Dispersion-engineered metasurfaces for high-sensitivity color image sensors

• Published in: Optical review (Tokyo, Japan) Vol. 31; no. 3; pp. 290 - 298
• Main Author: Miyata, Masashi
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.06.2024
• Subjects: Atomic; Lasers; Microwaves; Molecular; Optical and Plasma Physics; Optical Devices; Optics; Optics Awards 2022 for excellent papers; Photonics; Physics; Physics and Astronomy; Quantum Optics; RF and Optical Engineering; Special Section: Invited Review Paper; Metalens; Metasurface; Color imaging; Dispersion engineering; Image processing; Image sensor
• ISSN: 1340-6000; 1349-9432
• DOI: 10.1007/s10043-024-00882-8

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.