image: BIC-supporting metasurfaces can achieve the high-Q resonance. The Q factor can be controlled by changing the size of the introduced defect and further this relationship can be adjusted by the proposed design (bottom left). By optimizing the dimensions of the structures, a high-Q resonance can be easily achieved and the THG signal can be enhanced significantly. view more
Credit: Opto-Electronic Advances
In a new publication from Opto-Electronic Advances; DOI 10.29026/oea.2021.200030 , Researchers led by Professor Liu Yan from Xidian University, China and Professor Gan Xuetao from Northwestern Polytechnical University, China consider generation and application of the high-Q resonance in all-dielectric metasurfaces.
Metamaterials are artificial composite electromagnetic structures consisting of subwavelength units, which can realize efficient and flexible control of the electromagnetic waves. Metamaterials are an emerging research area for optoelectronics, physics, chemistry and materials, due to their novel physical properties and potential applications.
With the development in the fabrication of nanostructures, all-dielectric metasurfaces have attracted much research attention because of their high efficiency and low loss. However, metasurfaces based on traditional optical materials (such as silicon) can only support relatively low Q resonances, limiting their applications in lasing action, sensing, and nonlinear optics. A recently emerged concept of bound states in the continuum (BICs) provides a new solution to overcome this problem. The concept of BICs was first introduced in quantum mechanics. It represents a wave phenomenon of modes, which have the energy lying in the delocalized states inside the continuum. The BIC-supporting metasurfaces can achieve controllable high-Q resonance, which can extend their applicability to the devices requiring sharp spectral features.
The authors of this article propose a Si metasurface based on symmetry-broken blocks, which can achieve the high-Q resonance. Nanoparticles made of conventional materials can only support a relatively low quality factor. The concept of BIC provides a new solution to overcome this problem. This concept firstly appears in quantum mechanics, where a true BIC is a mathematical abstraction with infinite Q factor. In this work, symmetry breaking is introduced into the symmetric periodic structure and the ideal BICs turn into the leaky mode with a high Q factor. At the same time, the Q factor of the resonance can be controlled by varying the size of the introduced defects. In addition, by changing the design proposal, the relationship between the Q factor and defect size can also be adjusted. A high-Q resonance can be easily realized in this way and the nonlinear optical effect of the structure can be obviously enhanced at the resonance.
The research reported in this article paves a way to manipulate BICs and realize high-Q dynamic resonances, which constitutes a significant step towards the development of high-Q resonant photonic applications. innovative and advanced optical technologies.
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Article reference: Fang CZ, Yang QY, Yuan QC, Gan XT, Zhao JL et al. High-Q resonances governed by the quasi-bound states in the continuum in all-dielectric metasurfaces. Opto-Electron Adv 4, 200030 (2021). doi: 10.29026/oea.2021.200030
Keywords: all-dielectric metasurface, bound states in the continuum, optical nonlinearity, topological configuration
Author Biographies
Professor Liu Yan, Xidian University, China, mainly focuses on ferroelectric nanodevices and novel nanophotonic devices. Engaged in the research of semiconductor materials and devices, Professor Yan has made much pioneering research in high mobility channel CMOS and steep subthreshold swing devices and is now, undertaking the Major research plan of the National Natural Science Foundation of China and the Key Research and Development Program of the Ministry of Science and Technology. Recent activities over the last five years include the publication of more than 50 papers in mainstream journals and applications for more than 20 patents in related fields.
Professor Hao Yue, Chinese Academy of Sciences, is a senior member of the IEEE and executive director of the Chinese Association of Electronics. Professor Yue leads the expert group for the implementation of the major sci-tech items of "core electronic devices, high-end universal chips, and basic software products" and the microelectronic technology experts group of the General Armament Department of the People's Liberation Army of China. Professor Yue has published more than 150 papers to date during his academic career.
Professor Han Genquan, Xidian University, China is a member of the "Hundred Talent Program" supported by Shaanxi Province, China. Professor Genquan has made many breakthroughs in high mobility channel CMOS and Beyond CMOS devices, including the implementation of high-performance strain germanium-tin, strain germanium, and InGaAs MOSFET devices, germanium-tin tunneling field-effect transistor, and the negative capacitance of the transistor. Professor Genquan has published more than 150 papers, submitted applications for more than 30 patents and has been a frequent invited speaker at international conferences.
Professor Gan Xuetao, Northwestern Polytechnical University, China, is mainly engaged in the research of micro nanophotonics, including two-dimensional layered material optoelectronics and spectroscopy among other areas and is committed to providing new theories and technologies for new optical information processing, optical interconnection on-chip, and optoelectronic devices. Professor Xuetao has previously hosted National Science and Technology Fund "Excellent Youth Projects", "Surface Projects" and "Youth Projects". Professor Xuetao has been a frequent invited speaker at international and domestic academic conferences and has published more than 50 papers in international journals such as Nature Photonics, Light Science & Applications and Opto-Electronic Advances.
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