Direct-write microsphere photolithography of hierarchical infrared metasurfaces

• DOI: 10.1364/ao.427705
• Publication Date: 2021-07-09T13:30:18Z
• Authors: Chen Zhu; Chuang Qu; Edward C. Kinzel
• Keywords: 0103 physical sciences; 01 natural sciences

A direct-write configuration of microsphere photolithography (MPL) is investigated for the patterning of IR metasurfaces at large scales. MPL uses a self-assembled hexagonal close-packed array of microspheres as an optical element to generate photonic nanojets within a photoresist layer. The photonic jets can be positioned within the microsphere-defined unit cells by controlling the illumination’s angle of incidence (AOI). This allows the definition of complex antenna elements. A digital micromirror device is used to provide spatial modulation across the microsphere arrays and coordinated with a set of stages providing AOI control. This provides hierarchical patterning at the sub- and super-unit cell levels and is suitable for a range of metasurfaces. The constraints of this approach are analyzed and demonstrated with a polarization-dependent infrared perfect absorber/emitter, which agrees well with modeling.