.Orbital angular momentum(OAM)of an optical vortex has attracted great interest from the scientific community due to its significant values in high-capacity optical communications such as mode or wavelength division m....Orbital angular momentum(OAM)of an optical vortex has attracted great interest from the scientific community due to its significant values in high-capacity optical communications such as mode or wavelength division multiplexer/demultiplexer.Although several configurations have been developed to demultiplex an optical vortex,the multiwavelength high-order optical vortex(HOOV)demultiplexer remains elusive due to lack of effective control technologies.In this study,we present the design,fabrication,and test of metasurface optical elements for multiwavelength HOOV demultiplexing based on optical gyrator transformation transformations in the visible light range.Its realization in a metasurface form enables the combined measurement of OAM,the radial index p,and wavelength using a single optical component.Each wavelength channel HOOV can be independently converted to a high-order Hermitian–Gaussian beam mode,and each of the OAM beams is demultiplexed at the converter output.Furthermore,we extend the scheme to realize encoding of the three-digit gray code by controlling the wavelength or polarization state.Experimental results obtained at three wavelengths in the visible band exhibit good agreement with the numerical modeling.With the merits of ultracompact device size,simple optical configuration,and HOOV recognition ability,our approach may provide great potential applications in photonic integrated devices and systems for high-capacity and demultiplex-channel OAM communication.展开更多
In this paper, an ultrathin metalens has been proposed based on a holographic metasurface that consists of elongated apertures in 40 nm gold film, which exhibit intriguing properties such as on-and off-axis focusing a...In this paper, an ultrathin metalens has been proposed based on a holographic metasurface that consists of elongated apertures in 40 nm gold film, which exhibit intriguing properties such as on-and off-axis focusing and also can concentrate light into multiple, discrete spots for circularly polarized incident lights. First, the spatial transmission phase distributions of the designed metalens with arbitrary focusing can be obtained by computergenerated holography. Then, the discrete phase distributions can be continuously encoded by subwavelength nanoapertures with spatially varying orientations in gold film. The simulation results show that our designed metalens can work efficiently for different types of focusing. Finally, our metasurface shows superior broadband characteristics between 670 and 810 nm, and the corresponding focal lengths of the designed lenses also can be efficiently modulated with the incident lights at different wavelengths.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.62175050)Key Laboratory of Micro-systems and Micro-structures Manufacturing(Harbin Institute of Technology),Ministry of Education(Grant No.2019KM007)。
文摘.Orbital angular momentum(OAM)of an optical vortex has attracted great interest from the scientific community due to its significant values in high-capacity optical communications such as mode or wavelength division multiplexer/demultiplexer.Although several configurations have been developed to demultiplex an optical vortex,the multiwavelength high-order optical vortex(HOOV)demultiplexer remains elusive due to lack of effective control technologies.In this study,we present the design,fabrication,and test of metasurface optical elements for multiwavelength HOOV demultiplexing based on optical gyrator transformation transformations in the visible light range.Its realization in a metasurface form enables the combined measurement of OAM,the radial index p,and wavelength using a single optical component.Each wavelength channel HOOV can be independently converted to a high-order Hermitian–Gaussian beam mode,and each of the OAM beams is demultiplexed at the converter output.Furthermore,we extend the scheme to realize encoding of the three-digit gray code by controlling the wavelength or polarization state.Experimental results obtained at three wavelengths in the visible band exhibit good agreement with the numerical modeling.With the merits of ultracompact device size,simple optical configuration,and HOOV recognition ability,our approach may provide great potential applications in photonic integrated devices and systems for high-capacity and demultiplex-channel OAM communication.
基金financial supports for this work from the Fundamental Research Funds for the Central Universities (2015HGCH0010)the Foundation of Hefei University of Technology of China (HFUT. 407-037026)
文摘In this paper, an ultrathin metalens has been proposed based on a holographic metasurface that consists of elongated apertures in 40 nm gold film, which exhibit intriguing properties such as on-and off-axis focusing and also can concentrate light into multiple, discrete spots for circularly polarized incident lights. First, the spatial transmission phase distributions of the designed metalens with arbitrary focusing can be obtained by computergenerated holography. Then, the discrete phase distributions can be continuously encoded by subwavelength nanoapertures with spatially varying orientations in gold film. The simulation results show that our designed metalens can work efficiently for different types of focusing. Finally, our metasurface shows superior broadband characteristics between 670 and 810 nm, and the corresponding focal lengths of the designed lenses also can be efficiently modulated with the incident lights at different wavelengths.
