Studying Of Broad Band Perfect Absorption Metamaterials And Application

From last century, nano-technology is developing rapidly. Recently, we have focused on matematerials and surface plasmons in optical field. Matematerials are different from traditional materials, which can not be found in nature. Perfect absorption material as a particular branch have caught many scientists’ attention to study them since they exhibit perfect absorption responding to incident electromagnetic wave at their operate wavelength. The absorbers have been developed from infrared band to visible band, from single band to two bands, three bands and broad band stage. The perfect absorbers initially causes scientists’ motivation to study them coming from microwave region. The absorbers can improve radar performance and reduce radar echo so that makes the objects hidden themselves, which can be used in military. Nowadays,the use of the electromagnetic wave absorbers is not only in military, but also extended to civilian in many fields such as emitters, bio-sensors, photovotatics, spatial light modulators and so on.In this paper, three period structures consist of hexagonal prisms array, four hexagonal prisms forming into one unit cell and rings array are studied numerically by aid of finite difference in time domain(FDTD) algorithm in detail. The structures are traditionally formed by three layers based on metal-dielectric-metal design scheme. The top layer interacts with the incident electromagnetic waves and produces localized surface plasmon resonance, in this way, the electromagnetic energy can be confined in this structure. The middle layer is commonly high-loss dielectric materials in which resonance energy dissipates. The bottom layer acts as a reflector to prevent the incident electromagnetic wave transmit from this layer, so the thickness of this lay must be greater than the skin depth. In the future, designing absorbers with high-absorption,broad band, wide angle and polarization insensitive is our goal.When it comes to the hexagonal prism array, it is a novel optical absorber that has many advantages including flexible in size for fabrication and unique properties. The effects of the structure parameters on the absorbance and the absorption wavelength are investigated by FDTD Solutions software. The results show that the absorber nearly can absorb all the incident light and the absorption peaks increase from two to three as the size of the radius of the hexagonal prism ranging from 280 um to 400 nm. Surprisingly,the position of the first peak is much stable, which may possess great potential application in the future. In order to broaden the absorption band of the absorbers, the structure that different size of hexagonal prisms are regularly arranged in one unit cell is designed. Utilizing this method, a wide band absorber is obtained. In addition, a perfect absorber that is composed by three nested rings in one cell is also researched. This structure exhibits perfect absorption in a broad band and insensitive to the polarization of the incident beam because of the high symmetry of the structure.