A polarization sensor is described. It includes a quarter-wave plate to convert circularly polarized light into linearly polarized light. The quarter-wave plate is realized as a metasurface. The sensor also includes a linear polarizer to analyze the light generated by the quarter-wave plate, and a photodetector to receive the analyzed light. The sensor may be combined with other linear polarization sensors to form a sensor capable of complete measurement of the polarization state of incident light. An array of these sensors can be integrated directly onto image sensors to form a polarimetric imager.