Research On The Transmission Of Two-dimensional Terahertz Metallic Photonic Crystals

In this paper, we use muitiple-scattering approach and FDTD method for numerical calculation, to research on the transmission and slow light effects of two-dimensional terahertz metallic photonic crystals.Photonic crystal is a class of material exploiting periodicity to control and modulate properties of light. After the proposal in1987, photonic crystal has been paid a great deal of attention to. The existence of photonic band gap (PBG) is one of the most important properties. Light with frequency in the PBG is not able to transmit through photonic crystals. This property has a few possible applications, such as light waveguide, high-Q micro-resonators, filters, etc. The research and applications of photonic crystal physics, materials and devices provide a possible approach for the realization of large scale light integration, and it is significant to the prospects of IT. Of all kinds of photonic crystals, two-dimensional photonic crystal has been a hot spot in optical research area because of its relatively easy preparation and attractive prospects for micro planar optical-chips.For two-dimensional terahertz metallic photonic crystals without defects, we have demonstrated a kind of extraordinary resonance transmission in the photonic first pass band:in the regime of low-middle metal filling radio, resonances among the metallic cylinders lead to sharp and high resonance peaks of Lorentz type, layer dependency of the peak numbers. Based on a simple model proposed in this paper, we can intuitively understand the extraordinary transmission and roughly estimate resonance frequencies. Our results agree qualitatively with the experimental data reported in Appl. Phys. Lett.65,645. The effect of positional disorders of metallic cylinders has been investigated as well to simulate the transmission of real samples. Meanwhile, we have prepared a metallic photonic crystal sample to do experiments, with a result in which the first pass band (resonance transmission) and the second pass band are able to distinguish.Based on the muitiple-scattering approach, with FDTD method, we calculate the time delay of the transmission of Gaussian beam through two-dimensional metallic photonic crystals. A strong slow light effect has been found particularly at resonance frequency, because the incident light with particular frequency occurs resonance among the metallic cylinders. The apparent light velocity slows to1/26.5of the velocity in the air.Our work is helpful to understanding the transmission properties of two-dimensional metallic photonic crystals, and has application potential in filters, nonlinear or slow light devices, etc.