Flexible Manipulated Interference Lithography Incorporating Modulated Optical Fourier Transform System

Abstract

Spatial‐variant micro/nano‐structures are widely utilized in metasurfaces to modulate optical wave‐fronts into arbitrary shapes, performing as a new generation of flat optics. To flexibly fabricate micro/nano‐structures in real time, an optical Fourier transform system modulated by a diaphragm and a binary optical element (BOE) is proposed. Theoretical analysis shows that light field at image plane is a multiple result of twice Fourier transform of diaphragm and BOE's transmission field, with its amplitude and phase distribution independently manipulated by diaphragm and BOE. Inversely, diaphragm and BOE can be designed to get customized interference fields, where four fields with different vectors are generated for instance. Utilizing these four fields for time division multiplexing exposure, fringes inside circle/ring shapes with variant orientations are produced in photoresist film. Furthermore, multiple spatial variant fields can be obtained simultaneously while more symmetric distributed apertures acted as diaphragm, which shows great potential for the fabrication of segmented or interleaved spatial‐variant micro/nano‐structures in addition.