Chiral Lithography with Vortex Non-diffracted Laser for Orbital Angular Momentum Detection

Chiroptical response, demonstrating chiral interaction between optical vortex and chiral structure, plays an important role in variety of fields like optics and material science. However, the flexibility and efficiency of chiral structure fabrication are limited due to mask requirement and a point-by-point constructing strategy. In this paper, a novel chiral lithography method is proposed that utilizes optical vortex phase beam shaping to achieve chiral structure processing with high efficiency and flexibility. By programming topological charges of the vortex phase, chiral structures with adjustable appearance, rotation, and chirality can be produced using femtosecond laser single pulse exposure. Transmittance measurements of fabricated chiral structures array confirm a 66% helical dichroism that is predicted by simulation. Moreover, with the aid of convolutional neural networks (CNN), an accuracy of 98% in Orbital Angular Momentum (OAM) recognition can be achieved. This chiral lithography method provides an alternative for chiral structure fabrication and holds promise in the development of chiral optics, optical communications, and next-generation optical devices.