基于分形谐振器的远场超分辨率扫描成像  

Far-field super-resolution scanning imaging based on fractal resonator

作　　者：高强 李小秋[1,2] 周志鹏[1,2] 孙磊 Gao Qiang;Li Xiao-Qiu;Zhou Zhi-Peng;Sun Lei(Nanjing Research Institute of Electronic Technology,Nanjing 210039,China;National Key Laboratory of Antennas and Microwave Technology,Nanjing 210013,China;Institute of Applied Physics,University of Electronic Science and Technology of China,Chengdu 610054,China)

机构地区：[1]南京电子技术研究所,南京210039 [2]天线与微波技术国防科技重点实验室,南京210013 [3]电子科技大学应用物理研究所,成都610054

出　　处：《物理学报》2019年第24期146-152,共7页Acta Physica Sinica

摘　　要：为突破传统衍射极限实现远场超分辨率扫描成像,提出一种基于分形谐振器的微结构阵列用于目标远场超分辨率扫描成像.该阵列基于局域模谐振原理,将目标的超分辨率信息包含在频谱中传播到远场,可在远场通过频谱信息判断目标所在位置,从而不借助于格林函数实现超分辨率实时成像,成像过程简单方便.基于分形谐振器的设计使阵列具有多频点工作的特点,最终实现了λ/10的超分辨率成像.结合分形谐振器一阶谐振和三阶谐振的特点,提出一种可有效提升成像效率的新型的扫描成像方法.The resolution of traditional far-field imaging system is generally restricted by half of the wavelength of incident light due to the diffraction limit.The more specific reason is that evanescent waves carrying subwavelength information cannot propagate in the far field and make no contribution to the imaging.However,higher imaging resolution is required in practical applications.To realize the far-field super-resolution imaging,the imaging system should be able to collect both propagating waves and evanescent waves.Many designs have been proposed to solve this issue.In 2007,a far-field superlens was proposed by Liu et al.(Liu Z W,Durant S,Lee H,Pikus Y,Fang N,Xiong Y,Sun C,Zhang X 2007 Nano Lett.7403)to realize far-field super-resolution in optical range,which consisted of a silver film and a nanoscale grating coupler.The silver film was used to amplify the evanescent waves,which were then converted into propagating waves by the sub-wavelength gratings.However,the special material properties limit the freedom of design.In microwave band,the incident components can be converted into Bloch modes by the resonant metalens,which consists of subwavelength resonators,and then be radiated to far field.Nevertheless,Green function between antenna and target is necessary,which is difficult to obtain due to the complex and even time-dependent imaging environment in practical applications,especially for super-resolution imaging system.It has been demonstrated in recent research that frequency information can be associated with spatial information of imaging target by localization resonant modes.Therefore,super-resolution imaging can be realized based on frequency information,without using Green function.Thus,a novel microstructure array is proposed to realize the far-field super-resolution scanning imaging based on a fractal resonator.The fractal resonator can work at several frequencies because of the self-similarity,which provides higher selectivity according to practical conditions.Several working statuses can be obtained

关 键 词：远场 超分辨率扫描成像 分形谐振器 成像效率 

分 类 号：TN7[电子电信—电路与系统]