Research On Infrared Metamaterial Absorbers And Their Thermal Radiation Controlling Based On Surface Plasmon Polaritons

Infrared metamaterial absorber is a novel artificial electromagnetic material that emerges in recent years. The unique electromagnetic resonant characteristics make it as the highlight in artificial electromagnetic material research. The emergence of infrared metamaterial absorber has dramatically expanded the interaction manners of electromagnetic wave with materials in the infrared regime, and which have been exploited for the extensive potential applications in selective thermal emission, sensitive detection and infrared anti-detection, etc.In this dissertation, we studied on the infrared metamaterial absorber which is designed based on surface plasmon polaritions. In order to overcome the limitation of the single and narrow absorption bandwidth, studies have been carried out on the excitation mechanism of surface plasmon polaritions, the electromagnetic response and the resonant behaviors of the absorbers, and we have proposed several multiple-band and broad-band absorbers. Based on above, the approach of thermal radiation controlling using infrared metamaterial absorbers has been proposed to meet the requirements in the infrared anti-detection. The major work of this dissertation is as follows:(1) We have constructed the equivalent circuit model for the infrared metamaterial absorbers. According to the electromagnetic field and surface current distribution, an equivalent circuit model is built up to analyze the relationships between the absorption frequency, the structure parameters and the dielectric material parameters. Through this method, by combination the electromagnetic resonant characteristics of surface plasmon polaritions, we have found several critical factors that determine the absorption frequency of the absorber, and which is the design basis for the multiple-band and broad-band absorbers.(2) We have proposed the design approach for the multiple-band and broad-band absorbers based on the tuning of dielectric materials. Since most of the present multiple-band and broad-band absorbers were designed by manipulating the resonant patterns, we have put forward an alternative method. By using the multiple resonant layers with distinct dielectric materials, multiple-band and broad-band absorption could be achieved, which is tunning effect of the surface plasmon polaritions in the absorbers.Besides, we have found that the multiple absorption peaks may be contributed by different loss mechanism.(3) We have proposed a broad-band absorber based on the slowlight mode. The graded permittivity profile of the absorber offers the broad-band absorption and permits the engineering of the absorption spectrum. The absorber could efficiently absorb light even at large incident angles and can be polarization insensitive with properly design.(4) We have reported the approach of the thermal radiation controlling based on the infrared metamaterial absorbers. In the atmospheric window, by using the single-band and multiple-band absorbers, we have achieved the tuning of emissivity, radiant exitance and radiation temperature. Besides, the combinations of the single-band and multiple-band absorbers could act as the camouflage patterns under the thermal detection. In the non-atmospheric window, the designed absorbers could transfer the radiation energy in the waveband of 3~5 μm and 7.5~14 μm to 5~7.5 μm, which could reduce the infrared radiation signal in the detection waveband.In summary, we have designed the infrared metamaterial absorbers based on surface plasmon polaritions and researched on their thermal radiation controlling in this dissertation. The established design approach will help to develop the multiple-band and broad-band absorbers, and will make infrared metamaterial absorbers as a novel thermal radiation controlling material.