Highly efficient achromatic subdiffraction focusing lens in the near field with large numerical aperture  

作　　者：JIN CHEN HONGCHEN CHU YUN LAI HUANYANG CHEN WEILI SONG MINGJI CHEN DAINING FANG 

机构地区：[1]Institute of Advanced Structure Technology,Beijing Institute of Technology,Beijing 100081,China [2]National Laboratory of Solid State Microstructures,School of Physics,Nanjing University,Nanjing 210093,China [3]Institute of Electromagnetics and Acoustics and Department of Physics,Xiamen University,Xiamen 361005,China

出　　处：《Photonics Research》2021年第10期2088-2094,共7页光子学研究（英文版）

基　　金：National Key Research and Development Program of China(2017YPA0303702);National Natural Science Foundation of China(11634005,11872113,11974176,61671314).

摘　　要：The achromatic subdiffraction lens with large numerical aperture(NA)is of significant importance in optical imaging,photolithography,spectroscopy,and nanophotonics.However,most of the previous research on sub-diffraction lenses has been restricted by limited bandwidth and efficiency as well as severe chromatic aberrations.In this paper,a semicircular gradient index lens(sGRIN)with a modified refractive index profile originated from a Maxwell fish-eye lens is put forward to achieve highly efficient(above 81%)achromatic(4–20 GHz)subdiffraction focusing at the focusing line(around 0.28λ)with large NA of 1.3 and broadband diffraction-limited far-field radiation(4–16 GHz)theoretically,which overcomes the drawbacks of previous works.The presented lens is designed by gradient dielectric metamaterials.Evanescent waves ignited at the lens/air interface and transformation of electromagnetic(EM)waves with high spatial frequency in sGRIN to EM waves with low spatial frequency in air are responsible for subdiffraction focusing and diffraction-limited far-field radiation,respectively.Experimental results demonstrate the excellent performance of achromatic subdiffraction focusing and diffraction-limited far-field radiation.The presented lens has great potential to be applied in subdiffraction imaging systems.

关 键 词：CHROMATIC FIELD NUMERICAL 

分 类 号：TH74[机械工程—光学工程]