Hybrid laser precision engineering of transparent hard materials: challenges, solutions and applications

Abstract

Laser has been demonstrated to be a mature and versatile tool that presents great flexibility and applicability for the precision engineering of a wide range of materials over other established micromachining techniques. Past decades have witnessed its rapid development and extensive applications ranging from scientific researches to industrial manufacturing. Transparent hard materials remain several major technical challenges for conventional laser processing techniques due to their high hardness, great brittleness, and low optical absorption. A variety of hybrid laser processing technologies, such as laser-induced plasma-assisted ablation, laser-induced backside wet etching, and etching assisted laser micromachining, have been developed to overcome these barriers by introducing additional medium assistance or combining different process steps. This article reviews the basic principles and characteristics of these hybrid technologies. How these technologies are used to precisely process transparent hard materials and their recent advancements are introduced. These hybrid technologies show remarkable benefits in terms of efficiency, accuracy, and quality for the fabrication of microstructures and functional devices on the surface of or inside the transparent hard substrates, thus enabling widespread applications in the fields of microelectronics, bio-medicine, photonics, and microfluidics. A summary and outlook of the hybrid laser technologies are also highlighted.

Free‐Form Micro‐Optics Out of Crystals: Femtosecond Laser 3D Sculpturing

“…A femtosecond direct laser writing (DLW) is a flexible highprecision 3D processing technology, [11][12][13][14] with an additive manufacturing capability, for example via two(multi)-photon polymerization. It becomes a powerful tool for fabrication of micro-optical elements, [15] which is currently only suitable for photopolymers (resists and resins).…”

Rapid Fabrication of Smooth Micro-Optical Components on Glass by Etching-Assisted Femtosecond Laser Modification

“…Recently, etching-assisted fs-laser modification has been proposed to fabricate microoptical components on hard materials with high smoothness [32][33][34]. For example, Chen et al successfully fabricated microlens arrays (surface roughness of 56 nm) on silica glass by wet etching-assisted fs-laser modification [35]. However, this method can only fabricate concave microlenses with spherical profiles.…”

Density Regulation and Localization of Cell Clusters by Self-Assembled Femtosecond-Laser-Fabricated Micropillar Arrays

“…Femtosecond laser direct writing has emerged as a new technique for advanced micro- and nano-manufacturing, which can fabricate structures with ultrahigh precision and flexible morphologies , that have various applications. − As an inherently 3D microfabrication technology, ,− femtosecond laser two-photon polymerization (TPP) has distinct advantages and has huge potential for the processing of innovative 3D micro- and nano-structures in biomedicine. With respect to the regulation of cell behavior, various types of biocompatible microstructures have been prepared via TPP microfabrication, such as freestanding proteinaceous spiral structures and polyhedral frameworks, nanogap plasmonic structures in microfluidic chips, 3D nanoporous architectures, nanostructured Brownian surfaces, and submicrometric patterned surfaces .…”

“…Furthermore, the three-dimensional (3D) culture of cell clusters with control of both cluster size and density is hampered by the absence of techniques that allow the fabrication of precise and complex 3D patterned structures with rational topographical and mechanical properties. 10 Femtosecond laser direct writing has emerged as a new technique for advanced micro-and nano-manufacturing, 12 which can fabricate structures with ultrahigh precision 13 and flexible morphologies 14,15 that have various applications. 16−21 As an inherently 3D microfabrication technology, 16,22−26 femtosecond laser two-photon polymerization (TPP) has distinct advantages and has huge potential for the processing of innovative 3D micro-and nano-structures in biomedicine.…”