Polarization is one of the important characteristics of visible light that can not be detected by human visual system or traditional image sensors. In this paper, we report on an image sensor integrated focal plane 2 × 2 wire-grid polarizer filter mosaic targeted at visible spectrum fabricated in 65nm standard CMOS processing line, which enables the reconstruction of the polarization response characteristic for each pixel. Finite-Difference Time-Domain method has been used for the first time to optimize the extinction ratio in visible spectrum of the multilayer focal plane wire-grid polarizer. Experimental results show that an extinction ratio around 10 is achieved with a standard error of around 0.25% between the experimental results and the fitting sinusoidal polarization response curve. A phase error at the level of less than 2% to the measurement phase resolution is achieved. These results are the best reported for a monolithic wire-grid polarization image sensor design for visible spectrum.