Abstract:Fabricating precision microgrooves with controllable cross‐sections on difficult‐to‐machine materials is significantly valuable but still challenging. Herein, a patterned laser‐induced microjet‐assisted ablation method for cross‐sectional profiles controllable laser micromachining is proposed. During the liquid‐assisted laser ablation process, debris and bubbles that may disturb the laser energy deposition can be instantaneously expelled by a directional laser‐induced microjet. The Gaussian laser spot is spati… Show more
Hierarchical micro/nanostructures have garnered considerable attention for their capabilities in light modulation, but the flexible fabrication of designed optical functional structures at both micro and nano scales remains challenging. Here, a polarization‐modulated patterned laser ablation method complemented by flowing liquid is proposed to fabricate hierarchical microgrooves featuring tunable cross‐sections and engraved surface nanostructures with controllable periods and orientations. The liquid‐assisted ablation counters the shielding effect of ablation debris through laser‐induced microjets, ensuring accurate control of the microgroove's shape by modulating the laser pattern in the focal plane. Simultaneously, the absence of debris also permits the consistent formation of laser‐induced periodic surface structures (LIPSS) across the microgrooves. The LIPSS's period and orientation can be finely adjusted by manipulating the pulse energy and polarization within the patterned laser spot, facilitating the adaptable creation of hierarchical micro/nanostructures for optical application needs. As a demonstration, blazed gratings featuring orientation‐customized LIPSS are fabricated, which exhibit polarization‐dependent diffraction efficiency. The laser fabrication technique offers a highly versatile solution for sculpturing shape‐controllable hierarchical gratings on hard‐to‐machine materials, paving the way for the swift production of customized optical elements.
Hierarchical micro/nanostructures have garnered considerable attention for their capabilities in light modulation, but the flexible fabrication of designed optical functional structures at both micro and nano scales remains challenging. Here, a polarization‐modulated patterned laser ablation method complemented by flowing liquid is proposed to fabricate hierarchical microgrooves featuring tunable cross‐sections and engraved surface nanostructures with controllable periods and orientations. The liquid‐assisted ablation counters the shielding effect of ablation debris through laser‐induced microjets, ensuring accurate control of the microgroove's shape by modulating the laser pattern in the focal plane. Simultaneously, the absence of debris also permits the consistent formation of laser‐induced periodic surface structures (LIPSS) across the microgrooves. The LIPSS's period and orientation can be finely adjusted by manipulating the pulse energy and polarization within the patterned laser spot, facilitating the adaptable creation of hierarchical micro/nanostructures for optical application needs. As a demonstration, blazed gratings featuring orientation‐customized LIPSS are fabricated, which exhibit polarization‐dependent diffraction efficiency. The laser fabrication technique offers a highly versatile solution for sculpturing shape‐controllable hierarchical gratings on hard‐to‐machine materials, paving the way for the swift production of customized optical elements.
Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various applications. As a versatile approach, ultrafast laser ablation has been widely studied for surface micro/nano structuring. Increasing research efforts in this field have been devoted to gaining more control over the fabrication processes to meet the increasing need for creation of complex structures. In this paper, we focus on the in-situ deposition process following the plasma formation under ultrafast laser ablation. From an overview perspective, we firstly summarize the different roles that plasma plumes, from pulsed laser ablation of solids, play in different laser processing approaches. Then, the distinctive in-situ deposition process within surface micro/nano structuring is highlighted. Our experimental work demonstrated that the in-situ deposition during ultrafast laser surface structuring can be controlled as a localized micro-additive process to pile up secondary ordered structures, through which a unique kind of hierarchical structure with fort-like bodies sitting on top of micro cone arrays were fabricated as a showcase. The revealed laser-matter interaction mechanism can be inspiring for the development of new ultrafast laser fabrication approaches, adding a new dimension and more flexibility in controlling the fabrication of functional surface micro/nano structures.
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