Study On The Principle And Technology Of Polarization Manipulation With Metamaterials

Polarization manipulation has been a hot topic for quite a long time in the field of electromagnetic and has a wide range of applications,such as polarization imaging,anti-counterfeiting technology,target identification,optical communication,and biomedical.With the development of micro-electro-mechanical systems(MEMS),higher request for the miniaturization,integration and lightweight is imposed on the electromagnetic wave modulation components and systems.The study on the principle and technology of polarization manipulation based on novel metamaterials provides an effective technical means for the miniaturization and integration of the polarization control components and systems and has an important scientific and practical significance.In this paper,the comprehensive study on the principle and technology of polarization manipulation based on metamaterials was carried out under the support of 973 Program of China and National Natural Science Funds.On the basis of polarization control mechanism research,the polarization manipulation mechanism of novel metamaterials was carried out.The cross-polarization conversion efficiency for single-layer transmissive metamaterials was raised up to the theory limitation with the novel metamaterials design.The cross-polarized electromagnetic wave was separated from the co-polarizated component by introducing the local abrupt phase change and combining generalized Snell's law.In view of the low efficiency,small area and high cost of demonstrated process technology for optical metamaterials,such as electron beam lithography,focused ion beam etching and two-photon lithography technology,study on the processing technology of optical metamaterial was carried out and large-area optical polarization converter was prepared in this paper.At the same time,the research of axisymmetric polarization metamaterials was carried out.A metal-insulator-metal multilayer structure is put forward to realize the manipulation of polarization,phase and amplitude(vector field modulation)and a high-efficiency axisymmetric polarization metamaterials changing circular polarization beam into radial/azimuthal polarization was designed based on the full control of the light.The multifunctional structure improves the modulation freedom degree of the metamaterials and provides an effective method for the novel polarization control devices and other optical components.The main research work and innovative pionts are listed as follows:(1)The polarization manipulation principle of metamaterials was studied on the basis of analyzing the influence of geometric structure and arrangement of the unit cell on the electromagnetic response thoroughly.Then,the design schemes of polarization conversion metamaterials were confirmed.(2)The theoretical analysis and numerical simulation method for the metamaterials was studied.The relationship between the structure parameters and polarization conversion efficiency was analyzed through parameter sweeps with CST Microwave Studio and the design of the polarization converters with high-efficiency and wideband were carried out.(3)In view of the low efficiency,small area and high cost of previous process technology for optical metamaterials,an ellipse-shaped plasmonic planar resonator was adopted to design the high-efficiency optical polarization converter to reduce the processing difficulty.A large area,high efficiency optical polarization control device was prepared with orthogonal interference lithography.(4)In view of low conversion efficiency and high background interference problems for the transmissive polarization conversion metamaterials,the limitation of the conversion efficiency for the single-layer metamaterials was achieved with the proposed Quasi-continuous structure.A catenary structure was proposed to introduce local abrupt phase change and combine with the generalized Snell's law to control wavefront.The interference from co-polarization components was eliminated with this high-efficiency design.(5)Axisymmetric polarization metamaterials was studied in this paper.On the basis of princible research for changing circular polarization to radial/ azimuthal polarization,novel axisymmetric polarization generation metamaterials was designed.The improved conversion efficiency and high-purity were got with this design.(6)The samples of reflective polarization converter and transmissive directional polarization converter were measured on the ellipsometer and vector network analyzer,respectively.The PCR larger than 87.5% is obtained from 850 nm to 1930 nm for the reflective polarization converter.And,the the tested deflection angles are 52.83°,40.62° and 32.69° for f = 12,15 and 18 GHz,respectively.The measured results agree well with the theoretical analysis and simulations.