A polarization-insensitive infrared broadband achromatic metalens consisting of all-silicon anisotropic microstructures

Infrared lenses have a wide range of applications in thermal imaging and detection. Here, by designing a single layer metasurface consisting of anisotropic microstructures, we experimentally demonstrate a polarization-insensitive long-wavelength infrared achromatic metalens. The focal lengths of the fabricated metalens with a numerical aperture of 0.33 remain unchanged and maintain diffraction-limited performance for the incident wavelength varying from 8.5 to 11.5 μm, demonstrating the elimination of chromatic aberration with 30% operation bandwidth. We envision this metalens may pave the way to the development of ultracompact achromatic thermal imaging systems.