Long-Wavelength Infrared Edge-Enhanced Imaging with a Single-Layer Silicon Vortex Metalens

Long-wavelength infrared (LWIR) imaging systems usually suffer from bulkiness, high cost, and image edge blurring. To address these challenges, we propose a single-layer metalens with LWIR edge enhancement. It is fabricated with an all-silicon wafer with the lithography process. This silicon metalens works at 10.6 μm central wavelength and is polarization-insensitive, with a 9 mm diameter and a 0.45 numerical aperture. Simulation shows that the peak-to-peak (PTP) distance is about 20 μm. The sidelobe ratio (SR) is −20 dB. Experimental measured the PTP value reaches about 24 μm, and the imaging edge contrast exceeds 7.6 dB, showing an excellent edge enhancement. The minimum resolvable feature size is about 0.4 mm. These results demonstrate an effective enhancement of LWIR images. Moreover, it is a front-end all-optical preprocessing way, could inspire a series of lightweight, low-cost, intelligent LWIR imaging solutions.