Customizing Multicolored Orbital Angular Momentum Combs

Current orbital angular momentum (OAM) combs generating technology is hindered by bulky optical systems, limited control, and lack of multicolored information, impeding system integration and practical applications. We present a metasurface approach to realizing multicolored OAM comb engineering along the light propagation direction. The OAM combs are measured based on the intensity of bright spots in the generated intensity patterns that correspond to the weights of the OAM modes. Three OAM combs with different colors are generated at different observation planes. The positioning of transition points along the azimuthal direction is the key to shaping the OAM distribution of the generated beams. OAM combs with customized mode spacings and broad OAM spectra are obtained. Our approach provides a compact platform to realize OAM combs with multidimensional information in the domains of the OAM spectra, frequency, and space, which can significantly enhance the information capacity for potential applications in optical communications.