Fully continuous spiral phase plate for ultraintense optical vortices
Yuanhang Zhang, Shenglin Wen, Shengfei Wang, Jian Zhang, Caixue Tang, Haoyi Zuo, Fuhua Gao, Fei Fan, Qinghua Zhang, Qiao Xu
Abstract
Ultraintense optical vortices carrying orbital angular momentum have attracted much attention in strong-field laser physics due to their spiral phase and hollow intensity. This Letter introduces a fully continuous spiral phase plate (FC-SPP) that enables the generation of an ultraintense Laguerre–Gaussian beam. An optimization design method based on the spatial filter technique and chirp-z transform is proposed to match the polishing processing and the tightly focusing performance. To enable its use in high-power laser systems, a large-aperture (200 × 200 mm 2 ) FC-SPP has been fabricated on a fused silica substrate through magnetorheological finishing without the use of mask techniques. The far-field phase pattern and intensity distribution based on vector diffraction calculation were compared with those of ideal spiral phase plate and fabricated FC-SPP, which confirmed the high quality of the output vortex beams and their feasibility for producing high-intensity vortices.