Bio-inspired color-polarization imager for real-time in situ imaging

Abstract

Nature has a large repertoire of animals that take advantage of naturally abundant polarization phenomena. Among them, the mantis shrimp possesses one of the most advanced and elegant visual systems nature has developed, capable of high polarization sensitivity and hyperspectral imaging. Here, we demonstrate that by shifting the design paradigm away from the conventional paths adopted in the imaging and vision sensor fields and instead functionally mimicking the visual system of the mantis shrimp, we have developed a single-chip, low-power, high-resolution color-polarization imaging system. Our bio-inspired imager captures co-registered color and polarization information in real time with high resolution by monolithically integrating nanowire polarization filters with vertically stacked photodetectors. These photodetectors capture three different spectral channels per pixel by exploiting wavelength-dependent depth absorption of photons. Our bio-inspired imager comprises 1280 by 720 pixels with a dynamic range of 62 dB and a maximum signal-to-noise ratio of 48 dB. The quantum efficiency is above 30% over the entire visible spectrum, while achieving high polarization extinction ratios of ∼40 on each spectral channel. This technology is enabling underwater imaging studies of marine species, which exploit both color and polarization information, as well as applications in biomedical fields.