﻿ 法诺光栅的共振特性研究
 光学仪器  2019, Vol. 41 Issue (5): 71-75 PDF

Study on resonance characteristics of Fano grating
SHI Xin, WANG Haifeng
School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Abstract: The study of the resonance characteristics of sub-wavelength gratings has always been one of the most important part of optics. In this paper, a sub-wavelength one-dimensional grating design based on Fano resonance is proposed. Compared with the guided-mode resonance, the Fano resonance has stronger near-field enhancement, finer spectrum and higher sensing quality factor. The optical simulation software, FDTD Solutions, is used to simulate the structure of the grating. The parameters affecting the diffraction performance of the grating are studied in detail, including the period, refractive index and duty ratio of the grating. The simulation results show that Fano resonance lines have high resonance intensities, fine spectral lines and controllable resonance positions in the visible light region. Based on this discovery, the one-dimensional grating structures proposed in this work could be utilized as a wavelength selector with an accuracy of less than 1 nm.
Key words: subwavelength grating    Fano resonance    the visible light region

1 光栅结构的设计

 ${n_{\rm{av}}} = \sqrt {fn_{\rm{H}}^2 + \left( {1 - f} \right)n_{\rm{L}}^2}$ (1)

 图 1 法诺共振型光栅结构 Figure 1 The structure of Fano resonance grating

2 法诺共振光栅特性分析 2.1 入射光偏振方向对法诺共振效应的影响

 图 2 入射光两种偏振模式下的光栅反射率曲线 Figure 2 Fano grating reflectivity in the two polarized modes of incident light

2.2 光栅材料折射率对法诺共振效应的影响

 图 3 不同材料折射率时的光栅反射率曲线 Figure 3 Fano grating reflectivity of different refractive index of materials

2.3 光栅周期对法诺共振效应的影响

 图 4 不同光栅周期下的法诺光栅反射率曲线 Figure 4 Fano grating reflectivity curves of different grating period

2.4 光栅槽深对法诺共振效应的影响

 图 5 不同光栅槽深下的法诺光栅反射率曲线 Figure 5 Fano grating reflectivity of different grating thickness
2.5 填充系数对法诺共振效应的影响

 图 6 不同填充系数对应的法诺光栅反射率曲线 Figure 6 Fano grating reflectivity of different filling coefficient
2.6 入射角对法诺共振效应的影响

 图 7 不同入射角所对应的法诺光栅反射性能 Figure 7 Fano grating reflection of different angles of the incident light

3 应　用

 图 8 法诺共振光栅的共振光谱分布 Figure 8 Fano grating reflection
4 结　论

 [1] 祝绍箕. 衍射光栅[M]. 北京: 机械工业出版社, 1986. [2] HUTLEY M C. Dirffaction gratings[M]. London: Academic Press, 1982. [3] PRIAMBODO P S. Theoretical analysis, design, fabrication and characterization of dielectric and nonlinear guided-mode resonance optical filters[D]. Arlington: The University of Texas at Arlington, 2003. [4] THURMAN S T, MORRIS G M. Controlling the spectral response in guided-mode resonance filter design[J]. Applied Optics, 2003, 42(16): 3225–3233. DOI:10.1364/AO.42.003225 [5] ZHENG G G, ZHAO L L, QIAN L M, et al. Fano resonance and tunability of optical response in double-sided dielectric gratings[J]. Optics Communications, 2016, 358: 140–146. DOI:10.1016/j.optcom.2015.09.036 [6] WU C H, KHANIKAEV A B, ADATO R, et al. Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers[J]. Nature Materials, 2012, 11(1): 69–75. DOI:10.1038/nmat3161 [7] WANG J Q, YUAN B H, FAN C Z, et al. A novel planar metamaterial design for electromagnetically induced transparency and slow light[J]. Optics Express, 2013, 21(21): 25159–25166. DOI:10.1364/OE.21.025159 [8] FANO U. Effects of configuration interaction on intensities and phase shifts[J]. Physical Review, 1961, 124(6): 1866–1878. DOI:10.1103/PhysRev.124.1866 [9] NAZIR A, PANARO S, ZACCARIA R P, et al. Fano coil-type resonance for magnetic hot-spot generation[J]. Nano Letters, 2014, 14(6): 3166–3171. DOI:10.1021/nl500452p [10] 蔡东进. 电介质纳米结构中法诺共振效应的研究[D]. 太原: 太原理工大学, 2016. [11] 屈炜, 李静. 等离激元Fano共振纳米结构及其应用[J]. 新技术新工艺, 2017(5): 15–19. [12] 王琦. 导模共振亚波长器件的机理及特性研究[D]. 上海: 上海理工大学, 2012.