Birefringent dielectric multi-foci metalens for polarization detection

We propose a birefringent dielectric multi-foci metalens for polarization detection utilizing different transmission phases in two orthogonal directions, which consists of Si nanopillars with different sizes and more than 80% transmission efficiency. Implementing the superposition of the phase profiles in the x- and y-direction, the polarization states of the focal points include linear polarization state in the x-direction, linear polarization state in the y-direction, the incident polarization state, and the polarization state whose y-polarization component more shifted by pi/2 compared with the incident polarization state. Based on the intensities of the deflected and converged focal points on the same focal plane, the full polarization information of the incident polarized light can be determined with an analyzer. The multiplexing design method with compact and efficient features renders this technique very attractive for polarization detection and information processing.