Enhancing Photon Throughput of Miniaturized Passive Depth-Detection Cameras via Broadband Dispersion-Engineered Metalenses

With the continuous advancement of technology, there is a growing demand for depth-detection cameras with a small footprint and high photon throughput. Metalenses offer an excellent platform for implementing single-lens depth-detection cameras. However, the narrow operational bandwidth of the metalenses used in these miniaturized cameras significantly limits the photon throughput. Here, we propose a broadband dispersionless double-helix metalens (DL-DH metalens) to enhance the photon throughput and mitigate motion blur in miniaturized passive depth-detection cameras. Through engineering the dispersion, the DL-DH metalens was designed to achieve an irrotational double-helix point spread function (DH-PSF) over the broadband wavelength, thus eliminating the depth-detection error caused by chromatic aberration. The operational bandwidth of the fabricated metalens was expanded to 200 nm for obtaining higher-photon throughput, resulting in a 10-fold reduction in the exposure time compared with that observed for a narrow operational bandwidth of 30 nm. The sharp images could be captured by the DL-DH metalens to acquire accurate depth information, even in the presence of moving objects. Our proposed metalens provides a solution for enhancing the photon throughput in miniaturized passive depth-detection cameras operated in low-light environments.