Super-resolution direct laser writing via multiphoton and peripheral photoinhibition photolithography

Direct laser writing (DLW) with high resolution is highly desirable for fabricating arbitrary two-dimensional/three-dimensional (2D/3D) micro-/nanostructures with fine feature size for various applications. In this work, by a quasi-single-color (532 nm) dual-beam optical setup, a 100-nm lateral resolution has been achieved by both multiphoton DLW and PPI-DLW (DLW with peripheral photoinhibition), using a photoresist with a depletable photoinitiator and a radical quencher. A 120-nm lateral resolution can also be obtained even at a fast writing speed of 1000 µm/s. Typical 3D woodpiles with lateral rod spacing ranging from a = 300 nm to a = 225 nm have been printed, and the minimum axial period (318.15 nm) is below the respective diffraction-limited axial resolution (320 nm). The obtained resolution by our method surpasses that in most previous research works, indicating that our printing approach is a promising and feasible technique to achieve high-resolution 3D DLW for broad applications.