December 2, 2005
The optical properties of materials with a negative index of refraction were first considered theoretically by the Soviet physicist Victor Veselago in 1967. He predicted that such materials would show negative refraction (reversing the properties of many classical optical elements), flat lens imaging with no optical axis, reversed Doppler Effect, and reversal of radiation pressure. Such materials were first demonstrated experimentally at microwave frequencies in 2001. It was predicted in 2000 that these materials would also demonstrate amplification of evanescent electromagnetic waves and produce super-resolution images of near-field sources with arbitrarily precise resolution, under ideal conditions. We review briefly the theory and some of the experimental evidence demonstrating these effects, including our own work on ultra-low-loss superconducting metamaterials. We then discuss the abundant opportunities for new applications of negatively refracting materials for the rf and microwave frequency range. Examples include miniaturized microwave devices including compact electromagnetic resonators utilizing composites of positively and negatively refracting materials, and compact waveguide structures for guiding high power signals at frequencies well below the cutoff frequency of the waveguide. We also consider novel antenna applications including a highly directional antenna and an efficient short dipole antenna utilizing a shell of negatively refracting material to compensate the radiation reactance of the antenna. Progress in implementing these properties at rf, microwave, mm-wave and higher frequencies will also be mentioned.
Dr. Steven M. Anlage is a Professor of Physics and faculty affiliate of the Department of Electrical and Computer Engineering at the University of Maryland, College Park. He received his B.S. degree in Physics from Rensselaer Polytechnic Institute in 1982, and his M.S. and Ph.D. in Applied Physics from the California Institute of Technology in 1984 and 1987, respectively. His graduate work concerned the physics and materials properties of quasicrystals. His post-doctoral work with the Beasley-Geballe-Kapitulnik group at Stanford University (1987 - 1990) concentrated on high frequency properties of high temperature superconductors, including both basic physics and applications to tunable microwave devices. In 1990 he was appointed Assistant Professor of Physics in the Center for Superconductivity Research at the University of Maryland, then (1997) Associate Professor, and finally (2002) Full Professor of Physics. There his research in high frequency superconductivity has addressed questions of the pairing state symmetry of the cuprate superconductors, the dynamics of conductivity fluctuations and vortices, and microwave applications such as superconducting negative index of refraction metamaterials. He has also developed and patented a near-field scanning microwave microscope for quantitative local measurements of electronic materials (dielectrics, semiconductors, metals, and superconductors) down to nm length scales. He has worked with Neocera, Inc. to develop a commercial version of this microscope for the semiconductor industry. Prof. Anlage also performs microwave analog experiments of the Schrödinger equation to test theories of quantum chaos. As part of this work he has developed a statistical prediction model for effects of high-power microwave signals on electronics. There is related work on stimulating classical chaos at GHz frequencies in distributed nonlinear circuits. Dr. Anlage is a member of the American Physical Society, the IEEE, and the Materials Research Society. His research is funded by the National Science Foundation and DoD, and he is an active consultant to the US Government. He was a member of the NSF-funded Materials Research Science and Engineering Center at the University of Maryland from 1995-2005. He has co-authored more than 100 research papers in scientific journals.