Measuring phase and polarization singularities of light using spin-multiplexing metasurfaces

In recent years, light beams containing phase or polarization singularities, such as optical vortices (OVs) and cylindrical vector beams (CVBs), have contributed to significant applications including optical orbital angular momentum (OAM) communications, particle trapping and manipulation, and super-resolved imaging. However, traditional methods for detecting the phase and polarization singularities of light suffer from drawbacks, such as large device size, complicated optics, and limits in detection function. Here, we propose an alternative method for detecting simultaneously phase and polarization singularities based on a spin-multiplexing metasurface. Both numerical and experimental results demonstrate that the metasurface device can be used to measure accurately the topological charge of OVs and the polarization order of CVBs individually or simultaneously, and exhibit beneficial attributes such as a broadband response, compactness, and system simplification. This method offers great potential in applications such as singular optical beam shaping and high-capacity OAM/CVB multiplexing communication.