The Theoretical Study Of Propagation Characteristics Of Terahertz Wave Based On Grapheme Material

The innovative technology of high-performance photoelectric materials play an important role in many fields,including medical science,image and display technologies,military affairs,photo-communication,environmental monitoring, safety inspection and the development of industries process control. Graphene acts as the most attractive two-dimensional material,moreover,it had been proved that the grapheme can be used in all types of photoelectric detection from Thz to ultraviolet. When the grahene combines with the photonic crystal,the metal-dielectric construction which will produce SPs appears due to the grahene's metallicity.This composite structure change the grahene's properties by the external electric field and temperature change of external circumstances,in this way, Various of filtering functions can be achieved.First,we study the optical characteristics of grahene in Thz wave band. The tightbinding approach is used in the process of the grahene's band calculation to discuss the electron transition of the graphene.That grahene's conductivity can be adjusted by the dopant chemistry or applied voltages.Therefore the optical characteristics of grahene can be adjustable. Theoretically Based on the Maxwell equation,we study the propagation feature for SPs in the One-Dimensional Quasi-periodic Thue – Morse sequence which is covered by the grahene.Then, the transfer matrix method is used to derive the propagation feature for SPs in the DGD "sandwich construction" that is made up with the grahene and photonic crystal.We simulate the propagation feature for SPs in Thz wave band by numerical calculation. The numerical experiments show that the band-gap width and location would not change with the increases of Thue – Morse sequence iterms when the SPs incidence vertically.For the periodic photonic crystal which is covered by grahene,it can be adjusted by changing the permittivity and thickness of traditional dielectric materials,in this way,the propagation feature is also changed.Then we study the propagation feature for SPs in the one-dimensional disordered Fibonacci sequence. Similarly, the transfer matrix method is used to derive the propagation feature for SPs in the DGD "sandwich construction. We propose firstly a quasi-period Fibonacci photonic structure covered with graphene. The propagation of surface plasmons(SPs) in such a structure are investigated in detail. More subbands appear compared with that in the periodic structure covered with graphene. On condition that the chemical potential of graphene is much larger than, the PBG shifts to higher frequency as the chemical potential increases. Due to that optical conductivity are determined by chemical potential which can be controlled by the gate voltage. The band structure can be flexibly tuned by gate voltage.