Sub-diffraction-limit light field shaping through edge-singularity engineering

We propose and experimentally demonstrate a technique for shaping the light field in the sub-diffraction regime. Our technique relies on carefully engineering a phase singularity that is distributed continuously along a transverse curve. We develop a polynomial function to effectively describe this singularity curve, which results in an arbitrary light pattern with a feature size considerably down to the deep sub-diffraction limit. We experimentally verify the theoretical framework by demonstrating different cases of edge-singularity engineering for shaping the Gaussian envelope into desired morphologies. Our demonstrations open a novel, to the best of our knowledge, pathway to shaping the light field at the sub-diffraction-limit regime, which can find potential applications in various fields including the super-resolution imaging and precision detection.