超分辨弱旁瓣硅基超构透镜

Silicon-based super-resolution metalens with weak sidelobe

超表面是一种空间变化的超薄纳米结构,在光学超分辨聚焦透镜或系统中已经得到广泛研究和应用。然而,随着超构透镜聚焦光斑缩小,不可避免产生大旁瓣,限制了透镜视场和应用潜力。本文提出了一种设计大数值孔径(NA=0.944)超分辨弱旁瓣超构透镜的方法。针对波长λ=632.8 nm的圆偏振光,基于硅基超表面PB相位调控,实现了超分辨弱旁瓣点聚焦超构透镜。实验证明,可以实现聚焦光斑半高全宽FWHM=0.45λ,小于衍射极限0.53λ(衍射极限为0.5λ/NA),旁瓣比Sidelobe Ratio(SR)=0.07。该透镜的应用有望实现超分辨光学器件或系统微型化、轻量化和集成化。

Metasurface is a spatially varying ultrathin nanostructure that has been widely studied and used in optical super-resolution focusing,either in lenses or in systems.However,with the decrease of the focal spot size of the metalens,large sidelobes are inevitably generated,limiting the field of view and potential applications of the lens.In this paper,a method for producing super-resolution metalens with a large numerical aperture(NA=0.944)and weak sidelobe is presented.For a circularly polarized light with the wavelength ofλ=632.8 nm,a super-resolution pointfocusing with a weak sidelobe is realized based on PB phase regulation of silica-based metasurface.Experimental results show that the FWHM(full-width at half maximum)of our focusing spot is 0.45λ,which is less than the diffraction limit of 0.53λ(the diffraction limit is 0.5λ/NA),and the sidelobe ratio(SR)is 0.07.Our proposed super-resolution metalens bears the potential to realize the miniaturization,lightweight and integration of super-resolution optical devices or systems.