Efficient femtosecond laser fabrication of ultra-large-area Dammann gratings via line-field shaping.

We demonstrate efficient fabrication of ultra-large-area Dammann gratings using femtosecond laser line-field shaping. A cylindrical-lens phase loaded on a spatial light modulator reshapes a Gaussian beam into a high-aspect-ratio line focus, allowing rapid metal mask removal via continuous linear scanning. Compared with point-by-point writing, the efficiency is improved by around 10∧4 times, producing a 2-inch grating. Various splitting configurations (1 × 6, 2 × 2, 3 × 3, star-shaped, parallelogram) are realized with a uniformity of 98.58%. The fabricated gratings further generate structured light arrays (vortex, Airy, azimuthally modulated) as 6 × 6 highly uniform focal spots that preserve helical phase singularities and self-accelerating profiles without observable crosstalk. This approach provides a low-cost, high-throughput route for large-area Dammann gratings and advances parallel optical processing and structured light distribution.