Programmable twist-pitch engineering of helical magnetization needles

Quantitative control of the twist pitch of helical magnetization remains a fundamental challenge for three-dimensional all-optical magnetic manipulation. Although inverse-Faraday-effect-induced magnetization needles have been demonstrated previously, deterministic twist-pitch engineering and direct quantitative characterization remain unavailable. Here, we establish a quantitative methodology that enables deterministic twist-pitch engineering and direct retrieval of helical orientation through the complex angular moment. Uniform helical rotation is achieved while preserving longitudinal confinement, and prescribed twist pitches from 3λ to 6λ are reproduced with relative deviations below 0.2%. This work establishes a direct link between optical-field design, helical magnetization generation, and quantitative characterization, providing a practical route toward programmable spin-texture engineering and all-optical magnetization manipulation.