Achromatic varifocal metalens enabled by polarization-dependent superposition

Traditional varifocal metalenses are limited by their bulky dimensions and tuning complexity, suffering from inherent chromatic aberration that significantly reduces broadband applicability. In this Letter, a single-layer achromatic metalens with polarization-dependent focal length is proposed. An achromatic focusing over a range of 10-11.5 μm is achieved by interference of multi-atomic units with stable intensity superimposition. The focal length could be tuned from 0.93 to 1.05 mm with a low coefficient variation of <1.75% by simply adjusting the polarization of incident light. Our work opens new possibilities for portable imaging devices in the future.