On-chip integration of achromatic metalens arrays
Yao Zhang, Xiong Jiang, Geyang Qu, Jing Han, Chen Li, Baichuan Bo, Qifeng Ruan, Zhengtong Liu, Qinghai Song, Shumin Xiao
Abstract
Broadband achromatic metalenses and metalens arrays hold promise for enabling high-performance optical imaging in a compact form factor. Conventional visible-light achromatic metalenses are composed of transparent and high-refractive-index TiO2 or GaN nanopillars, but are strongly limited in mainstream silicon-based complementary metal-oxide-semiconductor (CMOS) processes. Herein, we report the realization of high-efficiency Si3N4 achromatic metalenses in the visible range and demonstrate their integration onto a commercial imaging chip. By improving nanofabrication techniques, we have dramatically increased the aspect ratio of Si3N4 nanostructures from ~17 to a high value of 43.33. Consequently, the group delay of the Si3N4 nanostructures is significantly increased and the averaged focusing efficiency of a Si3N4 metalens with a numerical aperture of 0.155 reaches 80.39%. Owing to the CMOS-compatibility of Si3N4, such high-quality metalenses have been integrated with commercial imaging sensors and demonstrated the capability of full-color optical imaging. This research paves a critical step towards chip-integrated meta-devices. Broadband achromatic metalenses hold promise for enabling high-performance optical imaging in a compact form factor. Here, the authors report the realization of high-efficiency Si3N4 achromatic metalenses in the visible range and demonstrate their integration onto a commercial imaging chip.