A Monolithic CMOS Image Sensor With Wire-Grid Polarizer Filter Mosaic in the Focal Plane

In this paper, we report on an image sensor with an integrated focal-plane 2 × 2 wire-grid polarizer for the visible spectrum, fabricated in a 65-nm standard CMOS technology. This imager enables the reconstruction of the polarization response for each pixel. Finite-difference time-domain method has been used to optimize the extinction ratio (ER) in the visible spectrum of a multilayered focal-plane wire-grid polarizer. Experimental results show that an ER of 16.35 dB is achieved with a standard error of ~ 0.25% between the experimental results and the fitting sinusoidal polarization response curve. Design guidelines for the wire-grid polarizer are derived based on numerical analysis and experimental results. Sensitivity ratio is defined to balance the tradeoff between the intensity sensitivity and polarization sensitivity of the imager.