Optimizing Airy Needle-like Beams for Long-Range Axial Manipulation and Super-Resolution Imaging

Realizing high-quality needle-like beams is crucial for various advanced applications such as microfabrication, super-resolution imaging, and micromanipulation. Here, we report a reliable method to achieve valuable Airy needle-like beams (ANBs) distinguished by both a large depth of focus and a high aspect ratio. This is accomplished by individually modulating and optimizing the amplitude of each ring of circular Airy beams. The proposed iterative algorithm can efficiently optimize these amplitude-modulation coefficients. In the focusing regions, the resulting ANBs exhibit remarkable properties, including axial flat-top (uniform) intensity distribution, extended depth of focus, high aspect ratio, and smaller focal spots. We further experimentally demonstrated that these characteristics endow ANBs with superior capabilities for multiplane microparticle trapping, axial transportation, and super-resolution imaging, particularly when integrated into optical manipulation systems and scanning confocal microscopy setups. The results suggest a wide range of potential applications of ANBs in optical manipulation, imaging, and laser writing.