Research On Tunable Periodic Structure Based On Dispersive Media

With the rapid development of modern communication technology, artificial electromagnetic materials have a lot of important applications in military and civil fields, because of its unique control characteristics of electromagnetic waves. Thus it has been a new focus of researchers. Periodic structure also attracted attention as a topology structure of artificial electromagnetic materials. In this paper, we study the periodic structure devices based on dispersive media. We focus on studying the photonic crystal devices and electromagnetically induced transparency, while the semiconductors and graphene have been introduced into the design of the periodic structure device. The physical properties of the semiconductor and graphene can be regulated by a number of parameters. Thus it can be used to design tunable periodic structure device with two dispersive medium. In this paper, we design two periodic structure devices, which are one-dimensional photonic crystal device based on semiconductor and electromagnetically induced transparency based on graphene. Their tunable transmission characteristics and other characteristics have been studied. The main research results of this paper and the main innovation involves the following aspects:1. Several algorithms on photonic crystals have been discussed. The eigen matrix method(EMM) has been discussed and derived. Transmission characteristic and omnidirectional band gap of one-dimensional non-magnetic semiconductor photonic crystal in terahertz have been studied by EMM. Since the device is not sensitive to polarization and incident angle of the incident electromagnetic wave, it can be used to design omnidirectional reflectors. We also discuss effect of each parameter(filling rate or the plasma frequency) on omnidirectional band gap.2. We design a mode splitter based on one-dimensional magnetic semiconductor photonic crystals. We discuss the magneto-optical Voigt effect of semiconductors. Physical properties of semiconductor materials and theoretical models are analyzed with magneto-optical Voigt effects. The transport properties of the proposed structure are also studied while the external magnetic field are changed. When the intensity of the external magnetic field changes, the frequency range in which TE mode and TM mode will be split can be tuned in a large frequency range.3. We design the electromagnetically induced transparency based on graphene. We study the physical properties and theoretical models of graphene and analyze the influence of various parameters on the dielectric constant. We also study the mechanism of graphene-based electromagnetically induced transparency. The characteristics of the structure can be tuned by varying the Fermi level. Thus the frequency of the transparent window can be tuned in a large frequency range without changing the structural parameters.