Meta-mirror: Enabling Frequency-Selective Reflection Through Phase -Dispersion Tailoring of a Metasurface

Significance 

Presently, metasurfaces have enabled full control of the electromagnetic waves thus leading to implementation of numerous applications such as flat lenses based on electromagnetic properties. Going with the current trends, future demand for efficient metasurfaces designs have attracted significant attention of researchers. Among the available metasurfaces, the reflective type, or called meta-mirror, enables full control of the reflected and scattered wavefronts. Unfortunately, for most natural materials, the dispersion characteristics depend on molecules that have little manipulation freedom. This makes it difficult to realize more advanced functions. Existing literature shows several attempts to develop advanced applications based on the dispersion properties of the meta-mirrors. However, existing metasurfaces are often limited by the difficulty of finding suitable meta-atoms with desired dispersion control.

To this note, Nanjing University researchers led by Professor Yijun Feng from the School of Electronic Science and Engineering developed a frequency-selective concept for coding of the meta-mirrors. They showed how to tailor the phase dispersion of the meta-mirror to perform the scattering properties of various frequency bands. Their work is currently published in the journal, Physical Review Applied.

In brief, the research team commenced their experimental work by designing a resonant meta-atom which was used as a binary coding element to achieve the desired in-phase function at the center frequency and out-of-phase function at the sidebands. Next, the meta-atoms in the metasurface were randomly distributed to obtain the back scattering reduction both numerically and experimentally in the two outside bands. Eventually, a comparison between the full-wave simulation and the experimental results were conducted to validate the feasibility of the newly developed meta-mirror.

The authors observed that the developed concept exhibited frequency-selective effects as compared to conventional metasurface designs for scattering reductions. Specifically, it could achieve high-efficient mirror reflection at center frequency window around 10.7 GHz and low diffusive scatterings in two sidebands with a frequency ranging from 7.5-9.5 GHz and 11.6-15 GHz. Additionally, it was worth noting that the functionality of the metasurfaces was not limited only to scattering reduction. In fact, it enabled full control of other wavefronts by simply tailoring the phase dispersion characteristics of the meta-atoms in question.

In summary, the study by Nanjing University scientists presented a combined frequency-selective scattering and specular reflection approach for reflective metasurface that utilizes tailored phase dispersion characteristics. Generally, the achieved frequency-selective scattering effects would advance the development of numerous electromagnetic devices such as the ground planes for antennas with the desired capacity to retain good in-band characteristics and reduce the out-of-band radar cross-section. Furthermore, Professor Yijun Feng and his research team aspire to enhance the impact of the frequency coding metasurface by taking into consideration the active materials.

Meta-mirror: Enabling Frequency-Selective Reflection Through Phase -Dispersion Tailoring of a Metasurface - Advances in Engineering

About the author

Boyu Sima was born in Nanjing, China, in 1987. He received the B.E. degree in School of Electronic and Optical Engineering from Nanjing University of Science and Technology, Nanjing, China, in 2013. He is currently pursuing the Ph.D. degree in electronic science and engineering in School of Electronic Science and Engineering, Nanjing University, Nanjing, China. His current research interests include electromagnetic metasurfaces and metamaterials.

About the author

Ke Chen received the B.S. and Ph. D. degrees in electronic science and engineering from Nanjing University, Nanjing, China, in 2012 and 2017, respectively. Currently, he is a Post-doctoral Research Fellow with the Department of Electronic Engineering, School of Electronic Science and Engineering, Nanjing University. His current research interests include electromagnetic metamaterials and metasurfaces, and their applications to novel microwave functional devices.

About the author

Yijun Feng received the M.Sc. and Ph.D. degrees from the Department of Electronic Science and Engineering, Nanjing University, in 1989 and 1992, respectively. Since 1992, he has been a faculty member and is currently a full professor in the School of Electronic Science and Engineering, Nanjing University. From September 1995 to July 1996, he was a visiting scientist with the Physics Department, Technical University of Denmark. From August 2001 to August 2002, he was a visiting researcher with the University of California at Berkeley.

Dr. Feng’s research interests include the electromagnetic metamaterial and application to microwave and photonic devices, electromagnetic wave theory, and novel microwave functional materials. He has conducted more than twenty scientific research projects including National 973, 863 Projects and the National Natural Science Foundation projects in China. He has received the 2010 Science and Technology Award (First grade) of Jiangsu Province, China, and the 1995 Scientific and Technological Progress Award by Minister of Education, China. He has authored or co-authored over 180 journal papers and over 150 referred international conference papers.

Reference

Sima, B., Chen, K., Luo, X., Zhao, J., & Feng, Y. (2018). Combining Frequency-Selective Scattering and Specular Reflection Through Phase-Dispersion Tailoring of a Metasurface. Physical Review Applied, 10(6).

Go To Physical Review Applied

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