Broadband orbital angular momentum beam generation based on polarization-insensitive reflect array

Electromagnetic waves carrying orbital angular momentum (OAM) can be applied in various regions. Much research endeavor has been devoted to developing broadband and polarization-insensitive OAM beams that are preferred in many intriguing applications. This work reports a broadband polarization-insensitive millimeter-wave OAM generator based on high-refractive-index brick-shaped dielectric resonators and studies the relationship between the permittivity of the bricks and OAM beam bandwidth. Based on proper design of the resonators, the broadband, polarization-insensitive, and full phase control can be realized in a broad millimeter-wave band. It is also found that the resonator with higher permittivity leads to a wider OAM beam bandwidth. This structure and conclusion can find a variety of applications in imaging, lithography, and information processing.