The Study Of Novel Optical Functional Devices Based On Graphene And Hyperbolic Metamaterial

Recent years, duo to the limited response to electromagnetic wave of conventional materials, especially in the frequency of terahertz(THz), most natural materials cannot respond to THz waves, which restricts the exploitation of THz electromagnetic waves, people turn their attention to new materials, such as graphene and artificial metamaterials. Due to their unusual properties, these new materials can realize optical phenomena that can’t be achieved with conventional materials.Graphene, a two-dimensional material with a thickness of only one atom layer, behaves like a metal in infrared and THz regime and supports the propagation of surface plasmon polaritons(SPPs). Besides, graphene has the advantage of tunability, low losses and extreme confinement of optical field, which paves a new way to develop tunable and sub-wavelength optical devices.Artificial metamaterials refer to media which is made up of periodic subwavelength structures. Such materials exhibit unique properties to control electromagnetic wave and can be used to realize negative refraction, super-resolution imaging and invisible cloaking, etc. One of the most important classes of artificial metamaterials is hyperbolic metamaterial(HMM). HMM display hyperbolic dispersion, which originates from one of the principal components of their electric or magnetic effective tensor having the opposite sign to the other two principal components. Such materials exhibit distinctive properties and have a variety of applications in negative refraction, enhancement of spontaneous emission, broadband absorber, etc.Based on the unique optical properties of graphene and HMM, the main work of this paper includes the following sections:(1) Graphene behaves like a metal in infrared and THz regime and could enable the propagation of surface plasmon polaritons(SPPs). By utilizing this property of graphene, we proposed a hybrid waveguide based on graphene, which could simultaneously achieve subwavelength confinement and long range propagation.(2) For the chemical potential of graphene could be tuned by applied voltage, we insert the graphene into the structure of double micro-resonator. By apply voltage to change the chemical potential of graphene, we could change the mode effective index of micro-resonator and thus change the resonate wavelength. By this way, we could change the transmission peak of the electromagnetically induced transparency.(3) Based on the principle of broadband absorption of tapered HMM, we propose to design a novel broadband THz bandpass filer consisting of two different-sized tapered HMM waveguide arrays. By properly selecting the geometrical parameters to control the absorption and transmission bands for each HMM waveguide, the designed bandpass filter is demonstrated to be capable of operating with a broad passband in the THz domain.