Generation of multi-freedom controllable helical beam through high-order Bessel beams

In this Letter, we propose a scheme to generate helical optical fields with multi-freedom controllable features. High-quality helical lobes with adjustable radii, chirality, and lobe numbers can be generated by tuning the phase term of two paired highorder Bessel beams. Furthermore, the pitch of the helical beam can be controlled by combining another rotational phase term. The validity of our scheme is demonstrated in both simulations and experiments. Our scheme is promising to facilitate the rapid fabrication of helical structures with diverse parameters, which are critical in various applications, such as optical metamaterials, biology, and particle transport.