基于严格耦合波理论的亚波长光栅合成孔径成像分析  

Synthetic Aperture Imaging Analysis of Sub-Wavelength Grating Based on Rigorous Coupled-Wave Analysis Method

作　　者：王柯威 肖康[2,3] 孙静 王中阳 Wang Kewei;Xiao Kang;Sun Jing;Wang Zhongyang(School of Physical Science and Technology,Shanghai Tech University,Shanghai 201210,China;Center for Research and Interdisciplinary,Shanghai Advanced Research Institute,Chinese Academy of Sciences,Shanghai 201210,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]上海科技大学物质科学与技术学院,上海201210 [2]中国科学院上海高等研究院基础交叉研究中心,上海201210 [3]中国科学院大学,北京100049

出　　处：《中国激光》2022年第24期29-38,共10页Chinese Journal of Lasers

基　　金：上海市科学技术委员会资助项目(20DZ2210300)。

摘　　要：合成孔径技术是一种能够有效实现超分辨成像的技术。目前的合成孔径成像技术大多以标量衍射理论为基础,但当成像目标的尺寸小于波长时,标量衍射理论中的近似与假设不再成立。因此,本团队在高斯光束照明条件下,以更为严格的耦合波理论为基础,分析了亚波长光栅的合成孔径成像技术。通过模拟仿真280 nm周期、140 nm线宽的一维矩形光栅的合成孔径成像,分析了光栅有界情况下,模式个数对光栅重构的影响以及恢复光栅结构所需的最少模式个数。接下来讨论了标量衍射理论相对于耦合波理论可能产生的误差。分析了照明光以±90°入射的理想情况下对光栅进行合成孔径成像的最小分辨率,并认为其仅与波长有关,可分辨的光栅周期最小为λ2,线宽分辨率为λ4。本文为合成孔径技术在亚波长光栅中的应用提供了更严格的理论基础。Objective Microscopy is an essential tool in most life science laboratories.However,the resolution of the microscope is limited by the numerical aperture(NA)of the objective and light wavelength,which is defined asλ/(2NA).In recent decades,methods such as stimulated emission depletion(STED),stochastic optical reconstruction microscopy(STORM),and photoactivated localization microscopy(PALM)have been proposed to overcome this limitation.However,in some fields,such as X-ray crystallography,wavefront sensing,and living cell imaging,label-free methods have demonstrated significant advantages.Aperture synthesis has been reported as one of the most effective label-free imaging methods that can be used to increase microscope resolution.Currently,most analyses of synthetic aperture techniques are based on scalar diffraction theory.However,for imaging objects smaller than the optical wavelength,the approximations and hypotheses in scalar diffraction theory are no longer valid.In this study,the imaging of subwavelength gratings is analyzed using the synthetic aperture method based on rigorous coupled-wave analysis(RCWA),which directly solves the Maxwell equation to obtain the analytical solution of the exit field under Gaussian beam illumination.The proposed method provides a more accurate analysis of synthetic-aperture imaging techniques for subwavelength gratings.Methods RCWA was used to analyze the diffraction of a grating incident by a plane wave.In practice,illumination is a focused Gaussian beam that can be expanded into a series of plane waves.Therefore,the output field distribution can be expressed as the product of each plane wave component of the rotated Gaussian beam and diffraction field at the corresponding incident angle solved by RCWA.A one-dimensional rectangular grating with a 280 nm period and 140 nm line width was employed in the simulation(Fig.1).RCWA under Gaussian beam illumination was used to analyze the output optical field and angular spectrum distribution with a half angle of 10°at different angl

关 键 词：全息 合成孔径成像 亚波长光栅 严格耦合波分析 超分辨成像 

分 类 号：O438.2[机械工程—光学工程]