Since the beginning of this century, an artificial composite called "left-handed material" has become more and more popular in the fields of solid state physics, material science, optics and applied electromagnetism, and its research has developed rapidly, but its appearance originated from the imagination of scientists in the former Soviet Union in the 1960s.
In physics, dielectric constant ε and permeability μ are two basic physical quantities to describe the properties of electromagnetic field in homogeneous media. In the known material world, for dielectrics, the dielectric constant ε and permeability μ are both positive values, and the electric field, magnetic field and wave vector form a right-handed relationship. This material is called right-handed material (RHM). This right-handed rule has always been regarded as the norm of the material world, but this norm began to encounter subversive challenges in the 1960s. 1967, Veselago, a physicist of the former Soviet Union, published a paper in an academic journal of the former Soviet Union, and reported for the first time his new discovery of electromagnetic properties of matter in theoretical research, that is, when ε and μ are both negative, the electric field, magnetic field and wave vector form a left-handed relationship. He called this imaginary substance left-handed material (LHM), and pointed out that the behavior of electromagnetic wave in left-handed material is opposite to that in right-handed material, such as negative refraction of light, negative cherenkov effect, anti-Doppler effect and so on. This paper caught the attention of an Englishman, and 1968 was translated into English and republished in another physics academic journal in the former Soviet Union. But few people realize that the world of materials has turned a new page.
Because the left-handed material is characterized by negative dielectric constant and permeability, it is also called "double negative medium (material)", usually referred to as "negative refractive index material" or "negative material" for short.
Second, the left-handed material-the breakthrough at the beginning of this century triggered people's infinite reverie.
The research and development of left-handed materials is not smooth sailing. In the thirty years after this subversive concept was put forward, although it has many novel properties, because it only stays in theory and no actual left-handed materials have been found in nature, this bizarre assumption was not immediately accepted, but was almost ignored, and it did not begin to turn around until the century approached. The reason is that the British scientist Pendry and others put forward a clever design structure to realize negative dielectric coefficient and negative permeability in 1998~ 1999. Since then, people have begun to pay more and more attention to this material. With the breakthrough of 200 1, the research of left-handed materials has gradually shown a whirlwind trend in the world.
In 200 1 year, physicists such as david smith of the University of California, San Diego, made a material with negative dielectric constant and negative permeability in microwave band for the first time at the suggestion of Pendry and others. They directed a beam of microwave at an artificial medium composed of copper rings and copper wires, and the microwave deflected at a negative angle, thus proving the existence of left-handed materials.
In July, 2002, scientists from ETHZ Laboratory in Switzerland announced that they had made three-dimensional left-handed materials, which would have a great impact on the electronic communication industry. The related research results were also published in the American Journal of Applied Physics that month.
At the end of 2002, Professor Kong Jinou of Massachusetts Institute of Technology proved the rationality of the existence of left-handed materials in theory, and said that this artificial medium can be used to make high directional antennas, focus microwave beams, realize "super lenses" and be used for electromagnetic wave stealth. The prospect of left-handed materials began to arouse the infinite reverie of academia, industry and especially the military.
2003 was a year in which many breakthroughs were made in the study of left-handed materials. Two groups of researchers led by C. Parazzoli of Boeing Phantom Engineering Company in Seattle, USA and G. Eleftheriades of the Department of Electrical Engineering of University of Toronto, Canada directly observed the law of negative refraction in the experiment. S. Foteinopoulou of Iowa State University also published the theoretical simulation results of left-handed materials with photonic crystals as the medium. E Cubukcu and K Eden of MIT published an article in Nature, describing the experimental results of negative refraction of electromagnetic waves in two-dimensional photonic crystals. Based on many discoveries of scientists, the development of left-handed materials entered the top ten scientific progress in the world in 2003, which attracted worldwide attention.
In 2004, Shanghai scientists began to appear in international academic circles. After two years of research and ingenious design, the research team led by Professor Zijian of Fudan University, the chief scientist of the "973" photonic crystal project, successfully realized the left-handed medium hyperplane imaging experiment by using surface wave scattering of water. The paper was published in the famous American magazine Physical Review, which immediately attracted great attention from the academic circles and was recommended as one of the key news of Nature magazine. The research group headed by Professor Chen Hong from Niels Bohr Institute of Solid State Physics of Tongji University began to study left-handed materials on 200 1. After two years of research, great progress has been made in the preparation and characterization of basic theories and materials. The results were published in the famous international journal of physics, reported at the international conference on microwave and millimeter wave technology in 2004, and will be reported at the international symposium on microwave optics technology held in Japan in 2005.
Left-handed materials quickly became a research hotspot in the scientific community at the beginning of this century. According to incomplete statistics, in major international academic journals, the research papers on left-handed materials published in 2000 and 20001year were 13 and 17 respectively, which rose to 60 in 2002 and exceeded 100 in 2003.
Thirdly, the realization of left-handed material manufacturing has given birth to its huge application prospect.
The huge application prospect of left-handed materials stems from its manufacturing realization. In 2000, Pendry suggested making "super lens" (also known as "ideal prism") to realize the application of left-handed materials. This proposal became a reality in 2004, and scientists have successfully manufactured planar microwave lenses using left-handed materials. In February, 2004, physicists from Moscow Institute of Theory and Applied Electromagnetism announced that they had successfully developed a super-resolution lens, but their technology required the observed object to almost touch the lens, which brought operational difficulties to practical application. In the same year, scientists at the University of Toronto in Canada made a left-handed lens, whose working principle is related to the radiation of microwave wavelength, which is located next to radio waves in the electromagnetic spectrum. The research achievements of scientists from the two countries were highly appreciated by the scientific community, and were rated as the most influential research progress of the International Physics Society in 2004 by american physical society.
In addition, according to the extraordinary characteristics of left-handed materials, scientists have predicted that they can be used in the design of communication systems and data storage media to make smaller mobile phones or larger storage media; The equivalent negative refractive medium circuit can effectively reduce the device size, broaden the frequency band and improve the device performance. In the future, left-handed materials will play an important role in the development of wireless communication.
4. Left-handed materials-included in the guide of key projects of the National Natural Science Foundation of China in 2005.
The study of left-handed materials has attracted the attention of relevant scientific circles in China. In addition to Shanghai scientists, scientists from Hong Kong University of Science and Technology, Institute of Physics of Chinese Academy of Sciences, Nanjing University, Peking University, Northwestern Polytechnical University and other units have taken the lead in this field. In 2005, the National Natural Science Foundation of China listed the study of left-handed materials and negative refraction effect in the key cross-project guide. In the topics of "Some Frontier Topics in Quasi-phase Matching Research" jointly organized by the Ministry of Mathematics and the Ministry of Engineering Materials, and "New Photonics Characteristics of Periodic and Aperiodic Microstructure" jointly organized by the Ministry of Mathematics and the Ministry of Information Science, the "Study on Basic Problems Related to Left-handed Materials" was listed as one of the main exploration contents. At the same time, the Information Department of the National Natural Science Foundation of China listed "Basic Research on Metamaterials Theory and Application" in the guide of key projects in 2005. Metamaterials are another name for left-handed materials.
At present, the general situation of the research on left-handed materials and negative refraction effect in China (including Shanghai) is as follows:
Institute of Physics, Chinese Academy of Sciences: The State Key Laboratory of Magnetism extensively explores and studies new magnetic functional materials, such as ferromagnetic shape memory alloys, which have high permeability and low loss (such as DC-DC converter materials and left-handed materials) at various high frequencies (up to 10- 100G); The micromachining laboratory of the institute is mainly devoted to the fabrication and application of low-dimensional artificial structures, including two-dimensional photonic crystals, superconducting quantum structures and devices with different structures and left-handed materials.
Hong Kong University of Science and Technology: Professor Chen Ziting, director of the Institute of Nanotechnology, is an internationally renowned expert in condensed matter physics and photonic crystal theory, mainly engaged in the research of photonic crystals and left-handed materials.
Nanjing University: Professor Feng Yijun from the Department of Electronic Science and Engineering, mainly engaged in the research of electromagnetic field and microwave technology, new artificial electromagnetic materials and microwave devices. At present, he is responsible for the theoretical and applied research of new artificial electromagnetic media (973 project of the National Key Basic Research and Development Plan) and left-handed artificial electromagnetic materials and microwave devices (doctoral program fund project of the Ministry of Education).
Tongji University: Professor Chen Hong and Professor Zhang from Niels Bohr Institute of Solid State Physics have made breakthroughs in the basic theory, characterization and device application of left-handed materials and negative refraction effect.
Fudan University: Led by Professor Zi Jian (chief scientist of the "973" project) and Professor Zhou Lei, it has made great progress in hyperplane imaging, characterization and device application (microwave antenna) of left-handed materials. At present, it has carried out cooperative research in this field with Tongji University, East China Normal University, Shanghai Institute of Microsystems of Chinese Academy of Sciences, Shanghai Institute of Technical Physics of Chinese Academy of Sciences, Institute of Physics of Chinese Academy of Sciences, Nanjing University, UCLC and AMES of the United States. Theoretical physics, condensed matter physics and optics are all national key disciplines and doctoral programs.
University of Shanghai for Science and Technology: headed by Academician Zhuang from the School of Optics and Electronic Information Engineering. Academician Zhuang has been engaged in applied optics, optical engineering and optoelectronics for a long time. He has designed 100 kinds of optical systems and instruments, and is the earliest researcher to develop optical system CAD in China. A variety of optical methods are proposed in the study of phase recovery of complex objects, which opens up a new research direction in this field. The developed CdSe CdSe liquid crystal light valve reached the international advanced level at that time.