A new publication from Opto-Electronic Sciences; DOI 10.29026/oea.2024.240082 , discusses high-precision multi-focus laser sculpting of microstructured glass components.

Glass materials are widely used in optical and optoelectronic device due to their low cost and excellent mechanical and optical properties. Among them, glass concave/convex linear structures with feature sizes ranging from several micrometers to hundreds of micrometers find intensive applications. For instances, cylindrical microlens arrays and microgroove arrays with various cross-sections are widely used for light field modulation, microfluidic chip flow channels, and optical module connectors. The inherent hardness, brittleness and low thermal conductivity of glass make it highly challenging to fabricate large-area glass microgrooves, especially those with tunable cross-sectional shapes.

As a non-contact subtractive manufacturing method, ultrafast laser processing plays an important role in the fabrication of glass microstructures. The extremely high peak power density and short pulse duration time help to achieve small thermal impact, few defects and high precision. However, relying solely on single-spot laser direct writing, the processing efficiency and the obtained surface quality are quite difficult to meet the real application requirements. Previous research has proven that the laser processing flexibility can be largely improved if beam shaping can be combined. There is an opportunity to achieve efficient and high-quality engraving of glass microstructures with arbitrary cross-sectional shapes on the glass surface by laser processing with beam shaping. The related research is both academically and industrially valuable.

Recently, the research team of Prof. Xu from Southern University of Science and Technology introduces a novel laser-based micromachining approach: the utilization of high-precision multi-focus laser to efficiently fabricate high-precision customizable glass grooves with a scale from tens to hundreds of micrometers (Fig. 1). This methodology effectively addresses the challenges of cross-sectional profile controllability and accuracy associated with glass groove fabrication. Specifically, the modulating algorithm developed as part of this approach corrects position deviations of multi-focus laser stemming from the glass’s refractive index and nonparaxial conditions. Additionally, it ameliorates the degradation in multi-focus energy uniformity caused by circular Moiré patterns on the phase diagram. This is achieved through a combination of coordinate randomization and energy adjustment strategies. (Fig. 2)

The outcome of our methodology is a precise multi-focus laser that seamlessly aligns with the designed groove profile. This alignment significantly expedites the production of glass grooves, a process further enhanced by subsequent chemical etching. The developed technique accommodates a wide range of groove geometries, including trapezoidal, high-aspect-ratio triangle, and semicircle grooves. Furthermore, the researchers have explored practical applications of these glass grooves, such as trapezoidal groove arrays ideal for optical fiber packaging (Fig. 3).

The significance of the research lies in its elucidation of the untapped potential and versatility inherent in laser structured glass for advanced applications. The work not only contributes to the advancement of optical and optoelectronic technologies but also paves the way for innovations in various industries reliant on structured glass-based systems.

Keywords: ultrafast laser processing / multi-focus shaping beam / micro-groove / glass

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Dr. Xu is a tenured associate professor at Department of Mechanical and Energy Engineering of Southern University of Science and Technology (Sustech). He got his PhD degree at Tohoku University in Japan, and continued to work as a JSPS research fellow and an assistant professor in the Nano-Precision Mechanical Fabrication Lab. of Tohoku University successively. He had successfully obtained JSPS (Japan Society for the Promotion of Science) Grants-in-Aid for Scientific Research (KAKENHI) twice in the area of ultraprecision micro-/nanofabrication technologies in Japan. In early 2017, Dr. Xu returned to China and joined in Department of Mechanical and Energy Engineering of Sustech. From then on, Dr. Xu began to establish an ultrafast laser micro-/nanofabrication Lab, focusing on developing new ultrafast laser micro-/nanofabrication technologies, the principles of interactions between ultrafast laser and materials, and the applications of laser-structured surfaces. Dr. Xu’s research projects in China have been funded by national and local funding agencies since 2017. In brief, 13 external competitive grants with a total funding amount exceeding 15 million RMB have been granted to him and his team members. Until now, Dr. Xu has published more than 40 peer-reviewed papers in journals such as Nature Communications, Optica, Laser & Photonics Reviews, Nano Letters, International Journal of Machine Tools and Manufacture, International Journal of Extreme Manufacturing, Advanced Functional Materials.
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Xu K, Huang PL, Huang LY et al. High-precision multi-focus laser sculpting of microstructured glass. Opto-Electron Adv 7, 240082 (2024). doi: 10.29026/oea.2024.240082