The New Structure Design And Study Of Properties Of Chiral Negative Refractive Material

Negative refractive material is a kind of new materials, which combines artificially designed geometrical structures with conventional materiasl to poss the electromagnetic properties that natural materials do not have. Negative refractive material has a great application prospect in military, medical, biological science, wireless communication and other fields. In late 1990 s, the structure and fabricating method of negative refractive material were proposed in theory for the first time and then successfully implemented in experiment, more and more researchers started to focus on the study of negative refractive material. In the continuous exploration, researchers have proposed many techniques such as transmission line structure, photonic crystal, chiral structure to achieve negative refractive index. Because that chiral negative refractive material can get negative refractive index with needless of implementing negative permittivity and negative permeability simultaneously,and it’s easy to manufacture, has simple structure and high quality factor, and refractive index is gradient in it, it has become one of the main methods to achieve negative refractive index.Most of the designed structures in these decades have disadvantages such as narrow bandwidth of application, giant electromagnetic loss, poor performance at tunableness and so on. To these issues, based on negative refractive material’s designing theory and chiral method of achieving negative refractive index, this paper proposes a metal resonant structure which uses electrical resonance mechanism, studys the transmission, refraction and tunable performance of the structure by numerical simulation method, uses inversion algorithm(including the Kramers-Kronig dispersion relations) to get the structure’s effective electromagnetic parameters. By changing the structure’s parameters to achieve negative refractive band’s tunable ability, through permittivity and permeability of the negative refractive bands are not negative simutaneously to explore the role which chirality plays, and then this paper proves that the structure has a good optical activity. Through the analysis of metal surface’s current and electric field’s distribution of each resonant frequency band to explore the resonant mechanism of the structure.Due to it’s inconvinent to tune negative refractive band by changing structure’s parameters in practical applications, this paper utilizes the ability that negative permeability can be achieved by ferromagnetic material, combines ferromagnetic materials with a negative refractive structure, tunes the working bands by changing the magnetic field intensity loaded in the ferromagnetic material. First, match ferromagnetic material with simple negative refractive structure which has been designed, change the thickness of the ferromagnetic material, matching mode, magnetic field intensity, through numerical simulation to analyze how they affect the composite material’s ability of transmiting, resonance and tuning to optimize the structure’s parameters of ferromagnetic materials and explore the best matching way between the ferromagnetic material and the negative refractive material. After the numerical simulation of the composite material, contrast the simulation results with that of the negative refractive structure which is unmatched with ferromagnetic material to analyze the effect of ferromagnetic material on optical activity, loss, strength of resonance and so on. This paper has a certain reference value to the design of chiral negative refractive material with multi-band and tunable performance and it has practical significance to promote chiral negative refraction material’s development.