The metasurface is a platform with a small footprint and abundant functionalities.With propagation phase and geometric phase,polarization multiplexing is possible.However,different response behaviors of propagation ph...The metasurface is a platform with a small footprint and abundant functionalities.With propagation phase and geometric phase,polarization multiplexing is possible.However,different response behaviors of propagation phase and geometric phase to wavelength have not been fully employed to widen the capabilities of metasurfaces.Here,we theoretically demonstrate that metasurfaces can achieve near-field and far-field decoupling with the same polarization at two wavelengths.First,we found a set of pillars whose propagation phase difference between two wavelengths covers the full range of 2π.Then,by rotating pillars to control the geometric phase,the phase at both wavelengths can cover the full range of 2π.Finally,by means of interference principle,arbitrary independent coding for the near field and far field of dual wavelengths is realized.In addition,when the far-field function is focusing,the focused spot is close to the diffraction limit,and,when the NA of the lens is very small,the final output focal length is four times of initial input focal length.This work circumvents the strong wavelength-dependent limitation of planar devices and paves the way toward designing multi-wavelength and multi-functional metadevices for scenarios such as AR applications,fluorescence microscopy,and stimulated emission depletion microscopy.展开更多
The chromatic aberration of metasurfaces limits their application. How to cancel or utilize the large chromatic dispersion of metasurfaces becomes an important issue. Here, we design Si-based metasurfaces to realize f...The chromatic aberration of metasurfaces limits their application. How to cancel or utilize the large chromatic dispersion of metasurfaces becomes an important issue. Here, we design Si-based metasurfaces to realize flexible chromatic dispersion manipulation in mid-infrared region. We demonstrate the broadband achromatic metalens and achromatic gradient metasurface to cancel the chromatic aberration over a continuous bandwidth(8–12 μm). In contrast, the metalens and gradient metasurface with enhanced chromatic dispersion have also been realized, where the focal length and deflection angle with different wavelengths vary more significantly than the conventional devices designed with geometric phase. These demonstrations indicate promising potential applications.展开更多
Metasurface is a new kind of 2D metamaterial that is able to manage a variety of light beam modulations through steering the phase of the scattering waves. In this work, we utilize the metasurface to manipulate the li...Metasurface is a new kind of 2D metamaterial that is able to manage a variety of light beam modulations through steering the phase of the scattering waves. In this work, we utilize the metasurface to manipulate the light beam in the mid-infrared regime. By using the metallic rod and the plate structure, the metasurface presents a high polarization conversion efficiency and a wide working bandwidth. With specially rotated metallic rods, the meta- surface can realize various light beam manipulations, such as negative reflection, beam collimation, and focusing. All of these results show that such a metasurface will have potential applications in future mid-infrared optics.展开更多
基金supported by the National Key Research and Development Program of China(No.2017YFA0303700)National Natural Science Foundation of China(Nos.11621091,11822406,11834007,11774164,and 11774162)Fundamental Research Funds for the Central Universities(No.020414380175)。
文摘The metasurface is a platform with a small footprint and abundant functionalities.With propagation phase and geometric phase,polarization multiplexing is possible.However,different response behaviors of propagation phase and geometric phase to wavelength have not been fully employed to widen the capabilities of metasurfaces.Here,we theoretically demonstrate that metasurfaces can achieve near-field and far-field decoupling with the same polarization at two wavelengths.First,we found a set of pillars whose propagation phase difference between two wavelengths covers the full range of 2π.Then,by rotating pillars to control the geometric phase,the phase at both wavelengths can cover the full range of 2π.Finally,by means of interference principle,arbitrary independent coding for the near field and far field of dual wavelengths is realized.In addition,when the far-field function is focusing,the focused spot is close to the diffraction limit,and,when the NA of the lens is very small,the final output focal length is four times of initial input focal length.This work circumvents the strong wavelength-dependent limitation of planar devices and paves the way toward designing multi-wavelength and multi-functional metadevices for scenarios such as AR applications,fluorescence microscopy,and stimulated emission depletion microscopy.
基金supported by the National Key R&D Program of China (Nos. 2017YFA0303700,2017YFA0303702,and 2016YFA0202103)the National Natural Science Foundation of China (Nos. 11822406,11834007,11774162,11674166,11674167,11674168,11621091,11774164,and 91850204)。
文摘The chromatic aberration of metasurfaces limits their application. How to cancel or utilize the large chromatic dispersion of metasurfaces becomes an important issue. Here, we design Si-based metasurfaces to realize flexible chromatic dispersion manipulation in mid-infrared region. We demonstrate the broadband achromatic metalens and achromatic gradient metasurface to cancel the chromatic aberration over a continuous bandwidth(8–12 μm). In contrast, the metalens and gradient metasurface with enhanced chromatic dispersion have also been realized, where the focal length and deflection angle with different wavelengths vary more significantly than the conventional devices designed with geometric phase. These demonstrations indicate promising potential applications.
基金supported by the National "973" Program of China(No.2012CB933501)the Program of "The Invention of the China Academy of Space Technology"
文摘Metasurface is a new kind of 2D metamaterial that is able to manage a variety of light beam modulations through steering the phase of the scattering waves. In this work, we utilize the metasurface to manipulate the light beam in the mid-infrared regime. By using the metallic rod and the plate structure, the metasurface presents a high polarization conversion efficiency and a wide working bandwidth. With specially rotated metallic rods, the meta- surface can realize various light beam manipulations, such as negative reflection, beam collimation, and focusing. All of these results show that such a metasurface will have potential applications in future mid-infrared optics.
