Terahertz Control Technology Based On The Metamaterial

In the past 10 years, Metamaterial and Transformation Optics theory(TO theory) have attracts lots of attention, because the former is the material that do not exist in nature, and the latter is a way to manipulate light flexibly. By alter either dimension or structure of metamaterial, we attain proper permittivity tensor and permeability tensor we need. That can help us to manipulate light path and the transmission, reflection absorption of light. Our aim in this thesis is manipulation of THz by using metamaterial. This thesis is divided in two parts, the first part include chapter 2, chapter3 and chapter 4, which proposed several devices based on the TO theory and discussed the potential application of these devices. The second part include chapter 5, which investigated the characteristic of a metamaterial – Metal Hole Arrays(MHA) – in terahertz range. The major content and contribution of the thesis can be conclude as follows:1) Based on the transformation optics, we propose a new strategy of illusion media consisting of homogeneous and anisotropic materials. By utilizing the illusion media, invisible cloak is theoretically realized, in which objects covered with the illusion media could not be detected. What the cloak does is to shift the region into another place where outside the trace of light, so that objects in that region can disappear. Another application of the illusion media is to create the antiobject-independent illusion optics which means that two objects appear to be like some other objects of our choice.2) By Using composite optical transformation, we propose a rotatable illusion media with positive permittivity and permeability to manipulate terahertz waves, and a new way to realize singular parameter independent cloaks when the incident wave with a certain width propagates from specific incident directions. The fundamental mechanism of this kind of cloak is that the illusion media can be able to avoid the incident wave interacting with the objects. Comparing with traditional transformation coordinate-based cloaks such as cylindrical-shaped cloaks, our cloaks are independent of singular material parameters. Furthermore, this type of rotatable illusion media can be applied to design tunable miniaturized high-directivity antenna.3) A novel invisible media based on transformation optics consisting of three regions to investigate invisibility was proposed here. What the media does is to compress the light to a small region so that the light can avoid interacting with objects, and then it would be recovered in the latter. Comparing with the traditional cylinder cloak, which require thelight propagating around the concealed region, the media would help us to avoid singularity of material parameters.4) We experimentally studied the transmission property of terahertz(THz) wave from metal hole arrays(MHAs) with different incident angle around x directions. The observed phenomena such as resonant frequencies shifts and mode splitting are explained by using momentum conservation rule. The theoretical results agreed well with experiments.