Electric And Magnetic Properties In The Left-handed Material

A novel type of material called left-handed material has caused great concern in the fields of solid state physics, material science, optics and applied electromagnetic. Left-handed material is a composite with simultaneously negative permittivity and permeability. We, therefore, call it left-handed material, or negative refractive material, i.e., negative material. Due to the experimental realization of this kind of material in 2000, it has stirred a growing interest among experimental and theoretical researchers. The peculiar properties of such a material suggest many valuable technical applications. For example, left-handed material can be used to produce advanced antennas, lasers, and "perfect lens"and so on. In experiments, a composite composed of arrays of wires with negative permittivity and split ring resonators with negative permeability can realize values of negative effective permittivity and negative effective permeability at the microwave region. Basing on this method, we advance the possibility of preparing left-handed material with a layered alternated nonmagnetic/magnetic composite. We calculate the effective permittivity and permeability of the layered composite by using of effective medium approximation. It is found that the composite may show left-handed properties at a certain frequency region by adjusting the volume fraction of one component of the composite. Moreover, we find that the direction of the incident electromagnetic wave affects the effective refractive index greatly. The permeability of metallic ferromagnetic materials is negative near the ferromagnetic resonance frequency, which provides an alternate way to prepare left-handed materials. According to this character, we also suggest a possibility of making a left-handed material with parallel ferromagnetic nanowires electrodeposited into an insulating polycarbonate membrane. When electromagnetic wave impinges on the material normally, we calculate the wave vectors of left and right circular polarizations by transfer matrix method. We find that the propagation direction of wave vector is opposite to its energy flow direction for right circular polarization, i.e., such a material shows left-handed properties. Because this kind of material is usually magnetic anisotropic in nature, we also investigate the magneto-optical properties of such a material and find that at the frequency region where the material exhibits left-handed property, both the Faraday rotation angle and ellipticity of the film show obvious change, which is expected to be a technical method to identify the left-handed properties of magnetic material. Compared with the pure ferromagnetic film, a larger Faraday rotation angle is obtained in our model. The insulating nature of the composite may overcome the drawback of the loss of the pure ferromagnetic film. In periodic photonic crystal containing left-handed material, there exist the omnidirectional reflection corresponding zero-average refractive index and omnidirectional reflection corresponding to Bragg reflection. In this thesis, we clarify whether omnidirectional reflection exists or not in one-dimensional quasi-periodic photonic crystal (Fibonacci sequence) containing left-handed material. In the light of the dispersion relation and transfer matrix method, we show that quasi-periodic photonic crystal can exhibit complete reflection at a given microwave frequency for all incident angles and both polarizations (TE and TM wave). The permittivity and permeability of left-handed materials are much related to the existence of omnidirectional reflection. At present, many works devote to investigate the properties of isotropic left-handed material. In practice, the materials investigated in experiments are strongly anisotropic. Therefore, it is of significance to investigate the properties of anisotropic left-handed material. Due to the anisotropy of the material, there are many specific properties, which are obviously distinct from isotropic left-handed material, such as, anomalous reflection and refraction at the interface of isotropic regular material and uniaxially anisotropic negative refractive material (the condition of total reflection is that incident angle is smaller not larger than the critical angle). The reflection shows frequency selective total oblique transmission that is distinct from the Brewster effect. In this thesis, weinvestigate the propagation character and the shifting of a Gaussian beam in a slab of anisotropic negative refractive medium. We derive the shifting of a Gaussian beam by using of Maxwell equations combined with boundary conditions. Our results indicate there exist two possible (positive or negative) beams shifting for anisotropic negative refractive medium due to the special anisotropic properties, which is distinct from the case of isotropic negative refractive slab. Physical insights are also presented by the isofrequency curves.