Biomimetic ZnS Windows Fabricated by Femtosecond Laser Optical Field Modulation Assisted with Wet Etching for High-Performance Infrared Monitoring of EV Charging

Femtosecond laser micromachining, a remarkable technology for fabricating various micro/nanostructures, struggles to balance processing efficiency and quality. Here, a method is proposed that combines femtosecond laser optical field modulation technology with the wet chemical etching process to efficiently fabricate high-quality microhole arrays on zinc sulfide (ZnS). Utilizing Bessel beams and subpulse sequences for fabrication, a machining error of less than 0.3 μm (defocus amount of 1 to 16 μm) and a significant improvement in the aspect ratio are achieved. Inspired by the antireflective properties of stink bug compound eyes, approximately 25 million biomimetic microholes with an aspect ratio of 0.75 are fabricated on the ZnS surface in under 42 min. Biomimetic ZnS demonstrates broadband transmission (average of 81.3% from 8 to 12 μm) and excellent transmittance (83.2% at 9.2 μm). The utilization of the biomimetic window for monitoring an outdoor electric vehicle charging station demonstrates an improvement of 6.7% to 12.4% in target discrimination, detail capture, texture rendering, and edge resolution in the captured infrared images, thereby highlighting the potential application advantages of high-quality biomimetic microholes.