Increasing the sensitivity of image sensors is a major challenge for current imaging technology. Researchers are tackling it because highly sensitive sensors enable objects to be recognized even in dark environments, which is critical for today’s smartphones, wearable devices, and automobiles. Unfortunately, conventional image-sensor architectures use light-absorptive color filters on every pixel, which fundamentally limits the detected light power per pixel. Recent advances in optical metasurfaces have led to the creation of pixelated light-transmissive color splitters with the potential to enhance sensor sensitivity. These metasurfaces can be used instead of color filters to distinguish primary colors, and unlike color filters, they can direct almost all of the incident light to the photodetectors, thereby maximizing the detectable light power. This review focuses on such metasurface-based color splitters enabling high-sensitivity color-image sensors. Their underlying principles are introduced with a focus on dispersion engineering. Then, their capabilities as optical elements are assessed on the basis of our recent findings. Finally, it is discussed how they can be used to create high-sensitivity color-image sensors.

提高图像传感器的灵敏度是当前成像技术的主要挑战。研究人员正在解决这个问题，因为高灵敏度的传感器即使在黑暗环境中也能识别物体，这对于当今的智能手机、可穿戴设备和汽车至关重要。不幸的是，传统的图像传感器架构在每个像素上都使用光吸收滤色镜，这从根本上限制了每个像素检测到的光功率。光学超表面的最新进展催生了像素化透光分色器，具有增强传感器灵敏度的潜力。这些超表面可以代替滤色镜来区分原色，并且与滤色镜不同的是，它们可以将几乎所有的入射光引导到光电探测器，从而最大化可检测的光功率。本综述重点关注这种基于超表面的分色器，可实现高灵敏度彩色图像传感器。介绍了它们的基本原理，重点是分散工程。然后，根据我们最近的发现评估它们作为光学元件的能力。最后，讨论了如何使用它们来创建高灵敏度彩色图像传感器。