A simulation study of grayscale ice lithography for spiral phase plates in near infrared wavelengths

Grayscale electron beam lithography (EBL) in amorphous solid water (ASW), known as ice lithography (IL), and in Polymethylmethacrylate (PMMA), respectively, for spiral phase plates (SPPs) are numerically simulated by using commercial software: Beamer, Tracer and Lab, aiming at characterizing the two lithography methods for three-dimensional nanostructures. It is found that IL is able to generate 3D SPP profiles with smoother surface than conventional EBL. Further simulation using finite difference time domain (FDTD) method is also conducted to investigate the effect of the surface roughness on the wavefront characteristics of the transformed vortex beams. Clear influence on the light regulation ability by surface roughness is found through comparison between ASW-based and PMMA-based SPPs, indicating that IL has better performance than conventional EBL in patterning 3D SPP structures. This research indicates that IL should be prospective for manufacturing high-quality micro and nanostructures with 3D profiles for modern optical devices. [Display omitted] •Characterize the difference in the roughness of spiral phase plates (SPPs) between ice lithography (IL) and conventional electron beam lithography (EBL) using simulation method.•Finite difference time domain (FDTD) method is conducted to investigate the comparison between ASW-based and PMMA-based SPPs on the wavefront characteristics, indicating that IL is better than conventional EBL in patterning 3D SPP structures.