Terahertz Two-dimensional Photonic Crystal Transmitter

The terahertz (THz) region that lies between the millimeter and infrared region in the electromagnetic spectrum, with frequencies ranging form 100 GHz to 10000GHz, is an important region. And it has been proved greatly potential applications in many domains including imaging, environment monitoring, medical diagnosing and broadband mobile communications. To date, progress in THz spectroscopy has been enormous such as THz-radiation emitters and detectors. THz spectroscopy techniques uses mainly free space propagation of this far-infrared electromagnetic (EM) wave and it is to some extent difficult to control and guide.Photonic crystals are optical structures with wavelength-scale periodic variations of the refractive index. There are frequency bands, which called photonic bandgap, in the periodic dielectric materials. If there are dot or line defects in the periodic dielectric, it will appear frequency bands in which electro magnetic wave can propagate. The photonic band gap structures have been experimentally used effectively in many domains, and can achieve special function by introducing defects in it. These performances do well in the terahertz ranges also. And an important reason for design the terahertz photonic crystal propagating devices is the availability of precision manufacturing techniques in sub-millimeter, as the fabrication of a photonic crystal for the optical region can be a high technical challenge and the size of photonic crystal in microwave is too big. Therefore, analyzing the photonic crystal material and design the terahertz photonic crystal are significant in applying the THz technology.The paper uses a method called Plane Wave Expansion method to study the bangap characteristic of the two dimensional photonic crystal in terahertz region. Studies how the radius and the refractive index of the dielectric cylinders affect the bandgap of the photonic crystal with two dimensional rectangular photonic lattice and triangular photonic lattice. Analyses some stuff that may be used in terahertz region as photonic material. Choose silicon and alumina as dielectric material to study the transmission characteristic of photonic waveguide in terahertz region. Some waveguides are designed including line waveguide, 45°bend waveguide, 60°bend waveguide, 90°bend waveguide, T-junction, Y-junction, etc. And change the defects one time a little to achieve wonderful transmission result. The results tell us that use photonic crystal structure to make electromagnetic waveguide will have good transmission result.