Large-area, high-numerical-aperture multi-level diffractive lens via inverse design

Flat lenses enable thinner, lighter, and simpler imaging systems. However, large-area and high-NA flat lenses have been elusive due to computational and fabrication challenges. Here we applied inverse design to create a multi-level diffractive lens (MDL) with thickness < 1.35 mu m, diameter of 4.13 mm, and NA = 0.9 at wavelength of 850 nm (bandwidth similar to 35 nm). Since the MDL is created in polymer, it can be cost-effectively replicated via imprint lithography. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement