Research On Infrared Absorption Characteristics Of Photonic Crystal And Its Application

Recently, perfect absorption of electromagnetic wave because of its wide applications is becoming more and more important research topic. For example, since that the energy of solar radiation is mainly gathered in the infrared wave band, good infrared absorbing materials can be used to collect the solar energy. Also the typical pathogens have their own absorption spectrum, so the infrared absorbing materials could be used in biological and medical diagnostics. Furthermore, it is demonstrated that infrared absorbing materials could be used in infrared imaging. Overall, the. infrared absorbing materials could have such wide applications at present and impact our. lives tremendously. However, there does not exist perfect, infrared absorbing materials in nature. In order to fabricate perfect infrared absorbing materials, people have made great effort to do some research work. Among these research work, using the photonic crystal structure in infrared absorption is one of the most interesting topics. Photonic crystal is a optical nanostructure where index of refraction changes periodically. in spatial. Photonic crystal has some great performances that could not be found in nature material, such as photonic band gap, negative index and so on. So by adjusting materials and structures of photonic crystal, we could achieve some device with special functions.This thesis involves the research of absorption characteristics and potential application of photonic crystal. The main work and results are as follows:Firstly, we research the absorption characteristics of one dimensional photonic crystal which mainly include bandwidth, polarization and angular feature and so on. Based on the great work of others, it is found that both wide-band and narrow-band absorption can be achieved using one dimensional photonic crystals. So in order to meet some purposes, we design a specific structure, which could realize the wide-band absorption near1.06um and high reflection from3um to5um and from8um to14um. What is more, how to make use of negative-index material to improve the angular characteristics of narrow-band absorption of one dimensional photonic crystal (1DPC) is also researched. Here a deposed photonic crystal composed of negative-index material and positive-index material is proposed and its angular and polarization characteristics are researched. Our results suggest that negative-index materials could improve greatly the angular characteristics of narrow-band absorption of1D PC effectively, which could make the1DPC fit in some special applications.Secondly, we also research the absorption characteristics of two dimensional PC. Here the2DPC mainly refers to metamaterial. In this part, we clarify the previous work systematically and accordingly to our own demand, the design work of the metamaterial owning criss-cross tungen patch arrays has been done. The design is mainly made up of three parts:criss-cross tungen patch, polymeric substance and metal ground. Its simulation results demonstrate that it can realize high absorption around10.6um. Furthermore, for TE mode, the absorption of this structure remains above98%in the range of incident angle from00to800; for TM mode, the absorption could remain above98%from00to400, which shows great angular and polarization performance. Therefore the metamaterial structure with perfect infrared absorption can be used to inhibit the infrared detection in10.6um.Finally, we research deeply the potential of metamaterial as sensors. Here a metamaterial with gold ring array are proposed and its simulation results demonstrate that the structure owns great characteristics of absorption. The absorption of this metamaterial structure is insensitive to incident angle and is independent of polarizations mode. So the structure used as sensors owns great advantages because that it do not only have a high value of Q, but also it do not need the assist of the waveguides. Furthermore, we research the relationship of its frequency shift with the displacement. Even though the simulation results show that the relationship is nonlinear, the frequency shift could reflect variance of pressure, which is good for the study of metamaterial as sensors.In summary, our work about the design of absorbers based on photonic crystal can provide a new way to further application, and it owns great reference value to theoretical study of photonic crystal absorber.