures. Some applications such as photonic crystal waveguide and tunable photonic bandgap are also investigated and demonstrated.