关键词: 法诺共振/
时域有限差分算法/
周期性结构
English Abstract
Optical property of X-two ring structure
Pan Ting-Ting,Cao Wen,
Deng Cai-Song,
Wang Ming,
Xia Wei,
Hao Hui
1.Key Laboratory on Opto-Electronic Technology of Jiangsu Province, School of Physics Science and Technology, Nanjing Normal University, Nanjing 210023, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 51775283, 51405240), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20161559), the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (Grant No. 16KJB510018), and the Postgraduate Research and Innovation Project of the University of Jiangsu Province, China (Grant No. KYLX16_1289).Received Date:04 December 2017
Accepted Date:04 April 2018
Published Online:05 August 2018
Abstract:In this paper, the metal periodic array structure of X-two ring based on the principle of Fano resonance is proposed, which is composed of two concentric rings around the center X. The optical properties of the structure are investigated by using the finite difference time domain method. According to the simulated transmission spectra, electric field distribution and charge distribution, when linearly polarized light is incident to the metal surface, Fano resonance can be excited and the interaction between resonance modes can be produced in the structure of X-two ring, which can make resonance valleys generated at different positions. Fano resonance is mainly formed by the coherent interference between a bright mode with the larger radiation broadening and a dark mode with the weak radiation broadening, thus the structural resonance valley of X-two ring based on Fano resonance is strongly dependent on the relative parameters of the structure (the arm length of X, the distance between the inner ring and outer ring, the width of the inner ring and outer ring, the period, the number of ring, and the angle of X). In other words, over the wavelength range of 450 nm to 3000 nm, the intensity and position of the structural resonance valley are adjustable as the change of the relative geometric parameters of the structure. In addition, due to weak radiation damping and strong local electromagnetic field enhancement of Fano resonance, the resonance frequency and line type can significantly shift with the change of the environmental refractive index. Therefore, the further analysis of the variation of the structural resonance valley under the conditions of different refractive indices can be concluded that the structure of X-two ring has a higher sensitivity to the refractive index of surrounding environment, up to 1300 nm/RIU. The above results show that the structure of X-two ring not only is simple, economical, compact and efficient, but also has great potential applications in refractive index sensors and some photonic devices.
Keywords: Fano resonance/
finite-difference time-domain method/
periodic structure
