Progress in Bioinspired Photodetectors Design for Visual Information Processing

Rapid development of modern science and technology has prompted explosive growth of data volumes, especially the visual information, which brings heavy pressure on information processing and computation. The classic technical route to improve the computation power of image processing units by reducing the critical dimension of the transistors according to Moore's law gradually fails due to the physical limit of transistors' footprint and the separated architectures. Inspired by human vision systems, retina-like photodetectors that mimic their spatial and temporal properties have attracted widespread attention. These developed architectures enable the early data processing in- or near-sensor, significantly reducing the computing power required in the back end. Herein, a comprehensive review on bioinspired photodetectors that possess the spatial and temporal properties of biological vision is provided. The properties of retina are summarized and presented first. Basic structure design and operation mechanism of those photodetectors with spatial properties of retina (including the distribution of receptive fields and the shape of the hemisphere) and temporal properties of retina (including the memory properties enabled learning and the light intensity adaptation) are reviewed thoroughly. Eventually, challenges and future perspectives are commented and provided to facilitate the rapid development of in- or near-sensor computing photodetectors.