In the area of polarization, the impact of flat optics has also been major leading to new compact high performance in line and terminating polarimeters. A powerful generalization of Fourier optics introduced (Matrix Fourier Optics) by Capasso and his team has led them to the demonstration of a new single shot ultracompact polarization sensitive camera consisting of a single metasurface and a sensor, which pixel by pixel reconstruct in real time the full Stokes vector of the scene, exhibiting superior performance to existing cameras based on division of amplitude, time and focal plane (Science 365, 6448 (2019), 150 citations). Capasso has published many seminal breakthrough papers on plasmonic metasurfaces. He demonstrated collimators on the facet of semiconductor laser for beam shaping in the near- and farfield, the earliest successful application of metasurfaces in active devices. He has obtained fundamental new results on the propagation of surface plasmons, such as the polarization controlled directional coupling of surface plasmon polaritons leading him to the first direct evidence of spin momentum locking in optics, and the demonstration of a localized long-range nondiffracting surface wave, the Cosine-Gauss plasmon beam.