Hybrid periodic microstructures fabricated on chromium films by SLM-assisted nanosecond laser processing

• Published in: Optics and lasers in engineering Vol. 178; p. 108216
• Main Authors: Zhou, Yuhao, Li, Ruihao, Liu, Shiting, Jiang, Shaoji, Huang, Min
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2024
• Subjects: Anisotropic structural colors; Dual-scale periodic structures; Grating diffraction; Laser-induced periodic surface structures; Spatial light modulator; Grating diffraction; Anisotropic structural colors; Laser-induced periodic surface structures; Spatial light modulator; Dual-scale periodic structures
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2024.108216

•A SLM-assisted ns-laser processing technique is proposed for fabricating large-area, uniform, and well-arranged periodic structures on Cr films.•2. For 1000-nm thick Cr films, the processed surface exhibits hybrid periodic microstructures comprised by modulated grating (MG) and laser induced periodic surface structures (LIPSS), that is, MG-LIPSS, which displays vivid anisotropic structural colors.•3. For 200-nm thick Cr films, the processed hybrid structures are a combination of MG and cracks, that is, MGC, which can be utilized as a transmission grating with diffraction effects. An effective technique for preparing different hybrid periodic structures on chromium (Cr) films of different thicknesses using a 1064-nm nanosecond laser assisted by spatial light modulator (SLM) is proposed. For 1000-nm Cr films, by combining periodic modulated grating (MG) patterned by SLM with laser-induced periodic surface structures (LIPSS), regular dual-scale MG-LIPSS can be fabricated, with the morphological characteristics controlled by laser fluence, effective pulse number, and MG period. Due to diffraction effects of MG and LIPSS, MG-LIPSS patterned surfaces exhibit vivid anisotropic structural colors. In contract to MG-LIPSS, complex periodic structures consisting of MG and cracks (MGC) are fabricated on 200-nm Cr films due to the more significant thermal stress of a thinner film. Although the cracks of MGC distributed randomly, MGC show a long-range order characteristic with a certain transmittance, which can be utilized as a transmission grating with diffraction effects. These results demonstrate that optical field modulated laser machining based on SLM offers an efficient, cost-effective, and controllable method for fabricating large-area periodic structures on Cr films. Moreover, variations in film thickness can be employed to explore hybrid microstructures with specific properties, and thus utilized in diverse applications, such as optical components and anti-counterfeiting measures.