LAUSR

Owing to its good air-stability and high refractive index, two-dimensional (2D) noble-metal dichalcogenide shows intriguing potentials for versatile flat optics applications. However, light field manipulation at the atomic scale is conventionally considered unattainable since the small thickness and intrinsic losses of 2D materials completely suppress both resonances and phase accumulation effects. Here we demonstrate that losses of structured atomic-thick PtSe2 films integrated on top of a uniform substrate can be utilized to create the spots of critical coupling, enabling singular phase behaviors with a remarkable π phase jump. This finding enables for the experimental demonstration of atomic-thick binary meta-optics that allows an angle-robust and high unit-thickness diffraction efficiency of 0.96%/nm in visible frequencies (given its thickness of merely 4.3 nm). Our results unlocks the potential of a new class of 2D flat optics for light field manipulation at an atomic thickness.