Improvement of on-pixel polarizer with 0.35 μm CMOS process for electro-optic imaging systems

In this paper, we propose an improved on-pixel polarizer structure for an image sensor, which was fabricated using the 0.35 μ m standard CMOS process with dual metal layers (Metal 1 and Metal 2), i.e. two layers of gratings with metal-wiring layers were stacked. By designing the line/space ratio as 0.7/0.7 μ m, the extinction ratio was significantly improved at a wavelength of 780 nm, which was over 1.4 times higher than that of a single-layer grating, and the detection sensitivity of the polarization change was enhanced by more than 1.8 times. We also demonstrated electro-optical imaging at radio frequency using this image sensor.